content/renderer/accessibility/renderer_accessibility_complete.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/renderer/accessibility/renderer_accessibility_complete.h"
   6
   7 #include <queue>
   8
   9 #include "base/bind.h"
  10 #include "base/message_loop/message_loop.h"
  11 #include "content/renderer/accessibility/blink_ax_enum_conversion.h"
  12 #include "content/renderer/render_view_impl.h"
  13 #include "third_party/WebKit/public/web/WebAXObject.h"
  14 #include "third_party/WebKit/public/web/WebDocument.h"
  15 #include "third_party/WebKit/public/web/WebInputElement.h"
  16 #include "third_party/WebKit/public/web/WebLocalFrame.h"
  17 #include "third_party/WebKit/public/web/WebNode.h"
  18 #include "third_party/WebKit/public/web/WebView.h"
  19 #include "ui/accessibility/ax_tree.h"
  20
  21 using blink::WebAXObject;
  22 using blink::WebDocument;
  23 using blink::WebNode;
  24 using blink::WebPoint;
  25 using blink::WebRect;
  26 using blink::WebSize;
  27 using blink::WebView;
  28
  29 namespace content {
  30
  31 RendererAccessibilityComplete::RendererAccessibilityComplete(
  32     RenderViewImpl* render_view)
  33     : RendererAccessibility(render_view),
  34       weak_factory_(this),
  35       tree_source_(render_view),
  36       serializer_(&tree_source_),
  37       last_scroll_offset_(gfx::Size()),
  38       ack_pending_(false) {
  39   WebAXObject::enableAccessibility();
  40
  41 #if !defined(OS_ANDROID)
  42   // Skip inline text boxes on Android - since there are no native Android
  43   // APIs that compute the bounds of a range of text, it's a waste to
  44   // include these in the AX tree.
  45   WebAXObject::enableInlineTextBoxAccessibility();
  46 #endif
  47
  48   const WebDocument& document = GetMainDocument();
  49   if (!document.isNull()) {
  50     // It's possible that the webview has already loaded a webpage without
  51     // accessibility being enabled. Initialize the browser's cached
  52     // accessibility tree by sending it a notification.
  53     HandleAXEvent(document.accessibilityObject(),
  54                   ui::AX_EVENT_LAYOUT_COMPLETE);
  55   }
  56 }
  57
  58 RendererAccessibilityComplete::~RendererAccessibilityComplete() {
  59 }
  60
  61 bool RendererAccessibilityComplete::OnMessageReceived(
  62     const IPC::Message& message) {
  63   bool handled = true;
  64   IPC_BEGIN_MESSAGE_MAP(RendererAccessibilityComplete, message)
  65     IPC_MESSAGE_HANDLER(AccessibilityMsg_SetFocus, OnSetFocus)
  66     IPC_MESSAGE_HANDLER(AccessibilityMsg_DoDefaultAction,
  67                         OnDoDefaultAction)
  68     IPC_MESSAGE_HANDLER(AccessibilityMsg_Events_ACK,
  69                         OnEventsAck)
  70     IPC_MESSAGE_HANDLER(AccessibilityMsg_ScrollToMakeVisible,
  71                         OnScrollToMakeVisible)
  72     IPC_MESSAGE_HANDLER(AccessibilityMsg_ScrollToPoint,
  73                         OnScrollToPoint)
  74     IPC_MESSAGE_HANDLER(AccessibilityMsg_SetTextSelection,
  75                         OnSetTextSelection)
  76     IPC_MESSAGE_HANDLER(AccessibilityMsg_FatalError, OnFatalError)
  77     IPC_MESSAGE_UNHANDLED(handled = false)
  78   IPC_END_MESSAGE_MAP()
  79   return handled;
  80 }
  81
  82 void RendererAccessibilityComplete::FocusedNodeChanged(const WebNode& node) {
  83   const WebDocument& document = GetMainDocument();
  84   if (document.isNull())
  85     return;
  86
  87   if (node.isNull()) {
  88     // When focus is cleared, implicitly focus the document.
  89     // TODO(dmazzoni): Make Blink send this notification instead.
  90     HandleAXEvent(document.accessibilityObject(), ui::AX_EVENT_BLUR);
  91   }
  92 }
  93
  94 void RendererAccessibilityComplete::DidFinishLoad(blink::WebLocalFrame* frame) {
  95   const WebDocument& document = GetMainDocument();
  96   if (document.isNull())
  97     return;
  98 }
  99
 100
 101 void RendererAccessibilityComplete::HandleWebAccessibilityEvent(
 102     const blink::WebAXObject& obj, blink::WebAXEvent event) {
 103   HandleAXEvent(obj, AXEventFromBlink(event));
 104 }
 105
 106 void RendererAccessibilityComplete::HandleAXEvent(
 107     const blink::WebAXObject& obj, ui::AXEvent event) {
 108   const WebDocument& document = GetMainDocument();
 109   if (document.isNull())
 110     return;
 111
 112   gfx::Size scroll_offset = document.frame()->scrollOffset();
 113   if (scroll_offset != last_scroll_offset_) {
 114     // Make sure the browser is always aware of the scroll position of
 115     // the root document element by posting a generic notification that
 116     // will update it.
 117     // TODO(dmazzoni): remove this as soon as
 118     // https://bugs.webkit.org/show_bug.cgi?id=73460 is fixed.
 119     last_scroll_offset_ = scroll_offset;
 120     if (!obj.equals(document.accessibilityObject())) {
 121       HandleAXEvent(document.accessibilityObject(),
 122                     ui::AX_EVENT_LAYOUT_COMPLETE);
 123     }
 124   }
 125
 126   // Add the accessibility object to our cache and ensure it's valid.
 127   AccessibilityHostMsg_EventParams acc_event;
 128   acc_event.id = obj.axID();
 129   acc_event.event_type = event;
 130
 131   // Discard duplicate accessibility events.
 132   for (uint32 i = 0; i < pending_events_.size(); ++i) {
 133     if (pending_events_[i].id == acc_event.id &&
 134         pending_events_[i].event_type ==
 135             acc_event.event_type) {
 136       return;
 137     }
 138   }
 139   pending_events_.push_back(acc_event);
 140
 141   if (!ack_pending_ && !weak_factory_.HasWeakPtrs()) {
 142     // When no accessibility events are in-flight post a task to send
 143     // the events to the browser. We use PostTask so that we can queue
 144     // up additional events.
 145     base::MessageLoop::current()->PostTask(
 146         FROM_HERE,
 147         base::Bind(&RendererAccessibilityComplete::
 148                        SendPendingAccessibilityEvents,
 149                    weak_factory_.GetWeakPtr()));
 150   }
 151 }
 152
 153 RendererAccessibilityType RendererAccessibilityComplete::GetType() {
 154   return RendererAccessibilityTypeComplete;
 155 }
 156
 157 void RendererAccessibilityComplete::SendPendingAccessibilityEvents() {
 158   const WebDocument& document = GetMainDocument();
 159   if (document.isNull())
 160     return;
 161
 162   if (pending_events_.empty())
 163     return;
 164
 165   if (render_view_->is_swapped_out())
 166     return;
 167
 168   ack_pending_ = true;
 169
 170   // Make a copy of the events, because it's possible that
 171   // actions inside this loop will cause more events to be
 172   // queued up.
 173   std::vector<AccessibilityHostMsg_EventParams> src_events =
 174       pending_events_;
 175   pending_events_.clear();
 176
 177   // Generate an event message from each Blink event.
 178   std::vector<AccessibilityHostMsg_EventParams> event_msgs;
 179
 180   // Loop over each event and generate an updated event message.
 181   for (size_t i = 0; i < src_events.size(); ++i) {
 182     AccessibilityHostMsg_EventParams& event =
 183         src_events[i];
 184
 185     WebAXObject obj = document.accessibilityObjectFromID(
 186         event.id);
 187     if (!obj.updateBackingStoreAndCheckValidity())
 188       continue;
 189
 190     // When we get a "selected children changed" event, Blink
 191     // doesn't also send us events for each child that changed
 192     // selection state, so make sure we re-send that whole subtree.
 193     if (event.event_type ==
 194         ui::AX_EVENT_SELECTED_CHILDREN_CHANGED) {
 195       serializer_.DeleteClientSubtree(obj);
 196     }
 197
 198     AccessibilityHostMsg_EventParams event_msg;
 199     event_msg.event_type = event.event_type;
 200     event_msg.id = event.id;
 201     serializer_.SerializeChanges(obj, &event_msg.update);
 202     event_msgs.push_back(event_msg);
 203
 204 #ifndef NDEBUG
 205     VLOG(0) << "Accessibility update: \n"
 206             << "routing id=" << routing_id()
 207             << " event="
 208             << AccessibilityEventToString(event.event_type)
 209             << "\n" << event_msg.update.ToString();
 210 #endif
 211   }
 212
 213   Send(new AccessibilityHostMsg_Events(routing_id(), event_msgs));
 214
 215   SendLocationChanges();
 216 }
 217
 218 void RendererAccessibilityComplete::SendLocationChanges() {
 219   std::vector<AccessibilityHostMsg_LocationChangeParams> messages;
 220
 221   // Do a breadth-first explore of the whole blink AX tree.
 222   base::hash_map<int, gfx::Rect> new_locations;
 223   std::queue<WebAXObject> objs_to_explore;
 224   objs_to_explore.push(tree_source_.GetRoot());
 225   while (objs_to_explore.size()) {
 226     WebAXObject obj = objs_to_explore.front();
 227     objs_to_explore.pop();
 228
 229     // See if we had a previous location. If not, this whole subtree must
 230     // be new, so don't continue to explore this branch.
 231     int id = obj.axID();
 232     base::hash_map<int, gfx::Rect>::iterator iter = locations_.find(id);
 233     if (iter == locations_.end())
 234       continue;
 235
 236     // If the location has changed, append it to the IPC message.
 237     gfx::Rect new_location = obj.boundingBoxRect();
 238     if (iter != locations_.end() && iter->second != new_location) {
 239       AccessibilityHostMsg_LocationChangeParams message;
 240       message.id = id;
 241       message.new_location = new_location;
 242       messages.push_back(message);
 243     }
 244
 245     // Save the new location.
 246     new_locations[id] = new_location;
 247   }
 248   locations_.swap(new_locations);
 249
 250   Send(new AccessibilityHostMsg_LocationChanges(routing_id(), messages));
 251 }
 252
 253 void RendererAccessibilityComplete::OnDoDefaultAction(int acc_obj_id) {
 254   const WebDocument& document = GetMainDocument();
 255   if (document.isNull())
 256     return;
 257
 258   WebAXObject obj = document.accessibilityObjectFromID(acc_obj_id);
 259   if (obj.isDetached()) {
 260 #ifndef NDEBUG
 261     LOG(WARNING) << "DoDefaultAction on invalid object id " << acc_obj_id;
 262 #endif
 263     return;
 264   }
 265
 266   obj.performDefaultAction();
 267 }
 268
 269 void RendererAccessibilityComplete::OnScrollToMakeVisible(
 270     int acc_obj_id, gfx::Rect subfocus) {
 271   const WebDocument& document = GetMainDocument();
 272   if (document.isNull())
 273     return;
 274
 275   WebAXObject obj = document.accessibilityObjectFromID(acc_obj_id);
 276   if (obj.isDetached()) {
 277 #ifndef NDEBUG
 278     LOG(WARNING) << "ScrollToMakeVisible on invalid object id " << acc_obj_id;
 279 #endif
 280     return;
 281   }
 282
 283   obj.scrollToMakeVisibleWithSubFocus(
 284       WebRect(subfocus.x(), subfocus.y(),
 285               subfocus.width(), subfocus.height()));
 286
 287   // Make sure the browser gets an event when the scroll
 288   // position actually changes.
 289   // TODO(dmazzoni): remove this once this bug is fixed:
 290   // https://bugs.webkit.org/show_bug.cgi?id=73460
 291   HandleAXEvent(document.accessibilityObject(),
 292                 ui::AX_EVENT_LAYOUT_COMPLETE);
 293 }
 294
 295 void RendererAccessibilityComplete::OnScrollToPoint(
 296     int acc_obj_id, gfx::Point point) {
 297   const WebDocument& document = GetMainDocument();
 298   if (document.isNull())
 299     return;
 300
 301   WebAXObject obj = document.accessibilityObjectFromID(acc_obj_id);
 302   if (obj.isDetached()) {
 303 #ifndef NDEBUG
 304     LOG(WARNING) << "ScrollToPoint on invalid object id " << acc_obj_id;
 305 #endif
 306     return;
 307   }
 308
 309   obj.scrollToGlobalPoint(WebPoint(point.x(), point.y()));
 310
 311   // Make sure the browser gets an event when the scroll
 312   // position actually changes.
 313   // TODO(dmazzoni): remove this once this bug is fixed:
 314   // https://bugs.webkit.org/show_bug.cgi?id=73460
 315   HandleAXEvent(document.accessibilityObject(),
 316                 ui::AX_EVENT_LAYOUT_COMPLETE);
 317 }
 318
 319 void RendererAccessibilityComplete::OnSetTextSelection(
 320     int acc_obj_id, int start_offset, int end_offset) {
 321   const WebDocument& document = GetMainDocument();
 322   if (document.isNull())
 323     return;
 324
 325   WebAXObject obj = document.accessibilityObjectFromID(acc_obj_id);
 326   if (obj.isDetached()) {
 327 #ifndef NDEBUG
 328     LOG(WARNING) << "SetTextSelection on invalid object id " << acc_obj_id;
 329 #endif
 330     return;
 331   }
 332
 333   // TODO(dmazzoni): support elements other than <input>.
 334   blink::WebNode node = obj.node();
 335   if (!node.isNull() && node.isElementNode()) {
 336     blink::WebElement element = node.to<blink::WebElement>();
 337     blink::WebInputElement* input_element =
 338         blink::toWebInputElement(&element);
 339     if (input_element && input_element->isTextField())
 340       input_element->setSelectionRange(start_offset, end_offset);
 341   }
 342 }
 343
 344 void RendererAccessibilityComplete::OnEventsAck() {
 345   DCHECK(ack_pending_);
 346   ack_pending_ = false;
 347   SendPendingAccessibilityEvents();
 348 }
 349
 350 void RendererAccessibilityComplete::OnSetFocus(int acc_obj_id) {
 351   const WebDocument& document = GetMainDocument();
 352   if (document.isNull())
 353     return;
 354
 355   WebAXObject obj = document.accessibilityObjectFromID(acc_obj_id);
 356   if (obj.isDetached()) {
 357 #ifndef NDEBUG
 358     LOG(WARNING) << "OnSetAccessibilityFocus on invalid object id "
 359                  << acc_obj_id;
 360 #endif
 361     return;
 362   }
 363
 364   WebAXObject root = document.accessibilityObject();
 365   if (root.isDetached()) {
 366 #ifndef NDEBUG
 367     LOG(WARNING) << "OnSetAccessibilityFocus but root is invalid";
 368 #endif
 369     return;
 370   }
 371
 372   // By convention, calling SetFocus on the root of the tree should clear the
 373   // current focus. Otherwise set the focus to the new node.
 374   if (acc_obj_id == root.axID())
 375     render_view()->GetWebView()->clearFocusedElement();
 376   else
 377     obj.setFocused(true);
 378 }
 379
 380 void RendererAccessibilityComplete::OnFatalError() {
 381   CHECK(false) << "Invalid accessibility tree.";
 382 }
 383
 384 }  // namespace content