Bug 1224976. Recover from singular-matrix cairo errors. r=mattwoodrow

gfx/2d/DrawTargetCairo.cpp

@@ -590,6 +590,7 @@ NeedIntermediateSurface(const Pattern& aPattern, const DrawOptions& aOptions)
 DrawTargetCairo::DrawTargetCairo()
   : mContext(nullptr)
   , mSurface(nullptr)
+  , mTransformSingular(false)
   , mLockedBits(nullptr)
 {
 }
@@ -775,6 +776,10 @@ DrawTargetCairo::DrawSurface(SourceSurface *aSurface,
                              const DrawSurfaceOptions &aSurfOptions,
                              const DrawOptions &aOptions)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext);
   AutoClearDeviceOffset clear(aSurface);
 
@@ -968,6 +973,10 @@ DrawTargetCairo::FillRect(const Rect &aRect,
                           const Pattern &aPattern,
                           const DrawOptions &aOptions)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext);
 
   bool restoreTransform = false;
@@ -1043,6 +1052,10 @@ DrawTargetCairo::CopySurface(SourceSurface *aSurface,
                              const IntRect &aSource,
                              const IntPoint &aDest)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext);
   AutoClearDeviceOffset clear(aSurface);
 
@@ -1065,6 +1078,10 @@ void
 DrawTargetCairo::CopyRect(const IntRect &aSource,
                           const IntPoint &aDest)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext);
 
   IntRect source = aSource;
@@ -1097,6 +1114,10 @@ DrawTargetCairo::CopyRect(const IntRect &aSource,
 void
 DrawTargetCairo::ClearRect(const Rect& aRect)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext);
 
   if (!mContext || aRect.Width() <= 0 || aRect.Height() <= 0 ||
@@ -1119,6 +1140,10 @@ DrawTargetCairo::StrokeRect(const Rect &aRect,
                             const StrokeOptions &aStrokeOptions /* = StrokeOptions() */,
                             const DrawOptions &aOptions /* = DrawOptions() */)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext);
 
   cairo_new_path(mContext);
@@ -1134,6 +1159,10 @@ DrawTargetCairo::StrokeLine(const Point &aStart,
                             const StrokeOptions &aStrokeOptions /* = StrokeOptions() */,
                             const DrawOptions &aOptions /* = DrawOptions() */)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext);
 
   cairo_new_path(mContext);
@@ -1149,6 +1178,10 @@ DrawTargetCairo::Stroke(const Path *aPath,
                         const StrokeOptions &aStrokeOptions /* = StrokeOptions() */,
                         const DrawOptions &aOptions /* = DrawOptions() */)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext, aPath);
 
   if (aPath->GetBackendType() != BackendType::CAIRO)
@@ -1165,6 +1198,10 @@ DrawTargetCairo::Fill(const Path *aPath,
                       const Pattern &aPattern,
                       const DrawOptions &aOptions /* = DrawOptions() */)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext, aPath);
 
   if (aPath->GetBackendType() != BackendType::CAIRO)
@@ -1193,6 +1230,10 @@ DrawTargetCairo::FillGlyphs(ScaledFont *aFont,
                             const DrawOptions &aOptions,
                             const GlyphRenderingOptions*)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext);
   AutoClearDeviceOffset clear(aPattern);
 
@@ -1232,6 +1273,10 @@ DrawTargetCairo::Mask(const Pattern &aSource,
                       const Pattern &aMask,
                       const DrawOptions &aOptions /* = DrawOptions() */)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext);
   AutoClearDeviceOffset clearSource(aSource);
   AutoClearDeviceOffset clearMask(aMask);
@@ -1270,6 +1315,10 @@ DrawTargetCairo::MaskSurface(const Pattern &aSource,
                              Point aOffset,
                              const DrawOptions &aOptions)
 {
+  if (mTransformSingular) {
+    return;
+  }
+
   AutoPrepareForDrawing prep(this, mContext);
   AutoClearDeviceOffset clearSource(aSource);
   AutoClearDeviceOffset clearMask(aMask);
@@ -1336,7 +1385,13 @@ DrawTargetCairo::PushClip(const Path *aPath)
   cairo_save(mContext);
 
   PathCairo* path = const_cast<PathCairo*>(static_cast<const PathCairo*>(aPath));
-  path->SetPathOnContext(mContext);
+
+  if (mTransformSingular) {
+    cairo_new_path(mContext);
+    cairo_rectangle(mContext, 0, 0, 0, 0);
+  } else {
+    path->SetPathOnContext(mContext);
+  }
   cairo_clip_preserve(mContext);
 }
 
@@ -1347,7 +1402,11 @@ DrawTargetCairo::PushClipRect(const Rect& aRect)
   cairo_save(mContext);
 
   cairo_new_path(mContext);
-  cairo_rectangle(mContext, aRect.X(), aRect.Y(), aRect.Width(), aRect.Height());
+  if (mTransformSingular) {
+    cairo_rectangle(mContext, 0, 0, 0, 0);
+  } else {
+    cairo_rectangle(mContext, aRect.X(), aRect.Y(), aRect.Width(), aRect.Height());
+  }
   cairo_clip_preserve(mContext);
 }
 
@@ -1364,9 +1423,6 @@ DrawTargetCairo::PopClip()
   cairo_restore(mContext);
 
   cairo_set_matrix(mContext, &mat);
-
-  MOZ_ASSERT(cairo_status(mContext) || GetTransform() == Matrix(mat.xx, mat.yx, mat.xy, mat.yy, mat.x0, mat.y0),
-             "Transforms are out of sync");
 }
 
 already_AddRefed<PathBuilder>
@@ -1709,11 +1765,14 @@ DrawTargetCairo::WillChange(const Path* aPath /* = nullptr */)
 void
 DrawTargetCairo::SetTransform(const Matrix& aTransform)
 {
-  mTransform = aTransform;
+  DrawTarget::SetTransform(aTransform);
 
-  cairo_matrix_t mat;
-  GfxMatrixToCairoMatrix(mTransform, mat);
-  cairo_set_matrix(mContext, &mat);
+  mTransformSingular = aTransform.IsSingular();
+  if (!mTransformSingular) {
+    cairo_matrix_t mat;
+    GfxMatrixToCairoMatrix(mTransform, mat);
+    cairo_set_matrix(mContext, &mat);
+  }
 }
 
 Rect

gfx/2d/DrawTargetCairo.h

@@ -209,6 +209,7 @@ private: // data
   cairo_t* mContext;
   cairo_surface_t* mSurface;
   IntSize mSize;
+  bool mTransformSingular;
 
   uint8_t* mLockedBits;
 

layout/reftests/canvas/1224976-1-ref.html

@@ -0,0 +1,2 @@
+<!DOCTYPE HTML>
+<div style="background:black; width:10px; height:10px"></div>

layout/reftests/canvas/1224976-1.html

@@ -0,0 +1,10 @@
+<!DOCTYPE HTML>
+<canvas id="c"></canvas>
+<script>
+var ctx = c.getContext('2d');
+ctx.scale(0,1);
+ctx.fillStyle = "black";
+ctx.fillRect(0, 0, 10, 10);
+ctx.setTransform(1, 0, 0, 1, 0, 0);
+ctx.fillRect(0, 0, 10, 10);
+</script>

layout/reftests/canvas/reftest.list

@@ -107,3 +107,4 @@ fuzzy-if(azureQuartz,2,128) fuzzy-if(d2d,12,21) fuzzy-if(d2d&&/^Windows\x20NT\x2
 fuzzy-if(Mulet,45,2) == 1107096-invisibles.html 1107096-invisibles-ref.html
 == 1151821-1.html 1151821-1-ref.html
 == 1201272-1.html 1201272-1-ref.html
+== 1224976-1.html 1224976-1-ref.html