Add IPCs to allow assistive technology to scroll the page

or select text.

BUG=104468,104469
TEST=none
Review URL: http://codereview.chromium.org/8776030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112817 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/accessibility/browser_accessibility_manager.cc

@@ -206,6 +206,22 @@ void BrowserAccessibilityManager::DoDefaultAction(
     delegate_->AccessibilityDoDefaultAction(node.renderer_id());
 }
 
+void BrowserAccessibilityManager::ChangeScrollPosition(
+    const BrowserAccessibility& node, int scroll_x, int scroll_y) {
+  if (delegate_) {
+    delegate_->AccessibilityChangeScrollPosition(
+        node.renderer_id(), scroll_x, scroll_y);
+  }
+}
+
+void BrowserAccessibilityManager::SetTextSelection(
+    const BrowserAccessibility& node, int start_offset, int end_offset) {
+  if (delegate_) {
+    delegate_->AccessibilitySetTextSelection(
+        node.renderer_id(), start_offset, end_offset);
+  }
+}
+
 gfx::Rect BrowserAccessibilityManager::GetViewBounds() {
   if (delegate_)
     return delegate_->GetViewBounds();

content/browser/accessibility/browser_accessibility_manager.h

@@ -30,6 +30,10 @@ class CONTENT_EXPORT BrowserAccessibilityDelegate {
   virtual ~BrowserAccessibilityDelegate() {}
   virtual void SetAccessibilityFocus(int acc_obj_id) = 0;
   virtual void AccessibilityDoDefaultAction(int acc_obj_id) = 0;
+  virtual void AccessibilityChangeScrollPosition(
+      int acc_obj_id, int scroll_x, int scroll_y) = 0;
+  virtual void AccessibilitySetTextSelection(
+      int acc_obj_id, int start_offset, int end_offset) = 0;
   virtual bool HasFocus() const = 0;
   virtual gfx::Rect GetViewBounds() const = 0;
 };
@@ -100,6 +104,14 @@ class CONTENT_EXPORT BrowserAccessibilityManager {
   // Tell the renderer to do the default action for this node.
   void DoDefaultAction(const BrowserAccessibility& node);
 
+  // Tell the renderer to scroll this node to the given position.
+  void ChangeScrollPosition(
+      const BrowserAccessibility& node, int scroll_x, int scroll_y);
+
+  // Tell the renderer to set the text selection on a node.
+  void SetTextSelection(
+      const BrowserAccessibility& node, int start_offset, int end_offset);
+
   // Retrieve the bounds of the parent View in screen coordinates.
   gfx::Rect GetViewBounds();
 

content/browser/renderer_host/render_widget_host.cc

@@ -1445,6 +1445,18 @@ void RenderWidgetHost::AccessibilitySetFocus(int object_id) {
   Send(new ViewMsg_SetAccessibilityFocus(routing_id(), object_id));
 }
 
+void RenderWidgetHost::AccessibilityChangeScrollPosition(
+    int object_id, int scroll_x, int scroll_y) {
+  Send(new ViewMsg_AccessibilityChangeScrollPosition(
+      routing_id(), object_id, scroll_x, scroll_y));
+}
+
+void RenderWidgetHost::AccessibilitySetTextSelection(
+    int object_id, int start_offset, int end_offset) {
+  Send(new ViewMsg_AccessibilitySetTextSelection(
+      routing_id(), object_id, start_offset, end_offset));
+}
+
 void RenderWidgetHost::ExecuteEditCommand(const std::string& command,
                                           const std::string& value) {
   Send(new ViewMsg_ExecuteEditCommand(routing_id(), command, value));

content/browser/renderer_host/render_widget_host.h

@@ -414,6 +414,14 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Channel::Listener,
   // Relay a request from assistive technology to set focus to a given node.
   void AccessibilitySetFocus(int object_id);
 
+  // Relay a request from assistive technology to scroll.
+  void AccessibilityChangeScrollPosition(
+      int acc_obj_id, int scroll_x, int scroll_y);
+
+  // Relay a request from assistive technology to set text selection.
+  void AccessibilitySetTextSelection(
+      int acc_obj_id, int start_offset, int end_offset);
+
   // Executes the edit command on the RenderView.
   void ExecuteEditCommand(const std::string& command,
                           const std::string& value);

content/browser/renderer_host/render_widget_host_view_win.cc

@@ -2072,6 +2072,24 @@ void RenderWidgetHostViewWin::AccessibilityDoDefaultAction(int acc_obj_id) {
   render_widget_host_->AccessibilityDoDefaultAction(acc_obj_id);
 }
 
+void RenderWidgetHostViewWin::AccessibilityChangeScrollPosition(
+    int acc_obj_id, int scroll_x, int scroll_y) {
+  if (!render_widget_host_)
+    return;
+
+  render_widget_host_->AccessibilityChangeScrollPosition(
+      acc_obj_id, scroll_x, scroll_y);
+}
+
+void RenderWidgetHostViewWin::AccessibilitySetTextSelection(
+    int acc_obj_id, int start_offset, int end_offset) {
+  if (!render_widget_host_)
+    return;
+
+  render_widget_host_->AccessibilitySetTextSelection(
+      acc_obj_id, start_offset, end_offset);
+}
+
 IAccessible* RenderWidgetHostViewWin::GetIAccessible() {
   if (render_widget_host_ && !render_widget_host_->renderer_accessible()) {
     // Attempt to detect screen readers by sending an event with our custom id.

content/browser/renderer_host/render_widget_host_view_win.h

@@ -220,6 +220,10 @@ class RenderWidgetHostViewWin
   // Implementation of BrowserAccessibilityDelegate:
   virtual void SetAccessibilityFocus(int acc_obj_id) OVERRIDE;
   virtual void AccessibilityDoDefaultAction(int acc_obj_id) OVERRIDE;
+  virtual void AccessibilityChangeScrollPosition(
+      int acc_obj_id, int scroll_x, int scroll_y) OVERRIDE;
+  virtual void AccessibilitySetTextSelection(
+      int acc_obj_id, int start_offset, int end_offset) OVERRIDE;
 
  protected:
   // Windows Message Handlers

content/common/view_messages.h

@@ -1100,6 +1100,20 @@ IPC_MESSAGE_ROUTED1(ViewMsg_SetAccessibilityFocus,
 IPC_MESSAGE_ROUTED1(ViewMsg_AccessibilityDoDefaultAction,
                     int /* object id */)
 
+// Relay a request from assistive technology to change the scroll position
+// of a scrollable container (like the whole page, an iframe, etc.).
+IPC_MESSAGE_ROUTED3(ViewMsg_AccessibilityChangeScrollPosition,
+                    int /* object id */,
+                    int /* New x scroll position */,
+                    int /* New y scroll position */)
+
+// Relay a request from assistive technology to set the cursor or
+// selection within an editable text element.
+IPC_MESSAGE_ROUTED3(ViewMsg_AccessibilitySetTextSelection,
+                    int /* object id */,
+                    int /* New start offset */,
+                    int /* New end offset */)
+
 // Tells the render view that a ViewHostMsg_AccessibilityNotifications
 // message was processed and it can send addition notifications.
 IPC_MESSAGE_ROUTED0(ViewMsg_AccessibilityNotifications_ACK)

content/renderer/renderer_accessibility.cc

@@ -10,6 +10,8 @@
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebAccessibilityObject.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebDocument.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFrame.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebInputElement.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebNode.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
 #include "webkit/glue/webaccessibility.h"
 
@@ -18,6 +20,7 @@ using WebKit::WebAccessibilityObject;
 using WebKit::WebDocument;
 using WebKit::WebFrame;
 using WebKit::WebNode;
+using WebKit::WebSize;
 using WebKit::WebView;
 using webkit_glue::WebAccessibility;
 
@@ -104,6 +107,10 @@ bool RendererAccessibility::OnMessageReceived(const IPC::Message& message) {
                         OnAccessibilityDoDefaultAction)
     IPC_MESSAGE_HANDLER(ViewMsg_AccessibilityNotifications_ACK,
                         OnAccessibilityNotificationsAck)
+    IPC_MESSAGE_HANDLER(ViewMsg_AccessibilityChangeScrollPosition,
+                        OnChangeScrollPosition)
+    IPC_MESSAGE_HANDLER(ViewMsg_AccessibilitySetTextSelection,
+                        OnSetTextSelection)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ -373,6 +380,75 @@ void RendererAccessibility::OnAccessibilityDoDefaultAction(int acc_obj_id) {
   obj.performDefaultAction();
 }
 
+void RendererAccessibility::OnChangeScrollPosition(
+    int acc_obj_id, int scroll_x, int scroll_y) {
+  if (!WebAccessibilityObject::accessibilityEnabled())
+    return;
+
+  const WebDocument& document = GetMainDocument();
+  if (document.isNull())
+    return;
+
+  WebAccessibilityObject root = document.accessibilityObject();
+
+  // TODO(dmazzoni): Support scrolling of any scrollable container,
+  // not just the main document frame.
+  if (acc_obj_id != root.axID())
+    return;
+
+  WebFrame* frame = document.frame();
+  if (!frame)
+    return;
+
+  WebSize min_offset = frame->minimumScrollOffset();
+  WebSize max_offset = frame->maximumScrollOffset();
+  scroll_x = std::max(min_offset.width, scroll_x);
+  scroll_x = std::min(max_offset.width, scroll_x);
+  scroll_y = std::max(min_offset.height, scroll_y);
+  scroll_y = std::min(max_offset.height, scroll_y);
+
+  frame->setScrollOffset(WebSize(scroll_x, scroll_y));
+  if (frame->view())
+    frame->view()->layout();
+
+  // Make sure the browser gets a notification when the scroll
+  // position actually changes.
+  // TODO(dmazzoni): remove this once this bug is fixed:
+  // https://bugs.webkit.org/show_bug.cgi?id=73460
+  PostAccessibilityNotification(
+      root,
+      WebKit::WebAccessibilityNotificationLayoutComplete);
+}
+
+void RendererAccessibility::OnSetTextSelection(
+    int acc_obj_id, int start_offset, int end_offset) {
+  if (!WebAccessibilityObject::accessibilityEnabled())
+    return;
+
+  const WebDocument& document = GetMainDocument();
+  if (document.isNull())
+    return;
+
+  WebAccessibilityObject obj = document.accessibilityObjectFromID(acc_obj_id);
+  if (!obj.isValid()) {
+#ifndef NDEBUG
+    if (logging_)
+      LOG(WARNING) << "SetTextSelection on invalid object id " << acc_obj_id;
+#endif
+    return;
+  }
+
+  // TODO(dmazzoni): support elements other than <input>.
+  WebKit::WebNode node = obj.node();
+  if (!node.isNull() && node.isElementNode()) {
+    WebKit::WebElement element = node.to<WebKit::WebElement>();
+    WebKit::WebInputElement* input_element =
+        WebKit::toWebInputElement(&element);
+    if (input_element && input_element->isTextField())
+      input_element->setSelectionRange(start_offset, end_offset);
+  }
+}
+
 void RendererAccessibility::OnAccessibilityNotificationsAck() {
   DCHECK(ack_pending_);
   ack_pending_ = false;

content/renderer/renderer_accessibility.h

@@ -82,9 +82,12 @@ class RendererAccessibility : public content::RenderViewObserver {
   // Handlers for messages from the browser to the renderer.
   void OnAccessibilityDoDefaultAction(int acc_obj_id);
   void OnAccessibilityNotificationsAck();
+  void OnChangeScrollPosition(int acc_obj_id, int scroll_x, int scroll_y);
   void OnEnableAccessibility();
   void OnSetAccessibilityFocus(int acc_obj_id);
 
+  void OnSetTextSelection(int acc_obj_id, int start_offset, int end_offset);
+
   // Whether or not this notification typically needs to send
   // updates to its children, too.
   bool ShouldIncludeChildren(const Notification& notification);