Bug 517737. Don't allow starting a drag if something is capturing the mouse. r=smaug(part of),enndeakin

--HG--
extra : rebase_source : 171cef43d1fef9337b49d6f3b9ca661c3e618437

content/base/src/nsGenericElement.cpp

@@ -1124,7 +1124,8 @@ nsNSElementTearoff::SetCapture(PRBool aRetargetToElement)
   if (node)
     return NS_OK;
 
-  nsIPresShell::SetCapturingContent(mContent, aRetargetToElement ? CAPTURE_RETARGETTOELEMENT : 0);
+  nsIPresShell::SetCapturingContent(mContent, CAPTURE_PREVENTDRAG |
+    (aRetargetToElement ? CAPTURE_RETARGETTOELEMENT : 0));
   return NS_OK;
 }
 

content/events/src/nsEventStateManager.cpp

@@ -1891,6 +1891,12 @@ nsEventStateManager::GenerateDragGesture(nsPresContext* aPresContext,
       }
     }
 
+    // If non-native code is capturing the mouse don't start a drag.
+    if (nsIPresShell::IsMouseCapturePreventingDrag()) {
+      StopTrackingDragGesture();
+      return;
+    }
+
     static PRInt32 pixelThresholdX = 0;
     static PRInt32 pixelThresholdY = 0;
 

layout/base/nsIPresShell.h

@@ -111,15 +111,19 @@ typedef PRUint32 nsFrameState;
 #define CAPTURE_IGNOREALLOWED 1
 // true if events should be targeted at the capturing content or its children
 #define CAPTURE_RETARGETTOELEMENT 2
+// true if the current capture wants drags to be prevented
+#define CAPTURE_PREVENTDRAG 4
 
 typedef struct CapturingContentInfo {
   // capture should only be allowed during a mousedown event
   PRPackedBool mAllowed;
   PRPackedBool mRetargetToElement;
+  PRPackedBool mPreventDrag;
   nsIContent* mContent;
 
   CapturingContentInfo() :
-    mAllowed(PR_FALSE), mRetargetToElement(PR_FALSE), mContent(nsnull) { }
+    mAllowed(PR_FALSE), mRetargetToElement(PR_FALSE), mPreventDrag(PR_FALSE),
+    mContent(nsnull) { }
 } CapturingContentInfo;
 
 #define NS_IPRESSHELL_IID     \
@@ -958,6 +962,9 @@ public:
    * descendants. That is, descendants of aContent receive mouse events as
    * they normally would, but mouse events outside of aContent are retargeted
    * to aContent.
+   *
+   * If CAPTURE_PREVENTDRAG is set then drags are prevented from starting while
+   * this capture is active.
    */
   static void SetCapturingContent(nsIContent* aContent, PRUint8 aFlags);
 
@@ -977,6 +984,15 @@ public:
     gCaptureInfo.mAllowed = aAllowed;
   }
 
+  /**
+   * Returns true if there is an active mouse capture that wants to prevent
+   * drags.
+   */
+  static PRBool IsMouseCapturePreventingDrag()
+  {
+    return gCaptureInfo.mPreventDrag && gCaptureInfo.mContent;
+  }
+
 protected:
   // IMPORTANT: The ownership implicit in the following member variables
   // has been explicitly checked.  If you add any members to this class,

layout/base/nsPresShell.cpp

@@ -5819,6 +5819,7 @@ nsIPresShell::SetCapturingContent(nsIContent* aContent, PRUint8 aFlags)
       NS_ADDREF(gCaptureInfo.mContent = aContent);
     }
     gCaptureInfo.mRetargetToElement = (aFlags & CAPTURE_RETARGETTOELEMENT) != 0;
+    gCaptureInfo.mPreventDrag = (aFlags & CAPTURE_PREVENTDRAG) != 0;
   }
 }
 

toolkit/content/tests/widgets/test_mousecapture.xul

@@ -130,6 +130,14 @@ function runTests()
                              $("leftbox"), "mousemove", "setCapture only works on elements in documents");
   synthesizeMouse(custom6, 2, 2, { type: "mouseup" });
 
+  // test that mousedown on an image with setCapture followed by a big enough
+  // mouse move does not start a drag (bug 517737)
+  var image = document.getElementById("image");
+  synthesizeMouse(image, 2, 2, { type: "mousedown" });
+  synthesizeMouseExpectEvent($("leftbox"), 2, 2, { type: "mousemove" },
+                             image, "mousemove", "setCapture works on images");
+  synthesizeMouse(image, 2, 2, { type: "mouseup" });
+
   var b = frames[0].document.getElementById("b");
   runCaptureTest(b, selectionCallback);
 
@@ -275,6 +283,13 @@ SimpleTest.waitForFocus(runTests);
   </select>
 </hbox>
 
+<hbox>
+  <img id="image" xmlns="http://www.w3.org/1999/xhtml"
+       onmousedown="this.setCapture();" onmouseup="this.releaseCapture();"
+       ondragstart="ok(false, 'should not get a drag when a setCapture is active');"
+       src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAUCAIAAAAC64paAAAAG0lEQVR42mP8z0A%2BYKJA76jmUc2jmkc1U0EzACKcASfOgGoMAAAAAElFTkSuQmCC"/>
+</hbox>
+
 <body id="body" xmlns="http://www.w3.org/1999/xhtml">
   <p id="display"/><div id="content" style="display: none"/><pre id="test"/>
 </body>