From a2ea25b37d675f1c1c973d80d03abe9fbe20a71c Mon Sep 17 00:00:00 2001
From: Alexander Surkov <surkov.alexander@gmail.com>
Date: Thu, 23 Feb 2012 12:16:57 +0900
Subject: [PATCH] Bug 727942 - childAtPoint may return incorrect accessibles
 when page zoomed, r=marcoz

---
 accessible/src/base/nsAccessible.cpp          |  6 +-
 .../tests/mochitest/bounds/test_zoom.html     | 13 ++---
 accessible/tests/mochitest/browser.js         | 15 +++++
 .../tests/mochitest/hittest/Makefile.in       |  3 +-
 .../tests/mochitest/hittest/test_zoom.html    | 57 +++++++++++++++++++
 accessible/tests/mochitest/layout.js          | 23 ++++++++
 6 files changed, 104 insertions(+), 13 deletions(-)
 create mode 100644 accessible/tests/mochitest/hittest/test_zoom.html

diff --git a/accessible/src/base/nsAccessible.cpp b/accessible/src/base/nsAccessible.cpp
index 870997c7bb3..f011d3e0aea 100644
--- a/accessible/src/base/nsAccessible.cpp
+++ b/accessible/src/base/nsAccessible.cpp
@@ -838,9 +838,9 @@ nsAccessible::ChildAtPoint(PRInt32 aX, PRInt32 aY,
 
   nsPresContext *presContext = frame->PresContext();
 
-  nsIntRect screenRect = frame->GetScreenRectExternal();
-  nsPoint offset(presContext->DevPixelsToAppUnits(aX - screenRect.x),
-                 presContext->DevPixelsToAppUnits(aY - screenRect.y));
+  nsRect screenRect = frame->GetScreenRectInAppUnits();
+  nsPoint offset(presContext->DevPixelsToAppUnits(aX) - screenRect.x,
+                 presContext->DevPixelsToAppUnits(aY) - screenRect.y);
 
   nsCOMPtr<nsIPresShell> presShell = presContext->PresShell();
   nsIFrame *foundFrame = presShell->GetFrameForPoint(frame, offset);
diff --git a/accessible/tests/mochitest/bounds/test_zoom.html b/accessible/tests/mochitest/bounds/test_zoom.html
index 70af0b096c2..ea79495f365 100644
--- a/accessible/tests/mochitest/bounds/test_zoom.html
+++ b/accessible/tests/mochitest/bounds/test_zoom.html
@@ -20,19 +20,14 @@
   <script type="application/javascript">
     function doTest()
     {
-      var p1 = currentTabDocument().body.firstElementChild;
-      var p2 = currentTabDocument().body.lastElementChild;
+      var tabDocument = currentTabDocument();
+      var p1 = tabDocument.body.firstElementChild;
+      var p2 = tabDocument.body.lastElementChild;
 
       testBounds(p1);
       testBounds(p2);
 
-      var docShell = currentTabWindow().
-        QueryInterface(Components.interfaces.nsIInterfaceRequestor).
-        getInterface(Components.interfaces.nsIWebNavigation).
-        QueryInterface(Components.interfaces.nsIDocShell);
-      var docViewer = docShell.contentViewer.
-        QueryInterface(Components.interfaces.nsIMarkupDocumentViewer);
-      docViewer.fullZoom = 2.0;
+      zoomDocument(tabDocument, 2.0);
 
       testBounds(p1);
       testBounds(p2);
diff --git a/accessible/tests/mochitest/browser.js b/accessible/tests/mochitest/browser.js
index 09bef2b845b..fd0b2468aa6 100644
--- a/accessible/tests/mochitest/browser.js
+++ b/accessible/tests/mochitest/browser.js
@@ -98,6 +98,21 @@ function reloadButton()
   return browserWindow().document.getElementById("urlbar-reload-button");
 }
 
+/**
+ * Zoom the given document.
+ */
+function zoomDocument(aDocument, aZoom)
+{
+  var docShell = aDocument.defaultView.
+    QueryInterface(Components.interfaces.nsIInterfaceRequestor).
+    getInterface(Components.interfaces.nsIWebNavigation).
+    QueryInterface(Components.interfaces.nsIDocShell);
+  var docViewer = docShell.contentViewer.
+    QueryInterface(Components.interfaces.nsIMarkupDocumentViewer);
+
+  docViewer.fullZoom = aZoom;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // private section
 
diff --git a/accessible/tests/mochitest/hittest/Makefile.in b/accessible/tests/mochitest/hittest/Makefile.in
index 3838210e892..00df3c28c25 100644
--- a/accessible/tests/mochitest/hittest/Makefile.in
+++ b/accessible/tests/mochitest/hittest/Makefile.in
@@ -46,9 +46,10 @@ include $(DEPTH)/config/autoconf.mk
 include $(topsrcdir)/config/rules.mk
 
 _TEST_FILES = \
+		test_browser.html \
 		test_general.html \
 		test_general.xul \
-		test_browser.html \
+		test_zoom.html \
 		$(NULL)
 
 libs:: $(_TEST_FILES)
diff --git a/accessible/tests/mochitest/hittest/test_zoom.html b/accessible/tests/mochitest/hittest/test_zoom.html
new file mode 100644
index 00000000000..3a19e17c3b8
--- /dev/null
+++ b/accessible/tests/mochitest/hittest/test_zoom.html
@@ -0,0 +1,57 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>childAtPoint when page is zoomed</title>
+  <link rel="stylesheet" type="text/css"
+        href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+
+  <script type="application/javascript"
+          src="../common.js"></script>
+  <script type="application/javascript"
+          src="../role.js"></script>
+  <script type="application/javascript"
+          src="../layout.js"></script>
+  <script type="application/javascript"
+          src="../browser.js"></script>
+
+  <script type="application/javascript">
+    function doTest()
+    {
+      var tabDocument = currentTabDocument();
+      var p1 = tabDocument.body.firstElementChild;
+      var p2 = tabDocument.body.lastElementChild;
+
+      hitTest(tabDocument, p1, p1.firstChild);
+      hitTest(tabDocument, p2, p2.firstChild);
+
+      zoomDocument(tabDocument, 2.0);
+
+      hitTest(tabDocument, p1, p1.firstChild);
+      hitTest(tabDocument, p2, p2.firstChild);
+
+      closeBrowserWindow();
+      SimpleTest.finish();
+    }
+
+    SimpleTest.waitForExplicitFinish();
+    openBrowserWindow(doTest,
+                      "data:text/html,<html><body><p>para 1</p><p>para 2</p></body></html>",
+                      { left: 100, top: 100 });
+  </script>
+</head>
+<body>
+
+  <a target="_blank"
+     href="https://bugzilla.mozilla.org/show_bug.cgi?id=727942"
+     title="childAtPoint may return incorrect accessibles when page zoomed">
+    Mozilla Bug 727942
+  </a>
+  <p id="display"></p>
+  <div id="content" style="display: none"></div>
+  <pre id="test">
+  </pre>
+</body>
+</html>
diff --git a/accessible/tests/mochitest/layout.js b/accessible/tests/mochitest/layout.js
index 5b94ccf4960..f22742575bc 100644
--- a/accessible/tests/mochitest/layout.js
+++ b/accessible/tests/mochitest/layout.js
@@ -22,6 +22,29 @@ function testChildAtPoint(aIdentifier, aX, aY, aFindDeepestChild,
   is(childAcc, actualChildAcc, msg);
 }
 
+/**
+ * Test if getChildAtPoint returns the given child and grand child accessibles
+ * at coordinates of child accessible (direct and deep hit test).
+ */
+function hitTest(aContainerID, aChildID, aGrandChildID)
+{
+  var container = getAccessible(aContainerID);
+  var child = getAccessible(aChildID);
+  var grandChild = getAccessible(aGrandChildID);
+
+  var [x, y] = getBoundsForDOMElm(child);
+
+  var actualChild = container.getChildAtPoint(x + 1, y + 1);
+  is(actualChild, child,
+     "Wrong child, expected: " + prettyName(child) +
+     ", got: " + prettyName(actualChild));
+
+  var actualGrandChild = container.getDeepestChildAtPoint(x + 1, y + 1);
+  is(actualGrandChild, grandChild,
+     "Wrong deepest child, expected: " + prettyName(grandChild) +
+     ", got: " + prettyName(actualGrandChild));
+}
+
 /**
  * Return child accessible at the given point.
  *