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plugins/qpa: Simplify backing store buffer handling

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The main reasoning behind double buffering was to avoid InternalWindow's
copy of m_frontBuffer detaching. But it already detaches when the qpa
calls blitImage(). So remove double buffering to simplify the backing
store.
This commit is contained in:
Vlad Zahorodnii 2023-07-03 09:53:47 +03:00
parent fc02990b77
commit 665e05d711
2 changed files with 11 additions and 31 deletions
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39
src/plugins/qpa/backingstore.cpp
View file

@ -28,28 +28,25 @@ BackingStore::~BackingStore() = default;
QPaintDevice *BackingStore::paintDevice()
{
return &m_backBuffer;
return &m_buffer;
}
void BackingStore::resize(const QSize &size, const QRegion &staticContents)
{
if (m_backBuffer.size() == size) {
if (m_buffer.size() == size) {
return;
}
const QPlatformWindow *platformWindow = static_cast<QPlatformWindow *>(window()->handle());
const qreal devicePixelRatio = platformWindow->devicePixelRatio();
m_backBuffer = QImage(size * devicePixelRatio, QImage::Format_ARGB32_Premultiplied);
m_backBuffer.setDevicePixelRatio(devicePixelRatio);
m_frontBuffer = QImage(size * devicePixelRatio, QImage::Format_ARGB32_Premultiplied);
m_frontBuffer.setDevicePixelRatio(devicePixelRatio);
m_buffer = QImage(size * devicePixelRatio, QImage::Format_ARGB32_Premultiplied);
m_buffer.setDevicePixelRatio(devicePixelRatio);
}
void BackingStore::beginPaint(const QRegion &region)
{
if (m_backBuffer.hasAlphaChannel()) {
if (m_buffer.hasAlphaChannel()) {
QPainter p(paintDevice());
p.setCompositionMode(QPainter::CompositionMode_Source);
const QColor blank = Qt::transparent;
@ -59,20 +56,6 @@ void BackingStore::beginPaint(const QRegion &region)
}
}
static QRect scaledRect(const QRect &rect, qreal devicePixelRatio)
{
return QRect(rect.topLeft() * devicePixelRatio, rect.size() * devicePixelRatio);
}
static void blitImage(const QImage &source, QImage &target, const QRegion &region)
{
QPainter painter(&target);
painter.setCompositionMode(QPainter::CompositionMode_Source);
for (const QRect &rect : region) {
painter.drawImage(rect, source, scaledRect(rect, source.devicePixelRatio()));
}
}
void BackingStore::flush(QWindow *window, const QRegion &region, const QPoint &offset)
{
Window *platformWindow = static_cast<Window *>(window->handle());
@ -81,17 +64,15 @@ void BackingStore::flush(QWindow *window, const QRegion &region, const QPoint &o
return;
}
blitImage(m_backBuffer, m_frontBuffer, region);
QRegion bufferDamage;
for (const QRect &rect : region) {
bufferDamage |= QRect(std::floor(rect.x() * m_backBuffer.devicePixelRatio()),
std::floor(rect.y() * m_backBuffer.devicePixelRatio()),
std::ceil(rect.width() * m_backBuffer.devicePixelRatio()),
std::ceil(rect.height() * m_backBuffer.devicePixelRatio()));
bufferDamage |= QRect(std::floor(rect.x() * m_buffer.devicePixelRatio()),
std::floor(rect.y() * m_buffer.devicePixelRatio()),
std::ceil(rect.width() * m_buffer.devicePixelRatio()),
std::ceil(rect.height() * m_buffer.devicePixelRatio()));
}
internalWindow->present(m_frontBuffer, bufferDamage);
internalWindow->present(m_buffer, bufferDamage);
}
}

3
src/plugins/qpa/backingstore.h
View file

@ -30,8 +30,7 @@ public:
void beginPaint(const QRegion &region) override;
private:
QImage m_backBuffer;
QImage m_frontBuffer;
QImage m_buffer;
};
}