Flutter Windows Embedder
flutter_platform_node_delegate.h
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1 // Copyright 2013 The Flutter 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 FLUTTER_SHELL_PLATFORM_COMMON_FLUTTER_PLATFORM_NODE_DELEGATE_H_
6 #define FLUTTER_SHELL_PLATFORM_COMMON_FLUTTER_PLATFORM_NODE_DELEGATE_H_
7 
8 #include "flutter/fml/mapping.h"
9 #include "flutter/shell/platform/embedder/embedder.h"
10 #include "flutter/third_party/accessibility/ax/ax_event_generator.h"
11 #include "flutter/third_party/accessibility/ax/platform/ax_platform_node_delegate_base.h"
12 
13 namespace flutter {
14 
15 typedef ui::AXNode::AXID AccessibilityNodeId;
16 
17 //------------------------------------------------------------------------------
18 /// The platform node delegate to be used in accessibility bridge. This
19 /// class is responsible for providing native accessibility object with
20 /// appropriate information, such as accessibility label/value/bounds.
21 ///
22 /// While most methods have default implementations and are ready to be used
23 /// as-is, the subclasses must override the GetNativeViewAccessible to return
24 /// native accessibility objects. To do that, subclasses should create and
25 /// maintain AXPlatformNode[s] which delegate their accessibility attributes to
26 /// this class.
27 ///
28 /// For desktop platforms, subclasses also need to override the GetBoundsRect
29 /// to apply window-to-screen transform.
30 ///
31 /// This class transforms bounds assuming the device pixel ratio is 1.0. See
32 /// the https://github.com/flutter/flutter/issues/74283 for more information.
33 class FlutterPlatformNodeDelegate : public ui::AXPlatformNodeDelegateBase {
34  public:
35  //----------------------------------------------------------------------------
36  /// The required interface to be able to own the flutter platform node
37  /// delegate.
38  class OwnerBridge {
39  public:
40  virtual ~OwnerBridge() = default;
41 
42  //---------------------------------------------------------------------------
43  /// @brief Gets the rectangular bounds of the ax node relative to
44  /// global coordinate
45  ///
46  /// @param[in] node The ax node to look up.
47  /// @param[in] offscreen the bool reference to hold the result whether
48  /// the ax node is outside of its ancestors' bounds.
49  /// @param[in] clip_bounds whether to clip the result if the ax node cannot
50  /// be fully contained in its ancestors' bounds.
51  virtual gfx::RectF RelativeToGlobalBounds(const ui::AXNode* node,
52  bool& offscreen,
53  bool clip_bounds) = 0;
54 
55  protected:
57 
58  //---------------------------------------------------------------------------
59  /// @brief Dispatch accessibility action back to the Flutter framework.
60  /// These actions are generated in the native accessibility
61  /// system when users interact with the assistive technologies.
62  /// For example, a
63  /// FlutterSemanticsAction::kFlutterSemanticsActionTap is
64  /// fired when user click or touch the screen.
65  ///
66  /// @param[in] target The semantics node id of the action
67  /// target.
68  /// @param[in] action The generated flutter semantics action.
69  /// @param[in] data Additional data associated with the
70  /// action.
72  FlutterSemanticsAction action,
73  fml::MallocMapping data) = 0;
74 
75  //---------------------------------------------------------------------------
76  /// @brief Get the native accessibility node with the given id.
77  ///
78  /// @param[in] id The id of the native accessibility node you
79  /// want to retrieve.
80  virtual gfx::NativeViewAccessible GetNativeAccessibleFromId(
81  AccessibilityNodeId id) = 0;
82 
83  //---------------------------------------------------------------------------
84  /// @brief Get the last id of the node that received accessibility
85  /// focus.
87 
88  //---------------------------------------------------------------------------
89  /// @brief Update the id of the node that is currently foucsed by the
90  /// native accessibility system.
91  ///
92  /// @param[in] node_id The id of the focused node.
93  virtual void SetLastFocusedId(AccessibilityNodeId node_id) = 0;
94  };
95 
97 
98  // |ui::AXPlatformNodeDelegateBase|
99  virtual ~FlutterPlatformNodeDelegate() override;
100 
101  // |ui::AXPlatformNodeDelegateBase|
102  const ui::AXUniqueId& GetUniqueId() const override { return unique_id_; }
103 
104  // |ui::AXPlatformNodeDelegateBase|
105  const ui::AXNodeData& GetData() const override;
106 
107  // |ui::AXPlatformNodeDelegateBase|
108  bool AccessibilityPerformAction(const ui::AXActionData& data) override;
109 
110  // |ui::AXPlatformNodeDelegateBase|
111  gfx::NativeViewAccessible GetParent() override;
112 
113  // |ui::AXPlatformNodeDelegateBase|
114  gfx::NativeViewAccessible GetFocus() override;
115 
116  // |ui::AXPlatformNodeDelegateBase|
117  int GetChildCount() const override;
118 
119  // |ui::AXPlatformNodeDelegateBase|
120  gfx::NativeViewAccessible ChildAtIndex(int index) override;
121 
122  // |ui::AXPlatformNodeDelegateBase|
123  gfx::Rect GetBoundsRect(
124  const ui::AXCoordinateSystem coordinate_system,
125  const ui::AXClippingBehavior clipping_behavior,
126  ui::AXOffscreenResult* offscreen_result) const override;
127 
128  // |ui::AXPlatformNodeDelegateBase|
129  gfx::NativeViewAccessible GetLowestPlatformAncestor() const override;
130 
131  // |ui::AXPlatformNodeDelegateBase|
132  ui::AXNodePosition::AXPositionInstance CreateTextPositionAt(
133  int offset) const override;
134 
135  //------------------------------------------------------------------------------
136  /// @brief Called only once, immediately after construction. The
137  /// constructor doesn't take any arguments because in the Windows
138  /// subclass we use a special function to construct a COM object.
139  /// Subclasses must call super.
140  virtual void Init(std::weak_ptr<OwnerBridge> bridge, ui::AXNode* node);
141 
142  //------------------------------------------------------------------------------
143  /// @brief Gets the underlying ax node for this platform node delegate.
144  ui::AXNode* GetAXNode() const;
145 
146  //------------------------------------------------------------------------------
147  /// @brief Gets the owner of this platform node delegate. This is useful
148  /// when you want to get the information about surrounding nodes
149  /// of this platform node delegate, e.g. the global rect of this
150  /// platform node delegate. This pointer is only safe in the
151  /// platform thread.
152  std::weak_ptr<OwnerBridge> GetOwnerBridge() const;
153 
154  // Get the platform node represented by this delegate.
155  virtual ui::AXPlatformNode* GetPlatformNode() const;
156 
157  // |ui::AXPlatformNodeDelegateBase|
158  virtual ui::AXPlatformNode* GetFromNodeID(int32_t id) override;
159 
160  // |ui::AXPlatformNodeDelegateBase|
161  virtual ui::AXPlatformNode* GetFromTreeIDAndNodeID(
162  const ui::AXTreeID& tree_id,
163  int32_t node_id) override;
164 
165  // |ui::AXPlatformNodeDelegateBase|
166  virtual const ui::AXTree::Selection GetUnignoredSelection() const override;
167 
168  private:
169  ui::AXNode* ax_node_;
170  std::weak_ptr<OwnerBridge> bridge_;
171  ui::AXUniqueId unique_id_;
172 };
173 
174 } // namespace flutter
175 
176 #endif // FLUTTER_SHELL_PLATFORM_COMMON_FLUTTER_PLATFORM_NODE_DELEGATE_H_
flutter::FlutterPlatformNodeDelegate::GetFromTreeIDAndNodeID
virtual ui::AXPlatformNode * GetFromTreeIDAndNodeID(const ui::AXTreeID &tree_id, int32_t node_id) override
Definition: flutter_platform_node_delegate.cc:150
flutter::FlutterPlatformNodeDelegate::ChildAtIndex
gfx::NativeViewAccessible ChildAtIndex(int index) override
Definition: flutter_platform_node_delegate.cc:87
flutter::FlutterPlatformNodeDelegate::OwnerBridge::~OwnerBridge
virtual ~OwnerBridge()=default
flutter::FlutterPlatformNodeDelegate::GetUniqueId
const ui::AXUniqueId & GetUniqueId() const override
Definition: flutter_platform_node_delegate.h:102
flutter::FlutterPlatformNodeDelegate::Init
virtual void Init(std::weak_ptr< OwnerBridge > bridge, ui::AXNode *node)
Called only once, immediately after construction. The constructor doesn't take any arguments because ...
Definition: flutter_platform_node_delegate.cc:20
flutter::FlutterPlatformNodeDelegate::GetOwnerBridge
std::weak_ptr< OwnerBridge > GetOwnerBridge() const
Gets the owner of this platform node delegate. This is useful when you want to get the information ab...
Definition: flutter_platform_node_delegate.cc:115
flutter::FlutterPlatformNodeDelegate::GetFromNodeID
virtual ui::AXPlatformNode * GetFromNodeID(int32_t id) override
Definition: flutter_platform_node_delegate.cc:140
flutter::FlutterPlatformNodeDelegate::CreateTextPositionAt
ui::AXNodePosition::AXPositionInstance CreateTextPositionAt(int offset) const override
Definition: flutter_platform_node_delegate.cc:136
flutter::FlutterPlatformNodeDelegate::GetUnignoredSelection
virtual const ui::AXTree::Selection GetUnignoredSelection() const override
Definition: flutter_platform_node_delegate.cc:160
flutter::FlutterPlatformNodeDelegate::GetPlatformNode
virtual ui::AXPlatformNode * GetPlatformNode() const
Definition: flutter_platform_node_delegate.cc:119
flutter::FlutterPlatformNodeDelegate::GetData
const ui::AXNodeData & GetData() const override
Definition: flutter_platform_node_delegate.cc:60
flutter::FlutterPlatformNodeDelegate::GetBoundsRect
gfx::Rect GetBoundsRect(const ui::AXCoordinateSystem coordinate_system, const ui::AXClippingBehavior clipping_behavior, ui::AXOffscreenResult *offscreen_result) const override
Definition: flutter_platform_node_delegate.cc:94
flutter::FlutterPlatformNodeDelegate::OwnerBridge::DispatchAccessibilityAction
virtual void DispatchAccessibilityAction(AccessibilityNodeId target, FlutterSemanticsAction action, fml::MallocMapping data)=0
Dispatch accessibility action back to the Flutter framework. These actions are generated in the nativ...
flutter::FlutterPlatformNodeDelegate::~FlutterPlatformNodeDelegate
virtual ~FlutterPlatformNodeDelegate() override
flutter::AccessibilityNodeId
ui::AXNode::AXID AccessibilityNodeId
Definition: flutter_platform_node_delegate.h:15
flutter
Definition: accessibility_bridge_windows.cc:11
flutter::FlutterPlatformNodeDelegate::OwnerBridge::GetLastFocusedId
virtual AccessibilityNodeId GetLastFocusedId()=0
Get the last id of the node that received accessibility focus.
flutter::FlutterPlatformNodeDelegate::OwnerBridge::RelativeToGlobalBounds
virtual gfx::RectF RelativeToGlobalBounds(const ui::AXNode *node, bool &offscreen, bool clip_bounds)=0
Gets the rectangular bounds of the ax node relative to global coordinate.
flutter::FlutterPlatformNodeDelegate::GetAXNode
ui::AXNode * GetAXNode() const
Gets the underlying ax node for this platform node delegate.
Definition: flutter_platform_node_delegate.cc:26
flutter::FlutterPlatformNodeDelegate::GetChildCount
int GetChildCount() const override
Definition: flutter_platform_node_delegate.cc:83
flutter::FlutterPlatformNodeDelegate::GetParent
gfx::NativeViewAccessible GetParent() override
Definition: flutter_platform_node_delegate.cc:64
flutter::FlutterPlatformNodeDelegate
Definition: flutter_platform_node_delegate.h:33
action
int action
Definition: keyboard_key_handler_unittests.cc:116
flutter::FlutterPlatformNodeDelegate::GetFocus
gfx::NativeViewAccessible GetFocus() override
Definition: flutter_platform_node_delegate.cc:73
flutter::FlutterPlatformNodeDelegate::AccessibilityPerformAction
bool AccessibilityPerformAction(const ui::AXActionData &data) override
Definition: flutter_platform_node_delegate.cc:30
flutter::FlutterPlatformNodeDelegate::OwnerBridge
Definition: flutter_platform_node_delegate.h:38
flutter::FlutterPlatformNodeDelegate::OwnerBridge::GetNativeAccessibleFromId
virtual gfx::NativeViewAccessible GetNativeAccessibleFromId(AccessibilityNodeId id)=0
Get the native accessibility node with the given id.
flutter::FlutterPlatformNodeDelegate::FlutterPlatformNodeDelegate
FlutterPlatformNodeDelegate()
flutter::FlutterPlatformNodeDelegate::GetLowestPlatformAncestor
gfx::NativeViewAccessible GetLowestPlatformAncestor() const override
Definition: flutter_platform_node_delegate.cc:124
flutter::FlutterPlatformNodeDelegate::OwnerBridge::SetLastFocusedId
virtual void SetLastFocusedId(AccessibilityNodeId node_id)=0
Update the id of the node that is currently foucsed by the native accessibility system.