From e1b0dfc1d406e132fd42ecebcc7bd260e9ef8f9b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Tor=20Arne=20Vestb=C3=B8?= Date: Wed, 31 Jul 2019 14:14:00 +0200 Subject: macOS: Choose appropriate NSWindow depth based on surface format Change-Id: I67e63412096ca11a8f056f5755525311756906ef Reviewed-by: Andy Nichols Reviewed-by: Timur Pocheptsov --- src/plugins/platforms/cocoa/qcocoabackingstore.mm | 31 +++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'src/plugins/platforms/cocoa/qcocoabackingstore.mm') diff --git a/src/plugins/platforms/cocoa/qcocoabackingstore.mm b/src/plugins/platforms/cocoa/qcocoabackingstore.mm index 5d5e406d8a..cb453f7613 100644 --- a/src/plugins/platforms/cocoa/qcocoabackingstore.mm +++ b/src/plugins/platforms/cocoa/qcocoabackingstore.mm @@ -75,6 +75,37 @@ QCFType QCocoaBackingStore::colorSpace() const QNSWindowBackingStore::QNSWindowBackingStore(QWindow *window) : QCocoaBackingStore(window) { + // Choose an appropriate window depth based on the requested surface format. + // On deep color displays the default bit depth is 16-bit, so unless we need + // that level of precision we opt out of it (and the expensive RGB32 -> RGB64 + // conversions that come with it if our backingstore depth does not match). + + NSWindow *nsWindow = static_cast(window->handle())->view().window; + auto colorSpaceName = NSColorSpaceFromDepth(nsWindow.depthLimit); + + static const int kDefaultBitDepth = 8; + auto surfaceFormat = window->requestedFormat(); + auto bitsPerSample = qMax(kDefaultBitDepth, qMax(surfaceFormat.redBufferSize(), + qMax(surfaceFormat.greenBufferSize(), surfaceFormat.blueBufferSize()))); + + // NSBestDepth does not seem to guarantee a window depth deep enough for the + // given bits per sample, even if documented as such. For example, requesting + // 10 bits per sample will not give us a 16-bit format, even if that's what's + // available. Work around this by manually bumping the bit depth. + bitsPerSample = !(bitsPerSample & (bitsPerSample - 1)) + ? bitsPerSample : qNextPowerOfTwo(bitsPerSample); + + auto bestDepth = NSBestDepth(colorSpaceName, bitsPerSample, 0, NO, nullptr); + + // Disable dynamic depth limit, otherwise our depth limit will be overwritten + // by AppKit if the window moves to a screen with a different depth. We call + // this before setting the depth limit, as the call will reset the depth to 0. + [nsWindow setDynamicDepthLimit:NO]; + + qCDebug(lcQpaBackingStore) << "Using" << NSBitsPerSampleFromDepth(bestDepth) + << "bit window depth for" << nsWindow; + + nsWindow.depthLimit = bestDepth; } QNSWindowBackingStore::~QNSWindowBackingStore() -- cgit v1.2.3