Add IPCs to allow assistive technology to scroll the page

content/renderer/renderer_accessibility.cc

 // Copyright (c) 2011 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 "base/command_line.h"
 #include "content/common/view_messages.h"
 #include "content/public/common/content_switches.h"
 #include "content/renderer/render_view_impl.h"
 #include "content/renderer/renderer_accessibility.h"
 #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"
 
 using WebKit::WebAccessibilityNotification;
 using WebKit::WebAccessibilityObject;
 using WebKit::WebDocument;
 using WebKit::WebFrame;
 using WebKit::WebNode;
+using WebKit::WebSize;
 using WebKit::WebView;
 using webkit_glue::WebAccessibility;
 
 bool WebAccessibilityNotificationToViewHostMsg(
     WebAccessibilityNotification notification,
     ViewHostMsg_AccEvent::Value* type) {
   switch (notification) {
     case WebKit::WebAccessibilityNotificationActiveDescendantChanged:
       *type = ViewHostMsg_AccEvent::ACTIVE_DESCENDANT_CHANGED;
       break;
@@ skipping 66 matching lines @@
 
 bool RendererAccessibility::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(RendererAccessibility, message)
     IPC_MESSAGE_HANDLER(ViewMsg_EnableAccessibility, OnEnableAccessibility)
     IPC_MESSAGE_HANDLER(ViewMsg_SetAccessibilityFocus, OnSetAccessibilityFocus)
     IPC_MESSAGE_HANDLER(ViewMsg_AccessibilityDoDefaultAction,
                         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;
 }
 
 void RendererAccessibility::FocusedNodeChanged(const WebNode& node) {
   if (!WebAccessibilityObject::accessibilityEnabled())
     return;
 
   const WebDocument& document = GetMainDocument();
@@ skipping 249 matching lines @@
 #ifndef NDEBUG
     if (logging_)
       LOG(WARNING) << "DoDefaultAction on invalid object id " << acc_obj_id;
 #endif
     return;
   }
 
   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;
   SendPendingAccessibilityNotifications();
 }
 
 void RendererAccessibility::OnEnableAccessibility() {
   if (WebAccessibilityObject::accessibilityEnabled())
     return;
 
@@ skipping 60 matching lines @@
 
 WebDocument RendererAccessibility::GetMainDocument() {
   WebView* view = render_view()->GetWebView();
   WebFrame* main_frame = view ? view->mainFrame() : NULL;
 
   if (main_frame)
     return main_frame->document();
   else
     return WebDocument();
 }