daniel/QTeletextMaker
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Add transparency to exported images

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This commit is contained in:
Gavin MacGregor
2025-07-27 14:10:06 +01:00
parent 4ef0b016aa
commit ead6700002
1 changed files with 40 additions and 15 deletions
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55
src/qteletextmaker/mainwindow.cpp
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@@ -190,24 +190,20 @@ void MainWindow::extractImages(QImage sceneImage[], bool smooth, bool flashExtra
{
// Prepare widget image for extraction
m_textScene->hideGUIElements(true);
// Disable exporting in Mix mode as it corrupts the background
bool reMix = m_textWidget->pageRender()->renderMode() == TeletextPageRender::RenderMix;
if (reMix)
m_textScene->setRenderMode(TeletextPageRender::RenderNormal);
const int flashTiming = flashExtract ? m_textWidget->flashTiming() : 0;
// Allocate initial image, with additional images for flashing if necessary
QImage interImage[6];
interImage[0] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_RGB32);
interImage[0] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_ARGB32);
if (flashTiming != 0) {
interImage[3] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_RGB32);
interImage[3] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_ARGB32);
if (flashTiming == 2) {
interImage[1] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_RGB32);
interImage[2] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_RGB32);
interImage[4] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_RGB32);
interImage[5] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_RGB32);
interImage[1] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_ARGB32);
interImage[2] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_ARGB32);
interImage[4] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_ARGB32);
interImage[5] = QImage(m_textScene->sceneRect().size().toSize(), QImage::Format_ARGB32);
}
}
@@ -215,17 +211,17 @@ void MainWindow::extractImages(QImage sceneImage[], bool smooth, bool flashExtra
for (int p=0; p<6; p++)
if (!interImage[p].isNull()) {
m_textWidget->pauseFlash(p);
// This ought to make the background transparent in Mix mode, but it doesn't
// if (m_textWidget->pageDecode()->mix())
// interImage.fill(QColor(0, 0, 0, 0));
// Alpha'd parts of image copied leave uninitialised pixels as uninitialised
// so prefill with the transparent "colour" first.
// When extracting flashing images, assume we're going to write a GIF
// which doesn't have alpha but instead swaps a selected colour for transparency.
interImage[p].fill(flashExtract ? QColor(1, 1, 1) : QColor(0, 0, 0, 0));
QPainter interPainter(&interImage[p]);
m_textScene->render(&interPainter);
}
// Now we've extracted the image we can put the GUI things back
m_textScene->hideGUIElements(false);
if (reMix)
m_textScene->setRenderMode(TeletextPageRender::RenderMix);
m_textWidget->resumeFlash();
// Now scale the extracted image(s) to the selected aspect ratio
@@ -283,6 +279,7 @@ void MainWindow::exportImage()
}
QImage scaledImage[6];
// Really could simplify the suffix parameter here...
extractImages(scaledImage, suffix != "gif", suffix == "gif");
if (suffix == "png") {
@@ -295,6 +292,34 @@ void MainWindow::exportImage()
if (suffix == "gif") {
QGifImage gif(scaledImage[0].size());
// Set a colourmap so we don't end up dithering into the default libgif palette
QList<QRgb> cTable;
if (m_textWidget->pageRender()->renderMode() == TeletextPageRender::RenderWhiteOnBlack)
gif.setGlobalColorTable(QList<QRgb>{ qRgb(0, 0, 0), qRgb(255, 255, 255) }, QColor(0, 0, 0));
else if (m_textWidget->pageRender()->renderMode() == TeletextPageRender::RenderBlackOnWhite)
gif.setGlobalColorTable(QList<QRgb>{ qRgb(255, 255, 255), qRgb(0, 0, 0) }, QColor(255, 255, 255));
else {
for (int i=0; i<32; i++)
if (i == 8) {
// Transparent colour mandatory for CLUT 1:0 on Level 2.5
// and optional on Level 1 for newsflash/subtitle or mix rendering
if (m_textWidget->pageDecode()->level() >= 2 ||
m_textWidget->pageRender()->renderMode() == TeletextPageRender::RenderMix ||
m_textWidget->document()->currentSubPage()->controlBit(PageBase::C5Newsflash) ||
m_textWidget->document()->currentSubPage()->controlBit(PageBase::C6Subtitle));
cTable.append(qRgb(1, 1, 1));
if (m_textWidget->pageDecode()->level() < 2)
break;
} else
cTable.append(m_textWidget->document()->currentSubPage()->CLUTtoQColor(i).rgb());
gif.setGlobalColorTable(cTable, QColor(0, 0, 0));
// QColor(1, 1, 1) won't always be present. Here's hoping that setting transparent
// colour to one that isn't in the colour table doesn't have any side effects...
gif.setDefaultTransparentColor(QColor(1, 1, 1));
}
if (scaledImage[3].isNull())
// No flashing
gif.addFrame(scaledImage[0], 0);