From 83fc52e3b4005d946c731577f8f49becae948c39 Mon Sep 17 00:00:00 2001 From: Holger Hans Peter Freyther Date: Mon, 2 Apr 2012 11:59:04 +0200 Subject: widgets: Fix painting to a fully transparent top level widget MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit QWS used to have a line to change the composite mode from SourceOver to Source for the top level widget. This wasn't used with QPA and I removed the internal DontSetCompositionMode in qtbase. It turns out that the QWS way is the most efficient one to initialize the background of the widget. The alternative is to have the QPlatformBackingStore::beginPaint always clear the entire to be painted area and then paint the background of the widget. The difference of painting each pixel once or twice is noticable on embedded platforms and in the range of one to two fps. Reproduce the issue with: echo "QWidget {background: transparent}" > style.css ./examples/widgets/wiggly/wiggly -stylesheet style.css Task-number: QTBUG-24526 Change-Id: Ica4c980bb3bf6eb87ddb5b510ac7493292d01543 Reviewed-by: Samuel Rødal Reviewed-by: Girish Ramakrishnan --- src/gui/painting/qplatformbackingstore_qpa.cpp | 3 --- src/widgets/kernel/qwidget.cpp | 12 +++++++++++- src/widgets/kernel/qwidget_p.h | 3 ++- 3 files changed, 13 insertions(+), 5 deletions(-) (limited to 'src') diff --git a/src/gui/painting/qplatformbackingstore_qpa.cpp b/src/gui/painting/qplatformbackingstore_qpa.cpp index ff7d91ccea..485190d301 100644 --- a/src/gui/painting/qplatformbackingstore_qpa.cpp +++ b/src/gui/painting/qplatformbackingstore_qpa.cpp @@ -114,9 +114,6 @@ QWindow* QPlatformBackingStore::window() const This function is called before painting onto the surface begins, with the \a region in which the painting will occur. - \note A platform providing a backing store with an alpha channel - needs to properly initialize the region to be painted. - \sa endPaint(), paintDevice() */ diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp index f02a67d9ea..662c9b7403 100644 --- a/src/widgets/kernel/qwidget.cpp +++ b/src/widgets/kernel/qwidget.cpp @@ -2137,7 +2137,15 @@ void QWidgetPrivate::paintBackground(QPainter *painter, const QRegion &rgn, int if ((flags & DrawAsRoot) && !(q->autoFillBackground() && autoFillBrush.isOpaque())) { const QBrush bg = q->palette().brush(QPalette::Window); - fillRegion(painter, rgn, bg); + if (!(flags & DontSetCompositionMode)) { + //copy alpha straight in + QPainter::CompositionMode oldMode = painter->compositionMode(); + painter->setCompositionMode(QPainter::CompositionMode_Source); + fillRegion(painter, rgn, bg); + painter->setCompositionMode(oldMode); + } else { + fillRegion(painter, rgn, bg); + } } if (q->autoFillBackground()) @@ -5229,6 +5237,8 @@ void QWidgetPrivate::render(QPaintDevice *target, const QPoint &targetOffset, else flags |= DontSubtractOpaqueChildren; + flags |= DontSetCompositionMode; + if (target->devType() == QInternal::Printer) { QPainter p(target); render_helper(&p, targetOffset, paintRegion, renderFlags); diff --git a/src/widgets/kernel/qwidget_p.h b/src/widgets/kernel/qwidget_p.h index 8107b6ca74..d3fcdce6a8 100644 --- a/src/widgets/kernel/qwidget_p.h +++ b/src/widgets/kernel/qwidget_p.h @@ -284,7 +284,8 @@ public: DrawInvisible = 0x08, DontSubtractOpaqueChildren = 0x10, DontDrawOpaqueChildren = 0x20, - DontDrawNativeChildren = 0x40 + DontDrawNativeChildren = 0x40, + DontSetCompositionMode = 0x80 }; enum CloseMode { -- cgit v1.2.3