Bug 1230686 - use RefPtr<DrawTarget>& instead of DrawTarget* to track changes in SurfaceFromElement. r=jmuizelaar

dom/canvas/WebGLContext.h

@@ -1311,7 +1311,7 @@ public:
         if (!mPixelStore_PremultiplyAlpha)
             flags |= nsLayoutUtils::SFE_PREFER_NO_PREMULTIPLY_ALPHA;
 
-        gfx::DrawTarget* idealDrawTarget = nullptr; // Don't care for now.
+        RefPtr<gfx::DrawTarget> idealDrawTarget = nullptr; // Don't care for now.
         return nsLayoutUtils::SurfaceFromElement(elem, flags, idealDrawTarget);
     }
 

layout/base/nsLayoutUtils.cpp

@@ -6889,7 +6889,7 @@ nsLayoutUtils::IsReallyFixedPos(nsIFrame* aFrame)
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromOffscreenCanvas(OffscreenCanvas* aOffscreenCanvas,
                                           uint32_t aSurfaceFlags,
-                                          DrawTarget* aTarget)
+                                          RefPtr<DrawTarget>& aTarget)
 {
   SurfaceFromElementResult result;
 
@@ -6904,7 +6904,7 @@ nsLayoutUtils::SurfaceFromOffscreenCanvas(OffscreenCanvas* aOffscreenCanvas,
     if (!result.mSourceSurface) {
       // If the element doesn't have a context then we won't get a snapshot. The canvas spec wants us to not error and just
       // draw nothing, so return an empty surface.
-      DrawTarget *ref = aTarget ? aTarget : gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget();
+      DrawTarget *ref = aTarget ? aTarget.get() : gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget();
       RefPtr<DrawTarget> dt = ref->CreateSimilarDrawTarget(IntSize(size.width, size.height),
                                                            SurfaceFormat::B8G8R8A8);
     if (dt) {
@@ -6927,7 +6927,7 @@ nsLayoutUtils::SurfaceFromOffscreenCanvas(OffscreenCanvas* aOffscreenCanvas,
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromElement(nsIImageLoadingContent* aElement,
                                   uint32_t aSurfaceFlags,
-                                  DrawTarget* aTarget)
+                                  RefPtr<DrawTarget>& aTarget)
 {
   SurfaceFromElementResult result;
   nsresult rv;
@@ -7020,7 +7020,7 @@ nsLayoutUtils::SurfaceFromElement(nsIImageLoadingContent* aElement,
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromElement(HTMLImageElement *aElement,
                                   uint32_t aSurfaceFlags,
-                                  DrawTarget* aTarget)
+                                  RefPtr<DrawTarget>& aTarget)
 {
   return SurfaceFromElement(static_cast<nsIImageLoadingContent*>(aElement),
                             aSurfaceFlags, aTarget);
@@ -7029,7 +7029,7 @@ nsLayoutUtils::SurfaceFromElement(HTMLImageElement *aElement,
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromElement(HTMLCanvasElement* aElement,
                                   uint32_t aSurfaceFlags,
-                                  DrawTarget* aTarget)
+                                  RefPtr<DrawTarget>& aTarget)
 {
   SurfaceFromElementResult result;
 
@@ -7044,7 +7044,7 @@ nsLayoutUtils::SurfaceFromElement(HTMLCanvasElement* aElement,
   if (!result.mSourceSurface) {
      // If the element doesn't have a context then we won't get a snapshot. The canvas spec wants us to not error and just
      // draw nothing, so return an empty surface.
-     DrawTarget *ref = aTarget ? aTarget : gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget();
+     DrawTarget *ref = aTarget ? aTarget.get() : gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget();
      RefPtr<DrawTarget> dt = ref->CreateSimilarDrawTarget(IntSize(size.width, size.height),
                                                           SurfaceFormat::B8G8R8A8);
      if (dt) {
@@ -7072,7 +7072,7 @@ nsLayoutUtils::SurfaceFromElement(HTMLCanvasElement* aElement,
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromElement(HTMLVideoElement* aElement,
                                   uint32_t aSurfaceFlags,
-                                  DrawTarget* aTarget)
+                                  RefPtr<DrawTarget>& aTarget)
 {
   SurfaceFromElementResult result;
 
@@ -7132,7 +7132,7 @@ nsLayoutUtils::SurfaceFromElement(HTMLVideoElement* aElement,
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromElement(dom::Element* aElement,
                                   uint32_t aSurfaceFlags,
-                                  DrawTarget* aTarget)
+                                  RefPtr<DrawTarget>& aTarget)
 {
   // If it's a <canvas>, we may be able to just grab its internal surface
   if (HTMLCanvasElement* canvas =

layout/base/nsLayoutUtils.h

@@ -2119,26 +2119,39 @@ public:
   // This function can be called on any thread.
   static SurfaceFromElementResult
   SurfaceFromOffscreenCanvas(mozilla::dom::OffscreenCanvas *aOffscreenCanvas,
-                             uint32_t aSurfaceFlags = 0,
+                             uint32_t aSurfaceFlags,
-                             DrawTarget *aTarget = nullptr);
+                             RefPtr<DrawTarget>& aTarget);
+  static SurfaceFromElementResult
+  SurfaceFromOffscreenCanvas(mozilla::dom::OffscreenCanvas *aOffscreenCanvas,
+                             uint32_t aSurfaceFlags = 0) {
+    RefPtr<DrawTarget> target = nullptr;
+    return SurfaceFromOffscreenCanvas(aOffscreenCanvas, aSurfaceFlags, target);
+  }
+
   static SurfaceFromElementResult SurfaceFromElement(mozilla::dom::Element *aElement,
-                                                     uint32_t aSurfaceFlags = 0,
+                                                     uint32_t aSurfaceFlags,
-                                                     DrawTarget *aTarget = nullptr);
+                                                     RefPtr<DrawTarget>& aTarget);
+  static SurfaceFromElementResult SurfaceFromElement(mozilla::dom::Element *aElement,
+                                                     uint32_t aSurfaceFlags = 0) {
+    RefPtr<DrawTarget> target = nullptr;
+    return SurfaceFromElement(aElement, aSurfaceFlags, target);
+  }
+
   static SurfaceFromElementResult SurfaceFromElement(nsIImageLoadingContent *aElement,
-                                                     uint32_t aSurfaceFlags = 0,
+                                                     uint32_t aSurfaceFlags,
-                                                     DrawTarget *aTarget = nullptr);
+                                                     RefPtr<DrawTarget>& aTarget);
   // Need an HTMLImageElement overload, because otherwise the
   // nsIImageLoadingContent and mozilla::dom::Element overloads are ambiguous
   // for HTMLImageElement.
   static SurfaceFromElementResult SurfaceFromElement(mozilla::dom::HTMLImageElement *aElement,
-                                                     uint32_t aSurfaceFlags = 0,
+                                                     uint32_t aSurfaceFlags,
-                                                     DrawTarget *aTarget = nullptr);
+                                                     RefPtr<DrawTarget>& aTarget);
   static SurfaceFromElementResult SurfaceFromElement(mozilla::dom::HTMLCanvasElement *aElement,
-                                                     uint32_t aSurfaceFlags = 0,
+                                                     uint32_t aSurfaceFlags,
-                                                     DrawTarget *aTarget = nullptr);
+                                                     RefPtr<DrawTarget>& aTarget);
   static SurfaceFromElementResult SurfaceFromElement(mozilla::dom::HTMLVideoElement *aElement,
-                                                     uint32_t aSurfaceFlags = 0,
+                                                     uint32_t aSurfaceFlags,
-                                                     DrawTarget *aTarget = nullptr);
+                                                     RefPtr<DrawTarget>& aTarget);
 
   /**
    * When the document is editable by contenteditable attribute of its root