Implement CRC2D.scrollPathIntoView() on Canvas

Source/core/html/canvas/CanvasRenderingContext2D.cpp

Index: Source/core/html/canvas/CanvasRenderingContext2D.cpp
diff --git a/Source/core/html/canvas/CanvasRenderingContext2D.cpp b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
index c7aee8fc69a605c7c06e9fafb1d49a4fd739a87b..f3cb8b36b247d96e808c96d14be2e7958bca714e 100644
--- a/Source/core/html/canvas/CanvasRenderingContext2D.cpp
+++ b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
@@ -1109,6 +1109,50 @@ bool CanvasRenderingContext2D::isPointInStrokeInternal(const Path& path, const f
     return path.strokeContains(transformedPoint, strokeData);
 }
 
+void CanvasRenderingContext2D::scrollPathIntoView()
+{
+    scrollPathIntoViewInternal(m_path);
+}
+
+void CanvasRenderingContext2D::scrollPathIntoView(Path2D* path2d, ExceptionState& exceptionState)
+{
+    if (!path2d) {
+        exceptionState.throwDOMException(TypeMismatchError, ExceptionMessages::argumentNullOrIncorrectType(1, "Path2D"));
+        return;
+    }
+
+    scrollPathIntoViewInternal(path2d->path());
+}
+
+void CanvasRenderingContext2D::scrollPathIntoViewInternal(const Path& path)
+{
+    if (!state().m_invertibleCTM || path.isEmpty())
+        return;
+
+    canvas()->document().updateLayoutIgnorePendingStylesheets();
+
+    // Apply transformation and get the bounding rect
+    Path transformedPath = path;
+    transformedPath.transform(state().m_transform);

[Justin Novosad, 2014/03/27 21:26:21]

I am fine with submitting this, but please create a new bug to track the fact
that there is a discrepancy between this implementation and the specification.
The specification still does not say that the Path2D flavor of
scrollPathIntoView is supposed to transform the path by the CTM, but it probably
should.

+    FloatRect boundingRect = transformedPath.boundingRect();
+
+    // Offset by the canvas rect (We should take border and padding into account).
+    RenderBoxModelObject* rbmo = canvas()->renderBoxModelObject();
+    IntRect canvasRect = canvas()->renderer()->absoluteBoundingBoxRect();
+    canvasRect.move(rbmo->borderLeft() + rbmo->paddingLeft(),
+        rbmo->borderTop() + rbmo->paddingTop());
+    LayoutRect pathRect = enclosingLayoutRect(boundingRect);
+    pathRect.moveBy(canvasRect.location());
+
+    if (canvas()->renderer()) {
+        canvas()->renderer()->scrollRectToVisible(
+            pathRect, ScrollAlignment::alignCenterAlways, ScrollAlignment::alignTopAlways);
+    }
+
+    // TODO: should implement "inform the user" that the caret and/or

[Justin Novosad, 2014/03/27 21:26:21]

If there isn't already a bug for this, please create one, and specify the URL
(crbug.com/xxx) in this comment

+    // selection the specified rectangle of the canvas.
+}
+
 void CanvasRenderingContext2D::clearRect(float x, float y, float width, float height)
 {
     if (!validateRectForCanvas(x, y, width, height))