Split decoder and render

decode.* will solely decode the teletext packets into a grid of characters and colours and other attributes stored in an agnostic way, then render.* will read this grid and render the characters onto the screen with the Qt specific methods.
2022-04-02 22:38:38 +01:00
parent 74ebc91ee6
commit e16bb15310
8 changed files with 1786 additions and 1267 deletions
--- a/decode.cpp
+++ b/decode.cpp
@@ -0,0 +1,992 @@
+/*
+ * Copyright (C) 2020-2022 Gavin MacGregor
+ *
+ * This file is part of QTeletextMaker.
+ *
+ * QTeletextMaker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * QTeletextMaker is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with QTeletextMaker.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <QMultiMap>
+//#include <QTime>
+#include <QPair>
+#include <algorithm>
+#include <vector>
+
+#include "decode.h"
+
+TeletextPageDecode::TeletextPageDecode()
+{
+	m_renderLevel = 0;
+
+	for (int r=0; r<25; r++)
+		for (int c=0; c<72; c++)
+			m_refresh[r][c] = false;
+
+	m_finalFullScreenColour = 0;
+	m_finalFullScreenQColor.setRgb(0, 0, 0);
+	for (int r=0; r<25; r++) {
+		m_fullRowColour[r] = 0;
+		m_fullRowQColor[r].setRgb(0, 0, 0);
+	}
+	m_leftSidePanelColumns = m_rightSidePanelColumns = 0;
+	m_textLayer.push_back(&m_level1Layer);
+	m_textLayer.push_back(new EnhanceLayer);
+}
+
+TeletextPageDecode::~TeletextPageDecode()
+{
+	while (m_textLayer.size()>1) {
+		delete m_textLayer.back();
+		m_textLayer.pop_back();
+	}
+}
+
+void TeletextPageDecode::setRefresh(int r, int c, bool refresh)
+{
+	m_refresh[r][c] = refresh;
+}
+
+void TeletextPageDecode::setTeletextPage(LevelOnePage *newCurrentPage)
+{
+	m_levelOnePage = newCurrentPage;
+	m_level1Layer.setTeletextPage(newCurrentPage);
+	updateSidePanels();
+}
+
+void TeletextPageDecode::setRenderLevel(int newRenderLevel)
+{
+	if (newRenderLevel == m_renderLevel)
+		return;
+	m_renderLevel = newRenderLevel;
+	decodePage();
+}
+
+void TeletextPageDecode::updateSidePanels()
+{
+	int oldLeftSidePanelColumns = m_leftSidePanelColumns;
+	int oldRightSidePanelColumns = m_rightSidePanelColumns;
+
+	if (m_renderLevel >= (3-m_levelOnePage->sidePanelStatusL25()) && m_levelOnePage->leftSidePanelDisplayed())
+		m_leftSidePanelColumns = (m_levelOnePage->sidePanelColumns() == 0) ? 16 : m_levelOnePage->sidePanelColumns();
+	else
+		m_leftSidePanelColumns = 0;
+
+	if (m_renderLevel >= (3-m_levelOnePage->sidePanelStatusL25()) && m_levelOnePage->rightSidePanelDisplayed())
+		m_rightSidePanelColumns = 16-m_levelOnePage->sidePanelColumns();
+	else
+		m_rightSidePanelColumns = 0;
+
+	if (m_leftSidePanelColumns != oldLeftSidePanelColumns || m_rightSidePanelColumns != oldRightSidePanelColumns) {
+		emit sidePanelsChanged();
+		decodePage();
+	}
+}
+
+void TeletextPageDecode::buildEnhanceMap(TextLayer *enhanceLayer, int tripletNumber)
+{
+	bool terminatorFound=false;
+	ActivePosition activePosition;
+	const X26Triplet *x26Triplet;
+	int originModifierR=0;
+	int originModifierC=0;
+
+	do {
+		x26Triplet = &m_levelOnePage->enhancements()->at(tripletNumber);
+		if (x26Triplet->isRowTriplet())
+			// Row address group
+			switch (x26Triplet->mode()) {
+				case 0x00: // Full screen colour
+					if (m_renderLevel >= 2 && ((x26Triplet->data() & 0x60) == 0x00) && !activePosition.isDeployed())
+						enhanceLayer->setFullScreenColour(x26Triplet->data());
+					break;
+				case 0x01: // Full row colour
+					if (m_renderLevel >= 2 && activePosition.setRow(x26Triplet->addressRow()) && ((x26Triplet->data() & 0x60) == 0x00 || (x26Triplet->data() & 0x60) == 0x60))
+						enhanceLayer->setFullRowColour(activePosition.row(), x26Triplet->data() & 0x1f, (x26Triplet->data() & 0x60) == 0x60);
+					break;
+				case 0x04: // Set active position
+					if (activePosition.setRow(x26Triplet->addressRow()) && m_renderLevel >= 2 && x26Triplet->data() < 40)
+						activePosition.setColumn(x26Triplet->data());
+					break;
+				case 0x07: // Address row 0
+					if (x26Triplet->address() == 0x3f && !activePosition.isDeployed()) {
+						activePosition.setRow(0);
+						activePosition.setColumn(8);
+						if (m_renderLevel >= 2 && ((x26Triplet->data() & 0x60) == 0x00 || (x26Triplet->data() & 0x60) == 0x60))
+							enhanceLayer->setFullRowColour(0, x26Triplet->data() & 0x1f, (x26Triplet->data() & 0x60) == 0x60);
+					}
+					break;
+				case 0x10: // Origin modifier
+					if (m_renderLevel >= 2 && (tripletNumber+1) < m_levelOnePage->enhancements()->size() && m_levelOnePage->enhancements()->at(tripletNumber+1).mode() >= 0x11 && m_levelOnePage->enhancements()->at(tripletNumber+1).mode() <= 0x13 && x26Triplet->address() >= 40 && x26Triplet->data() < 72) {
+						originModifierR = x26Triplet->address()-40;
+						originModifierC = x26Triplet->data();
+					}
+					break;
+				case 0x11 ... 0x13: // Invoke Object
+					if (m_renderLevel >= 2) {
+						if ((x26Triplet->address() & 0x18) == 0x08) {
+							// Local Object
+							// Check if the pointer in the Invocation triplet is valid
+							// Can't point to triplets 13-15; only triplets 0-12 per packet
+							if ((x26Triplet->data() & 0x0f) > 12)
+								break;
+							int tripletPointer = ((x26Triplet->data() >> 4) | ((x26Triplet->address() & 1) << 3)) * 13 + (x26Triplet->data() & 0x0f);
+							// Can't point to triplet beyond the end of the Local Enhancement Data
+							if ((tripletPointer+1) >= m_levelOnePage->enhancements()->size())
+								break;
+							// Check if we're pointing to an actual Object Definition of the same type
+							if ((x26Triplet->mode() | 0x04) != m_levelOnePage->enhancements()->at(tripletPointer).mode())
+								break;
+							// The Object Definition can't declare it's at triplet 13-15; only triplets 0-12 per packet
+							if ((m_levelOnePage->enhancements()->at(tripletPointer).data() & 0x0f) > 12)
+								break;
+							// Check if the Object Definition triplet is where it declares it is
+							if ((((m_levelOnePage->enhancements()->at(tripletPointer).data() >> 4) | ((m_levelOnePage->enhancements()->at(tripletPointer).address() & 1) << 3)) * 13 + (m_levelOnePage->enhancements()->at(tripletPointer).data() & 0x0f)) != tripletPointer)
+								break;
+							// Check if (sub)Object type can be invoked by Object type we're within
+							if (enhanceLayer->objectType() >= (x26Triplet->mode() & 0x03))
+								break;
+							// Is the object required at the current presentation Level?
+							if (m_renderLevel == 2 && (m_levelOnePage->enhancements()->at(tripletPointer).address() & 0x08) == 0x00)
+								break;
+							if (m_renderLevel == 3 && (m_levelOnePage->enhancements()->at(tripletPointer).address() & 0x10) == 0x00)
+								break;
+							EnhanceLayer *newLayer = new EnhanceLayer;
+							m_textLayer.push_back(newLayer);
+							newLayer->setObjectType(x26Triplet->mode() & 0x03);
+							newLayer->setOrigin(enhanceLayer->originR() + activePosition.row() + originModifierR, enhanceLayer->originC() + activePosition.column() + originModifierC);
+							buildEnhanceMap(newLayer, tripletPointer+1);
+						} else
+							qDebug("POP or GPOP");
+						originModifierR = originModifierC = 0;
+					}
+					break;
+				case 0x15 ... 0x17: // Define Object, also used as terminator
+					terminatorFound = true;
+					break;
+				case 0x1f: // Terminator
+					if (x26Triplet->address() == 63)
+						terminatorFound = true;
+					break;
+			}
+		else {
+			// Column address group
+			bool columnTripletActioned = true;
+			switch (x26Triplet->mode()) {
+				// First we deal with column triplets that are also valid at Level 1.5
+				case 0x0b: // G3 mosaic character at Level 2.5
+					if (m_renderLevel <= 1)
+						break;
+					// fall-through
+				case 0x02: // G3 mosaic character at Level 1.5
+				case 0x0f: // G2 character
+				case 0x10 ... 0x1f: // Diacritical mark
+					if (activePosition.setColumn(x26Triplet->addressColumn()) && x26Triplet->data() >= 0x20)
+						enhanceLayer->enhanceMap.insert(qMakePair(activePosition.row(), activePosition.column()), qMakePair(x26Triplet->mode() | 0x20, x26Triplet->data()));
+					break;
+				// Make sure that PDC and reserved triplets don't affect the Active Position
+				case 0x04 ... 0x06: // 0x04 and 0x05 are reserved, 0x06 for PDC
+				case 0x0a: // Reserved
+					break;
+				default:
+					columnTripletActioned = false;
+			}
+			// All remaining possible column triplets at Level 2.5 affect the Active Position
+			if (m_renderLevel >= 2 && !columnTripletActioned && activePosition.setColumn(x26Triplet->addressColumn()))
+				enhanceLayer->enhanceMap.insert(qMakePair(activePosition.row(), activePosition.column()), qMakePair(x26Triplet->mode() | 0x20, x26Triplet->data()));
+		}
+		tripletNumber++;
+	} while (!terminatorFound && tripletNumber < m_levelOnePage->enhancements()->size());
+}
+
+void TeletextPageDecode::decodePage()
+{
+	int currentFullRowColour, downwardsFullRowColour;
+	int renderedFullScreenColour;
+	struct {
+		bool operator() (TextLayer *i, TextLayer *j) { return (i->objectType() < j->objectType()); }
+	} compareLayer;
+
+//	QTime renderPageTime;
+
+//	renderPageTime.start();
+
+	updateSidePanels();
+
+	while (m_textLayer.size()>2) {
+		delete m_textLayer.back();
+		m_textLayer.pop_back();
+	}
+
+	renderedFullScreenColour = (m_renderLevel >= 2) ? m_levelOnePage->defaultScreenColour() : 0;
+	downwardsFullRowColour = (m_renderLevel >= 2) ? m_levelOnePage->defaultRowColour() : 0;
+	setFullScreenColour(renderedFullScreenColour);
+	for (int r=0; r<25; r++)
+		setFullRowColour(r, downwardsFullRowColour);
+
+	m_textLayer[1]->enhanceMap.clear();
+
+	if (m_renderLevel > 0 && !m_levelOnePage->enhancements()->isEmpty()) {
+		m_textLayer[1]->setFullScreenColour(-1);
+		for (int r=0; r<25; r++)
+			m_textLayer[1]->setFullRowColour(r, -1, false);
+		buildEnhanceMap(m_textLayer[1]);
+
+		if (m_textLayer.size() > 2)
+			std::stable_sort(m_textLayer.begin()+2, m_textLayer.end(), compareLayer);
+
+		if (m_renderLevel >= 2) {
+			if (m_textLayer[1]->fullScreenColour() != -1)
+				downwardsFullRowColour = m_textLayer[1]->fullScreenColour();
+			for (int r=0; r<25; r++) {
+				for (int l=0; l<2; l++) {
+					if (r == 0 && m_textLayer[l]->fullScreenColour() != - 1)
+						renderedFullScreenColour = m_textLayer[l]->fullScreenColour();
+					if (m_textLayer[l]->fullRowColour(r) == - 1)
+						currentFullRowColour = downwardsFullRowColour;
+					else {
+						currentFullRowColour = m_textLayer[l]->fullRowColour(r);
+						if (m_textLayer[l]->fullRowDownwards(r))
+							downwardsFullRowColour = currentFullRowColour;
+					}
+				}
+				setFullRowColour(r ,currentFullRowColour);
+			}
+			setFullScreenColour(renderedFullScreenColour);
+		}
+	}
+
+	for (int r=0; r<25; r++)
+		decodeRow(r);
+//	qDebug("Full page render: %d ms", renderPageTime.elapsed());
+}
+
+void TeletextPageDecode::decodeRow(int r)
+{
+	int c;
+	int phaseNumberRender = 0;
+	bool decodeNextRow = false;
+	bool applyRightHalf = false;
+	bool previouslyDoubleHeight, previouslyBottomHalf, underlined;
+	bool doubleHeightFound = false;
+	textCharacter resultCharacter, layerCharacter;
+	applyAttributes layerApplyAttributes;
+	textAttributes underlyingAttributes, resultAttributes;
+	int level1CharSet;
+
+	for (c=0; c<72; c++) {
+		textCell oldTextCell = m_cell[r][c];
+
+		resultAttributes = underlyingAttributes;
+		for (int l=0; l<m_textLayer.size(); l++) {
+			layerCharacter = m_textLayer[l]->character(r, c);
+			if (layerCharacter.code != 0x00)
+				resultCharacter = layerCharacter;
+			if (l == 0) {
+//				m_cell[r][c].level1Mosaic = (resultCharacter.set == 24 || resultCharacter.set == 25) && m_levelOnePage->character(r, c) >= 0x20;
+				m_cell[r][c].level1Mosaic = (resultCharacter.set == 24 || resultCharacter.set == 25);
+				if (!m_cell[r][c].level1Mosaic)
+					level1CharSet = resultCharacter.set;
+				m_cell[r][c].level1CharSet = level1CharSet;
+			}
+
+			layerApplyAttributes = { false, false, false, false, false, false, false, false };
+			m_textLayer[l]->attributes(r, c, &layerApplyAttributes);
+			if (layerApplyAttributes.copyAboveAttributes) {
+				resultAttributes = m_cell[r-1][c].attribute;
+				layerApplyAttributes.copyAboveAttributes = false;
+				break;
+			}
+			if (layerApplyAttributes.applyForeColour) {
+				resultAttributes.foreColour = layerApplyAttributes.attribute.foreColour;
+				if (l == 0 && m_renderLevel >= 2)
+					resultAttributes.foreColour |= m_foregroundRemap[m_levelOnePage->colourTableRemap()];
+			}
+			if (layerApplyAttributes.applyBackColour) {
+				resultAttributes.backColour = layerApplyAttributes.attribute.backColour;
+				if (l == 0) {
+					if (m_renderLevel >= 2)
+						if (resultAttributes.backColour == 0x20)
+							resultAttributes.backColour = (c > 39 || m_levelOnePage->blackBackgroundSubst()) ? m_fullRowColour[r] : m_backgroundRemap[m_levelOnePage->colourTableRemap()];
+						else
+							resultAttributes.backColour |= m_backgroundRemap[m_levelOnePage->colourTableRemap()];
+					else
+						if (resultAttributes.backColour == 0x20)
+							resultAttributes.backColour = 0x00;
+				}
+			}
+
+			if (layerApplyAttributes.applyFlash) {
+				//BUG Adaptive Objects disrupt inc/dec flash
+				resultAttributes.flash = layerApplyAttributes.attribute.flash;
+				if (resultAttributes.flash.mode != 0)
+					phaseNumberRender = (resultAttributes.flash.ratePhase == 4 || resultAttributes.flash.ratePhase == 5) ? 1 : resultAttributes.flash.ratePhase;
+			}
+			if (layerApplyAttributes.applyDisplayAttributes)
+				resultAttributes.display = layerApplyAttributes.attribute.display;
+			else {
+				// Selecting contiguous mosaics wih a triplet will override an earlier Level 1 separated mosaics attribute until a further Level 1 contiguous mosaic attribute is encountered
+				resultAttributes.display.forceContiguous = (layerApplyAttributes.applyContiguousOnly) ? false : underlyingAttributes.display.forceContiguous;
+				if (layerApplyAttributes.applyTextSizeOnly) {
+					resultAttributes.display.doubleHeight = layerApplyAttributes.attribute.display.doubleHeight;
+					resultAttributes.display.doubleWidth = layerApplyAttributes.attribute.display.doubleWidth;
+				}
+				if (layerApplyAttributes.applyBoxingOnly)
+					resultAttributes.display.boxingWindow = layerApplyAttributes.attribute.display.boxingWindow;
+				if (layerApplyAttributes.applyConcealOnly || layerApplyAttributes.applyForeColour)
+					resultAttributes.display.conceal = layerApplyAttributes.attribute.display.conceal;
+			}
+			if (m_textLayer[l]->objectType() <= 1)
+				underlyingAttributes = resultAttributes;
+
+			if (m_renderLevel == 0)
+				break;
+		}
+
+		underlined = false;
+		if (resultAttributes.display.underlineSeparated) {
+			if (resultCharacter.set == 24)
+				resultCharacter.set = 25;
+			else
+				underlined = resultCharacter.set < 24;
+		}
+		if (resultAttributes.display.forceContiguous && resultCharacter.set == 25)
+			resultCharacter.set = 24;
+
+		resultAttributes.flash.phaseNumber = phaseNumberRender;
+
+		previouslyDoubleHeight = m_cell[r][c].attribute.display.doubleHeight;
+		previouslyBottomHalf = m_cell[r][c].bottomHalf;
+
+		m_cell[r][c].character = resultCharacter;
+		m_cell[r][c].attribute = resultAttributes;
+
+		if (m_cell[r][c] != oldTextCell) {
+			m_refresh[r][c] = true;
+
+			if (static_cast<Level1Layer *>(m_textLayer[0])->rowHeight(r) == Level1Layer::TopHalf) {
+				m_refresh[r+1][c] = true;
+				decodeNextRow = true;
+			}
+
+			if ((m_cell[r][c].attribute.display.doubleHeight || oldTextCell.attribute.display.doubleHeight) && r < 25)
+				m_refresh[r+1][c] = true;
+			if ((m_cell[r][c].attribute.display.doubleWidth || oldTextCell.attribute.display.doubleWidth) && c < 72)
+				m_refresh[r][c+1] = true;
+			if (((m_cell[r][c].attribute.display.doubleHeight && m_cell[r][c].attribute.display.doubleWidth) || (oldTextCell.attribute.display.doubleHeight && oldTextCell.attribute.display.doubleWidth)) && r < 25 && c < 72)
+				m_refresh[r+1][c+1] = true;
+		}
+
+		if (resultAttributes.flash.ratePhase == 4 && ++phaseNumberRender == 4)
+			phaseNumberRender = 1;
+		if (resultAttributes.flash.ratePhase == 5 && --phaseNumberRender == 0)
+			phaseNumberRender = 3;
+
+		if (r > 0)
+			m_cell[r][c].bottomHalf = m_cell[r-1][c].attribute.display.doubleHeight && !m_cell[r-1][c].bottomHalf;
+		if ((resultAttributes.display.doubleHeight != previouslyDoubleHeight) || (m_cell[r][c].bottomHalf != previouslyBottomHalf))
+			decodeNextRow = true;
+		m_cell[r][c].rightHalf = applyRightHalf;
+
+		if (resultAttributes.display.doubleHeight)
+			doubleHeightFound = true;
+		if (resultAttributes.display.doubleWidth || (m_cell[r][c].bottomHalf && c > 0 && m_cell[r-1][c-1].rightHalf))
+			applyRightHalf ^= true;
+		else
+			applyRightHalf = false;
+	}
+
+	if (decodeNextRow && r<24)
+		decodeRow(r+1);
+}
+
+textCell& TeletextPageDecode::cellAtCharacterOrigin(int r, int c)
+{
+/*	if (m_cell[r][c].bottomHalf && r > 0) {
+		if (m_cell[r][c].rightHalf && c > 0)
+			// Double size
+			return m_cell[r-1][c-1];
+		else
+			// Double height
+			return m_cell[r-1][c];
+	} else {
+		if (m_cell[r][c].rightHalf && c > 0)
+			// Double width
+			return m_cell[r][c-1];
+		else
+			// Normal size
+			return m_cell[r][c];
+	}*/
+	switch (cellCharacterFragment(r, c)) {
+		case TeletextPageDecode::DoubleHeightBottomHalf:
+		case TeletextPageDecode::DoubleSizeBottomLeftQuarter:
+			return m_cell[r-1][c];
+		case TeletextPageDecode::DoubleWidthRightHalf:
+		case TeletextPageDecode::DoubleSizeTopRightQuarter:
+			return m_cell[r][c-1];
+		case TeletextPageDecode::DoubleSizeBottomRightQuarter:
+			return m_cell[r-1][c-1];
+		default:
+			return m_cell[r][c];
+	}
+}
+
+QColor TeletextPageDecode::cellQColor(int r, int c, ColourPart colourPart)
+{
+	const textCell& cell = cellAtCharacterOrigin(r, c);
+	const bool newsFlashOrSubtitle = m_levelOnePage->controlBit(PageBase::C5Newsflash) || m_levelOnePage->controlBit(PageBase::C6Subtitle);
+	int resultCLUT;
+
+	switch (colourPart) {
+		case Foreground:
+			if (!cell.attribute.display.invert)
+				resultCLUT = cell.attribute.foreColour;
+			else
+				resultCLUT = cell.attribute.backColour;
+			break;
+		case Background:
+			if (!cell.attribute.display.invert)
+				resultCLUT = cell.attribute.backColour;
+			else
+				resultCLUT = cell.attribute.foreColour;
+			break;
+		case FlashForeground:
+			if (!cell.attribute.display.invert)
+				resultCLUT = cell.attribute.foreColour ^ 8;
+			else
+				resultCLUT = cell.attribute.backColour ^ 8;
+			break;
+	}
+
+	if (resultCLUT == 8) {
+		// Transparent CLUT - either Full Row Colour or Video
+		// Logic of table C.1 in spec implemented to find out which it is
+		if (cell.attribute.display.boxingWindow != newsFlashOrSubtitle)
+			return QColor(Qt::transparent);
+
+		int rowColour;
+
+		if (cellCharacterFragment(r, c) == TeletextPageDecode::DoubleHeightBottomHalf ||
+		    cellCharacterFragment(r, c) == TeletextPageDecode::DoubleSizeBottomLeftQuarter ||
+		    cellCharacterFragment(r, c) == TeletextPageDecode::DoubleSizeBottomRightQuarter)
+			rowColour = m_fullRowColour[r-1];
+		else
+			rowColour = m_fullRowColour[r];
+
+		if (rowColour == 8)
+			return QColor(Qt::transparent);
+		else
+			return m_levelOnePage->CLUTtoQColor(rowColour, m_renderLevel);
+	} else if (!cell.attribute.display.boxingWindow && newsFlashOrSubtitle)
+		return QColor(Qt::transparent);
+
+	return m_levelOnePage->CLUTtoQColor(resultCLUT, m_renderLevel);
+}
+
+QColor TeletextPageDecode::cellForegroundQColor(int r, int c)
+{
+	return cellQColor(r, c, Foreground);
+}
+
+QColor TeletextPageDecode::cellBackgroundQColor(int r, int c)
+{
+	return cellQColor(r, c, Background);
+}
+
+QColor TeletextPageDecode::cellFlashForegroundQColor(int r, int c)
+{
+	return cellQColor(r, c, FlashForeground);
+}
+
+TeletextPageDecode::CharacterFragment TeletextPageDecode::cellCharacterFragment(int r, int c) const
+{
+	if (m_cell[r][c].bottomHalf && r > 0) {
+		if (m_cell[r][c].rightHalf && c > 0)
+			return CharacterFragment::DoubleSizeBottomRightQuarter;
+		else if (m_cell[r-1][c].attribute.display.doubleWidth)
+			return CharacterFragment::DoubleSizeBottomLeftQuarter;
+		else
+			return CharacterFragment::DoubleHeightBottomHalf;
+	} else if (m_cell[r][c].rightHalf && c > 0) {
+		if (m_cell[r][c-1].attribute.display.doubleHeight)
+			return CharacterFragment::DoubleSizeTopRightQuarter;
+		else
+			return CharacterFragment::DoubleWidthRightHalf;
+	}
+
+	if (m_cell[r][c].attribute.display.doubleHeight) {
+		if (m_cell[r][c].attribute.display.doubleWidth)
+			return CharacterFragment::DoubleSizeTopLeftQuarter;
+		else
+			return CharacterFragment::DoubleHeightTopHalf;
+	} else if (m_cell[r][c].attribute.display.doubleWidth)
+		return CharacterFragment::DoubleWidthLeftHalf;
+
+	return CharacterFragment::NormalSize;
+}
+
+inline void TeletextPageDecode::setFullScreenColour(int newColour)
+{
+	if (newColour == 8 || m_levelOnePage->controlBit(PageBase::C5Newsflash) || m_levelOnePage->controlBit(PageBase::C6Subtitle)) {
+		m_finalFullScreenQColor = QColor(0, 0, 0, 0);
+		emit fullScreenColourChanged(QColor(0, 0, 0, 0));
+		return;
+	}
+	QColor newFullScreenQColor = m_levelOnePage->CLUTtoQColor(newColour, m_renderLevel);
+	m_finalFullScreenColour = newColour;
+	if (m_finalFullScreenQColor != newFullScreenQColor) {
+		m_finalFullScreenQColor = newFullScreenQColor;
+		emit fullScreenColourChanged(m_finalFullScreenQColor);
+	}
+}
+
+inline void TeletextPageDecode::setFullRowColour(int row, int newColour)
+{
+	m_fullRowColour[row] = newColour;
+
+	if (newColour == 8 || m_levelOnePage->controlBit(PageBase::C5Newsflash) || m_levelOnePage->controlBit(PageBase::C6Subtitle)) {
+		m_fullRowQColor[row] = QColor(0, 0, 0, 0);
+		emit fullRowColourChanged(row, QColor(0, 0, 0, 0));
+		return;
+	}
+	QColor newFullRowQColor = m_levelOnePage->CLUTtoQColor(newColour, m_renderLevel);
+	if (m_fullRowQColor[row] != newFullRowQColor) {
+		for (int c=0; c<72; c++) {
+			if (m_cell[row][c].attribute.foreColour == 8 || m_cell[row][c].attribute.backColour == 8)
+				setRefresh(row, c, true);
+		}
+		m_fullRowQColor[row] = newFullRowQColor;
+		emit fullRowColourChanged(row, m_fullRowQColor[row]);
+	}
+}
+
+void TextLayer::setTeletextPage(LevelOnePage *newCurrentPage) { m_levelOnePage = newCurrentPage; }
+void TextLayer::setFullScreenColour(int newColour) { m_layerFullScreenColour = newColour; }
+
+void TextLayer::setFullRowColour(int r, int newColour, bool newDownwards)
+{
+	m_layerFullRowColour[r] = newColour;
+	m_layerFullRowDownwards[r] = newDownwards;
+}
+
+void EnhanceLayer::setObjectType(int newObjectType) { m_objectType = newObjectType; }
+
+void EnhanceLayer::setOrigin(int r, int c)
+{
+	m_originR = r;
+	m_originC = c;
+}
+
+Level1Layer::Level1Layer()
+{
+	for (int r=0; r<25; r++) {
+		m_rowHasDoubleHeightAttr[r] = false;
+		m_rowHeight[r] = Normal;
+	}
+}
+
+EnhanceLayer::EnhanceLayer()
+{
+	for (int r=0; r<25; r++) {
+		m_layerFullRowColour[r] = -1;
+		m_layerFullRowDownwards[r] = false;
+	}
+}
+
+textCharacter EnhanceLayer::character(int r, int c)
+{
+	r -= m_originR;
+	c -= m_originC;
+	if (r < 0 || c < 0)
+		return { 0, 0 };
+
+	// QPair.first is triplet mode, QPair.second is triplet data
+	QList<QPair<int, int>> enhancements = enhanceMap.values(qMakePair(r, c));
+
+	if (enhancements.size() > 0)
+		for (int i=0; i<enhancements.size(); i++)
+			switch (enhancements.at(i).first) {
+				case 0x2b: // G3 mosaic character at Level 2.5
+				case 0x22: // G3 mosaic character at Level 1.5
+					return { enhancements.at(i).second, 26 };
+				case 0x29: // G0 character at Level 2.5
+					return { enhancements.at(i).second, 0 };
+				case 0x2f: // G2 character
+					return { enhancements.at(i).second, 7 };
+				case 0x30 ... 0x3f: // Diacritical
+					// Deal with @ symbol replacing * symbol - clause 15.6.1 note 3 in spec
+					if (enhancements.at(i).first == 0x30 && enhancements.at(i).second == 0x2a)
+						return { 0x40, 0 };
+					else
+						return { enhancements.at(i).second, 0, enhancements.at(i).first & 0x0f };
+				case 0x21: // G1 character
+					if ((enhancements.at(i).second) >= 0x20)
+						return { enhancements.at(i).second, (enhancements.at(i).second & 0x20) ? 24 : 0 };
+			}
+	return { 0, 0 };
+}
+
+void EnhanceLayer::attributes(int r, int c, applyAttributes *layerApplyAttributes)
+{
+	r -= m_originR;
+	c -= m_originC;
+	if (r < 0 || c < 0)
+		return;
+	if (m_objectType == 2) {
+		// Adaptive Object - find rightmost column addressed on this row if we haven't already
+		if (r != m_rowCached) {
+			m_rightMostColumn[r] = 0;
+			m_rowCached = r;
+			for (int cc=39; cc>0; cc--)
+				if (enhanceMap.contains(qMakePair(r, cc))) {
+					m_rightMostColumn[r] = cc;
+					break;
+				}
+		}
+		// On new row, default to attributes already on page
+		// At end of rightmost column, let go of all attributes
+		if (c == 0 || c == m_rightMostColumn[r]+1)
+			m_applyAttributes = { false, false, false, false, false, false, false, false };
+		else {
+			// Re-apply attributes that Object has defined previously on this row
+			if (m_applyAttributes.applyForeColour) {
+				layerApplyAttributes->applyForeColour = true;
+				layerApplyAttributes->attribute.foreColour = m_applyAttributes.attribute.foreColour;
+			}
+			if (m_applyAttributes.applyBackColour) {
+				layerApplyAttributes->applyBackColour = true;
+				layerApplyAttributes->attribute.backColour = m_applyAttributes.attribute.backColour;
+			}
+			//BUG Adaptive Objects disrupt inc/dec flash
+			if (m_applyAttributes.applyFlash) {
+				layerApplyAttributes->applyFlash = true;
+				layerApplyAttributes->attribute.flash.mode = m_applyAttributes.attribute.flash.mode;
+				layerApplyAttributes->attribute.flash.ratePhase = m_applyAttributes.attribute.flash.ratePhase;
+			}
+			if (m_applyAttributes.applyDisplayAttributes) {
+				layerApplyAttributes->applyDisplayAttributes = true;
+				layerApplyAttributes->attribute.display = m_applyAttributes.attribute.display;
+			}
+		}
+	}
+	if (m_objectType == 3) {
+		if (r == 0 && c == 0) {
+			// Passive Objects always start with all these default attributes
+			m_applyAttributes.applyForeColour = true;
+			m_applyAttributes.attribute.foreColour = 0x07;
+			m_applyAttributes.applyBackColour = true;
+			m_applyAttributes.attribute.backColour = 0x00;
+			m_applyAttributes.applyDisplayAttributes = true;
+			m_applyAttributes.applyFlash = true;
+			m_applyAttributes.attribute.flash.mode = 0;
+			m_applyAttributes.attribute.flash.ratePhase = 0;
+			m_applyAttributes.attribute.display.doubleHeight = false;
+			m_applyAttributes.attribute.display.doubleWidth = false;
+			m_applyAttributes.attribute.display.boxingWindow = false;
+			m_applyAttributes.attribute.display.conceal = false;
+			m_applyAttributes.attribute.display.invert = false;
+			m_applyAttributes.attribute.display.underlineSeparated = false;
+			m_applyAttributes.attribute.display.forceContiguous = false;
+		}
+		if (character(r+m_originR, c+m_originC).code == 0x00)
+			// Passive Object attributes only apply where it also defines a character
+			// In this case, wrench the pointer-parameter to alter only the attributes of the Object
+			layerApplyAttributes = &m_applyAttributes;
+		else
+			*layerApplyAttributes = m_applyAttributes;
+	}
+
+	// QPair.first is triplet mode, QPair.second is triplet data
+	QList<QPair<int, int>> enhancements = enhanceMap.values(qMakePair(r, c));
+
+	for (int i=0; i<enhancements.size(); i++)
+		switch (enhancements.at(i).first) {
+			case 0x20: // Foreground colour
+				if ((enhancements.at(i).second & 0x60) == 0) {
+					layerApplyAttributes->applyForeColour = true;
+					layerApplyAttributes->attribute.foreColour = enhancements.at(i).second;
+				}
+				break;
+			case 0x23: // Background colour
+				if ((enhancements.at(i).second & 0x60) == 0) {
+					layerApplyAttributes->applyBackColour = true;
+					layerApplyAttributes->attribute.backColour = enhancements.at(i).second;
+				}
+				break;
+			case 0x27: // Additional flash functions
+				if ((enhancements.at(i).second & 0x60) == 0 && (enhancements.at(i).second & 0x18) != 0x18) { // Avoid reserved rate/phase
+					layerApplyAttributes->applyFlash = true;
+					layerApplyAttributes->attribute.flash.mode = enhancements.at(i).second & 0x03;
+					layerApplyAttributes->attribute.flash.ratePhase = (enhancements.at(i).second >> 2) & 0x07;
+				}
+				break;
+			case 0x2c: // Display attributes
+				layerApplyAttributes->applyDisplayAttributes = true;
+				layerApplyAttributes->attribute.display.doubleHeight = enhancements.at(i).second & 0x01;
+				layerApplyAttributes->attribute.display.boxingWindow = enhancements.at(i).second & 0x02;
+				layerApplyAttributes->attribute.display.conceal = enhancements.at(i).second & 0x04;
+				layerApplyAttributes->attribute.display.invert = enhancements.at(i).second & 0x10;
+				layerApplyAttributes->attribute.display.underlineSeparated = enhancements.at(i).second & 0x20;
+				// Selecting contiguous mosaics wih a triplet will override an earlier Level 1 separated mosaics attribute
+				layerApplyAttributes->attribute.display.forceContiguous = !layerApplyAttributes->attribute.display.underlineSeparated;
+				layerApplyAttributes->attribute.display.doubleWidth = enhancements.at(i).second & 0x40;
+				break;
+		}
+	if (m_objectType >= 2)
+		m_applyAttributes = *layerApplyAttributes;
+}
+
+
+void Level1Layer::updateRowCache(int r)
+{
+	level1CacheAttributes buildCacheAttributes;
+	bool doubleHeightAttrFound = false;
+
+	for (int c=0; c<40; c++) {
+		unsigned char charCode = m_levelOnePage->character(r, c);
+		// Set at spacing attributes
+		switch (charCode) {
+			case 0x0c: // Normal size
+				if (buildCacheAttributes.sizeCode != 0x0c) // Size CHANGE resets held mosaic to space
+					buildCacheAttributes.holdChar = 0x20;
+				buildCacheAttributes.sizeCode = 0x0c;
+				break;
+			case 0x19: // Contiguous mosaics
+				buildCacheAttributes.separated = false;
+				break;
+			case 0x1a: // Separated mosaics
+				buildCacheAttributes.separated = true;
+				break;
+			case 0x1c: // Black background
+				buildCacheAttributes.backColour = 0x00;
+				break;
+			case 0x1d: // New background
+				buildCacheAttributes.backColour = buildCacheAttributes.foreColour & 0x07;
+				break;
+			case 0x1e: // Hold mosaics
+				buildCacheAttributes.held = true;
+				break;
+		}
+
+		if (buildCacheAttributes.mosaics && (charCode & 0x20)) {
+			buildCacheAttributes.holdChar = charCode;
+			buildCacheAttributes.holdSeparated = buildCacheAttributes.separated;
+		}
+
+		m_attributeCache[c] = buildCacheAttributes;
+
+		// Set-after spacing attributes
+		switch (charCode) {
+			case 0x00 ... 0x07: // Alphanumeric + foreground colour
+				buildCacheAttributes.foreColour = charCode;
+				buildCacheAttributes.mosaics = false;
+				buildCacheAttributes.holdChar = 0x20; // Switch from mosaics to alpha resets held mosaic
+				buildCacheAttributes.holdSeparated = false;
+				break;
+			case 0x10 ... 0x17: // Mosaic + foreground colour
+				buildCacheAttributes.foreColour = charCode & 0x07;
+				buildCacheAttributes.mosaics = true;
+				break;
+			case 0x0d: // Double height
+			case 0x0f: // Double size
+				doubleHeightAttrFound = true;
+				// fall-through
+			case 0x0e: // Double width
+				if (buildCacheAttributes.sizeCode != charCode) // Size CHANGE resets held mosaic to space
+					buildCacheAttributes.holdChar = 0x20;
+				buildCacheAttributes.sizeCode = charCode;
+				break;
+			case 0x1b: // ESC/switch
+				buildCacheAttributes.escSwitch ^= true;
+				break;
+			case 0x1f: // Release mosaics
+				buildCacheAttributes.held = false;
+				break;
+		}
+	}
+
+	if (doubleHeightAttrFound != m_rowHasDoubleHeightAttr[r]) {
+		m_rowHasDoubleHeightAttr[r] = doubleHeightAttrFound;
+		for (int dr=r; dr<24; dr++)
+			if (m_rowHasDoubleHeightAttr[dr]) {
+				m_rowHeight[dr] = TopHalf;
+				m_rowHeight[++dr] = BottomHalf;
+			} else
+				m_rowHeight[dr] = Normal;
+	}
+}
+
+textCharacter Level1Layer::character(int r, int c)
+{
+	textCharacter result;
+
+	if (r != m_rowCached)
+		updateRowCache(r);
+	if (c > 39 || m_rowHeight[r] == BottomHalf)
+		return { 0x20, 0 };
+	result.code = m_levelOnePage->character(r, c);
+	if (m_levelOnePage->secondCharSet() != 0xf && m_attributeCache[c].escSwitch)
+		result.set = g0CharacterMap.value(((m_levelOnePage->secondCharSet() << 3) | m_levelOnePage->secondNOS()), 0);
+	else
+		result.set = g0CharacterMap.value(((m_levelOnePage->defaultCharSet() << 3) | m_levelOnePage->defaultNOS()), 0);
+	if (result.code < 0x20) {
+		result.code = m_attributeCache[c].held ? m_attributeCache[c].holdChar : 0x20;
+		if (m_attributeCache[c].held && c > 0)
+			result.set = 24+m_attributeCache[c].holdSeparated;
+//		else
+//			result.set = m_attributeCache[c].mosaics*24;
+	} else if (m_attributeCache[c].mosaics && (result.code & 0x20))
+		result.set = 24+m_attributeCache[c].separated;
+	return result;
+}
+
+void Level1Layer::attributes(int r, int c, applyAttributes *layerApplyAttributes)
+{
+	unsigned char characterCode;
+
+	if (m_rowHeight[r] == BottomHalf) {
+		layerApplyAttributes->copyAboveAttributes = true;
+		return;
+	}
+	if (r != m_rowCached)
+		updateRowCache(r);
+	if (c == 0 || c == 40 || c == 56) {
+		// Start of row default conditions, also when crossing into side panels
+		layerApplyAttributes->applyForeColour = true;
+		layerApplyAttributes->attribute.foreColour = 0x07;
+		layerApplyAttributes->applyBackColour = true;
+		layerApplyAttributes->attribute.backColour = 0x20;
+		layerApplyAttributes->applyDisplayAttributes = true;
+		layerApplyAttributes->applyFlash = true;
+		layerApplyAttributes->attribute.flash.mode = 0;
+		layerApplyAttributes->attribute.flash.ratePhase = 0;
+		layerApplyAttributes->attribute.display.doubleHeight = false;
+		layerApplyAttributes->attribute.display.doubleWidth = false;
+		layerApplyAttributes->attribute.display.boxingWindow = false;
+		layerApplyAttributes->attribute.display.conceal = false;
+		layerApplyAttributes->attribute.display.invert = false;
+		layerApplyAttributes->attribute.display.underlineSeparated = false;
+		layerApplyAttributes->attribute.display.forceContiguous = false;
+		//TODO fontstyle
+	}
+	if (c > 39)
+		return;
+	if (c > 0) {
+		// Set-after
+		characterCode = m_levelOnePage->character(r, c-1);
+		switch (characterCode) {
+			case 0x00 ... 0x07: // Alphanumeric + Foreground colour
+			case 0x10 ... 0x17: // Mosaic + Foreground colour
+				layerApplyAttributes->applyForeColour = true;
+				layerApplyAttributes->attribute.foreColour = characterCode & 0x07;
+				layerApplyAttributes->attribute.display.conceal = false;
+				break;
+			case 0x08: // Flashing
+				layerApplyAttributes->applyFlash = true;
+				layerApplyAttributes->attribute.flash.mode = 1;
+				layerApplyAttributes->attribute.flash.ratePhase = 0;
+				break;
+			case 0x0a: // End box
+				if (m_levelOnePage->character(r, c) == 0x0a) {
+					layerApplyAttributes->applyBoxingOnly = true;
+					layerApplyAttributes->attribute.display.boxingWindow = false;
+				}
+				break;
+			case 0x0b: // Start box
+				if (m_levelOnePage->character(r, c) == 0x0b) {
+					layerApplyAttributes->applyBoxingOnly = true;
+					layerApplyAttributes->attribute.display.boxingWindow = true;
+				}
+				break;
+			case 0x0d: // Double height
+				layerApplyAttributes->applyTextSizeOnly = true;
+				layerApplyAttributes->attribute.display.doubleHeight = true;
+				layerApplyAttributes->attribute.display.doubleWidth = false;
+				break;
+			case 0x0e: // Double width
+				layerApplyAttributes->applyTextSizeOnly = true;
+				layerApplyAttributes->attribute.display.doubleHeight = false;
+				layerApplyAttributes->attribute.display.doubleWidth = true;
+				break;
+			case 0x0f: // Double size
+				layerApplyAttributes->applyTextSizeOnly = true;
+				layerApplyAttributes->attribute.display.doubleHeight = true;
+				layerApplyAttributes->attribute.display.doubleWidth = true;
+				break;
+		}
+	}
+	// Set-at
+	characterCode = m_levelOnePage->character(r, c);
+	switch (characterCode) {
+		case 0x09: // Steady
+			layerApplyAttributes->applyFlash = true;
+			layerApplyAttributes->attribute.flash.mode = 0;
+			layerApplyAttributes->attribute.flash.ratePhase = 0;
+			break;
+		case 0x0c: // Normal size
+			layerApplyAttributes->applyTextSizeOnly = true;
+			layerApplyAttributes->attribute.display.doubleHeight = false;
+			layerApplyAttributes->attribute.display.doubleWidth = false;
+			break;
+		case 0x18: // Conceal
+			layerApplyAttributes->applyConcealOnly = true;
+			layerApplyAttributes->attribute.display.conceal = true;
+			break;
+		case 0x19: // Contiguous mosaics
+			layerApplyAttributes->applyContiguousOnly = true;
+			break;
+		case 0x1c: // Black background
+			layerApplyAttributes->applyBackColour = true;
+			layerApplyAttributes->attribute.backColour = 0x20;
+			break;
+		case 0x1d: // New background
+			layerApplyAttributes->applyBackColour = true;
+			layerApplyAttributes->attribute.backColour = m_attributeCache[c].backColour;
+			break;
+	}
+}
+
+
+ActivePosition::ActivePosition()
+{
+	m_row = m_column = -1;
+}
+
+bool ActivePosition::setRow(int newRow)
+{
+	if (newRow < m_row)
+		return false;
+	if (newRow > m_row) {
+		m_row = newRow;
+		m_column = -1;
+	}
+	return true;
+}
+
+bool ActivePosition::setColumn(int newColumn)
+{
+	if (newColumn < m_column)
+		return false;
+	if (m_row == -1)
+		m_row = 0;
+	m_column = newColumn;
+	return true;
+}
+/*
+bool ActivePosition::setRowAndColumn(int newRow, int newColumn)
+{
+	if (!setRow(newRow))
+		return false;
+	return setColumn(newColumn);
+}
+*/
--- a/decode.h
+++ b/decode.h
@@ -0,0 +1,306 @@
+/*
+ * Copyright (C) 2020-2022 Gavin MacGregor
+ *
+ * This file is part of QTeletextMaker.
+ *
+ * QTeletextMaker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * QTeletextMaker is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with QTeletextMaker.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef DECODE_H
+#define DECODE_H
+
+#include <QMap>
+#include <QMultiMap>
+#include <QPair>
+#include <vector>
+
+#include "levelonepage.h"
+
+struct textCharacter {
+	unsigned char code=0x20;
+	int set=0;
+	int diacritical=0;
+};
+
+inline bool operator!=(const textCharacter &lhs, const textCharacter &rhs)
+{
+	return lhs.code        != rhs.code         ||
+	       lhs.set         != rhs.set          ||
+	       lhs.diacritical != rhs.diacritical;
+}
+
+struct displayAttributes {
+	bool doubleHeight=false;
+	bool doubleWidth=false;
+	bool boxingWindow=false;
+	bool conceal=false;
+	bool invert=false;
+	bool underlineSeparated=false;
+	bool forceContiguous=false;
+};
+
+inline bool operator!=(const displayAttributes &lhs, const displayAttributes &rhs)
+{
+	return lhs.doubleHeight       != rhs.doubleHeight       ||
+	       lhs.doubleWidth        != rhs.doubleWidth        ||
+	       lhs.boxingWindow       != rhs.boxingWindow       ||
+	       lhs.conceal            != rhs.conceal            ||
+	       lhs.invert             != rhs.invert             ||
+	       lhs.underlineSeparated != rhs.underlineSeparated ||
+	       lhs.forceContiguous    != rhs.forceContiguous;
+}
+
+struct textAttributes {
+	int foreColour=0x07;
+	int backColour=0x00;
+	struct flashFunctions {
+		int mode=0;
+		int ratePhase=0;
+		int phaseNumber=0;
+	} flash;
+	displayAttributes display;
+	/* font style */
+};
+
+inline bool operator!=(const textAttributes &lhs, const textAttributes &rhs)
+{
+	return lhs.foreColour        != rhs.foreColour        ||
+	       lhs.backColour        != rhs.backColour        ||
+	       lhs.flash.mode        != rhs.flash.mode        ||
+	       lhs.flash.ratePhase   != rhs.flash.ratePhase   ||
+	       lhs.flash.phaseNumber != rhs.flash.phaseNumber ||
+	       lhs.display           != rhs.display;
+}
+
+struct textCell {
+	textCharacter character;
+	textAttributes attribute;
+	bool bottomHalf=false;
+	bool rightHalf=false;
+	bool level1Mosaic=false;
+	int level1CharSet=0;
+};
+
+inline bool operator!=(const textCell &lhs, const textCell &rhs)
+{
+	return lhs.character     != rhs.character    ||
+	       lhs.attribute     != rhs.attribute    ||
+	       lhs.bottomHalf    != rhs.bottomHalf   ||
+	       lhs.rightHalf     != rhs.rightHalf    ||
+	       lhs.level1Mosaic  != rhs.level1Mosaic ||
+	       lhs.level1CharSet != rhs.level1CharSet;
+}
+
+struct applyAttributes {
+	bool applyForeColour=false;
+	bool applyBackColour=false;
+	bool applyFlash=false;
+	bool applyDisplayAttributes=false;
+	bool applyTextSizeOnly=false;
+	bool applyBoxingOnly=false;
+	bool applyConcealOnly=false;
+	bool applyContiguousOnly=false;
+	bool copyAboveAttributes=false;
+	textAttributes attribute;
+};
+
+class ActivePosition
+{
+public:
+	ActivePosition();
+	int row() const { return (m_row == -1) ? 0 : m_row; }
+	int column() const { return (m_column == -1) ? 0 : m_column; }
+	bool isDeployed() const { return m_row != -1; }
+	bool setRow(int);
+	bool setColumn(int);
+//	bool setRowAndColumn(int, int);
+
+private:
+	int m_row, m_column;
+};
+
+
+class TextLayer
+{
+public:
+//	TextLayer(TeletextPage* thePage) : currentPage(thePage) { };
+	virtual ~TextLayer() = default;
+	void setTeletextPage(LevelOnePage *);
+	virtual textCharacter character(int, int) =0;
+	virtual void attributes(int, int, applyAttributes *) =0;
+	virtual int fullScreenColour() const =0;
+	virtual int fullRowColour(int) const =0;
+	virtual bool fullRowDownwards(int) const =0;
+	virtual int objectType() const =0;
+	virtual int originR() const { return 0; };
+	virtual int originC() const { return 0; };
+	void setFullScreenColour(int);
+	void setFullRowColour(int, int, bool);
+
+	// Key QPair is row and column, value QPair is triplet mode and data
+	QMultiMap<QPair<int, int>, QPair<int, int>> enhanceMap;
+
+protected:
+	LevelOnePage* m_levelOnePage;
+	int m_layerFullScreenColour=-1;
+	int m_layerFullRowColour[25];
+	bool m_layerFullRowDownwards[25];
+	applyAttributes m_applyAttributes;
+};
+
+class EnhanceLayer: public TextLayer
+{
+public:
+	EnhanceLayer();
+	textCharacter character(int, int);
+	void attributes(int, int, applyAttributes *);
+	int fullScreenColour() const { return m_layerFullScreenColour; };
+	int fullRowColour(int r) const { return m_layerFullRowColour[r]; };
+	bool fullRowDownwards(int r) const { return m_layerFullRowDownwards[r]; };
+	int objectType() const { return m_objectType; };
+	int originR() const { return m_originR; };
+	int originC() const { return m_originC; };
+	void setObjectType(int);
+	void setOrigin(int, int);
+
+protected:
+	int m_objectType=0;
+	int m_originR=0;
+	int m_originC=0;
+	int m_rowCached=-1;
+	int m_rightMostColumn[25];
+};
+
+class Level1Layer: public TextLayer
+{
+public:
+	enum RowHeight { Normal=-1, TopHalf, BottomHalf };
+
+//	Level1Layer(TeletextPage *thePage) : TextLayer(thePage) { };
+	Level1Layer();
+	textCharacter character(int, int);
+	void attributes(int, int, applyAttributes *);
+	int fullScreenColour() const { return -1; };
+	int fullRowColour(int) const { return -1; };
+	bool fullRowDownwards(int) const { return false; };
+	int objectType() const { return 0; }
+	RowHeight rowHeight(int r) const { return m_rowHeight[r]; };
+
+private:
+	void updateRowCache(int);
+
+	struct level1CacheAttributes {
+		int foreColour=0x07;
+		int backColour=0x00;
+		unsigned char sizeCode=0x0c;
+		bool mosaics=false;
+		bool separated=false;
+		bool held=false;
+		bool escSwitch=false;
+		unsigned char holdChar=0x20;
+		bool holdSeparated=false;
+	};
+	level1CacheAttributes m_attributeCache[40];
+	int m_rowCached=-1;
+	bool m_rowHasDoubleHeightAttr[25];
+	RowHeight m_rowHeight[25];
+};
+
+class TeletextPageDecode : public QObject
+{
+	Q_OBJECT
+
+public:
+	enum CharacterFragment { NormalSize, DoubleHeightTopHalf, DoubleHeightBottomHalf, DoubleWidthLeftHalf, DoubleWidthRightHalf, DoubleSizeTopLeftQuarter, DoubleSizeTopRightQuarter, DoubleSizeBottomLeftQuarter, DoubleSizeBottomRightQuarter };
+
+	TeletextPageDecode();
+	~TeletextPageDecode();
+	bool refresh(int r, int c) const { return m_refresh[r][c]; }
+	void setRefresh(int, int, bool);
+	void decodePage();
+	void decodeRow(int r);
+	LevelOnePage *teletextPage() const { return m_levelOnePage; };
+	void setTeletextPage(LevelOnePage *);
+	void updateSidePanels();
+	void buildEnhanceMap(TextLayer *, int=0);
+
+	unsigned char cellCharacterCode(int r, int c) { return cellAtCharacterOrigin(r, c).character.code; };
+	int cellCharacterSet(int r, int c) { return cellAtCharacterOrigin(r, c).character.set; };
+	int cellCharacterDiacritical(int r, int c) { return cellAtCharacterOrigin(r, c).character.diacritical; };
+	int cellForegroundCLUT(int r, int c) { return cellAtCharacterOrigin(r, c).attribute.foreColour; };
+	int cellBackgroundCLUT(int r, int c) { return cellAtCharacterOrigin(r, c).attribute.backColour; };
+	QColor cellForegroundQColor(int, int);
+	QColor cellBackgroundQColor(int, int);
+	QColor cellFlashForegroundQColor(int, int);
+	int cellFlashMode(int r, int c) { return cellAtCharacterOrigin(r, c).attribute.flash.mode; };
+	int cellFlashRatePhase(int r, int c) { return cellAtCharacterOrigin(r, c).attribute.flash.ratePhase; };
+	int cellFlash2HzPhaseNumber(int r, int c) { return cellAtCharacterOrigin(r, c).attribute.flash.phaseNumber; };
+	CharacterFragment cellCharacterFragment(int, int) const;
+	bool cellBoxed(int r, int c) { return cellAtCharacterOrigin(r, c).attribute.display.boxingWindow; };
+	bool cellConceal(int r, int c) { return cellAtCharacterOrigin(r, c).attribute.display.conceal; };
+	bool cellUnderlined(int r, int c) { return cellAtCharacterOrigin(r, c).attribute.display.underlineSeparated && cellAtCharacterOrigin(r, c).character.set < 24; };
+
+	bool level1MosaicAttribute(int r, int c) const { return m_cell[r][c].level1Mosaic; };
+	int level1CharSet(int r, int c) const { return m_cell[r][c].level1CharSet; };
+
+	QColor fullScreenQColor() const { return m_finalFullScreenQColor; };
+	QColor fullRowQColor(int r) const { return m_fullRowQColor[r]; };
+	int leftSidePanelColumns() const { return m_leftSidePanelColumns; };
+	int rightSidePanelColumns() const { return m_rightSidePanelColumns; };
+
+public slots:
+	void setRenderLevel(int);
+
+signals:
+	void fullScreenColourChanged(QColor);
+	void fullRowColourChanged(int, QColor);
+	void sidePanelsChanged();
+
+protected:
+	inline void setFullScreenColour(int);
+	inline void setFullRowColour(int, int);
+	textCell& cellAtCharacterOrigin(int, int);
+
+	int m_finalFullScreenColour, m_renderLevel;
+	QColor m_finalFullScreenQColor;
+	int m_leftSidePanelColumns, m_rightSidePanelColumns;
+	Level1Layer m_level1Layer;
+	std::vector<TextLayer *> m_textLayer;
+	const int m_foregroundRemap[8] = { 0,  0,  0,  8,  8, 16, 16, 16 };
+	const int m_backgroundRemap[8] = { 0,  8, 16,  8, 16,  8, 16, 24 };
+
+private:
+	enum ColourPart { Foreground, Background, FlashForeground };
+
+	QColor cellQColor(int, int, ColourPart);
+
+	textCell m_cell[25][72];
+	bool m_refresh[25][72];
+	LevelOnePage* m_levelOnePage;
+	int m_fullRowColour[25];
+	QColor m_fullRowQColor[25];
+};
+
+static const QMap<int, int> g0CharacterMap {
+	{ 0x00, 12 }, { 0x01, 15 }, { 0x02, 22 }, { 0x03, 16 }, { 0x04, 14 }, { 0x05, 19 }, { 0x06, 11 },
+	{ 0x08, 18 }, { 0x09, 15 }, { 0x0a, 22 }, { 0x0b, 16 }, { 0x0c, 14 }, { 0x0e, 11 },
+	{ 0x10, 12 }, { 0x11, 15 }, { 0x12, 22 }, { 0x13, 16 }, { 0x14, 14 }, { 0x15, 19 }, { 0x16, 23 },
+	{ 0x1d, 21 }, { 0x1f, 20 },
+	{ 0x20,  1 }, { 0x21, 15 }, { 0x22, 13 }, { 0x23, 17 }, { 0x24,  2 }, { 0x25,  3 }, { 0x26, 11 },
+	{ 0x36, 23 }, { 0x37,  4 },
+	{ 0x40, 12 }, { 0x44, 14 }, { 0x47,  5 },
+	{ 0x55,  6 }, { 0x57,  5 }
+};
+
+#endif
--- a/mainwidget.cpp
+++ b/mainwidget.cpp
@@ -38,6 +38,7 @@

 #include "mainwidget.h"

+#include "decode.h"
 #include "document.h"
 #include "keymap.h"
 #include "levelonecommands.h"
@@ -52,16 +53,18 @@ TeletextWidget::TeletextWidget(QFrame *parent) : QFrame(parent)
 	this->setAttribute(Qt::WA_InputMethodEnabled, true);
 	m_teletextDocument = new TeletextDocument();
 	m_levelOnePage = m_teletextDocument->currentSubPage();
-	m_pageRender.setTeletextPage(m_levelOnePage);
+	m_pageDecode.setTeletextPage(m_levelOnePage);
+	m_pageRender.setDecoder(&m_pageDecode);
 	m_insertMode = false;
 	m_selectionInProgress = false;
 	setFocusPolicy(Qt::StrongFocus);
 	m_flashTiming = m_flashPhase = 0;
 	connect(&m_pageRender, &TeletextPageRender::flashChanged, this, &TeletextWidget::updateFlashTimer);
-	connect(&m_pageRender, &TeletextPageRender::sidePanelsChanged, this, &TeletextWidget::changeSize);
+	connect(&m_pageDecode, &TeletextPageDecode::sidePanelsChanged, this, &TeletextWidget::changeSize);
 	connect(m_teletextDocument, &TeletextDocument::subPageSelected, this, &TeletextWidget::subPageSelected);
 	connect(m_teletextDocument, &TeletextDocument::contentsChange, this, &TeletextWidget::refreshRow);
 	connect(m_teletextDocument, &TeletextDocument::refreshNeeded, this, &TeletextWidget::refreshPage);
+	connect(m_teletextDocument, &TeletextDocument::colourChanged, &m_pageRender, &TeletextPageRender::colourChanged);
 }

 TeletextWidget::~TeletextWidget()
@@ -85,20 +88,21 @@ void TeletextWidget::inputMethodEvent(QInputMethodEvent* event)
 void TeletextWidget::subPageSelected()
 {
 	m_levelOnePage = m_teletextDocument->currentSubPage();
-	m_pageRender.setTeletextPage(m_levelOnePage);
-	refreshPage();
+	m_pageDecode.setTeletextPage(m_levelOnePage);
+	m_pageDecode.decodePage();
+	m_pageRender.renderPage(true);
+	update();
 }

 void TeletextWidget::refreshRow(int rowChanged)
 {
-	m_pageRender.renderPage(rowChanged);
+	m_pageDecode.decodeRow(rowChanged);
 	update();
 }

 void TeletextWidget::refreshPage()
 {
-	m_pageRender.decodePage();
-	m_pageRender.renderPage();
+	m_pageDecode.decodePage();
 	update();
 }

@@ -107,11 +111,12 @@ void TeletextWidget::paintEvent(QPaintEvent *event)
 	Q_UNUSED(event);
 	QPainter widgetPainter(this);

-	widgetPainter.drawPixmap(m_pageRender.leftSidePanelColumns()*12, 0, *m_pageRender.pagePixmap(m_flashPhase), 0, 0, 480, 250);
-	if (m_pageRender.leftSidePanelColumns())
-		widgetPainter.drawPixmap(0, 0, *m_pageRender.pagePixmap(m_flashPhase), 864-m_pageRender.leftSidePanelColumns()*12, 0, m_pageRender.leftSidePanelColumns()*12, 250);
-	if (m_pageRender.rightSidePanelColumns())
-		widgetPainter.drawPixmap(480+m_pageRender.leftSidePanelColumns()*12, 0, *m_pageRender.pagePixmap(m_flashPhase), 480, 0, m_pageRender.rightSidePanelColumns()*12, 250);
+	m_pageRender.renderPage();
+	widgetPainter.drawPixmap(m_pageDecode.leftSidePanelColumns()*12, 0, *m_pageRender.pagePixmap(m_flashPhase), 0, 0, 480, 250);
+	if (m_pageDecode.leftSidePanelColumns())
+		widgetPainter.drawPixmap(0, 0, *m_pageRender.pagePixmap(m_flashPhase), 864-m_pageDecode.leftSidePanelColumns()*12, 0, m_pageDecode.leftSidePanelColumns()*12, 250);
+	if (m_pageDecode.rightSidePanelColumns())
+		widgetPainter.drawPixmap(480+m_pageDecode.leftSidePanelColumns()*12, 0, *m_pageRender.pagePixmap(m_flashPhase), 480, 0, m_pageDecode.rightSidePanelColumns()*12, 250);
 }

 void TeletextWidget::updateFlashTimer(int newFlashTimer)
@@ -155,25 +160,29 @@ void TeletextWidget::setInsertMode(bool insertMode)
 	m_insertMode = insertMode;
 }

-void TeletextWidget::toggleReveal(bool revealOn)
+void TeletextWidget::setReveal(bool reveal)
 {
-	m_pageRender.setReveal(revealOn);
+	m_pageRender.setReveal(reveal);
 	update();
 }

-void TeletextWidget::toggleMix(bool mixOn)
+void TeletextWidget::setMix(bool mix)
 {
-	m_pageRender.setMix(mixOn);
+	m_pageRender.setMix(mix);
+	update();
+}
+
+void TeletextWidget::setShowControlCodes(bool showControlCodes)
+{
+	m_pageRender.setShowControlCodes(showControlCodes);
 	update();
 }

 void TeletextWidget::setControlBit(int bitNumber, bool active)
 {
 	m_levelOnePage->setControlBit(bitNumber, active);
-	if (bitNumber == 1 || bitNumber == 2) {
-		m_pageRender.decodePage();
-		m_pageRender.renderPage();
-	}
+	if (bitNumber == 1 || bitNumber == 2)
+		m_pageDecode.decodePage();
 }

 void TeletextWidget::setDefaultCharSet(int newDefaultCharSet)
@@ -189,31 +198,27 @@ void TeletextWidget::setDefaultNOS(int newDefaultNOS)
 void TeletextWidget::setDefaultScreenColour(int newColour)
 {
 	m_levelOnePage->setDefaultScreenColour(newColour);
-	m_pageRender.decodePage();
-	m_pageRender.renderPage();
+	m_pageDecode.decodePage();
 }

 void TeletextWidget::setDefaultRowColour(int newColour)
 {
 	m_levelOnePage->setDefaultRowColour(newColour);
-	m_pageRender.decodePage();
-	m_pageRender.renderPage();
+	m_pageDecode.decodePage();
 	update();
 }

 void TeletextWidget::setColourTableRemap(int newMap)
 {
 	m_levelOnePage->setColourTableRemap(newMap);
-	m_pageRender.decodePage();
-	m_pageRender.renderPage();
+	m_pageDecode.decodePage();
 	update();
 }

 void TeletextWidget::setBlackBackgroundSubst(bool substOn)
 {
 	m_levelOnePage->setBlackBackgroundSubst(substOn);
-	m_pageRender.decodePage();
-	m_pageRender.renderPage();
+	m_pageDecode.decodePage();
 	update();
 }

@@ -225,18 +230,18 @@ void TeletextWidget::setSidePanelWidths(int newLeftSidePanelColumns, int newRigh
 		m_levelOnePage->setSidePanelColumns((newLeftSidePanelColumns == 16) ? 0 : newLeftSidePanelColumns);
 	else
 		m_levelOnePage->setSidePanelColumns((newRightSidePanelColumns == 0) ? 0 : 16-newRightSidePanelColumns);
-	m_pageRender.updateSidePanels();
+	m_pageDecode.updateSidePanels();
 }

 void TeletextWidget::setSidePanelAtL35Only(bool newSidePanelAtL35Only)
 {
 	m_levelOnePage->setSidePanelStatusL25(!newSidePanelAtL35Only);
-	m_pageRender.updateSidePanels();
+	m_pageDecode.updateSidePanels();
 }

 void TeletextWidget::changeSize()
 {
-	setFixedSize(QSize(480+(pageRender()->leftSidePanelColumns()+pageRender()->rightSidePanelColumns())*12, 250));
+	setFixedSize(QSize(480+(pageDecode()->leftSidePanelColumns()+pageDecode()->rightSidePanelColumns())*12, 250));
 	emit sizeChanged();
 }

@@ -245,14 +250,14 @@ void TeletextWidget::keyPressEvent(QKeyEvent *event)
 	if (event->key() < 0x01000000) {
 		// A character-typing key was pressed
 		// Try to keymap it, if not keymapped then plain ASCII code (may be) returned
-		char mappedKeyPress = keymapping[m_pageRender.level1CharSet(m_teletextDocument->cursorRow(), m_teletextDocument->cursorColumn())].value(event->text().at(0), *qPrintable(event->text()));
+		char mappedKeyPress = keymapping[m_pageDecode.level1CharSet(m_teletextDocument->cursorRow(), m_teletextDocument->cursorColumn())].value(event->text().at(0), *qPrintable(event->text()));
 		if (mappedKeyPress < 0x20)
 			return;
 		// If outside ASCII map then the character can't be represented by current Level 1 character set
 		// Map it to block character so it doesn't need to be inserted-between later on
 		if (mappedKeyPress & 0x80)
 			mappedKeyPress = 0x7f;
-		if (m_pageRender.level1MosaicAttribute(m_teletextDocument->cursorRow(), m_teletextDocument->cursorColumn()) && (mappedKeyPress < 0x40 || mappedKeyPress > 0x5f)) {
+		if (m_pageDecode.level1MosaicAttribute(m_teletextDocument->cursorRow(), m_teletextDocument->cursorColumn()) && (mappedKeyPress < 0x40 || mappedKeyPress > 0x5f)) {
 			// We're on a mosaic and a blast-through character was NOT pressed
 			if (event->key() >= Qt::Key_1 && event->key() <= Qt::Key_9 && event->modifiers() & Qt::KeypadModifier) {
 				switch (event->key()) {
@@ -382,8 +387,8 @@ void TeletextWidget::keyPressEvent(QKeyEvent *event)
 			m_teletextDocument->selectSubPagePrevious();
 			break;
 		case Qt::Key_F5:
-			m_pageRender.decodePage();
-			m_pageRender.renderPage();
+			m_pageDecode.decodePage();
+			m_pageRender.renderPage(true);
 			update();
 			break;
 		default:
@@ -420,7 +425,7 @@ void TeletextWidget::selectionToClipboard()
 			nativeData[i++] = m_teletextDocument->currentSubPage()->character(r, c);

 			if (m_teletextDocument->currentSubPage()->character(r, c) >= 0x20)
-				plainTextData.append(keymapping[m_pageRender.level1CharSet(r, c)].key(m_teletextDocument->currentSubPage()->character(r, c), m_teletextDocument->currentSubPage()->character(r, c)));
+				plainTextData.append(keymapping[m_pageDecode.level1CharSet(r, c)].key(m_teletextDocument->currentSubPage()->character(r, c), m_teletextDocument->currentSubPage()->character(r, c)));
 			else
 				plainTextData.append(' ');
 		}
@@ -453,13 +458,13 @@ void TeletextWidget::copy()

 void TeletextWidget::paste()
 {
-	m_teletextDocument->undoStack()->push(new PasteCommand(m_teletextDocument, m_pageRender.level1CharSet(m_teletextDocument->cursorRow(), m_teletextDocument->cursorColumn())));
+	m_teletextDocument->undoStack()->push(new PasteCommand(m_teletextDocument, m_pageDecode.level1CharSet(m_teletextDocument->cursorRow(), m_teletextDocument->cursorColumn())));
 }

 QPair<int, int> TeletextWidget::mouseToRowAndColumn(const QPoint &mousePosition)
 {
 	int row = mousePosition.y() / 10;
-	int column = mousePosition.x() / 12 - m_pageRender.leftSidePanelColumns();
+	int column = mousePosition.x() / 12 - m_pageDecode.leftSidePanelColumns();
 	if (row < 1)
 		row = 1;
 	if (row > 24)
@@ -655,6 +660,22 @@ void LevelOneScene::updateSelection()
 	m_selectionRectItem->setVisible(true);
 }

+void LevelOneScene::setMix(bool mix)
+{
+	if (mix) {
+		m_fullScreenTopRectItem->setBrush(Qt::transparent);
+		m_fullScreenBottomRectItem->setBrush(Qt::transparent);
+		for (int r=0; r<25; r++) {
+			m_fullRowLeftRectItem[r]->setBrush(Qt::transparent);
+			m_fullRowRightRectItem[r]->setBrush(Qt::transparent);
+		}
+	} else {
+		setFullScreenColour(static_cast<TeletextWidget *>(m_levelOneProxyWidget->widget())->pageDecode()->fullScreenQColor());
+		for (int r=0; r<25; r++)
+			setFullRowColour(r, static_cast<TeletextWidget *>(m_levelOneProxyWidget->widget())->pageDecode()->fullRowQColor(r));
+	}
+}
+
 void LevelOneScene::toggleGrid(bool gridOn)
 {
 	m_grid = gridOn;
@@ -700,12 +721,16 @@ bool LevelOneScene::eventFilter(QObject *object, QEvent *event)

 void LevelOneScene::setFullScreenColour(const QColor &newColor)
 {
-	m_fullScreenTopRectItem->setBrush(QBrush(newColor));
-	m_fullScreenBottomRectItem->setBrush(QBrush(newColor));
+	if (!static_cast<TeletextWidget *>(m_levelOneProxyWidget->widget())->pageRender()->mix()) {
+		m_fullScreenTopRectItem->setBrush(newColor);
+		m_fullScreenBottomRectItem->setBrush(newColor);
+	}
 }

 void LevelOneScene::setFullRowColour(int row, const QColor &newColor)
 {
-	m_fullRowLeftRectItem[row]->setBrush(QBrush(newColor));
-	m_fullRowRightRectItem[row]->setBrush(QBrush(newColor));
+	if (!static_cast<TeletextWidget *>(m_levelOneProxyWidget->widget())->pageRender()->mix()) {
+		m_fullRowLeftRectItem[row]->setBrush(newColor);
+		m_fullRowRightRectItem[row]->setBrush(newColor);
+	}
 }
--- a/mainwidget.h
+++ b/mainwidget.h
@@ -29,6 +29,7 @@
 #include <QTextStream>
 #include <vector>

+#include "decode.h"
 #include "document.h"
 #include "levelonepage.h"
 #include "render.h"
@@ -46,12 +47,14 @@ public:
 	void toggleCharacterBit(unsigned char);
 	bool insertMode() const { return m_insertMode; };
 	void setInsertMode(bool);
+	bool showControlCodes() const { return m_pageRender.showControlCodes(); };

-	QSize sizeHint() { return QSize(480+(pageRender()->leftSidePanelColumns()+pageRender()->rightSidePanelColumns())*12, 250); }
+	QSize sizeHint() { return QSize(480+(pageDecode()->leftSidePanelColumns()+pageDecode()->rightSidePanelColumns())*12, 250); }

 	void inputMethodEvent(QInputMethodEvent *);

 	TeletextDocument* document() const { return m_teletextDocument; }
+	TeletextPageDecode *pageDecode() { return &m_pageDecode; }
 	TeletextPageRender *pageRender() { return &m_pageRender; }

 signals:
@@ -61,8 +64,9 @@ signals:
 public slots:
 	void subPageSelected();
 	void refreshPage();
-	void toggleReveal(bool);
-	void toggleMix(bool);
+	void setReveal(bool);
+	void setMix(bool);
+	void setShowControlCodes(bool);
 	void updateFlashTimer(int);
 	void pauseFlash(bool);
 	void refreshRow(int);
@@ -92,6 +96,7 @@ protected:
 	void focusInEvent(QFocusEvent *event) override;
 	void focusOutEvent(QFocusEvent *event) override;

+	TeletextPageDecode m_pageDecode;
 	TeletextPageRender m_pageRender;

 private:
@@ -119,6 +124,7 @@ public:
 public slots:
 	void updateCursor();
 	void updateSelection();
+	void setMix(bool);
 	void toggleGrid(bool);
 	void hideGUIElements(bool);
 	void setFullScreenColour(const QColor &);
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -157,28 +157,32 @@ void MainWindow::exportPNG()
 	// Prepare widget image for extraction
 	m_textWidget->pauseFlash(true);
 	m_textScene->hideGUIElements(true);
-	bool reshowCodes = m_textWidget->pageRender()->showCodes();
-	if (reshowCodes)
-		m_textWidget->pageRender()->setShowCodes(false);
+	bool reshowControlCodes = m_textWidget->showControlCodes();
+	if (reshowControlCodes)
+		m_textWidget->setShowControlCodes(false);
 	// Disable exporting in Mix mode as it corrupts the background
 	bool reMix = m_textWidget->pageRender()->mix();
-	if (reMix)
-		m_textWidget->pageRender()->setMix(false);
+	if (reMix) {
+		m_textWidget->setMix(false);
+		m_textScene->setMix(false);
+	}

 	// Extract the image from the scene
 	QImage interImage = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_RGB32);
 //	This ought to make the background transparent in Mix mode, but it doesn't
-//	if (m_textWidget->pageRender()->mix())
+//	if (m_textWidget->pageDecode()->mix())
 //		interImage.fill(QColor(0, 0, 0, 0));
 	QPainter interPainter(&interImage);
 	m_textScene->render(&interPainter);

 	// Now we've extracted the image we can put the GUI things back
 	m_textScene->hideGUIElements(false);
-	if (reshowCodes)
-		m_textWidget->pageRender()->setShowCodes(true);
-	if (reMix)
-		m_textWidget->pageRender()->setMix(true);
+	if (reshowControlCodes)
+		m_textWidget->setShowControlCodes(true);
+	if (reMix) {
+		m_textWidget->setMix(true);
+		m_textScene->setMix(true);
+	}
 	m_textWidget->pauseFlash(false);

 	// Now scale the extracted image to the selected aspect ratio
@@ -256,8 +260,8 @@ void MainWindow::init()
 	connect(m_textWidget->document(), &TeletextDocument::aboutToChangeSubPage, m_x26DockWidget, &X26DockWidget::unloadX26List);
 	connect(m_textWidget->document(), &TeletextDocument::subPageSelected, this, &MainWindow::updatePageWidgets);
 	connect(m_textWidget, &TeletextWidget::sizeChanged, this, &MainWindow::setSceneDimensions);
-	connect(m_textWidget->pageRender(), &TeletextPageRender::fullScreenColourChanged, m_textScene, &LevelOneScene::setFullScreenColour);
-	connect(m_textWidget->pageRender(), &TeletextPageRender::fullRowColourChanged, m_textScene, &LevelOneScene::setFullRowColour);
+	connect(m_textWidget->pageDecode(), &TeletextPageDecode::fullScreenColourChanged, m_textScene, &LevelOneScene::setFullScreenColour);
+	connect(m_textWidget->pageDecode(), &TeletextPageDecode::fullRowColourChanged, m_textScene, &LevelOneScene::setFullRowColour);
 	connect(m_textWidget, &TeletextWidget::insertKeyPressed, this, &MainWindow::toggleInsertMode);

 	connect(m_textScene, &LevelOneScene::mouseZoomIn, this, &MainWindow::zoomIn);
@@ -456,13 +460,14 @@ void MainWindow::createActions()
 	revealAct->setCheckable(true);
 	revealAct->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_R));
 	revealAct->setStatusTip(tr("Toggle reveal"));
-	connect(revealAct, &QAction::toggled, m_textWidget, &TeletextWidget::toggleReveal);
+	connect(revealAct, &QAction::toggled, m_textWidget, &TeletextWidget::setReveal);

 	QAction *mixAct = viewMenu->addAction(tr("&Mix"));
 	mixAct->setCheckable(true);
 	mixAct->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_M));
 	mixAct->setStatusTip(tr("Toggle mix"));
-	connect(mixAct, &QAction::toggled, m_textWidget, &TeletextWidget::toggleMix);
+	connect(mixAct, &QAction::toggled, m_textWidget, &TeletextWidget::setMix);
+	connect(mixAct, &QAction::toggled, m_textScene, &LevelOneScene::setMix);

 	QAction *gridAct = viewMenu->addAction(tr("&Grid"));
 	gridAct->setCheckable(true);
@@ -470,11 +475,11 @@ void MainWindow::createActions()
 	gridAct->setStatusTip(tr("Toggle the text grid"));
 	connect(gridAct, &QAction::toggled, m_textScene, &LevelOneScene::toggleGrid);

-	QAction *showCodesAct = viewMenu->addAction(tr("Show codes"));
-	showCodesAct->setCheckable(true);
-	showCodesAct->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_T));
-	showCodesAct->setStatusTip(tr("Toggle showing of control codes"));
-	connect(showCodesAct, &QAction::toggled, m_textWidget->pageRender(), &TeletextPageRender::setShowCodes);
+	QAction *showControlCodesAct = viewMenu->addAction(tr("Show control codes"));
+	showControlCodesAct->setCheckable(true);
+	showControlCodesAct->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_T));
+	showControlCodesAct->setStatusTip(tr("Toggle showing of control codes"));
+	connect(showControlCodesAct, &QAction::toggled, m_textWidget, &TeletextWidget::setShowControlCodes);

 	viewMenu->addSeparator();

@@ -668,7 +673,7 @@ void MainWindow::setSceneDimensions()
 	else
 		newSceneWidth = m_textWidget->width() + leftRightBorders[m_viewBorder]*2;

-	m_textScene->setBorderDimensions(newSceneWidth, 250+topBottomBorders[m_viewBorder]*2, m_textWidget->width(), m_textWidget->pageRender()->leftSidePanelColumns(), m_textWidget->pageRender()->rightSidePanelColumns());
+	m_textScene->setBorderDimensions(newSceneWidth, 250+topBottomBorders[m_viewBorder]*2, m_textWidget->width(), m_textWidget->pageDecode()->leftSidePanelColumns(), m_textWidget->pageDecode()->rightSidePanelColumns());
 	m_textView->setTransform(QTransform((1+(float)m_viewZoom/2)*aspectRatioHorizontalScaling[m_viewAspectRatio], 0, 0, 1+(float)m_viewZoom/2, 0, 0));
 }

@@ -792,10 +797,10 @@ void MainWindow::createStatusBar()
 		statusBar()->addPermanentWidget(m_levelRadioButton[i]);
 	}
 	m_levelRadioButton[0]->toggle();
-	connect(m_levelRadioButton[0], &QAbstractButton::clicked, [=]() { m_textWidget->pageRender()->setRenderLevel(0); m_textWidget->update(); });
-	connect(m_levelRadioButton[1], &QAbstractButton::clicked, [=]() { m_textWidget->pageRender()->setRenderLevel(1); m_textWidget->update(); });
-	connect(m_levelRadioButton[2], &QAbstractButton::clicked, [=]() { m_textWidget->pageRender()->setRenderLevel(2); m_textWidget->update(); });
-	connect(m_levelRadioButton[3], &QAbstractButton::clicked, [=]() { m_textWidget->pageRender()->setRenderLevel(3); m_textWidget->update(); });
+	connect(m_levelRadioButton[0], &QAbstractButton::clicked, [=]() { m_textWidget->pageDecode()->setRenderLevel(0); m_textWidget->update(); });
+	connect(m_levelRadioButton[1], &QAbstractButton::clicked, [=]() { m_textWidget->pageDecode()->setRenderLevel(1); m_textWidget->update(); });
+	connect(m_levelRadioButton[2], &QAbstractButton::clicked, [=]() { m_textWidget->pageDecode()->setRenderLevel(2); m_textWidget->update(); });
+	connect(m_levelRadioButton[3], &QAbstractButton::clicked, [=]() { m_textWidget->pageDecode()->setRenderLevel(3); m_textWidget->update(); });
 	statusBar()->showMessage(tr("Ready"));
 }

@@ -902,7 +907,7 @@ void MainWindow::loadFile(const QString &fileName)

 	levelSeen = m_textWidget->document()->levelRequired();
 	m_levelRadioButton[levelSeen]->toggle();
-	m_textWidget->pageRender()->setRenderLevel(levelSeen);
+	m_textWidget->pageDecode()->setRenderLevel(levelSeen);
 	updatePageWidgets();

 	QApplication::restoreOverrideCursor();
--- a/qteletextmaker.pro
+++ b/qteletextmaker.pro
@@ -1,7 +1,8 @@
 QT += widgets
 requires(qtConfig(filedialog))

-HEADERS       = document.h \
+HEADERS       = decode.h \
+                document.h \
                hamming.h \
                keymap.h \
                levelonecommands.h \
@@ -19,7 +20,8 @@ HEADERS       = document.h \
                x26dockwidget.h \
                x26model.h \
                x26triplets.h
-SOURCES       = document.cpp \
+SOURCES       = decode.cpp \
+                document.cpp \
                levelonecommands.cpp \
                levelonepage.cpp \
                loadsave.cpp \
--- a/render.cpp
+++ b/render.cpp
--- a/render.h
+++ b/render.h
@@ -21,169 +21,17 @@
 #define RENDER_H

 #include <QBitmap>
-#include <QMap>
-#include <QMultiMap>
-#include <QPair>
-#include <vector>
+#include <QSet>
+#include <QPixmap>

-#include "levelonepage.h"
-
-
-struct textCharacter {
-	unsigned char code=0x20;
-	int set=0;
-	int diacritical=0;
-};
-
-struct displayAttributes {
-	bool doubleHeight=false;
-	bool doubleWidth=false;
-	bool boxingWindow=false;
-	bool conceal=false;
-	bool invert=false;
-	bool underlineSeparated=false;
-	bool forceContiguous=false;
-};
-
-struct textAttributes {
-	int foreColour=0x07;
-	int backColour=0x00;
-	struct flashFunctions {
-		int mode=0;
-		int ratePhase=0;
-		int phaseNumber=0;
-	} flash;
-	displayAttributes display;
-	/* font style */
-};
-
-struct textCell {
-	textCharacter character;
-	textAttributes attribute;
-	bool bottomHalf=false;
-	bool rightHalf=false;
-	bool level1Mosaic=false;
-	int level1CharSet=0;
-};
-
-struct applyAttributes {
-	bool applyForeColour=false;
-	bool applyBackColour=false;
-	bool applyFlash=false;
-	bool applyDisplayAttributes=false;
-	bool applyTextSizeOnly=false;
-	bool applyBoxingOnly=false;
-	bool applyConcealOnly=false;
-	bool applyContiguousOnly=false;
-	bool copyAboveAttributes=false;
-	textAttributes attribute;
-};
-
-class ActivePosition
-{
-public:
-	ActivePosition();
-	int row() const { return (m_row == -1) ? 0 : m_row; }
-	int column() const { return (m_column == -1) ? 0 : m_column; }
-	bool isDeployed() const { return m_row != -1; }
-	bool setRow(int);
-	bool setColumn(int);
-//	bool setRowAndColumn(int, int);
-
-private:
-	int m_row, m_column;
-};
-
-
-class TextLayer
-{
-public:
-//	TextLayer(TeletextPage* thePage) : currentPage(thePage) { };
-	virtual ~TextLayer() = default;
-	void setTeletextPage(LevelOnePage *);
-	virtual textCharacter character(int, int) =0;
-	virtual void attributes(int, int, applyAttributes *) =0;
-	virtual int fullScreenColour() const =0;
-	virtual int fullRowColour(int) const =0;
-	virtual bool fullRowDownwards(int) const =0;
-	virtual int objectType() const =0;
-	virtual int originR() const { return 0; };
-	virtual int originC() const { return 0; };
-	void setFullScreenColour(int);
-	void setFullRowColour(int, int, bool);
-
-	// Key QPair is row and column, value QPair is triplet mode and data
-	QMultiMap<QPair<int, int>, QPair<int, int>> enhanceMap;
-
-protected:
-	LevelOnePage* m_levelOnePage;
-	int m_layerFullScreenColour=-1;
-	int m_layerFullRowColour[25];
-	bool m_layerFullRowDownwards[25];
-	applyAttributes m_applyAttributes;
-};
-
-class EnhanceLayer: public TextLayer
-{
-public:
-	EnhanceLayer();
-	textCharacter character(int, int);
-	void attributes(int, int, applyAttributes *);
-	int fullScreenColour() const { return m_layerFullScreenColour; };
-	int fullRowColour(int r) const { return m_layerFullRowColour[r]; };
-	bool fullRowDownwards(int r) const { return m_layerFullRowDownwards[r]; };
-	int objectType() const { return m_objectType; };
-	int originR() const { return m_originR; };
-	int originC() const { return m_originC; };
-	void setObjectType(int);
-	void setOrigin(int, int);
-
-protected:
-	int m_objectType=0;
-	int m_originR=0;
-	int m_originC=0;
-	int m_rowCached=-1;
-	int m_rightMostColumn[25];
-};
-
-class Level1Layer: public TextLayer
-{
-public:
-//	Level1Layer(TeletextPage *thePage) : TextLayer(thePage) { };
-	Level1Layer();
-	textCharacter character(int, int);
-	void attributes(int, int, applyAttributes *);
-	int fullScreenColour() const { return -1; };
-	int fullRowColour(int) const { return -1; };
-	bool fullRowDownwards(int) const { return false; };
-	int objectType() const { return 0; }
-	bool isRowBottomHalf(int r) const { return m_rowHeight[r]==RHbottomhalf; }
-
-private:
-	void updateRowCache(int);
-
-	struct level1CacheAttributes {
-		int foreColour=0x07;
-		int backColour=0x00;
-		unsigned char sizeCode=0x0c;
-		bool mosaics=false;
-		bool separated=false;
-		bool held=false;
-		bool escSwitch=false;
-		unsigned char holdChar=0x20;
-		bool holdSeparated=false;
-	};
-	level1CacheAttributes m_attributeCache[40];
-	int m_rowCached=-1;
-	bool m_rowHasDoubleHeightAttr[25];
-	enum rowHeightEnum { RHnormal=-1, RHtophalf, RHbottomhalf } m_rowHeight[25];
-};
+#include "decode.h"

 class TeletextFontBitmap
 {
 public:
 	TeletextFontBitmap();
 	~TeletextFontBitmap();
+
 	QBitmap *rawBitmap() const { return s_fontBitmap; }

 private:
@@ -198,67 +46,38 @@ class TeletextPageRender : public QObject
 public:
 	TeletextPageRender();
 	~TeletextPageRender();
-	void decodePage();
-	void renderPage();
-	void renderPage(int r);
-	bool mix() const { return m_mix; };
-	bool showCodes() const { return m_showCodes; };
-	void setTeletextPage(LevelOnePage *);
-	void updateSidePanels();
-	void buildEnhanceMap(TextLayer *, int=0);
+
 	QPixmap* pagePixmap(int i) const { return m_pagePixmap[i]; };
-	bool level1MosaicAttribute(int r, int c) const { return m_cell[r][c].level1Mosaic; };
-	int level1CharSet(int r, int c) const { return m_cell[r][c].level1CharSet; };
-	int leftSidePanelColumns() const { return m_leftSidePanelColumns; };
-	int rightSidePanelColumns() const { return m_rightSidePanelColumns; };
+	bool mix() const { return m_mix; };
+	void setDecoder(TeletextPageDecode *);
+	void renderPage(bool force=false);
+	bool showControlCodes() const { return m_showControlCodes; };

 public slots:
+	void colourChanged(int);
 	void setReveal(bool);
 	void setMix(bool);
-	void setShowCodes(bool);
-	void setRenderLevel(int);
+	void setShowControlCodes(bool);

 signals:
-	void fullScreenColourChanged(QColor);
-	void fullRowColourChanged(int, QColor);
 	void flashChanged(int);
-	void sidePanelsChanged();

 protected:
-	void updateFlashRequired(int);
-	inline void setFullScreenColour(int);
-	inline void setFullRowColour(int, int);
-
 	TeletextFontBitmap m_fontBitmap;
 	QPixmap* m_pagePixmap[6];
-	int m_finalFullScreenColour, m_renderLevel;
-	QColor m_finalFullScreenQColor;
-	int m_leftSidePanelColumns, m_rightSidePanelColumns;
-	bool m_reveal, m_mix, m_showCodes;
-	Level1Layer m_level1Layer;
-	std::vector<TextLayer *> m_textLayer;
-	const int m_foregroundRemap[8] = { 0,  0,  0,  8,  8, 16, 16, 16 };
-	const int m_backgroundRemap[8] = { 0,  8, 16,  8, 16,  8, 16, 24 };
+	textCell m_cell[25][72];
+	unsigned char m_controlCodeCache[25][40];
+	bool m_reveal, m_mix, m_showControlCodes;
+	QSet<QPair<int, int>> m_flash1HzCells;
+	QSet<QPair<int, int>> m_flash2HzCells;
+	int m_flashBuffersHz;

 private:
-	textCell m_cell[25][72];
-	LevelOnePage* m_levelOnePage;
-	int m_flashRequired;
-	int m_fullRowColour[25];
-	QColor m_fullRowQColor[25];
-	int m_flashRow[25];
-	bool m_concealRow[25];
-};
+	inline void drawFromFontBitmap(QPainter &, int, int, unsigned char, int, TeletextPageDecode::CharacterFragment);
+	inline void drawCharacter(QPainter &, int, int, unsigned char, int, int, TeletextPageDecode::CharacterFragment);
+	void updateFlashBuffers();

-static const QMap<int, int> g0CharacterMap {
-	{ 0x00, 12 }, { 0x01, 15 }, { 0x02, 22 }, { 0x03, 16 }, { 0x04, 14 }, { 0x05, 19 }, { 0x06, 11 },
-	{ 0x08, 18 }, { 0x09, 15 }, { 0x0a, 22 }, { 0x0b, 16 }, { 0x0c, 14 }, { 0x0e, 11 },
-	{ 0x10, 12 }, { 0x11, 15 }, { 0x12, 22 }, { 0x13, 16 }, { 0x14, 14 }, { 0x15, 19 }, { 0x16, 23 },
-	{ 0x1d, 21 }, { 0x1f, 20 },
-	{ 0x20,  1 }, { 0x21, 15 }, { 0x22, 13 }, { 0x23, 17 }, { 0x24,  2 }, { 0x25,  3 }, { 0x26, 11 },
-	{ 0x36, 23 }, { 0x37,  4 },
-	{ 0x40, 12 }, { 0x44, 14 }, { 0x47,  5 },
-	{ 0x55,  6 }, { 0x57,  5 }
+	TeletextPageDecode *m_decoder;
 };

 #endif