Optimise rendering of pages with flashing characters

Previously every character on the page was drawn up to six times. Now the
page is drawn once, quickly copied up to five times and then only the
flashing characters are redrawn on the copies.

render.cpp

@@ -55,9 +55,11 @@ TeletextPageRender::TeletextPageRender()
 	m_showControlCodes = false;
 	m_flashBuffersHz = 0;
 
-	for (int r=0; r<25; r++)
+	for (int r=0; r<25; r++) {
+		m_flashingRow[r] = 0;
 		for (int c=0; c<40; c++)
 			m_controlCodeCache[r][c] = 0x7f;
+	}
 }
 
 TeletextPageRender::~TeletextPageRender()
@@ -182,44 +184,24 @@ inline void TeletextPageRender::drawCharacter(QPainter &pixmapPainter, int r, in
 
 void TeletextPageRender::renderPage(bool force)
 {
-	QPainter pixmapPainter[6];
-	int previousFlashBuffersHz = m_flashBuffersHz;
-
-	// If force-rendering (such as showing a new or different subpage) then
-	// we don't render flashing cells initially as it greatly speeds things up
-	// when rendering on top of an already flashing page.
-	// At the end of this method, if flashing cells are present then this method
-	// recursively calls itself with force=false to render the flashing cells.
-	if (force) {
-		m_flashBuffersHz = 0;
-		previousFlashBuffersHz = 0;
-		emit flashChanged(0);
-	}
-
-	pixmapPainter[0].begin(m_pagePixmap[0]);
-	pixmapPainter[0].setBackgroundMode(Qt::OpaqueMode);
-	if (m_flashBuffersHz != 0) {
-		pixmapPainter[3].begin(m_pagePixmap[3]);
-		pixmapPainter[3].setBackgroundMode(Qt::OpaqueMode);
-		if (m_flashBuffersHz == 2) {
-			pixmapPainter[1].begin(m_pagePixmap[1]);
-			pixmapPainter[1].setBackgroundMode(Qt::OpaqueMode);
-			pixmapPainter[2].begin(m_pagePixmap[2]);
-			pixmapPainter[2].setBackgroundMode(Qt::OpaqueMode);
-			pixmapPainter[4].begin(m_pagePixmap[4]);
-			pixmapPainter[4].setBackgroundMode(Qt::OpaqueMode);
-			pixmapPainter[5].begin(m_pagePixmap[5]);
-			pixmapPainter[5].setBackgroundMode(Qt::OpaqueMode);
-		}
-	}
-
 	for (int r=0; r<25; r++)
-		for (int c=0; c<72; c++) {
+		renderRow(r, 0, force);
+}
 
+void TeletextPageRender::renderRow(int r, int ph, bool force)
+{
+	QPainter pixmapPainter;
+	int flashingRow = 0;
+	bool rowRefreshed = false;
+
+	pixmapPainter.begin(m_pagePixmap[ph]);
+	pixmapPainter.setBackgroundMode(Qt::OpaqueMode);
+
+	for (int c=0; c<72; c++) {
 		bool controlCodeChanged = false;
 
 		// Ensure that shown control codes are refreshed
-			if (m_showControlCodes && c < 40 && (m_controlCodeCache[r][c] != 0x7f || m_decoder->teletextPage()->character(r, c) < 0x20)) {
+		if (ph == 0 && m_showControlCodes && c < 40 && (m_controlCodeCache[r][c] != 0x7f || m_decoder->teletextPage()->character(r, c) < 0x20)) {
 			controlCodeChanged = m_controlCodeCache[r][c] != m_decoder->teletextPage()->character(r, c);
 			if (controlCodeChanged) {
 				if (m_decoder->teletextPage()->character(r, c) < 0x20)
@@ -229,10 +211,21 @@ void TeletextPageRender::renderPage(bool force)
 			}
 		}
 
+		if (ph == 0) {
+			if (m_decoder->cellFlashMode(r, c) != 0)
+				flashingRow = (m_decoder->cellFlashRatePhase(r, c) == 0) ? 1 : 2;
+		} else
+			force = m_decoder->cellFlashMode(r, c) != 0;
+
+		// If drawing into a flash pixmap buffer, "force" is set on a flashing cell only
+		// and since the refresh and controlCodeChanged variables will be false at this point
+		// only flashing cells will be drawn
 		if (m_decoder->refresh(r, c) || force || controlCodeChanged) {
 			unsigned char characterCode;
 			int characterSet, characterDiacritical;
 
+			rowRefreshed = true;
+
 			if (!m_reveal && m_decoder->cellConceal(r, c)) {
 				characterCode = 0x20;
 				characterSet = 0;
@@ -243,163 +236,149 @@ void TeletextPageRender::renderPage(bool force)
 				characterDiacritical = m_decoder->cellCharacterDiacritical(r, c);
 			}
 
-				// QSet::insert won't insert a duplicate value already in the set
+			if (m_decoder->cellFlashMode(r, c) == 0)
-				// QSet::remove doesn't mind if we try to remove a value that's not there
+				pixmapPainter.setPen(m_decoder->cellForegroundQColor(r, c));
-				if (m_flashBuffersHz == 0 && m_decoder->cellFlashMode(r, c) != 0) {
+			else {
-					if (m_decoder->cellFlashRatePhase(r, c) == 0)
+				// Flashing cell, decide if phase in this cycle is on or off
-						m_flash1HzCells.insert(qMakePair(r, c));
-					else
-						m_flash2HzCells.insert(qMakePair(r, c));
-					if (!force)
-						updateFlashBuffers();
-				} else if (m_decoder->cellFlashMode(r, c) == 0) {
-					m_flash1HzCells.remove(qMakePair(r, c));
-					m_flash2HzCells.remove(qMakePair(r, c));
-					if (!force)
-						updateFlashBuffers();
-				} else if (m_decoder->cellFlashRatePhase(r, c) == 0) {
-					m_flash1HzCells.insert(qMakePair(r, c));
-					m_flash2HzCells.remove(qMakePair(r, c));
-					if (!force)
-						updateFlashBuffers();
-				} else {
-					m_flash1HzCells.remove(qMakePair(r, c));
-					m_flash2HzCells.insert(qMakePair(r, c));
-					if (!force)
-						updateFlashBuffers();
-				}
-
-				// If flash rate has gone up, prepare painters for the other buffers
-				if (m_flashBuffersHz > previousFlashBuffersHz) {
-					if (previousFlashBuffersHz == 0) {
-						pixmapPainter[3].begin(m_pagePixmap[3]);
-						pixmapPainter[3].setBackgroundMode(Qt::OpaqueMode);
-					}
-					if (m_flashBuffersHz == 2) {
-						pixmapPainter[1].begin(m_pagePixmap[1]);
-						pixmapPainter[1].setBackgroundMode(Qt::OpaqueMode);
-						pixmapPainter[2].begin(m_pagePixmap[2]);
-						pixmapPainter[2].setBackgroundMode(Qt::OpaqueMode);
-						pixmapPainter[4].begin(m_pagePixmap[4]);
-						pixmapPainter[4].setBackgroundMode(Qt::OpaqueMode);
-						pixmapPainter[5].begin(m_pagePixmap[5]);
-						pixmapPainter[5].setBackgroundMode(Qt::OpaqueMode);
-					}
-					previousFlashBuffersHz = m_flashBuffersHz;
-				}
-
-				// If flash rate has gone down, end the painters so we don't crash
-				// if the pixmaps get copied due to the flash rate going up again
-				if (m_flashBuffersHz < previousFlashBuffersHz) {
-					if (previousFlashBuffersHz == 2) {
-						pixmapPainter[1].end();
-						pixmapPainter[2].end();
-						pixmapPainter[4].end();
-						pixmapPainter[5].end();
-					}
-					if (m_flashBuffersHz == 0)
-						pixmapPainter[3].end();
-
-					previousFlashBuffersHz = m_flashBuffersHz;
-				}
-
-				if (m_flashBuffersHz == 0) {
-					pixmapPainter[0].setPen(m_decoder->cellForegroundQColor(r, c));
-					if (!m_mix || m_decoder->cellBoxed(r, c))
-						pixmapPainter[0].setBackground(m_decoder->cellBackgroundQColor(r, c));
-					else
-						pixmapPainter[0].setBackground(Qt::transparent);
-					drawCharacter(pixmapPainter[0], r, c, characterCode, characterSet, characterDiacritical, m_decoder->cellCharacterFragment(r, c));
-				} else {
-					for (int i=0; i<6; i++) {
-						if (m_flashBuffersHz == 1 && (i == 1 || i == 2 || i == 4 || i == 5))
-							continue;
-
 				bool phaseOn;
 
 				if (m_decoder->cellFlashRatePhase(r, c) == 0)
-							phaseOn = (i < 3) ^ (m_decoder->cellFlashMode(r, c) == 2);
+					phaseOn = (ph < 3) ^ (m_decoder->cellFlashMode(r, c) == 2);
 				else
-							phaseOn = ((i == m_decoder->cellFlash2HzPhaseNumber(r, c)-1) || (i == m_decoder->cellFlash2HzPhaseNumber(r, c)+2)) ^ (m_decoder->cellFlashMode(r, c) == 2);
+					phaseOn = ((ph == m_decoder->cellFlash2HzPhaseNumber(r, c)-1) || (ph == m_decoder->cellFlash2HzPhaseNumber(r, c)+2)) ^ (m_decoder->cellFlashMode(r, c) == 2);
+
+				// If flashing to adjacent CLUT select the appropriate foreground colour
+				if (m_decoder->cellFlashMode(r, c) == 3 && !phaseOn)
+					pixmapPainter.setPen(m_decoder->cellFlashForegroundQColor(r, c));
+				else
+					pixmapPainter.setPen(m_decoder->cellForegroundQColor(r, c));
+
+				// If flashing mode is Normal or Invert, draw a space instead of a character on phase
+				if ((m_decoder->cellFlashMode(r, c) == 1 || m_decoder->cellFlashMode(r, c) == 2) && !phaseOn) {
+					// Character 0x00 draws space without underline
+					characterCode = 0x00;
+					characterSet = 0;
+					characterDiacritical = 0;
+				}
+			}
 
 			if (!m_mix || m_decoder->cellBoxed(r, c))
-							pixmapPainter[i].setBackground(m_decoder->cellBackgroundQColor(r, c));
+				pixmapPainter.setBackground(m_decoder->cellBackgroundQColor(r, c));
 			else
-							pixmapPainter[i].setBackground(Qt::transparent);
+				pixmapPainter.setBackground(Qt::transparent);
-						if (m_decoder->cellFlashMode(r, c) == 3 && !phaseOn)
+
-							pixmapPainter[i].setPen(m_decoder->cellFlashForegroundQColor(r, c));
+			drawCharacter(pixmapPainter, r, c, characterCode, characterSet, characterDiacritical, m_decoder->cellCharacterFragment(r, c));
-						else
-							pixmapPainter[i].setPen(m_decoder->cellForegroundQColor(r, c));
-						if ((m_decoder->cellFlashMode(r, c) == 1 || m_decoder->cellFlashMode(r, c) == 2) && !phaseOn)
-							// Character 0x00 draws space without underline
-							drawCharacter(pixmapPainter[i], r, c, 0x00, 0, 0, m_decoder->cellCharacterFragment(r, c));
-						else
-							drawCharacter(pixmapPainter[i], r, c, characterCode, characterSet, characterDiacritical, m_decoder->cellCharacterFragment(r, c));
-					}
-				}
 
 			if (m_showControlCodes && c < 40 && m_decoder->teletextPage()->character(r, c) < 0x20) {
-					pixmapPainter[0].setBackground(QColor(0, 0, 0, 128));
+				pixmapPainter.setBackground(QColor(0, 0, 0, 128));
-					pixmapPainter[0].setPen(QColor(255, 255, 255, 224));
+				pixmapPainter.setPen(QColor(255, 255, 255, 224));
-					pixmapPainter[0].drawPixmap(c*12, r*10, *m_fontBitmap.rawBitmap(), (m_decoder->teletextPage()->character(r, c)+32)*12, 250, 12, 10);
+				pixmapPainter.drawPixmap(c*12, r*10, *m_fontBitmap.rawBitmap(), (m_decoder->teletextPage()->character(r, c)+32)*12, 250, 12, 10);
-					if (m_flashBuffersHz == 1) {
+			}
-						pixmapPainter[3].setBackground(QColor(0, 0, 0, 128));
-						pixmapPainter[3].setPen(QColor(255, 255, 255, 224));
-						pixmapPainter[3].drawPixmap(c*12, r*10, *m_fontBitmap.rawBitmap(), (m_decoder->teletextPage()->character(r, c)+32)*12, 250, 12, 10);
-					} else if (m_flashBuffersHz == 2)
-						for (int i=1; i<6; i++) {
-							pixmapPainter[i].setBackground(QColor(0, 0, 0, 128));
-							pixmapPainter[i].setPen(QColor(255, 255, 255, 224));
-							pixmapPainter[i].drawPixmap(c*12, r*10, *m_fontBitmap.rawBitmap(), (m_decoder->teletextPage()->character(r, c)+32)*12, 250, 12, 10);
 		}
 	}
 
-				if (force && m_decoder->cellFlashMode(r, c) != 0)
+	pixmapPainter.end();
-					m_decoder->setRefresh(r, c, true);
-				else
-					m_decoder->setRefresh(r, c, false);
-			}
-		}
 
-	pixmapPainter[0].end();
+	if (ph != 0)
-	if (m_flashBuffersHz != 0) {
-		pixmapPainter[3].end();
-		if (m_flashBuffersHz == 2) {
-			pixmapPainter[1].end();
-			pixmapPainter[2].end();
-			pixmapPainter[4].end();
-			pixmapPainter[5].end();
-		}
-	}
-
-	if (force && (!m_flash1HzCells.isEmpty() || !m_flash2HzCells.isEmpty()))
-		renderPage();
-}
-
-void TeletextPageRender::updateFlashBuffers()
-{
-	int highestFlashHz;
-
-	if (!m_flash2HzCells.isEmpty())
-		highestFlashHz = 2;
-	else
-		highestFlashHz = !m_flash1HzCells.isEmpty();
-
-	if (highestFlashHz == m_flashBuffersHz)
 		return;
 
-	if (highestFlashHz > m_flashBuffersHz) {
+	if (flashingRow == 3)
+		flashingRow = 2;
+	if (flashingRow != m_flashingRow[r])
+		setRowFlashStatus(r, flashingRow);
+
+	for (int c=0; c<72; c++)
+		m_decoder->setRefresh(r, c, false);
+
+	// If row had changes rendered and flashing is present anywhere on the screen,
+	// copy this rendered line into the other flash pixmap buffers and then re-render
+	// the flashing cells in those buffers
+	if (rowRefreshed && m_flashBuffersHz > 0) {
+		pixmapPainter.begin(m_pagePixmap[3]);
+		pixmapPainter.setCompositionMode(QPainter::CompositionMode_Clear);
+		pixmapPainter.eraseRect(0, r*10, 864, 10);
+		pixmapPainter.setCompositionMode(QPainter::CompositionMode_SourceOver);
+		pixmapPainter.drawPixmap(0, r*10, *m_pagePixmap[0], 0, r*10, 864, 10);
+		pixmapPainter.end();
+
+		renderRow(r, 3);
+
+		if (m_flashBuffersHz == 2) {
+			pixmapPainter.begin(m_pagePixmap[1]);
+			pixmapPainter.setCompositionMode(QPainter::CompositionMode_Clear);
+			pixmapPainter.eraseRect(0, r*10, 864, 10);
+			pixmapPainter.setCompositionMode(QPainter::CompositionMode_SourceOver);
+			pixmapPainter.drawPixmap(0, r*10, *m_pagePixmap[0], 0, r*10, 864, 10);
+			pixmapPainter.end();
+			pixmapPainter.begin(m_pagePixmap[2]);
+			pixmapPainter.setCompositionMode(QPainter::CompositionMode_Clear);
+			pixmapPainter.eraseRect(0, r*10, 864, 10);
+			pixmapPainter.setCompositionMode(QPainter::CompositionMode_SourceOver);
+			pixmapPainter.drawPixmap(0, r*10, *m_pagePixmap[0], 0, r*10, 864, 10);
+			pixmapPainter.end();
+			pixmapPainter.begin(m_pagePixmap[4]);
+			pixmapPainter.setCompositionMode(QPainter::CompositionMode_Clear);
+			pixmapPainter.eraseRect(0, r*10, 864, 10);
+			pixmapPainter.setCompositionMode(QPainter::CompositionMode_SourceOver);
+			pixmapPainter.drawPixmap(0, r*10, *m_pagePixmap[3], 0, r*10, 864, 10);
+			pixmapPainter.end();
+			pixmapPainter.begin(m_pagePixmap[5]);
+			pixmapPainter.setCompositionMode(QPainter::CompositionMode_Clear);
+			pixmapPainter.eraseRect(0, r*10, 864, 10);
+			pixmapPainter.setCompositionMode(QPainter::CompositionMode_SourceOver);
+			pixmapPainter.drawPixmap(0, r*10, *m_pagePixmap[3], 0, r*10, 864, 10);
+			pixmapPainter.end();
+
+			renderRow(r, 1);
+			renderRow(r, 2);
+			renderRow(r, 4);
+			renderRow(r, 5);
+		}
+	}
+}
+
+void TeletextPageRender::setRowFlashStatus(int r, int rowFlashHz)
+{
+	m_flashingRow[r] = rowFlashHz;
+
+	if (rowFlashHz == m_flashBuffersHz)
+		return;
+
+	if (rowFlashHz < m_flashBuffersHz) {
+		// New flash Hz for this row is lower than the entire screen flash Hz
+		// Check the other rows if they still need flashing at the current flash Hz
+		// If not, reduce the screen flash Hz
+		int highestRowFlashHz = rowFlashHz;
+
+		for (int ri=0; ri<25; ri++)
+			if (m_flashingRow[ri] > highestRowFlashHz) {
+				highestRowFlashHz = m_flashingRow[ri];
+				if (highestRowFlashHz == 2)
+					break;
+			}
+
+		if (highestRowFlashHz > rowFlashHz)
+			rowFlashHz = highestRowFlashHz;
+		if (rowFlashHz == m_flashBuffersHz)
+			return;
+
+		m_flashBuffersHz = rowFlashHz;
+		emit flashChanged(m_flashBuffersHz);
+		return;
+	}
+
+	// If we get here, new flash Hz for this row is higher than the entire flash Hz
+	// so prepare the pixmap flash buffers
 	if (m_flashBuffersHz == 0)
 		*m_pagePixmap[3] = m_pagePixmap[0]->copy();
-		if (highestFlashHz == 2) {
+	if (rowFlashHz == 2) {
 		*m_pagePixmap[1] = m_pagePixmap[0]->copy();
 		*m_pagePixmap[2] = m_pagePixmap[0]->copy();
 		*m_pagePixmap[4] = m_pagePixmap[3]->copy();
 		*m_pagePixmap[5] = m_pagePixmap[3]->copy();
 	}
-	}
 
-	m_flashBuffersHz = highestFlashHz;
+	m_flashBuffersHz = rowFlashHz;
 	emit flashChanged(m_flashBuffersHz);
 }
 

render.h

@@ -21,7 +21,6 @@
 #define RENDER_H
 
 #include <QBitmap>
-#include <QSet>
 #include <QPixmap>
 
 #include "decode.h"
@@ -67,14 +66,14 @@ protected:
 	QPixmap* m_pagePixmap[6];
 	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;
+	int m_flashingRow[25];
 
 private:
 	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();
+	void renderRow(int, int, bool force=false);
+	void setRowFlashStatus(int, int);
 
 	TeletextPageDecode *m_decoder;
 };