chrome/renderer/resources/extensions/automation_custom_bindings.js

   1 // Copyright 2014 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 // Custom bindings for the automation API.
   6 var AutomationNode = require('automationNode').AutomationNode;
   7 var AutomationRootNode = require('automationNode').AutomationRootNode;
   8 var automation = require('binding').Binding.create('automation');
   9 var automationInternal =
  10     require('binding').Binding.create('automationInternal').generate();
  11 var eventBindings = require('event_bindings');
  12 var Event = eventBindings.Event;
  13 var forEach = require('utils').forEach;
  14 var lastError = require('lastError');
  15 var logging = requireNative('logging');
  16 var schema = requireNative('automationInternal').GetSchemaAdditions();
  17
  18 /**
  19  * A namespace to export utility functions to other files in automation.
  20  */
  21 window.automationUtil = function() {};
  22
  23 // TODO(aboxhall): Look into using WeakMap
  24 var idToAutomationRootNode = {};
  25 var idToCallback = {};
  26
  27 var DESKTOP_TREE_ID = 0;
  28
  29 automationUtil.storeTreeCallback = function(id, callback) {
  30   if (!callback)
  31     return;
  32
  33   var targetTree = idToAutomationRootNode[id];
  34   if (!targetTree) {
  35     // If we haven't cached the tree, hold the callback until the tree is
  36     // populated by the initial onAccessibilityEvent call.
  37     if (id in idToCallback)
  38       idToCallback[id].push(callback);
  39     else
  40       idToCallback[id] = [callback];
  41   } else {
  42     callback(targetTree);
  43   }
  44 };
  45
  46 automation.registerCustomHook(function(bindingsAPI) {
  47   var apiFunctions = bindingsAPI.apiFunctions;
  48
  49   // TODO(aboxhall, dtseng): Make this return the speced AutomationRootNode obj.
  50   apiFunctions.setHandleRequest('getTree', function getTree(tabId, callback) {
  51     // enableTab() ensures the renderer for the active or specified tab has
  52     // accessibility enabled, and fetches its ax tree id to use as
  53     // a key in the idToAutomationRootNode map. The callback to
  54     // enableTab is bound to the callback passed in to getTree(), so that once
  55     // the tree is available (either due to having been cached earlier, or after
  56     // an accessibility event occurs which causes the tree to be populated), the
  57     // callback can be called.
  58     automationInternal.enableTab(tabId, function onEnable(id) {
  59       if (lastError.hasError(chrome)) {
  60         callback();
  61         return;
  62       }
  63       automationUtil.storeTreeCallback(id, callback);
  64     });
  65   });
  66
  67   var desktopTree = null;
  68   apiFunctions.setHandleRequest('getDesktop', function(callback) {
  69     desktopTree =
  70         idToAutomationRootNode[DESKTOP_TREE_ID];
  71     if (!desktopTree) {
  72       if (DESKTOP_TREE_ID in idToCallback)
  73         idToCallback[DESKTOP_TREE_ID].push(callback);
  74       else
  75         idToCallback[DESKTOP_TREE_ID] = [callback];
  76
  77       // TODO(dtseng): Disable desktop tree once desktop object goes out of
  78       // scope.
  79       automationInternal.enableDesktop(function() {
  80         if (lastError.hasError(chrome)) {
  81           delete idToAutomationRootNode[
  82               DESKTOP_TREE_ID];
  83           callback();
  84           return;
  85         }
  86       });
  87     } else {
  88       callback(desktopTree);
  89     }
  90   });
  91 });
  92
  93 // Listen to the automationInternal.onAccessibilityEvent event, which is
  94 // essentially a proxy for the AccessibilityHostMsg_Events IPC from the
  95 // renderer.
  96 automationInternal.onAccessibilityEvent.addListener(function(data) {
  97   var id = data.treeID;
  98   var targetTree = idToAutomationRootNode[id];
  99   if (!targetTree) {
 100     // If this is the first time we've gotten data for this tree, it will
 101     // contain all of the tree's data, so create a new tree which will be
 102     // bootstrapped from |data|.
 103     targetTree = new AutomationRootNode(id);
 104     idToAutomationRootNode[id] = targetTree;
 105   }
 106   if (!privates(targetTree).impl.onAccessibilityEvent(data))
 107     return;
 108
 109   // If we're not waiting on a callback to getTree(), we can early out here.
 110   if (!(id in idToCallback))
 111     return;
 112
 113   // We usually get a 'placeholder' tree first, which doesn't have any url
 114   // attribute or child nodes. If we've got that, wait for the full tree before
 115   // calling the callback.
 116   // TODO(dmazzoni): Don't send down placeholder (crbug.com/397553)
 117   if (id != DESKTOP_TREE_ID && !targetTree.attributes.url &&
 118       targetTree.children.length == 0) {
 119     return;
 120   }
 121
 122   // If the tree wasn't available when getTree() was called, the callback will
 123   // have been cached in idToCallback, so call and delete it now that we
 124   // have the complete tree.
 125   for (var i = 0; i < idToCallback[id].length; i++) {
 126     console.log('calling getTree() callback');
 127     var callback = idToCallback[id][i];
 128     callback(targetTree);
 129   }
 130   delete idToCallback[id];
 131 });
 132
 133 automationInternal.onAccessibilityTreeDestroyed.addListener(function(id) {
 134   var targetTree = idToAutomationRootNode[id];
 135   if (targetTree) {
 136     privates(targetTree).impl.destroy();
 137     delete idToAutomationRootNode[id];
 138   } else {
 139     logging.WARNING('no targetTree to destroy');
 140   }
 141   delete idToAutomationRootNode[id];
 142 });
 143
 144 exports.binding = automation.generate();
 145
 146 // Add additional accessibility bindings not specified in the automation IDL.
 147 // Accessibility and automation share some APIs (see
 148 // ui/accessibility/ax_enums.idl).
 149 forEach(schema, function(k, v) {
 150   exports.binding[k] = v;
 151 });