content/browser/accessibility/browser_accessibility_manager_android.h

   1 // Copyright 2013 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 #ifndef CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_ANDROID_H_
   6 #define CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_ANDROID_H_
   7
   8 #include "base/android/scoped_java_ref.h"
   9 #include "content/browser/accessibility/browser_accessibility_manager.h"
  10 #include "content/browser/android/content_view_core_impl.h"
  11
  12 namespace content {
  13
  14 namespace aria_strings {
  15   extern const char kAriaLivePolite[];
  16   extern const char kAriaLiveAssertive[];
  17 }
  18
  19 // A Java counterpart will be generated for this enum.
  20 // GENERATED_JAVA_ENUM_PACKAGE: org.chromium.content.browser.accessibility
  21 enum ScrollDirection {
  22   FORWARD,
  23   BACKWARD,
  24   UP,
  25   DOWN,
  26   LEFT,
  27   RIGHT
  28 };
  29
  30 // From android.view.accessibility.AccessibilityNodeInfo in Java:
  31 enum AndroidMovementGranularity {
  32   ANDROID_ACCESSIBILITY_NODE_INFO_MOVEMENT_GRANULARITY_CHARACTER = 1,
  33   ANDROID_ACCESSIBILITY_NODE_INFO_MOVEMENT_GRANULARITY_WORD = 2,
  34   ANDROID_ACCESSIBILITY_NODE_INFO_MOVEMENT_GRANULARITY_LINE = 4
  35 };
  36
  37 // From android.view.accessibility.AccessibilityEvent in Java:
  38 enum {
  39   ANDROID_ACCESSIBILITY_EVENT_TEXT_CHANGED = 16,
  40   ANDROID_ACCESSIBILITY_EVENT_TEXT_SELECTION_CHANGED = 8192,
  41   ANDROID_ACCESSIBILITY_EVENT_TEXT_TRAVERSED_AT_MOVEMENT_GRANULARITY = 131072
  42 };
  43
  44 class BrowserAccessibilityAndroid;
  45
  46 class CONTENT_EXPORT BrowserAccessibilityManagerAndroid
  47     : public BrowserAccessibilityManager {
  48  public:
  49   BrowserAccessibilityManagerAndroid(
  50       base::android::ScopedJavaLocalRef<jobject> content_view_core,
  51       const SimpleAXTreeUpdate& initial_tree,
  52       BrowserAccessibilityDelegate* delegate,
  53       BrowserAccessibilityFactory* factory = new BrowserAccessibilityFactory());
  54
  55   ~BrowserAccessibilityManagerAndroid() override;
  56
  57   static SimpleAXTreeUpdate GetEmptyDocument();
  58
  59   void SetContentViewCore(
  60       base::android::ScopedJavaLocalRef<jobject> content_view_core);
  61
  62   // By default, the tree is pruned for a better screen reading experience,
  63   // including:
  64   //   * If the node has only static text children
  65   //   * If the node is focusable and has no focusable children
  66   //   * If the node is a heading
  67   // This can be turned off to generate a tree that more accurately reflects
  68   // the DOM and includes style changes within these nodes.
  69   void set_prune_tree_for_screen_reader(bool prune) {
  70     prune_tree_for_screen_reader_ = prune;
  71   }
  72   bool prune_tree_for_screen_reader() { return prune_tree_for_screen_reader_; }
  73
  74   // Implementation of BrowserAccessibilityManager.
  75   void NotifyAccessibilityEvent(ui::AXEvent event_type,
  76                                 BrowserAccessibility* node) override;
  77
  78   // --------------------------------------------------------------------------
  79   // Methods called from Java via JNI
  80   // --------------------------------------------------------------------------
  81
  82   // Tree methods.
  83   jint GetRootId(JNIEnv* env, jobject obj);
  84   jboolean IsNodeValid(JNIEnv* env, jobject obj, jint id);
  85   void HitTest(JNIEnv* env, jobject obj, jint x, jint y);
  86
  87   // Methods to get information about a specific node.
  88   jboolean IsEditableText(JNIEnv* env, jobject obj, jint id);
  89   jint GetEditableTextSelectionStart(JNIEnv* env, jobject obj, jint id);
  90   jint GetEditableTextSelectionEnd(JNIEnv* env, jobject obj, jint id);
  91
  92   // Populate Java accessibility data structures with info about a node.
  93   jboolean PopulateAccessibilityNodeInfo(
  94       JNIEnv* env, jobject obj, jobject info, jint id);
  95   jboolean PopulateAccessibilityEvent(
  96       JNIEnv* env, jobject obj, jobject event, jint id, jint event_type);
  97
  98   // Perform actions.
  99   void Click(JNIEnv* env, jobject obj, jint id);
 100   void Focus(JNIEnv* env, jobject obj, jint id);
 101   void Blur(JNIEnv* env, jobject obj);
 102   void ScrollToMakeNodeVisible(JNIEnv* env, jobject obj, jint id);
 103   void SetTextFieldValue(JNIEnv* env, jobject obj, jint id, jstring value);
 104   void SetSelection(JNIEnv* env, jobject obj, jint id, jint start, jint end);
 105   jboolean AdjustSlider(JNIEnv* env, jobject obj, jint id, jboolean increment);
 106
 107   // Return the id of the next node in tree order in the direction given by
 108   // |forwards|, starting with |start_id|, that matches |element_type|,
 109   // where |element_type| is a special uppercase string from TalkBack or
 110   // BrailleBack indicating general categories of web content like
 111   // "SECTION" or "CONTROL".  Return 0 if not found.
 112   jint FindElementType(JNIEnv* env, jobject obj, jint start_id,
 113                        jstring element_type, jboolean forwards);
 114
 115   // Respond to a ACTION_[NEXT/PREVIOUS]_AT_MOVEMENT_GRANULARITY action
 116   // and move the cursor/selection within the given node id. We keep track
 117   // of our own selection in BrowserAccessibilityManager.java for static
 118   // text, but if this is an editable text node, updates the selected text
 119   // in Blink, too, and either way calls
 120   // Java_BrowserAccessibilityManager_finishGranularityMove with the
 121   // result.
 122   jboolean NextAtGranularity(JNIEnv* env, jobject obj,
 123                              jint granularity, jboolean extend_selection,
 124                              jint id, jint cursor_index);
 125   jboolean PreviousAtGranularity(JNIEnv* env, jobject obj,
 126                                  jint granularity, jboolean extend_selection,
 127                                  jint id, jint cursor_index);
 128
 129   // Helper functions to compute the next start and end index when moving
 130   // forwards or backwards by character, word, or line. This part is
 131   // unit-tested; the Java interfaces above are just wrappers. Both of these
 132   // take a single cursor index as input and return the boundaries surrounding
 133   // the next word or line. If moving by character, the output start and
 134   // end index will be the same.
 135   bool NextAtGranularity(
 136       int32 granularity, int cursor_index,
 137       BrowserAccessibilityAndroid* node, int32* start_index, int32* end_index);
 138   bool PreviousAtGranularity(
 139       int32 granularity, int cursor_index,
 140       BrowserAccessibilityAndroid* node, int32* start_index, int32* end_index);
 141
 142   // Set accessibility focus. This sends a message to the renderer to
 143   // asynchronously load inline text boxes for this node only, enabling more
 144   // accurate movement by granularities on this node.
 145   void SetAccessibilityFocus(JNIEnv* env, jobject obj, jint id);
 146
 147   // Returns true if the object is a slider.
 148   bool IsSlider(JNIEnv* env, jobject obj, jint id);
 149
 150   // Scrolls any scrollable container by about 80% of one page in the
 151   // given direction.
 152   bool Scroll(JNIEnv* env, jobject obj, jint id, int direction);
 153
 154  protected:
 155   // AXTreeDelegate overrides.
 156   void OnAtomicUpdateFinished(
 157       ui::AXTree* tree,
 158       bool root_changed,
 159       const std::vector<ui::AXTreeDelegate::Change>& changes) override;
 160
 161   bool UseRootScrollOffsetsWhenComputingBounds() override;
 162
 163  private:
 164   // This gives BrowserAccessibilityManager::Create access to the class
 165   // constructor.
 166   friend class BrowserAccessibilityManager;
 167
 168   // A weak reference to the Java BrowserAccessibilityManager object.
 169   // This avoids adding another reference to BrowserAccessibilityManager and
 170   // preventing garbage collection.
 171   // Premature garbage collection is prevented by the long-lived reference in
 172   // ContentViewCore.
 173   JavaObjectWeakGlobalRef java_ref_;
 174
 175   // Handle a hover event from the renderer process.
 176   void HandleHoverEvent(BrowserAccessibility* node);
 177
 178   // See docs for set_prune_tree_for_screen_reader, above.
 179   bool prune_tree_for_screen_reader_;
 180
 181   DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityManagerAndroid);
 182 };
 183
 184 bool RegisterBrowserAccessibilityManager(JNIEnv* env);
 185
 186 }
 187
 188 #endif  // CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_ANDROID_H_