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| author | Laszlo Agocs <laszlo.agocs@theqtcompany.com> | 2016-01-14 17:48:38 +0100 |
|---|---|---|
| committer | Allan Sandfeld Jensen <allan.jensen@theqtcompany.com> | 2016-01-17 01:31:55 +0000 |
| commit | 1172e18c3c180f2f3641e6c29688199eb5c46650 (patch) | |
| tree | 0c0e5df6c065ca73664d8e2a18a7bb782c1214cd /src/plugins/platforms/windows | |
| parent | 9bb24615ad8644cfb7879ed42ee36b4497541805 (diff) | |
Promote backingstore image format to alpha
Like xcb does since 1bcfc3de7586ddb9f5d1b778b97b26ae3dc9584d.
For TranslucentBackground (ARGB32_Premultiplied) there is no change
in practice. For RGB32 we will promote to ARGB32_Premultiplied
but everything should behave like before, except that we do not rely
on undefined behavior anymore when QOpenGL/QuickWidget is in use. For
RGB16 this will enable QOpenGL/QuickWidget since there the hole
punching mechanism needs an alpha channel always.
Change-Id: Id04ea548cee245ec91642f1358a5e501b62ff64c
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>
Diffstat (limited to 'src/plugins/platforms/windows')
| -rw-r--r-- | src/plugins/platforms/windows/qwindowsbackingstore.cpp | 18 | ||||
| -rw-r--r-- | src/plugins/platforms/windows/qwindowsbackingstore.h | 1 |
2 files changed, 15 insertions, 4 deletions
diff --git a/src/plugins/platforms/windows/qwindowsbackingstore.cpp b/src/plugins/platforms/windows/qwindowsbackingstore.cpp index 135c9eb601..a6b1d0af26 100644 --- a/src/plugins/platforms/windows/qwindowsbackingstore.cpp +++ b/src/plugins/platforms/windows/qwindowsbackingstore.cpp @@ -39,6 +39,7 @@ #include <QtGui/QWindow> #include <QtGui/QPainter> #include <private/qhighdpiscaling_p.h> +#include <private/qimage_p.h> #include <QtCore/QDebug> @@ -52,7 +53,8 @@ QT_BEGIN_NAMESPACE */ QWindowsBackingStore::QWindowsBackingStore(QWindow *window) : - QPlatformBackingStore(window) + QPlatformBackingStore(window), + m_alphaNeedsFill(false) { qCDebug(lcQpaBackingStore) << __FUNCTION__ << this << window; } @@ -144,8 +146,16 @@ void QWindowsBackingStore::resize(const QSize &size, const QRegion ®ion) << " from: " << (m_image.isNull() ? QSize() : m_image->image().size()); } #endif - const QImage::Format format = window()->format().hasAlpha() ? - QImage::Format_ARGB32_Premultiplied : QWindowsNativeImage::systemFormat(); + QImage::Format format = window()->format().hasAlpha() ? + QImage::Format_ARGB32_Premultiplied : QWindowsNativeImage::systemFormat(); + + // The backingstore composition (enabling render-to-texture widgets) + // punches holes in the backingstores using the alpha channel. Hence + // the need for a true alpha format. + if (QImage::toPixelFormat(format).alphaUsage() == QPixelFormat::UsesAlpha) + m_alphaNeedsFill = true; + else // upgrade but here we know app painting does not rely on alpha hence no need to fill + format = qt_alphaVersionForPainting(format); QWindowsNativeImage *oldwni = m_image.data(); QWindowsNativeImage *newwni = new QWindowsNativeImage(size.width(), size.height(), format); @@ -186,7 +196,7 @@ void QWindowsBackingStore::beginPaint(const QRegion ®ion) if (QWindowsContext::verbose > 1) qCDebug(lcQpaBackingStore) <<__FUNCTION__ << region; - if (m_image->image().hasAlphaChannel()) { + if (m_alphaNeedsFill) { QPainter p(&m_image->image()); p.setCompositionMode(QPainter::CompositionMode_Source); const QColor blank = Qt::transparent; diff --git a/src/plugins/platforms/windows/qwindowsbackingstore.h b/src/plugins/platforms/windows/qwindowsbackingstore.h index 4badcf1b09..1d644923bb 100644 --- a/src/plugins/platforms/windows/qwindowsbackingstore.h +++ b/src/plugins/platforms/windows/qwindowsbackingstore.h @@ -65,6 +65,7 @@ public: private: QScopedPointer<QWindowsNativeImage> m_image; + bool m_alphaNeedsFill; }; QT_END_NAMESPACE |