Implement accessibility support for CSS-transformed iframes.

content/browser/accessibility/browser_accessibility.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/accessibility/browser_accessibility.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
 #include "content/common/accessibility_messages.h"
 #include "ui/accessibility/ax_text_utils.h"
+#include "ui/gfx/geometry/rect_f.h"
 
 namespace content {
 
 #if !defined(PLATFORM_HAS_NATIVE_ACCESSIBILITY_IMPL)
 // static
 BrowserAccessibility* BrowserAccessibility::Create() {
   return new BrowserAccessibility();
 }
 #endif
 
@@ skipping 842 matching lines @@
       continue;
     }
 
     // Union each additional child's bounds.
     bounds->Union(child_bounds);
   }
 }
 
 gfx::Rect BrowserAccessibility::ElementBoundsToLocalBounds(gfx::Rect bounds)
     const {
+  // If this element has a transform, apply it and we're done.

[aboxhall, 2016/02/24 19:38:21]

Why is this true in the case where, e.g., the parent also has a transform?

Also, this comment doesn't seem to match up to the block that immediately
follows it.

+  if (GetRole() == ui::AX_ROLE_ROOT_WEB_AREA &&
+      GetParent() &&
+      GetParent()->manager() != manager() &&
+      manager()->delegate()) {

[aboxhall, 2016/02/24 18:46:07]

When would this be false?

[dmazzoni, 2016/02/24 18:53:26]

Only in unit tests

+    manager()->delegate()->AccessibilityTransformToRootCoordSpace(&bounds);
+    return bounds;
+  } else if (!GetData().transform.IsIdentity()) {
+    gfx::RectF boundsf(bounds);
+    GetData().transform.TransformRect(&boundsf);
+    return gfx::Rect(boundsf.x(), boundsf.y(),
+                     boundsf.width(), boundsf.height());
+  }
+
   // Walk up the parent chain. Every time we encounter a Web Area, offset
   // based on the scroll bars and then offset based on the origin of that
   // nested web area.
   BrowserAccessibility* parent = GetParent();
   bool need_to_offset_web_area =
       (GetRole() == ui::AX_ROLE_WEB_AREA ||
        GetRole() == ui::AX_ROLE_ROOT_WEB_AREA);
   while (parent) {
+    bool parent_is_in_different_tree = parent->manager() != manager();
+
     if (need_to_offset_web_area &&
         parent->GetLocation().width() > 0 &&
-        parent->GetLocation().height() > 0) {
+        parent->GetLocation().height() > 0 &&
+        parent->GetData().transform.IsIdentity() &&
+        !parent_is_in_different_tree) {
       bounds.Offset(parent->GetLocation().x(), parent->GetLocation().y());
       need_to_offset_web_area = false;
     }
 
     // On some platforms, we don't want to take the root scroll offsets
     // into account.
     if (parent->GetRole() == ui::AX_ROLE_ROOT_WEB_AREA &&
         !manager()->UseRootScrollOffsetsWhenComputingBounds()) {
       break;
     }
 
     if (parent->GetRole() == ui::AX_ROLE_WEB_AREA ||
         parent->GetRole() == ui::AX_ROLE_ROOT_WEB_AREA) {
       int sx = 0;
       int sy = 0;
       if (parent->GetIntAttribute(ui::AX_ATTR_SCROLL_X, &sx) &&
           parent->GetIntAttribute(ui::AX_ATTR_SCROLL_Y, &sy)) {
         bounds.Offset(-sx, -sy);
       }
       need_to_offset_web_area = true;
+
+      if (parent_is_in_different_tree && manager()->delegate()) {
+        manager()->delegate()->AccessibilityTransformToRootCoordSpace(&bounds);
+        break;
+      } else if (!parent->GetData().transform.IsIdentity()) {
+        gfx::RectF boundsf(bounds);
+        parent->GetData().transform.TransformRect(&boundsf);
+        bounds = gfx::Rect(boundsf.x(), boundsf.y(),
+                           boundsf.width(), boundsf.height());
+        need_to_offset_web_area = false;
+      }
     }
+
     parent = parent->GetParent();
   }
 
   return bounds;
 }
 
 }  // namespace content