diff options
Diffstat (limited to 'src/plugins/platforms/ios/qiosbackingstore.mm')
| -rw-r--r-- | src/plugins/platforms/ios/qiosbackingstore.mm | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/src/plugins/platforms/ios/qiosbackingstore.mm b/src/plugins/platforms/ios/qiosbackingstore.mm index 357a3db3c9..076e34c1a5 100644 --- a/src/plugins/platforms/ios/qiosbackingstore.mm +++ b/src/plugins/platforms/ios/qiosbackingstore.mm @@ -66,6 +66,33 @@ void QIOSPaintDevice::ensureActiveTarget() m_backingStore->makeCurrent(); } +/*! + \class QIOSBackingStore + + \brief The QPlatformBackingStore on iOS. + + QBackingStore enables the use of QPainter to paint on a QWindow, as opposed + to rendering to a QWindow through the use of OpenGL with QOpenGLContext. + + Historically, the iOS port initially implemented the backing store by using + an QOpenGLPaintDevice as its paint device, triggering the use of the OpenGL + paint engine for QPainter based drawing. This was due to raster drawing + operations being too slow when not being NEON-optimized, and got the port + up and running quickly. + + As of 3e892e4a97, released in Qt 5.7, the backing store now uses a QImage, + for its paint device, giving normal raster-based QPainter operations, and + enabling features such as antialiased drawing. + + To account for regressions in performance, the old code path is still + available by setting the surface type of the QWindow to OpenGLSurface. + This surface type is normally used when rendering though QOpenGLContext, + but will in the case of QIOSBackingStore trigger the old OpenGL based + painter. + + This fallback path is not too intrusive, as the QImage based path still + uses OpenGL to composite the image at flush() time using composeAndFlush. +*/ QIOSBackingStore::QIOSBackingStore(QWindow *window) : QRasterBackingStore(window) , m_context(new QOpenGLContext) |