Add basic support for accessibility hit testing within web contents.

BUG=59890
TEST=Manual. Inspect32.

Review URL: http://codereview.chromium.org/4292001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@64943 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/accessibility/browser_accessibility.cc

@@ -5,6 +5,7 @@
 #include "chrome/browser/accessibility/browser_accessibility.h"
 
 #include "base/logging.h"
+#include "base/string_number_conversions.h"
 #include "chrome/browser/accessibility/browser_accessibility_manager.h"
 
 BrowserAccessibility::BrowserAccessibility()
@@ -110,3 +111,65 @@ BrowserAccessibility* BrowserAccessibility::GetNextSibling() {
 
   return NULL;
 }
+
+gfx::Rect BrowserAccessibility::GetBoundsRect() {
+  gfx::Rect bounds = location_;
+
+  // Adjust the bounds by the top left corner of the containing view's bounds
+  // in screen coordinates.
+  gfx::Point top_left = manager_->GetViewBounds().origin();
+  bounds.Offset(top_left);
+
+  // Adjust top left position by the root document's scroll offset.
+  BrowserAccessibility* root = manager_->GetRoot();
+  int scroll_x = 0;
+  int scroll_y = 0;
+  root->GetAttributeAsInt(
+    WebAccessibility::ATTR_DOC_SCROLLX, &scroll_x);
+  root->GetAttributeAsInt(
+    WebAccessibility::ATTR_DOC_SCROLLY, &scroll_y);
+  bounds.Offset(-scroll_x, -scroll_y);
+
+  return bounds;
+}
+
+BrowserAccessibility* BrowserAccessibility::BrowserAccessibilityForPoint(
+    const gfx::Point& point) {
+  // Walk the children recursively looking for the BrowserAccessibility that
+  // most tightly encloses the specified point.
+  for (int i = children_.size() - 1; i >= 0; --i) {
+    BrowserAccessibility* child = children_[i];
+    if (child->GetBoundsRect().Contains(point))
+      return child->BrowserAccessibilityForPoint(point);
+  }
+  return this;
+}
+
+bool BrowserAccessibility::HasAttribute(
+    WebAccessibility::Attribute attribute) {
+  return (attributes_.find(attribute) != attributes_.end());
+}
+
+bool BrowserAccessibility::GetAttribute(
+    WebAccessibility::Attribute attribute, string16* value) {
+  std::map<int32, string16>::iterator iter = attributes_.find(attribute);
+  if (iter != attributes_.end()) {
+    *value = iter->second;
+    return true;
+  }
+
+  return false;
+}
+
+bool BrowserAccessibility::GetAttributeAsInt(
+    WebAccessibility::Attribute attribute, int* value_int) {
+  string16 value_str;
+
+  if (!GetAttribute(attribute, &value_str))
+    return false;
+
+  if (!base::StringToInt(value_str, value_int))
+    return false;
+
+  return true;
+}

chrome/browser/accessibility/browser_accessibility.h

@@ -90,6 +90,12 @@ class BrowserAccessibility {
   // of its parent.
   BrowserAccessibility* GetNextSibling();
 
+  // Returns the bounds of this object in screen coordinates.
+  gfx::Rect GetBoundsRect();
+
+  // Returns the deepest descendant that contains the specified point.
+  BrowserAccessibility* BrowserAccessibilityForPoint(const gfx::Point& point);
+
   // Accessors
   const std::map<int32, string16>& attributes() const { return attributes_; }
   int32 child_id() const { return child_id_; }
@@ -118,6 +124,20 @@ class BrowserAccessibility {
  protected:
   BrowserAccessibility();
 
+  // Return true if this attribute is in the attributes map.
+  bool HasAttribute(WebAccessibility::Attribute attribute);
+
+  // Retrieve the string value of an attribute from the attribute map and
+  // returns true if found.
+  bool GetAttribute(WebAccessibility::Attribute attribute, string16* value);
+
+  // Retrieve the value of an attribute from the attribute map and
+  // if found and nonempty, try to convert it to an integer.
+  // Returns true only if both the attribute was found and it was successfully
+  // converted to an integer.
+  bool GetAttributeAsInt(
+      WebAccessibility::Attribute attribute, int* value_int);
+
   // The manager of this tree of accessibility objects; needed for
   // global operations like focus tracking.
   BrowserAccessibilityManager* manager_;

chrome/browser/accessibility/browser_accessibility_manager.cc

@@ -226,6 +226,12 @@ void BrowserAccessibilityManager::DoDefaultAction(
     delegate_->AccessibilityDoDefaultAction(node.renderer_id());
 }
 
+gfx::Rect BrowserAccessibilityManager::GetViewBounds() {
+  if (delegate_)
+    return delegate_->GetViewBounds();
+  return gfx::Rect();
+}
+
 bool BrowserAccessibilityManager::CanModifyTreeInPlace(
     BrowserAccessibility* current_root,
     const WebAccessibility& new_root) {

chrome/browser/accessibility/browser_accessibility_manager.h

@@ -15,7 +15,6 @@
 #include "gfx/native_widget_types.h"
 #include "webkit/glue/webaccessibility.h"
 
-
 class BrowserAccessibility;
 #if defined(OS_WIN)
 class BrowserAccessibilityManagerWin;
@@ -30,6 +29,7 @@ class BrowserAccessibilityDelegate {
   virtual void SetAccessibilityFocus(int acc_obj_id) = 0;
   virtual void AccessibilityDoDefaultAction(int acc_obj_id) = 0;
   virtual bool HasFocus() = 0;
+  virtual gfx::Rect GetViewBounds() const = 0;
 };
 
 class BrowserAccessibilityFactory {
@@ -81,6 +81,9 @@ class BrowserAccessibilityManager {
   // Tell the renderer to do the default action for this node.
   void DoDefaultAction(const BrowserAccessibility& node);
 
+  // Retrieve the bounds of the parent View in screen coordinates.
+  gfx::Rect GetViewBounds();
+
   // Called when the renderer process has notified us of about tree changes.
   // Send a notification to MSAA clients of the change.
   void OnAccessibilityNotifications(

chrome/browser/accessibility/browser_accessibility_win.cc

@@ -53,15 +53,31 @@ HRESULT BrowserAccessibilityWin::accDoDefaultAction(VARIANT var_id) {
   return S_OK;
 }
 
-STDMETHODIMP BrowserAccessibilityWin::accHitTest(LONG x_left, LONG y_top,
-                                                 VARIANT* child) {
+STDMETHODIMP BrowserAccessibilityWin::accHitTest(
+    LONG x_left, LONG y_top, VARIANT* child) {
   if (!instance_active_)
     return E_FAIL;
 
   if (!child)
     return E_INVALIDARG;
 
-  return E_NOTIMPL;
+  gfx::Point point(x_left, y_top);
+  if (!GetBoundsRect().Contains(point)) {
+    // Return S_FALSE and VT_EMPTY when the outside the object's boundaries.
+    child->vt = VT_EMPTY;
+    return S_FALSE;
+  }
+
+  BrowserAccessibility* result = BrowserAccessibilityForPoint(point);
+  if (result == this) {
+    // Point is within this object.
+    child->vt = VT_I4;
+    child->lVal = CHILDID_SELF;
+  } else {
+    child->vt = VT_DISPATCH;
+    child->pdispVal = result->toBrowserAccessibilityWin()->NewReference();
+  }
+  return S_OK;
 }
 
 STDMETHODIMP BrowserAccessibilityWin::accLocation(LONG* x_left, LONG* y_top,
@@ -77,16 +93,11 @@ STDMETHODIMP BrowserAccessibilityWin::accLocation(LONG* x_left, LONG* y_top,
   if (!target)
     return E_INVALIDARG;
 
-  // Find the top left corner of the containing window in screen coords, and
-  // adjust the output position by this amount.
-  HWND parent_hwnd = manager_->GetParentView();
-  POINT top_left = {0, 0};
-  ::ClientToScreen(parent_hwnd, &top_left);
-
-  *x_left = target->location_.x + top_left.x;
-  *y_top  = target->location_.y + top_left.y;
-  *width  = target->location_.width;
-  *height = target->location_.height;
+  gfx::Rect bounds = target->GetBoundsRect();
+  *x_left = bounds.x();
+  *y_top  = bounds.y();
+  *width  = bounds.width();
+  *height = bounds.height();
 
   return S_OK;
 }
@@ -1156,22 +1167,6 @@ BrowserAccessibilityWin* BrowserAccessibilityWin::GetTargetFromChildID(
   return manager_->GetFromChildID(child_id)->toBrowserAccessibilityWin();
 }
 
-bool BrowserAccessibilityWin::HasAttribute(
-    WebAccessibility::Attribute attribute) {
-  return (attributes_.find(attribute) != attributes_.end());
-}
-
-bool BrowserAccessibilityWin::GetAttribute(
-    WebAccessibility::Attribute attribute, string16* value) {
-  std::map<int32, string16>::iterator iter = attributes_.find(attribute);
-  if (iter != attributes_.end()) {
-    *value = iter->second;
-    return true;
-  }
-
-  return false;
-}
-
 HRESULT BrowserAccessibilityWin::GetAttributeAsBstr(
     WebAccessibility::Attribute attribute, BSTR* value_bstr) {
   string16 str;
@@ -1188,19 +1183,6 @@ HRESULT BrowserAccessibilityWin::GetAttributeAsBstr(
   return S_OK;
 }
 
-bool BrowserAccessibilityWin::GetAttributeAsInt(
-    WebAccessibility::Attribute attribute, int* value_int) {
-  string16 value_str;
-
-  if (!GetAttribute(attribute, &value_str))
-    return false;
-
-  if (!base::StringToInt(value_str, value_int))
-    return false;
-
-  return true;
-}
-
 string16 BrowserAccessibilityWin::Escape(string16 str) {
   return EscapeQueryParamValueUTF8(str, false);
 }

chrome/browser/accessibility/browser_accessibility_win.h

@@ -457,26 +457,12 @@ class BrowserAccessibilityWin
   // bitmasks defined in webkit/glue/webaccessibility.h.
   void InitRoleAndState();
 
-  // Return true if this attribute is in the attributes map.
-  bool HasAttribute(WebAccessibility::Attribute attribute);
-
-  // Retrieve the string value of an attribute from the attribute map and
-  // returns true if found.
-  bool GetAttribute(WebAccessibility::Attribute attribute, string16* value);
-
   // Retrieve the string value of an attribute from the attribute map and
   // if found and nonempty, allocate a new BSTR (with SysAllocString)
   // and return S_OK. If not found or empty, return S_FALSE.
   HRESULT GetAttributeAsBstr(
       WebAccessibility::Attribute attribute, BSTR* value_bstr);
 
-  // Retrieve the value of an attribute from the attribute map and
-  // if found and nonempty, try to convert it to an integer.
-  // Returns true only if both the attribute was found and it was successfully
-  // converted to an integer.
-  bool GetAttributeAsInt(
-      WebAccessibility::Attribute attribute, int* value_int);
-
   // Escape a string like it would be escaped for a URL or HTML form.
   string16 Escape(string16 str);
 

webkit/glue/webaccessibility.cc

@@ -19,6 +19,7 @@
 #include "third_party/WebKit/WebKit/chromium/public/WebInputElement.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebNamedNodeMap.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebNode.h"
+#include "third_party/WebKit/WebKit/chromium/public/WebSize.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebString.h"
 
 using WebKit::WebAccessibilityCache;
@@ -366,6 +367,10 @@ void WebAccessibility::Init(const WebKit::WebAccessibilityObject& src,
     const WebKit::WebDocumentType& doctype = document.doctype();
     if (!doctype.isNull())
       attributes[ATTR_DOC_DOCTYPE] = doctype.name();
+
+    const gfx::Size& scroll_offset = document.frame()->scrollOffset();
+    attributes[ATTR_DOC_SCROLLX] = base::IntToString16(scroll_offset.width());
+    attributes[ATTR_DOC_SCROLLY] = base::IntToString16(scroll_offset.height());
   }
 
   // Add the source object to the cache and store its id.

webkit/glue/webaccessibility.h

@@ -162,6 +162,8 @@ struct WebAccessibility {
     ATTR_DOC_TITLE,
     ATTR_DOC_MIMETYPE,
     ATTR_DOC_DOCTYPE,
+    ATTR_DOC_SCROLLX,
+    ATTR_DOC_SCROLLY,
 
     // Editable text attributes
     ATTR_TEXT_SEL_START,