macOS: Modernize QCocoaBackingStore::flush()

Instead of forwarding the flush to the view, using CoreGraphics to blit
the backing store to the window, we do everything in flush(), and use
higher level AppKit APIs to do the blit.

This simplifies the flow and code quite a bit, and also supports blitting
of individual regions in a flush instead of the whole bounding rect.

Change-Id: I2173c1a7763fe652a94125c7e3ae93a655412cd3
Reviewed-by: Jake Petroules <jake.petroules@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

1 files changed, 6 insertions, 130 deletions

diff --git a/src/plugins/platforms/cocoa/qnsview.mm b/src/plugins/platforms/cocoa/qnsview.mm
index 73d308213d..e531e79c8f 100644
--- a/src/plugins/platforms/cocoa/qnsview.mm
+++ b/src/plugins/platforms/cocoa/qnsview.mm
@@ -134,7 +134,6 @@ static QTouchDevice *touchDevice = 0;
 - (id) init
 {
     if (self = [super initWithFrame:NSZeroRect]) {
-        m_backingStore = 0;
         m_maskImage = 0;
         m_shouldInvalidateWindowShadow = false;
         m_buttons = Qt::NoButton;
@@ -267,11 +266,6 @@ static QTouchDevice *touchDevice = 0;
     }
 }
 
-- (void)viewDidMoveToWindow
-{
-    m_backingStore = Q_NULLPTR;
-}
-
 - (QWindow *)topLevelWindow
 {
     if (!m_platformWindow)
@@ -316,67 +310,6 @@ static QTouchDevice *touchDevice = 0;
     [super removeFromSuperview];
 }
 
-- (void)flushBackingStore:(QCocoaBackingStore *)backingStore region:(const QRegion &)region offset:(QPoint)offset
-{
-    qCDebug(lcQpaCocoaWindow) << "[QNSView flushBackingStore:]" << m_platformWindow->window() << region.rectCount() << region.boundingRect() << offset;
-
-    m_backingStore = backingStore;
-    m_backingStoreOffset = offset * m_backingStore->paintDevice()->devicePixelRatio();
-
-    // FIXME: Clean up this method now that the drawRect logic has been merged into it
-
-    const NSRect dirtyRect = region.boundingRect().toCGRect();
-
-    // Normally a NSView is drawn via drawRect, as part of the display cycle in the
-    // main runloop, via setNeedsDisplay and friends. AppKit will lock focus on each
-    // individual view, starting with the top level and then traversing any subviews,
-    // calling drawRect for each of them. This pull model results in expose events
-    // sent to Qt, which result in drawing to the backingstore and flushing it.
-    // Qt may also decide to paint and flush the backingstore via e.g. timers,
-    // or other events such as mouse events, in which case we're in a push model.
-    // If there is no focused view, it means we're in the latter case, and need
-    // to manually flush the NSWindow after drawing to its graphic context.
-    const bool drawingOutsideOfDisplayCycle = ![NSView focusView];
-
-    // We also need to ensure the flushed view has focus, so that the graphics
-    // context is set up correctly (coordinate system, clipping, etc). Outside
-    // of the normal display cycle there is no focused view, as explained above,
-    // so we have to handle it manually. There's also a corner case inside the
-    // normal display cycle due to way QWidgetBackingStore composits native child
-    // widgets, where we'll get a flush of a native child during the drawRect of
-    // its parent/ancestor, and the parent/ancestor being the one locked by AppKit.
-    // In this case we also need to lock and unlock focus manually.
-    const bool shouldHandleViewLockManually = [NSView focusView] != self;
-    if (shouldHandleViewLockManually && ![self lockFocusIfCanDraw]) {
-        qWarning() << "failed to lock focus of" << self;
-        return;
-    }
-
-    if (m_platformWindow->m_drawContentBorderGradient)
-        NSDrawWindowBackground(dirtyRect);
-
-    [self drawBackingStoreUsingCoreGraphics:dirtyRect];
-
-    if (shouldHandleViewLockManually)
-        [self unlockFocus];
-
-    if (drawingOutsideOfDisplayCycle)
-        [self.window flushWindow];
-
-    [self invalidateWindowShadowIfNeeded];
-}
-
-- (void)clearBackingStore
-{
-    m_backingStore = nullptr;
-}
-
-- (void)clearBackingStore:(QCocoaBackingStore *)backingStore
-{
-    if (backingStore == m_backingStore)
-        m_backingStore = 0;
-}
-
 - (BOOL) hasMask
 {
     return !m_maskRegion.isEmpty();
@@ -418,6 +351,11 @@ static QTouchDevice *touchDevice = 0;
     m_maskImage = qt_mac_toCGImageMask(maskImage);
 }
 
+- (CGImageRef)maskImage
+{
+    return m_maskImage;
+}
+
 - (void)invalidateWindowShadowIfNeeded
 {
     if (m_shouldInvalidateWindowShadow && m_platformWindow->isContentView()) {
@@ -452,69 +390,7 @@ static QTouchDevice *touchDevice = 0;
     m_platformWindow->handleExposeEvent(exposedRegion);
 }
 
-// Draws the backing store content to the QNSView using Core Graphics.
-// This function assumes that the QNSView is in a configuration that
-// supports Core Graphics, such as "classic" mode or layer mode with
-// the default layer.
-- (void)drawBackingStoreUsingCoreGraphics:(NSRect)dirtyRect
-{
-    if (!m_backingStore)
-        return;
-
-    // Calculate source and target rects. The target rect is the dirtyRect:
-    CGRect dirtyWindowRect = NSRectToCGRect(dirtyRect);
-
-    // The backing store source rect will be larger on retina displays.
-    // Scale dirtyRect by the device pixel ratio:
-    const qreal devicePixelRatio = m_backingStore->paintDevice()->devicePixelRatio();
-    CGRect dirtyBackingRect = CGRectMake(dirtyRect.origin.x * devicePixelRatio,
-                                         dirtyRect.origin.y * devicePixelRatio,
-                                         dirtyRect.size.width * devicePixelRatio,
-                                         dirtyRect.size.height * devicePixelRatio);
-
-    NSGraphicsContext *nsGraphicsContext = [NSGraphicsContext currentContext];
-    CGContextRef cgContext = (CGContextRef) [nsGraphicsContext graphicsPort];
-
-    // Translate coordiate system from CoreGraphics (bottom-left) to NSView (top-left):
-    CGContextSaveGState(cgContext);
-    int dy = dirtyWindowRect.origin.y + CGRectGetMaxY(dirtyWindowRect);
-
-    CGContextTranslateCTM(cgContext, 0, dy);
-    CGContextScaleCTM(cgContext, 1, -1);
-
-    // If a mask is set, modify the sub image accordingly:
-    CGImageRef subMask = 0;
-    if (m_maskImage) {
-        subMask = CGImageCreateWithImageInRect(m_maskImage, dirtyWindowRect);
-        CGContextClipToMask(cgContext, dirtyWindowRect, subMask);
-    }
-
-    // Clip out and draw the correct sub image from the (shared) backingstore:
-    CGRect backingStoreRect = CGRectMake(
-        dirtyBackingRect.origin.x + m_backingStoreOffset.x(),
-        dirtyBackingRect.origin.y + m_backingStoreOffset.y(),
-        dirtyBackingRect.size.width,
-        dirtyBackingRect.size.height
-    );
-    CGImageRef bsCGImage = qt_mac_toCGImage(m_backingStore->toImage());
-    CGImageRef cleanImg = CGImageCreateWithImageInRect(bsCGImage, backingStoreRect);
-
-    // Optimization: Copy frame buffer content instead of blending for
-    // top-level windows where Qt fills the entire window content area.
-    // (But don't overpaint the title-bar gradient)
-    if (m_platformWindow->isContentView() && !m_platformWindow->m_drawContentBorderGradient)
-        CGContextSetBlendMode(cgContext, kCGBlendModeCopy);
-
-    CGContextDrawImage(cgContext, dirtyWindowRect, cleanImg);
-
-    // Clean-up:
-    CGContextRestoreGState(cgContext);
-    CGImageRelease(cleanImg);
-    CGImageRelease(subMask);
-    CGImageRelease(bsCGImage);
-}
-
-- (BOOL) isFlipped
+- (BOOL)isFlipped
 {
     return YES;
 }