diff options
| -rw-r--r-- | src/gui/painting/qbackingstore.cpp | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/src/gui/painting/qbackingstore.cpp b/src/gui/painting/qbackingstore.cpp index 762938e764..5b4faf1c80 100644 --- a/src/gui/painting/qbackingstore.cpp +++ b/src/gui/painting/qbackingstore.cpp @@ -227,8 +227,18 @@ void QBackingStore::flush(const QRegion ®ion, QWindow *window, const QPoint & Q_ASSERT(window == topLevelWindow || topLevelWindow->isAncestorOf(window, QWindow::ExcludeTransients)); - handle()->flush(window, QHighDpi::toNativeLocalRegion(region, window), - QHighDpi::toNativeLocalPosition(offset, window)); + QRegion nativeRegion = QHighDpi::toNativeLocalRegion(region, window); + QPoint nativeOffset; + if (!offset.isNull()) { + nativeOffset = QHighDpi::toNativeLocalPosition(offset, window); + // Under fractional DPR, rounding of region and offset may accumulate to an off-by-one + QPoint topLeft = region.boundingRect().topLeft() + offset; + QPoint nativeTopLeft = QHighDpi::toNativeLocalPosition(topLeft, window); + QPoint diff = nativeTopLeft - (nativeRegion.boundingRect().topLeft() + nativeOffset); + Q_ASSERT(qMax(qAbs(diff.x()), qAbs(diff.y())) <= 1); + nativeRegion.translate(diff); + } + handle()->flush(window, nativeRegion, nativeOffset); } /*! |