Bug 1850871 - Resize canvas in ImageBitmapRenderingContext::TransferF…

…romImageBitmap. r=gfx-reviewers,lsalzman

This patch makes it so that when a new ImageBitmap is provided to an
ImageBitmapRenderingContext, we resize its owning canvas rather than
crop or scale the given ImageBitmap to fit inside the canvas dimensions.

See discussion in whatwg/html#7833.

Differential Revision: https://phabricator.services.mozilla.com/D188126

UltraBlame original commit: cbd593a4819d1bc653fae6d21f86b25c9b1bdd58

dom/canvas/ImageBitmapRenderingContext.cpp

@@ -418,6 +418,66 @@ return
 }
 if
 (
+mCanvasElement
+)
+{
+mCanvasElement
+-
+>
+SetSize
+(
+mImage
+-
+>
+GetSize
+(
+)
+aRv
+)
+;
+}
+else
+if
+(
+mOffscreenCanvas
+)
+{
+mOffscreenCanvas
+-
+>
+SetSize
+(
+mImage
+-
+>
+GetSize
+(
+)
+aRv
+)
+;
+}
+if
+(
+NS_WARN_IF
+(
+aRv
+.
+Failed
+(
+)
+)
+)
+{
+mImage
+=
+nullptr
+;
+return
+;
+}
+if
+(
 aImageBitmap
 -
 >
@@ -487,6 +547,52 @@ mHeight
 =
 aHeight
 ;
+if
+(
+mOffscreenCanvas
+)
+{
+OffscreenCanvasDisplayData
+data
+;
+data
+.
+mSize
+=
+{
+mWidth
+mHeight
+}
+;
+data
+.
+mIsOpaque
+=
+GetIsOpaque
+(
+)
+;
+data
+.
+mIsAlphaPremult
+=
+true
+;
+data
+.
+mDoPaintCallbacks
+=
+false
+;
+mOffscreenCanvas
+-
+>
+UpdateDisplayData
+(
+data
+)
+;
+}
 return
 NS_OK
 ;

dom/canvas/OffscreenCanvas.cpp

@@ -817,6 +817,97 @@ void
 OffscreenCanvas
 :
 :
+SetSize
+(
+const
+nsIntSize
+&
+aSize
+ErrorResult
+&
+aRv
+)
+{
+if
+(
+mNeutered
+)
+{
+aRv
+.
+ThrowInvalidStateError
+(
+"
+Cannot
+set
+dimensions
+of
+placeholder
+canvas
+transferred
+to
+worker
+.
+"
+)
+;
+return
+;
+}
+if
+(
+NS_WARN_IF
+(
+aSize
+.
+IsEmpty
+(
+)
+)
+)
+{
+aRv
+.
+ThrowRangeError
+(
+"
+OffscreenCanvas
+size
+is
+empty
+must
+be
+non
+-
+empty
+.
+"
+)
+;
+return
+;
+}
+mWidth
+=
+aSize
+.
+width
+;
+mHeight
+=
+aSize
+.
+height
+;
+CanvasAttrChanged
+(
+)
+;
+}
+void
+OffscreenCanvas
+:
+:
 GetContext
 (
 JSContext

dom/canvas/OffscreenCanvas.h

@@ -647,6 +647,18 @@ mNeutered
 mCurrentContext
 ;
 }
+void
+SetSize
+(
+const
+nsIntSize
+&
+aSize
+ErrorResult
+&
+aRv
+)
+;
 nsIPrincipal
 *
 GetExpandedReader