From 997c7019bc7259e3b6f87bdee9aab9cff3f96053 Mon Sep 17 00:00:00 2001
From: David Anderson <danderson@mozilla.com>
Date: Tue, 31 Oct 2017 12:02:32 -0700
Subject: [PATCH] Don't cache DrawTargetCaptures in nsCanvasFrame. (bug 1395478
 part 10, r=mattwoodrow)

--HG--
extra : rebase_source : fc0746099e910f1e46842f292f60b2f00ee25f38
---
 gfx/2d/2D.h                      | 12 ++++++++++++
 gfx/2d/DrawTargetCapture.cpp     |  7 +++++++
 gfx/2d/DrawTargetCapture.h       |  2 ++
 layout/generic/nsCanvasFrame.cpp |  6 +++---
 4 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/gfx/2d/2D.h b/gfx/2d/2D.h
index 6a02a30cc538..348526dee7a7 100644
--- a/gfx/2d/2D.h
+++ b/gfx/2d/2D.h
@@ -1273,6 +1273,18 @@ public:
     return CreateSimilarDrawTarget(aSize, aFormat);
   }
 
+  /**
+   * Create a similar draw target, but if the draw target is not backed by a
+   * raster backend (for example, it is capturing or recording), force it to
+   * create a raster target instead. This is intended for code that wants to
+   * cache pixels, and would have no effect if it were caching a recording.
+   */
+  virtual RefPtr<DrawTarget>
+  CreateSimilarRasterTarget(const IntSize& aSize, SurfaceFormat aFormat) const
+  {
+    return CreateSimilarDrawTarget(aSize, aFormat);
+  }
+
   /**
    * Create a path builder with the specified fillmode.
    *
diff --git a/gfx/2d/DrawTargetCapture.cpp b/gfx/2d/DrawTargetCapture.cpp
index a172b0e9495f..2e0b2171c86a 100644
--- a/gfx/2d/DrawTargetCapture.cpp
+++ b/gfx/2d/DrawTargetCapture.cpp
@@ -405,5 +405,12 @@ DrawTargetCaptureImpl::CreateSimilarDrawTarget(const IntSize &aSize, SurfaceForm
   return MakeAndAddRef<DrawTargetCaptureImpl>(GetBackendType(), aSize, aFormat);
 }
 
+RefPtr<DrawTarget>
+DrawTargetCaptureImpl::CreateSimilarRasterTarget(const IntSize& aSize, SurfaceFormat aFormat) const
+{
+  MOZ_ASSERT(!mRefDT->IsCaptureDT());
+  return mRefDT->CreateSimilarDrawTarget(aSize, aFormat);
+}
+
 } // namespace gfx
 } // namespace mozilla
diff --git a/gfx/2d/DrawTargetCapture.h b/gfx/2d/DrawTargetCapture.h
index 355031516acc..9880a1bd55dc 100644
--- a/gfx/2d/DrawTargetCapture.h
+++ b/gfx/2d/DrawTargetCapture.h
@@ -128,6 +128,8 @@ public:
 
   virtual already_AddRefed<DrawTarget>
     CreateSimilarDrawTarget(const IntSize &aSize, SurfaceFormat aFormat) const override;
+  virtual RefPtr<DrawTarget>
+    CreateSimilarRasterTarget(const IntSize& aSize, SurfaceFormat aFormat) const override;
 
   virtual already_AddRefed<PathBuilder> CreatePathBuilder(FillRule aFillRule = FillRule::FILL_WINDING) const override
   {
diff --git a/layout/generic/nsCanvasFrame.cpp b/layout/generic/nsCanvasFrame.cpp
index a0c0b8132c17..bb835f00a9c8 100644
--- a/layout/generic/nsCanvasFrame.cpp
+++ b/layout/generic/nsCanvasFrame.cpp
@@ -383,9 +383,9 @@ nsDisplayCanvasBackgroundImage::Paint(nsDisplayListBuilder* aBuilder,
       return;
     }
 
-    dt = destDT->CreateSimilarDrawTarget(IntSize::Ceil(destRect.width,
-                                                       destRect.height),
-                                         SurfaceFormat::B8G8R8A8);
+    dt = destDT->CreateSimilarRasterTarget(IntSize::Ceil(destRect.width,
+                                                         destRect.height),
+                                           SurfaceFormat::B8G8R8A8);
     if (dt && dt->IsValid()) {
       RefPtr<gfxContext> ctx = gfxContext::CreateOrNull(dt);
       MOZ_ASSERT(ctx); // already checked draw target above