ui/accessibility/platform/ax_platform_node_delegate.h

   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 #ifndef UI_ACCESSIBILITY_PLATFORM_AX_PLATFORM_NODE_DELEGATE_H_
   6 #define UI_ACCESSIBILITY_PLATFORM_AX_PLATFORM_NODE_DELEGATE_H_
   7
   8 #include "ui/accessibility/ax_enums.h"
   9 #include "ui/accessibility/ax_export.h"
  10 #include "ui/gfx/geometry/vector2d.h"
  11 #include "ui/gfx/native_widget_types.h"
  12
  13 namespace ui {
  14
  15 struct AXNodeData;
  16 class AXPlatformNode;
  17
  18 // An object that wants to be accessible should derive from this class.
  19 // AXPlatformNode subclasses use this interface to query all of the information
  20 // about the object in order to implement native accessibility APIs.
  21 //
  22 // Note that AXPlatformNode has support for accessibility trees where some
  23 // of the objects in the tree are not implemented using AXPlatformNode.
  24 // For example, you may have a native window with platform-native widgets
  25 // in it, but in that window you have custom controls that use AXPlatformNode
  26 // to provide accessibility. That's why GetParent, ChildAtIndex, HitTestSync,
  27 // and GetFocus all return a gfx::NativeViewAccessible - so you can return a
  28 // native accessible if necessary, and AXPlatformNode::GetNativeViewAccessible
  29 // otherwise.
  30 class AX_EXPORT AXPlatformNodeDelegate {
  31  public:
  32   // Get the accessibility data that should be exposed for this node.
  33   // Virtually all of the information is obtained from this structure
  34   // (role, state, name, cursor position, etc.) - the rest of this interface
  35   // is mostly to implement support for walking the accessibility tree.
  36   virtual const AXNodeData& GetData() = 0;
  37
  38   // Get the parent of the node, which may be an AXPlatformNode or it may
  39   // be a native accessible object implemented by another class.
  40   virtual gfx::NativeViewAccessible GetParent() = 0;
  41
  42   // Get the number of children of this node.
  43   virtual int GetChildCount() = 0;
  44
  45   // Get the child of a node given a 0-based index.
  46   virtual gfx::NativeViewAccessible ChildAtIndex(int index) = 0;
  47
  48   // Get the offset to convert local coordinates to screen global coordinates.
  49   virtual gfx::Vector2d GetGlobalCoordinateOffset() = 0;
  50
  51   // Do a *synchronous* hit test of the given location in global screen
  52   // coordinates, and the node within this node's subtree (inclusive) that's
  53   // hit, if any.
  54   //
  55   // If the result is anything other than this object or NULL, it will be
  56   // hit tested again recursively - that allows hit testing to work across
  57   // implementation classes. It's okay to take advantage of this and return
  58   // only an immediate child and not the deepest descendant.
  59   //
  60   // This function is mainly used by accessibility debugging software.
  61   // Platforms with touch accessibility use a different asynchronous interface.
  62   virtual gfx::NativeViewAccessible HitTestSync(int x, int y) = 0;
  63
  64   // Return the node within this node's subtree (inclusive) that currently
  65   // has focus.
  66   virtual gfx::NativeViewAccessible GetFocus() = 0;
  67
  68   //
  69   // Events.
  70   //
  71
  72   // Return the platform-native GUI object that should be used as a target
  73   // for accessibility events.
  74   virtual gfx::AcceleratedWidget GetTargetForNativeAccessibilityEvent() = 0;
  75
  76   //
  77   // Actions.
  78   //
  79
  80   // Perform the default action, e.g. click a button, follow a link, or
  81   // toggle a checkbox.
  82   virtual void DoDefaultAction() = 0;
  83
  84   // Change the value of a control, such as the text content of a text field.
  85   virtual bool SetStringValue(const base::string16& new_value) = 0;
  86 };
  87
  88 }  // namespace ui
  89
  90 #endif  // UI_ACCESSIBILITY_PLATFORM_AX_PLATFORM_NODE_DELEGATE_H_