Make CGContext display scale-agnostic by propagating the scale into D…

…irect2D's DPI. A CGContext rendering to a scaled surface will not apply a scale transformation. The scaling logic has been moved into render target creation. Fixes microsoft#1180.
DHowett-MSFT · Oct 18, 2016 · c0beac7 · c0beac7
1 parent 0f7de5a
commit c0beac7
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Showing 4 changed files with 14 additions and 10 deletions.
diff --git a/Frameworks/CoreGraphics/CGContext.mm b/Frameworks/CoreGraphics/CGContext.mm
@@ -588,6 +588,7 @@ static void __CGContextDrawGeometry(CGContextRef context, ID2D1Geometry* geometr
     FAIL_FAST_IF_FAILED(renderTarget.As(&deviceContext));
 
     D2D1_SIZE_F targetSize = renderTarget->GetSize();
+    //D2D1_SIZE_U unscaledTargetSize = renderTarget->GetPixelSize();
     ComPtr<ID2D1Image> originalTarget;
     deviceContext->GetTarget(&originalTarget);
 
@@ -599,6 +600,9 @@ static void __CGContextDrawGeometry(CGContextRef context, ID2D1Geometry* geometr
 
     CGAffineTransform& currentTransform = currentState.transform;
     CGAffineTransform transform = CGAffineTransformScale(currentTransform, 1.0, -1.0);
+    // undo the scale (propagated to DPI)
+    //transform = CGAffineTransformScale(transform, targetSize.width/(double)unscaledTargetSize.width, targetSize.height/(double)unscaledTargetSize.height);
+    // undo the slide (slide was in points, must be done after scale is undone)
     transform = CGAffineTransformTranslate(transform, 0., targetSize.height);
     deviceContext->SetTransform({ transform.a, transform.b, transform.c, transform.d, transform.tx, transform.ty });
 
@@ -1434,12 +1438,14 @@ CGImageRef CGBitmapContextGetImage(CGContextRef context) {
     return ((__CGBitmapContext*)context)->Impl().image.get();
 }
 
-CGContextRef _CGBitmapContextCreateWithTexture(int width, int height, DisplayTexture* texture, DisplayTextureLocking* locking) {
+CGContextRef _CGBitmapContextCreateWithTexture(
+    int width, int height, float scale, DisplayTexture* texture, DisplayTextureLocking* locking) {
     CGImageRef newImage = nullptr;
     __CGSurfaceInfo surfaceInfo = _CGSurfaceInfoInit(width, height, _ColorARGB);
     newImage = new CGGraphicBufferImage(surfaceInfo, texture, locking);
 
     ComPtr<ID2D1RenderTarget> renderTarget = newImage->Backing()->GetRenderTarget();
+    renderTarget->SetDpi(96 * scale, 96 * scale);
 
     __CGBitmapContext* context = __CGBitmapContext::CreateInstance(kCFAllocatorDefault);
     __CGContextInitWithRenderTarget(context, renderTarget.Get());

diff --git a/Frameworks/QuartzCore/CALayer.mm b/Frameworks/QuartzCore/CALayer.mm
@@ -352,14 +352,14 @@ void ReleaseDisplayTexture(DisplayTexture* tex) {
 
 static LockingBufferInterface _globallockingBufferInterface;
 
-CGContextRef CreateLayerContentsBitmapContext32(int width, int height) {
+CGContextRef CreateLayerContentsBitmapContext32(int width, int height, float scale) {
     DisplayTexture* tex = NULL;
 
     if ([NSThread isMainThread]) {
         tex = GetCACompositor()->CreateWritableBitmapTexture32(width, height);
     }
 
-    CGContextRef ret = _CGBitmapContextCreateWithTexture(width, height, tex, &_globallockingBufferInterface);
+    CGContextRef ret = _CGBitmapContextCreateWithTexture(width, height, scale, tex, &_globallockingBufferInterface);
 
     if (tex) {
         _globallockingBufferInterface.ReleaseDisplayTexture(tex);
@@ -573,7 +573,7 @@ - (void)display {
             // As an optimization, CALayer would use a bitmap context with a solid background colour
             // instead of a DisplayTexture. Since bitmap contexts are currently broken as part of #1072,
             // we'll fall back to always using the writable bitmap buffer.
-            drawContext = CreateLayerContentsBitmapContext32(width, height);
+            drawContext = CreateLayerContentsBitmapContext32(width, height, priv->contentsScale);
             priv->drewOpaque = FALSE;
             priv->ownsContents = TRUE;
         }
@@ -609,10 +609,7 @@ - (void)display {
         }
 
         if (target->Backing()->Height() != 0) {
-            CGContextTranslateCTM(drawContext, 0, float(target->Backing()->Height()));
-        }
-        if (priv->contentsScale != 1.0f) {
-            CGContextScaleCTM(drawContext, priv->contentsScale, priv->contentsScale);
+            CGContextTranslateCTM(drawContext, 0, float(target->Backing()->Height())/priv->contentsScale);
         }
 
         CGContextScaleCTM(drawContext, 1.0f, -1.0f);

diff --git a/Frameworks/QuartzCore/CAShapeLayer.mm b/Frameworks/QuartzCore/CAShapeLayer.mm
@@ -35,7 +35,7 @@
 NSString* const kCALineCapRound = @"kCALineCapRound";
 NSString* const kCALineCapSquare = @"kCALineCapSquare";
 
-CGContextRef CreateLayerContentsBitmapContext32(int width, int height);
+CGContextRef CreateLayerContentsBitmapContext32(int width, int height, float scale);
 
 @implementation CAShapeLayer {
     CGPathRef _path;
@@ -92,7 +92,7 @@ - (void)layoutSublayers {
     int width = (int)(bbox.size.width * scale);
     int height = (int)(bbox.size.height * scale);
 
-    CGContextRef drawContext = CreateLayerContentsBitmapContext32(width, height);
+    CGContextRef drawContext = CreateLayerContentsBitmapContext32(width, height, scale);
 
     CGContextTranslateCTM(drawContext, 0, height);
     if (scale != 1.0f) {

diff --git a/Frameworks/include/CGContextInternal.h b/Frameworks/include/CGContextInternal.h
@@ -29,6 +29,7 @@
 
 COREGRAPHICS_EXPORT CGContextRef _CGBitmapContextCreateWithTexture(int width,
                                                                    int height,
+                                                                   float scale,
                                                                    DisplayTexture* texture = NULL,
                                                                    DisplayTextureLocking* locking = NULL);
 COREGRAPHICS_EXPORT CGContextRef _CGBitmapContextCreateWithFormat(int width, int height, __CGSurfaceFormat fmt);