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ed58844e8a
The C++ text input model used by Windows and Linux currently uses UTF-32. The intention was to facilitate handling of arrow keys, backspace/delete, etc., however since part of what is synchronized with the engine is cursor+selection offsets, and those offsets are defined in terms of UTF-16 code units, this causes very bad interactions with the framework-side model. This converts to using UTF-16, rather than UTF-32, so that the offsets align with the framework. It also adds surrogate pair handling to the operations that adjust indexes, to avoid breaking surrogate pairs. (Arbitrary grapheme cluster handling is out of scope for this PR; while definitely desirable in the long term, surrogate pair handling is much more critical since improper handling yields invalid UTF-16, which breaks the text field). This partially fixes https://github.com/flutter/flutter/issues/55014. A framework-side fix is also necessary (since currently both the engine and the framework attempt to handle arrow keys, which is another out-of-scope-for-this-PR issue), but even without the framework fix this dramatically improves the cursor behavior on Windows when there are surrogate pairs somewhere in the string since at least the two sides agree on what indexes mean. Includes minor plumbing changes to the text input plumbing on Windows so that we're not pointlessly converting from UTF-16 to UTF-32 and then back to UTF-16.
36 lines
1.1 KiB
C++
36 lines
1.1 KiB
C++
// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_KEYBOARD_HOOK_HANDLER_H_
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#define FLUTTER_SHELL_PLATFORM_WINDOWS_KEYBOARD_HOOK_HANDLER_H_
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#include "flutter/shell/platform/windows/public/flutter_windows.h"
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#include <string>
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namespace flutter {
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class Win32FlutterWindow;
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// Abstract class for handling keyboard input events.
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class KeyboardHookHandler {
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public:
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virtual ~KeyboardHookHandler() = default;
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// A function for hooking into keyboard input.
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virtual void KeyboardHook(Win32FlutterWindow* window,
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int key,
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int scancode,
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int action,
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char32_t character) = 0;
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// A function for hooking into Unicode text input.
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virtual void TextHook(Win32FlutterWindow* window,
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const std::u16string& text) = 0;
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};
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} // namespace flutter
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#endif // FLUTTER_SHELL_PLATFORM_WINDOWS_KEYBOARD_HOOK_HANDLER_H_
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