Bug 1082486 - Part 4 - Check whether nsCaret shows in the scroll frame. r=roc

This patch check whether nsCaret shows in scroll frame. If yes, touch
caret will show, and its position will be clamp to scroll frame as
before. Otherwise, we hide it since the nsCaret will not be seen in this
case.

layout/base/TouchCaret.cpp

@@ -371,7 +371,6 @@ TouchCaret::UpdatePositionIfNeeded()
   if (!IsDisplayable()) {
     SetVisibility(false);
     return;
-
   }
 
   if (mVisible) {
@@ -427,6 +426,11 @@ TouchCaret::IsDisplayable()
     return false;
   }
 
+  if (!IsCaretShowingInScrollFrame()) {
+    TOUCHCARET_LOG("Caret does not show in the scrollable frame!");
+    return false;
+  }
+
   return true;
 }
 
@@ -457,6 +461,37 @@ TouchCaret::GetTouchCaretPosition()
   return pos;
 }
 
+bool
+TouchCaret::IsCaretShowingInScrollFrame()
+{
+  nsRect caretRect;
+  nsIFrame* caretFrame = GetCaretFocusFrame(&caretRect);
+
+  nsIFrame* closestScrollFrame =
+    nsLayoutUtils::GetClosestFrameOfType(caretFrame, nsGkAtoms::scrollFrame);
+
+  while (closestScrollFrame) {
+    nsIScrollableFrame* sf = do_QueryFrame(closestScrollFrame);
+    nsRect scrollPortRect = sf->GetScrollPortRect();
+
+    nsRect caretRectRelativeToScrollFrame = caretRect;
+    nsLayoutUtils::TransformRect(caretFrame, closestScrollFrame,
+                                 caretRectRelativeToScrollFrame);
+
+    // Check whether nsCaret appears in the scroll frame or not.
+    if (!scrollPortRect.Intersects(caretRectRelativeToScrollFrame)) {
+      return false;
+    }
+
+    // Get next ancestor scroll frame.
+    closestScrollFrame =
+      nsLayoutUtils::GetClosestFrameOfType(closestScrollFrame->GetParent(),
+                                           nsGkAtoms::scrollFrame);
+  }
+
+  return true;
+}
+
 nsPoint
 TouchCaret::ClampPositionToScrollFrame(const nsPoint& aPosition)
 {
@@ -467,6 +502,7 @@ TouchCaret::ClampPositionToScrollFrame(const nsPoint& aPosition)
   // Clamp the touch caret position to the scrollframe boundary.
   nsIFrame* closestScrollFrame =
     nsLayoutUtils::GetClosestFrameOfType(focusFrame, nsGkAtoms::scrollFrame);
+
   while (closestScrollFrame) {
     nsIScrollableFrame* sf = do_QueryFrame(closestScrollFrame);
     nsRect visualRect = sf->GetScrollPortRect();

layout/base/TouchCaret.h

@@ -117,6 +117,12 @@ private:
    */
   nsPoint GetTouchCaretPosition();
 
+  /**
+   * Check whether nsCaret shows in the scroll frame boundary, i.e. its rect
+   * intersects scroll frame's rect.
+   */
+  bool IsCaretShowingInScrollFrame();
+
   /**
    * Clamp the position of the touch caret to the scroll frame boundary.
    * The returned point is relative to the canvas frame.