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Implement DRCS rendering

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External pages with DRCS definitions can be loaded using the options in the
"DRCS pages" submenu within the "View" menu. Two DRCS pages can be loaded,
one for Global DRCS definitions and the other for Normal DRCS definitions.

Level 2.5 mode 0 PTUs are fully supported.

Partial support for Level 3.5 mode 1, 2 and 3 PTUs. DCLUTs defined in X/28/1
on the main page are not yet implemented; the characters currently appear in
the default DCLUTs described in D.1.6 and D.2.2 of the ETSI spec.
This commit is contained in:
Gavin MacGregor
2025-06-09 18:57:16 +01:00
parent 519c961cff
commit e1ba67484f
8 changed files with 536 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

193
src/qteletextdecoder/decode.cpp
View File

@@ -19,9 +19,16 @@
#include "decode.h"
#include <QByteArray>
#include <QImage>
#include <QList>
#include <QMultiMap>
#include "drcspage.h"
#include "levelonepage.h"
#include "pagebase.h"
TeletextPageDecode::Invocation::Invocation()
{
m_tripletList = nullptr;
@@ -113,6 +120,7 @@ void TeletextPageDecode::Invocation::buildMap(int level)
if (targetRow == 0)
m_fullRowCLUTMap.insert(targetRow, triplet);
break;
case 0x18: // DRCS mode
case 0x20: // Foreground colour
case 0x23: // Background colour
case 0x27: // Additional flash functions
@@ -128,6 +136,7 @@ void TeletextPageDecode::Invocation::buildMap(int level)
case 0x22: // G3 character at Level 1.5
case 0x29: // G0 character
case 0x2b: // G3 character at Level 2.5
case 0x2d: // DRCS character
case 0x2f: // G2 character
m_characterMap.insert(qMakePair(targetRow, targetColumn), triplet);
m_rightMostColumn.insert(targetRow, targetColumn);
@@ -184,6 +193,9 @@ TeletextPageDecode::TeletextPageDecode()
m_fullRowQColor[r].setRgb(0, 0, 0);
}
m_leftSidePanelColumns = m_rightSidePanelColumns = 0;
m_drcsPage[GlobalDRCSPage] = nullptr;
m_drcsPage[NormalDRCSPage] = nullptr;
}
TeletextPageDecode::~TeletextPageDecode()
@@ -203,6 +215,28 @@ void TeletextPageDecode::setTeletextPage(LevelOnePage *newCurrentPage)
updateSidePanels();
}
void TeletextPageDecode::setDRCSPage(DRCSPageType pageType, QList<DRCSPage> *pages)
{
m_drcsPage[pageType] = pages;
bool refreshRequired = false;
for (int r=0; r<25; r++)
for (int c=0; c<72; c++)
if (m_cell[r][c].character.drcsSource != NoDRCS) {
m_refresh[r][c] = true;
refreshRequired = true;
}
if (refreshRequired)
decodePage();
}
void TeletextPageDecode::clearDRCSPage(DRCSPageType pageType)
{
setDRCSPage(pageType, nullptr);
}
void TeletextPageDecode::setLevel(int level)
{
if (level == m_level)
@@ -218,6 +252,116 @@ void TeletextPageDecode::setLevel(int level)
decodePage();
}
QImage TeletextPageDecode::drcsImage(DRCSSource pageType, int subTable, int chr, bool flashPhOn)
{
if (pageType == NoDRCS)
return QImage();
// Check if page is loaded and if the subpage exists
const QList<DRCSPage>* drcsPage = m_drcsPage[pageType-1];
if (drcsPage == nullptr || subTable >= drcsPage->size())
return QImage();
// Level 2.5: only and always mode 0 (12x10x1) and doesn't use X/28/3
// Level 3.5: if X/28/3 is absent, drcsMode below returns mode 0
if (m_level == 2 || drcsPage->at(subTable).drcsMode(chr) == 0) {
uchar rawData[20];
if (!drcsPage->at(subTable).ptu(chr, rawData))
return QImage();
QImage result = QImage(rawData, 12, 10, 2, QImage::Format_Mono);
return result.copy();
}
// Level 3.5: obey X/28/3 "subsequent PTU" and "no data" values, ignore reserved values
const int drcsMode = drcsPage->at(subTable).drcsMode(chr);
if (drcsMode > 3)
return QImage();
uchar rawData[120];
if (drcsMode != 3) {
// mode 1 (12x10x2) or mode 2 (12x10x4)
// Each complete bitplane stored sequentially across multiple PTUs
uchar bitplaneArr[4][20] = { };
// Get the PTUs for each bitplane
drcsPage->at(subTable).ptu(chr, bitplaneArr[0]);
if (chr < 47)
drcsPage->at(subTable).ptu(chr+1, bitplaneArr[1]);
if (drcsMode == 2) {
if (chr < 46)
drcsPage->at(subTable).ptu(chr+2, bitplaneArr[2]);
if (chr < 45)
drcsPage->at(subTable).ptu(chr+3, bitplaneArr[3]);
}
// Now assemble the bitplanes into byte-per-pixel data
for (int x=0; x<12; x++)
for (int y=0; y<10; y++) {
const int scanByte = y*2 + (x > 7);
const int scanBit = 7 - x%8;
rawData[x + y*12] = bitplaneArr[0][scanByte] >> scanBit & 1;
rawData[x + y*12] |= (bitplaneArr[1][scanByte] >> scanBit & 1) << 1;
if (drcsMode == 2) {
rawData[x + y*12] |= (bitplaneArr[2][scanByte] >> scanBit & 1) << 2;
rawData[x + y*12] |= (bitplaneArr[3][scanByte] >> scanBit & 1) << 3;
}
}
} else {
// mode 3 (6x5x4)
// Interleaved: First row of six pixels is stored four times sequentially, one for
// each bitplane, then second row of pixels four times, and so on
const int pktNo = (chr+2)/2;
if (!drcsPage->at(subTable).packetExists(pktNo))
return QImage();
QByteArray pkt;
if (chr % 2 == 0)
pkt = drcsPage->at(subTable).packet(pktNo).first(20);
else
pkt = drcsPage->at(subTable).packet(pktNo).last(20);
for (int x=0; x<6; x++)
for (int y=0; y<5; y++) {
const int scanByte = y * 4;
const int scanBit = 5 - x;
uchar pixel;
pixel = pkt.at(scanByte) >> scanBit & 1;
pixel |= (pkt.at(scanByte+1) >> scanBit & 1) << 1;
pixel |= (pkt.at(scanByte+2) >> scanBit & 1) << 2;
pixel |= (pkt.at(scanByte+3) >> scanBit & 1) << 3;
rawData[x*2 + y*24 ] = pixel;
rawData[x*2+1 + y*24 ] = pixel;
rawData[x*2 + y*24+12] = pixel;
rawData[x*2+1 + y*24+12] = pixel;
}
}
QImage result = QImage(rawData, 12, 10, 12, QImage::Format_Indexed8);
// Now put in the colours
// TODO read colours from X/28/1, for now we put in the default colours
for (int i=0; i<16; i++) {
if (flashPhOn)
result.setColor(i, m_levelOnePage->CLUTtoQColor(i).rgb());
else
result.setColor(i, m_levelOnePage->CLUTtoQColor(i ^ 8).rgb());
if (i == 3 && drcsMode == 1)
break;
}
return result.copy();
}
void TeletextPageDecode::updateSidePanels()
{
int oldLeftSidePanelColumns = m_leftSidePanelColumns;
@@ -315,7 +459,8 @@ TeletextPageDecode::textCharacter TeletextPageDecode::characterFromTriplets(cons
for (int a=triplets.size()-1; a>=0; a--) {
const X26Triplet triplet = triplets.at(a);
if (triplet.data() < 0x20)
// Data values below 0x20 are reserved, except for DRCS character
if (triplet.data() < 0x20 && triplet.modeExt() != 0x2d)
continue;
const unsigned char charCode = triplet.data();
@@ -353,6 +498,9 @@ TeletextPageDecode::textCharacter TeletextPageDecode::characterFromTriplets(cons
case 0x2b: // G3 character at Level 2.5
result = { charCode, 26, 0 };
break;
case 0x2d: // DRCS character
result.drcsSource = (charCode & 0x40) == 0x40 ? NormalDRCS : GlobalDRCS;
result.drcsChar = charCode & 0x3f;
}
}
@@ -631,6 +779,7 @@ void TeletextPageDecode::decodeRow(int r)
bool applyAdapt = false;
drcsMode *drcsModePtr;
// Adaptive Invocation that is applying an attribute
// If we're not tracking an Adaptive Invocation yet, start tracking this one
// Otherwise check if this Invocation is the the same one as we are tracking
@@ -645,6 +794,16 @@ void TeletextPageDecode::decodeRow(int r)
}
switch (triplet.modeExt()) {
case 0x18: // DRCS mode
drcsModePtr = (triplet.data() & 0x40) == 0x40 ? &painter->nDrcs : &painter->gDrcs;
if ((triplet.data() & 0x30) != 0x00) {
drcsModePtr->level2p5 = triplet.data() & 0x10;
drcsModePtr->level3p5 = triplet.data() & 0x20;
// "used" is never set to true on Level 3.5, to allow all 16 sub-tables
if (!drcsModePtr->used)
drcsModePtr->subTable = triplet.data() & 0x0f;
}
break;
case 0x20: // Foreground colour
if (applyAdapt)
adapForeground = true;
@@ -733,6 +892,7 @@ void TeletextPageDecode::decodeRow(int r)
if (c < 40 && m_rowHeight[r] != BottomHalf) {
m_level1ActivePainter.result.character.diacritical = 0;
m_level1ActivePainter.result.character.drcsSource = NoDRCS;
if (m_levelOnePage->character(r, c) >= 0x20) {
m_level1ActivePainter.result.character.code = m_levelOnePage->character(r, c);
if (m_cellLevel1MosaicChar[r][c]) {
@@ -773,7 +933,36 @@ void TeletextPageDecode::decodeRow(int r)
for (int i=0; i<m_invocations[t].size(); i++) {
painter = (t == 0) ? &m_level1ActivePainter : &m_adapPassPainter[t-1][i];
const textCharacter result = characterFromTriplets(m_invocations[t].at(i).charactersMappedAt(r, c));
textCharacter result = characterFromTriplets(m_invocations[t].at(i).charactersMappedAt(r, c));
if (result.drcsSource) {
drcsMode *drcsModePtr = result.drcsSource == NormalDRCS ? &painter->nDrcs : &painter->gDrcs;
if ((m_level == 2 && drcsModePtr->level2p5) || (m_level == 3 && drcsModePtr->level3p5)) {
// "code" is zero if an X/26 character is NOT invoked in the same cell
if (result.code == 0x00)
result.code = 0x20;
result.drcsSubTable = drcsModePtr->subTable;
if (m_level < 3)
drcsModePtr->used = true;
} else
// DRCS character not required at the current level
result.drcsSource = NoDRCS;
}
// If the DRCS character in question is not downloaded, scrap all that hard work
// looking it up.
// Ideally we'd leave it in case somebody wants to find which character was meant
// to be invoked, but things like underlying Level 1 characters still needing to
// appear when the DRCS characters are not (yet) downloaded are too complex to
// figure out with this too complex decoder.
if (result.drcsSource) {
const QList<DRCSPage>* drcsPage = m_drcsPage[result.drcsSource-1];
if (drcsPage == nullptr || result.drcsSubTable >= drcsPage->size() || !drcsPage->at(result.drcsSubTable).ptu(result.drcsChar, nullptr)) {
result.drcsSource = NoDRCS;
result.code = 0x00;
}
}
if (t == 0 && result.code == 0x00)
continue;