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Avoid a double memory copy during bindTexture

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If a painter is active on a QPixmap being uploaded, it will be copied
twice, first to create a QImage and then from QImage into a texture.

The first copy is unnecessary since the QImage is only temporary, so
we can force it to be created as a reference instead of a copy.

Change-Id: Iabcfb514a634446a01f1c4031349c185ec09290b
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>
This commit is contained in:
Allan Sandfeld Jensen 2014-04-23 13:07:04 +02:00 committed by The Qt Project
parent 8ab1323842
commit fab46b1c6f
1 changed files with 13 additions and 1 deletions
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14
src/opengl/qgl.cpp
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@ -2497,7 +2497,19 @@ QGLTexture *QGLContextPrivate::bindTexture(const QPixmap &pixmap, GLenum target,
}
if (!texture) {
QImage image = pixmap.toImage();
QImage image;
QPaintEngine* paintEngine = pixmap.paintEngine();
if (!paintEngine || paintEngine->type() != QPaintEngine::Raster)
image = pixmap.toImage();
else {
// QRasterPixmapData::toImage() will deep-copy the backing QImage if there's an active QPainter on it.
// For performance reasons, we don't want that here, so we temporarily redirect the paint engine.
QPaintDevice* currentPaintDevice = paintEngine->paintDevice();
paintEngine->setPaintDevice(0);
image = pixmap.toImage();
paintEngine->setPaintDevice(currentPaintDevice);
}
// If the system depth is 16 and the pixmap doesn't have an alpha channel
// then we convert it to RGB16 in the hope that it gets uploaded as a 16
// bit texture which is much faster to access than a 32-bit one.