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text_input_manager.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_WINDOWS_TEXT_INPUT_MANAGER_H_
6 #define FLUTTER_SHELL_PLATFORM_WINDOWS_TEXT_INPUT_MANAGER_H_
7
8 #include <Windows.h>
9 #include <Windowsx.h>
10
11 #include <optional>
12 #include <string>
13
14 #include "flutter/fml/macros.h"
15 #include "flutter/shell/platform/common/geometry.h"
16
17 namespace flutter {
18
19 // Management interface for IME-based text input on Windows.
20 //
21 // When inputting text in CJK languages, text is entered via a multi-step
22 // process, where direct keyboard input is buffered into a composing string,
23 // which is then converted into the desired characters by selecting from a
24 // candidates list and committing the change to the string.
25 //
26 // This implementation wraps the Win32 IMM32 APIs and provides a mechanism for
27 // creating and positioning the IME window, a system caret, and the candidates
28 // list as well as for accessing composing and results string contents.
29 class TextInputManager {
30 public:
31 TextInputManager() noexcept = default;
32 virtual ~TextInputManager() = default;
33
34 // Sets the window handle with which the IME is associated.
35 void SetWindowHandle(HWND window_handle);
36
37 // Creates a new IME window and system caret.
38 //
39 // This method should be invoked in response to the WM_IME_SETCONTEXT and
40 // WM_IME_STARTCOMPOSITION events.
41 void CreateImeWindow();
42
43 // Destroys the current IME window and system caret.
44 //
45 // This method should be invoked in response to the WM_IME_ENDCOMPOSITION
46 // event.
47 void DestroyImeWindow();
48
49 // Updates the current IME window and system caret position.
50 //
51 // This method should be invoked when handling user input via
52 // WM_IME_COMPOSITION events.
53 void UpdateImeWindow();
54
55 // Updates the current IME window and system caret position.
56 //
57 // This method should be invoked when handling cursor position/size updates.
58 void UpdateCaretRect(const Rect& rect);
59
60 // Returns the cursor position relative to the start of the composing range.
61 virtual long GetComposingCursorPosition() const;
62
63 // Returns the contents of the composing string.
64 //
65 // This may be called in response to WM_IME_COMPOSITION events where the
66 // GCS_COMPSTR flag is set in the lparam. In some IMEs, this string may also
67 // be set in events where the GCS_RESULTSTR flag is set. This contains the
68 // in-progress composing string.
69 virtual std::optional<std::u16string> GetComposingString() const;
70
71 // Returns the contents of the result string.
72 //
73 // This may be called in response to WM_IME_COMPOSITION events where the
74 // GCS_RESULTSTR flag is set in the lparam. This contains the final string to
75 // be committed in the composing region when composition is ended.
76 virtual std::optional<std::u16string> GetResultString() const;
77
78 /// Aborts IME composing.
79 ///
80 /// Aborts composing, closes the candidates window, and clears the contents
81 /// of the composing string.
82 void AbortComposing();
83
84 private:
85 // Returns either the composing string or result string based on the value of
86 // the |type| parameter.
87 std::optional<std::u16string> GetString(int type) const;
88
89 // Moves the IME composing and candidates windows to the current caret
90 // position.
91 void MoveImeWindow(HIMC imm_context);
92
93 // The window with which the IME windows are associated.
94 HWND window_handle_ = nullptr;
95
96 // True if IME-based composing is active.
97 bool ime_active_ = false;
98
99 // The system caret rect.
100 Rect caret_rect_ = {{0, 0}, {0, 0}};
101
102 FML_DISALLOW_COPY_AND_ASSIGN(TextInputManager);
103 };
104
105 } // namespace flutter
106
107 #endif // FLUTTER_SHELL_PLATFORM_WINDOWS_TEXT_INPUT_MANAGER_H_
flutter::Rect
Definition: geometry.h:56
flutter::TextInputManager
Definition: text_input_manager.h:29
flutter::TextInputManager::CreateImeWindow
void CreateImeWindow()
Definition: text_input_manager.cc:51
flutter::TextInputManager::UpdateCaretRect
void UpdateCaretRect(const Rect &rect)
Definition: text_input_manager.cc:91
flutter::TextInputManager::GetComposingString
virtual std::optional< std::u16string > GetComposingString() const
Definition: text_input_manager.cc:118
flutter::TextInputManager::SetWindowHandle
void SetWindowHandle(HWND window_handle)
Definition: text_input_manager.cc:47
flutter::TextInputManager::DestroyImeWindow
void DestroyImeWindow()
Definition: text_input_manager.cc:68
flutter::TextInputManager::TextInputManager
TextInputManager() noexcept=default
flutter::TextInputManager::UpdateImeWindow
void UpdateImeWindow()
Definition: text_input_manager.cc:80
flutter::TextInputManager::AbortComposing
void AbortComposing()
Definition: text_input_manager.cc:126
flutter::TextInputManager::GetResultString
virtual std::optional< std::u16string > GetResultString() const
Definition: text_input_manager.cc:122
flutter::TextInputManager::GetComposingCursorPosition
virtual long GetComposingCursorPosition() const
Definition: text_input_manager.cc:104
geometry.h
type
enum flutter::testing::@88::KeyboardChange::Type type
flutter
Definition: accessibility_bridge_windows.cc:11