Bug 1290293 - Part 1. Make assert ensuring RBGX surfaces set alpha to 0xFF only check sampled bytes. r=mchang

gfx/2d/DrawTargetSkia.cpp

@@ -139,6 +139,29 @@ WriteRGBXFormat(uint8_t* aData, const IntSize &aSize,
 }
 
 #ifdef DEBUG
+static IntRect
+CalculateSurfaceBounds(const IntSize &aSize, const Rect* aBounds, const Matrix* aMatrix)
+{
+  IntRect surfaceBounds(IntPoint(0, 0), aSize);
+  if (!aBounds) {
+    return surfaceBounds;
+  }
+
+  MOZ_ASSERT(aMatrix);
+  Matrix inverse(*aMatrix);
+  if (!inverse.Invert()) {
+    return surfaceBounds;
+  }
+
+  IntRect bounds;
+  Rect sampledBounds = inverse.TransformBounds(*aBounds);
+  if (!sampledBounds.ToIntRect(&bounds)) {
+    return surfaceBounds;
+  }
+
+  return surfaceBounds.Intersect(bounds);
+}
+
 static bool
 VerifyRGBXFormat(uint8_t* aData, const IntSize &aSize, const int32_t aStride, SurfaceFormat aFormat)
 {
@@ -170,27 +193,32 @@ VerifyRGBXFormat(uint8_t* aData, const IntSize &aSize, const int32_t aStride, Su
 // Since checking every pixel is expensive, this only checks the four corners and center
 // of a surface that their alpha value is 0xFF.
 static bool
-VerifyRGBXCorners(uint8_t* aData, const IntSize &aSize, const int32_t aStride, SurfaceFormat aFormat)
+VerifyRGBXCorners(uint8_t* aData, const IntSize &aSize, const int32_t aStride, SurfaceFormat aFormat, const Rect* aBounds = nullptr, const Matrix* aMatrix = nullptr)
 {
   if (aFormat != SurfaceFormat::B8G8R8X8 || aSize.IsEmpty()) {
     return true;
   }
 
-  int height = aSize.height;
-  int width = aSize.width;
-  const int pixelSize = 4;
-  const int strideDiff = aStride - (width * pixelSize);
-  MOZ_ASSERT(width * pixelSize <= aStride);
+  IntRect bounds = CalculateSurfaceBounds(aSize, aBounds, aMatrix);
+  if (bounds.IsEmpty()) {
+    return true;
+  }
 
-  const int topLeft = 0;
-  const int topRight = width * pixelSize - pixelSize;
-  const int bottomRight = aStride * height - strideDiff - pixelSize;
-  const int bottomLeft = aStride * height - aStride;
+  const int height = bounds.height;
+  const int width = bounds.width;
+  const int pixelSize = 4;
+  MOZ_ASSERT(aSize.width * pixelSize <= aStride);
+
+  const int translation = bounds.y * aStride + bounds.x * pixelSize;
+  const int topLeft = translation;
+  const int topRight = topLeft + (width - 1) * pixelSize;
+  const int bottomLeft = translation + (height - 1) * aStride;
+  const int bottomRight = bottomLeft + (width - 1) * pixelSize;
 
   // Lastly the center pixel
-  int middleRowHeight = height / 2;
-  int middleRowWidth = (width / 2) * pixelSize;
-  const int middle = aStride * middleRowHeight + middleRowWidth;
+  const int middleRowHeight = height / 2;
+  const int middleRowWidth = (width / 2) * pixelSize;
+  const int middle = translation + aStride * middleRowHeight + middleRowWidth;
 
   const int offsets[] = { topLeft, topRight, bottomRight, bottomLeft, middle };
   for (int offset : offsets) {
@@ -198,7 +226,9 @@ VerifyRGBXCorners(uint8_t* aData, const IntSize &aSize, const int32_t aStride, S
         int row = offset / aStride;
         int column = (offset % aStride) / pixelSize;
         gfxCriticalError() << "RGBX corner pixel at (" << column << "," << row << ") in "
-                           << width << "x" << height << " surface is not opaque: "
+                           << aSize.width << "x" << aSize.height << " surface, bounded by "
+                           << "(" << bounds.x << "," << bounds.y << "," << width << ","
+                           << height << ") is not opaque: "
                            << int(aData[offset]) << ","
                            << int(aData[offset+1]) << ","
                            << int(aData[offset+2]) << ","
@@ -211,7 +241,7 @@ VerifyRGBXCorners(uint8_t* aData, const IntSize &aSize, const int32_t aStride, S
 #endif
 
 static sk_sp<SkImage>
-GetSkImageForSurface(SourceSurface* aSurface)
+GetSkImageForSurface(SourceSurface* aSurface, const Rect* aBounds = nullptr, const Matrix* aMatrix = nullptr)
 {
   if (!aSurface) {
     gfxDebug() << "Creating null Skia image from null SourceSurface";
@@ -238,7 +268,8 @@ GetSkImageForSurface(SourceSurface* aSurface)
 
   // Skia doesn't support RGBX surfaces so ensure that the alpha value is opaque white.
   MOZ_ASSERT(VerifyRGBXCorners(surf->GetData(), surf->GetSize(),
-                               surf->Stride(), surf->GetFormat()));
+                               surf->Stride(), surf->GetFormat(),
+                               aBounds, aMatrix));
   return image;
 }
 
@@ -410,7 +441,7 @@ ExtractAlphaForSurface(SourceSurface* aSurface)
 }
 
 static void
-SetPaintPattern(SkPaint& aPaint, const Pattern& aPattern, Float aAlpha = 1.0, Point aOffset = Point(0, 0))
+SetPaintPattern(SkPaint& aPaint, const Pattern& aPattern, Float aAlpha = 1.0, Point aOffset = Point(0, 0), const Rect* aBounds = nullptr)
 {
   switch (aPattern.GetType()) {
     case PatternType::COLOR: {
@@ -472,7 +503,7 @@ SetPaintPattern(SkPaint& aPaint, const Pattern& aPattern, Float aAlpha = 1.0, Po
     }
     case PatternType::SURFACE: {
       const SurfacePattern& pat = static_cast<const SurfacePattern&>(aPattern);
-      sk_sp<SkImage> image = GetSkImageForSurface(pat.mSurface);
+      sk_sp<SkImage> image = GetSkImageForSurface(pat.mSurface, aBounds, &pat.mMatrix);
       if (!image) {
         aPaint.setColor(SK_ColorTRANSPARENT);
         break;
@@ -520,11 +551,11 @@ GetClipBounds(SkCanvas *aCanvas)
 }
 
 struct AutoPaintSetup {
-  AutoPaintSetup(SkCanvas *aCanvas, const DrawOptions& aOptions, const Pattern& aPattern, const Rect* aMaskBounds = nullptr, Point aOffset = Point(0, 0))
+  AutoPaintSetup(SkCanvas *aCanvas, const DrawOptions& aOptions, const Pattern& aPattern, const Rect* aMaskBounds = nullptr, Point aOffset = Point(0, 0), const Rect* aSourceBounds = nullptr)
     : mNeedsRestore(false), mAlpha(1.0)
   {
     Init(aCanvas, aOptions, aMaskBounds, false);
-    SetPaintPattern(mPaint, aPattern, mAlpha, aOffset);
+    SetPaintPattern(mPaint, aPattern, mAlpha, aOffset, aSourceBounds);
   }
 
   AutoPaintSetup(SkCanvas *aCanvas, const DrawOptions& aOptions, const Rect* aMaskBounds = nullptr, bool aForceGroup = false)
@@ -753,7 +784,7 @@ DrawTargetSkia::FillRect(const Rect &aRect,
 
   MarkChanged();
   SkRect rect = RectToSkRect(aRect);
-  AutoPaintSetup paint(mCanvas.get(), aOptions, aPattern, &aRect);
+  AutoPaintSetup paint(mCanvas.get(), aOptions, aPattern, &aRect, Point(0, 0), &aRect);
 
   mCanvas->drawRect(rect, paint.mPaint);
 }