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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.
128 lines
4.1 KiB
C++
128 lines
4.1 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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#include "flutter/shell/platform/windows/key_event_handler.h"
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#include <windows.h>
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#include <iostream>
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#include "flutter/shell/platform/common/cpp/json_message_codec.h"
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static constexpr char kChannelName[] = "flutter/keyevent";
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static constexpr char kKeyCodeKey[] = "keyCode";
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static constexpr char kScanCodeKey[] = "scanCode";
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static constexpr char kCharacterCodePointKey[] = "characterCodePoint";
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static constexpr char kModifiersKey[] = "modifiers";
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static constexpr char kKeyMapKey[] = "keymap";
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static constexpr char kTypeKey[] = "type";
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static constexpr char kWindowsKeyMap[] = "windows";
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static constexpr char kKeyUp[] = "keyup";
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static constexpr char kKeyDown[] = "keydown";
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namespace flutter {
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// Re-definition of the modifiers for compatibility with the Flutter framework.
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// These have to be in sync with the framework's RawKeyEventDataWindows
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// modifiers definition.
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// https://github.com/flutter/flutter/blob/19ff596979e407c484a32f4071420fca4f4c885f/packages/flutter/lib/src/services/raw_keyboard_windows.dart#L203
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const int kShift = 1 << 0;
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const int kShiftLeft = 1 << 1;
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const int kShiftRight = 1 << 2;
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const int kControl = 1 << 3;
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const int kControlLeft = 1 << 4;
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const int kControlRight = 1 << 5;
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const int kAlt = 1 << 6;
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const int kAltLeft = 1 << 7;
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const int kAltRight = 1 << 8;
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const int kWinLeft = 1 << 9;
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const int kWinRight = 1 << 10;
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const int kCapsLock = 1 << 11;
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const int kNumLock = 1 << 12;
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const int kScrollLock = 1 << 13;
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namespace {
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/// Calls GetKeyState() an all modifier keys and packs the result in an int,
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/// with the re-defined values declared above for compatibility with the Flutter
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/// framework.
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int GetModsForKeyState() {
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int mods = 0;
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if (GetKeyState(VK_SHIFT) < 0)
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mods |= kShift;
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if (GetKeyState(VK_LSHIFT) < 0)
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mods |= kShiftLeft;
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if (GetKeyState(VK_RSHIFT) < 0)
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mods |= kShiftRight;
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if (GetKeyState(VK_CONTROL) < 0)
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mods |= kControl;
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if (GetKeyState(VK_LCONTROL) < 0)
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mods |= kControlLeft;
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if (GetKeyState(VK_RCONTROL) < 0)
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mods |= kControlRight;
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if (GetKeyState(VK_MENU) < 0)
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mods |= kAlt;
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if (GetKeyState(VK_LMENU) < 0)
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mods |= kAltLeft;
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if (GetKeyState(VK_RMENU) < 0)
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mods |= kAltRight;
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if (GetKeyState(VK_LWIN) < 0)
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mods |= kWinLeft;
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if (GetKeyState(VK_RWIN) < 0)
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mods |= kWinRight;
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if (GetKeyState(VK_CAPITAL) < 0)
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mods |= kCapsLock;
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if (GetKeyState(VK_NUMLOCK) < 0)
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mods |= kNumLock;
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if (GetKeyState(VK_SCROLL) < 0)
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mods |= kScrollLock;
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return mods;
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}
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} // namespace
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KeyEventHandler::KeyEventHandler(flutter::BinaryMessenger* messenger)
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: channel_(
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std::make_unique<flutter::BasicMessageChannel<rapidjson::Document>>(
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messenger,
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kChannelName,
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&flutter::JsonMessageCodec::GetInstance())) {}
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KeyEventHandler::~KeyEventHandler() = default;
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void KeyEventHandler::TextHook(Win32FlutterWindow* window,
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const std::u16string& code_point) {}
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void KeyEventHandler::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) {
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// TODO: Translate to a cross-platform key code system rather than passing
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// the native key code.
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rapidjson::Document event(rapidjson::kObjectType);
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auto& allocator = event.GetAllocator();
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event.AddMember(kKeyCodeKey, key, allocator);
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event.AddMember(kScanCodeKey, scancode, allocator);
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event.AddMember(kCharacterCodePointKey, character, allocator);
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event.AddMember(kKeyMapKey, kWindowsKeyMap, allocator);
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event.AddMember(kModifiersKey, GetModsForKeyState(), allocator);
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switch (action) {
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case WM_KEYDOWN:
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event.AddMember(kTypeKey, kKeyDown, allocator);
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break;
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case WM_KEYUP:
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event.AddMember(kTypeKey, kKeyUp, allocator);
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break;
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default:
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std::cerr << "Unknown key event action: " << action << std::endl;
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return;
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}
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channel_->Send(event);
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}
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} // namespace flutter
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