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qpa: Simplify backing store blitting

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We can use QPainter::drawImage() to update the dirty area of the front
buffer. This way, we don't need to call std::copy().
This commit is contained in:
Vlad Zahorodnii 2021-04-26 10:38:18 +03:00
parent 6adc8973d3
commit c103eb8f5c
1 changed files with 6 additions and 17 deletions
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23
src/plugins/qpa/backingstore.cpp
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@ -12,6 +12,8 @@
#include "internal_client.h"
#include <QPainter>
namespace KWin
{
namespace QPA
@ -47,29 +49,16 @@ void BackingStore::resize(const QSize &size, const QRegion &staticContents)
m_frontBuffer.setDevicePixelRatio(devicePixelRatio);
}
static void blitImage(const QImage &source, QImage &target, const QRect &rect)
static QRect scaledRect(const QRect &rect, qreal devicePixelRatio)
{
Q_ASSERT(source.format() == QImage::Format_ARGB32_Premultiplied);
Q_ASSERT(target.format() == QImage::Format_ARGB32_Premultiplied);
const int devicePixelRatio = target.devicePixelRatio();
const int x = rect.x() * devicePixelRatio;
const int y = rect.y() * devicePixelRatio;
const int width = rect.width() * devicePixelRatio;
const int height = rect.height() * devicePixelRatio;
for (int i = y; i < y + height; ++i) {
const uint32_t *in = reinterpret_cast<const uint32_t *>(source.scanLine(i));
uint32_t *out = reinterpret_cast<uint32_t *>(target.scanLine(i));
std::copy(in + x, in + x + width, out + x);
}
return QRect(rect.topLeft() * devicePixelRatio, rect.size() * devicePixelRatio);
}
static void blitImage(const QImage &source, QImage &target, const QRegion &region)
{
QPainter painter(&target);
for (const QRect &rect : region) {
blitImage(source, target, rect);
painter.drawImage(rect, source, scaledRect(rect, source.devicePixelRatio()));
}
}