WPF 自定义文本框输入法 IME 跟随光标

    /// <summary>
    /// 表示控件支持被输入法
    /// </summary>
    interface IIMETextEditor
    {
        /// <summary>
        /// 获取当前使用的字体名
        /// </summary>
        /// <returns></returns>
        string GetFontFamilyName();

        /// <summary>
        /// 获取字号大小，单位和 WPF 的 FontSize 相同
        /// </summary>
        /// <returns></returns>
        int GetFontSize();

        /// <summary>
        /// 获取输入框的左上角的点，用于设置输入法的左上角。此点相对于 <see cref="IIMETextEditor"/> 所在元素坐标。对大部分控件来说，都应该是 0,0 点
        /// </summary>
        /// <returns></returns>
        Point GetTextEditorLeftTop();

        /// <summary>
        /// 获取光标的输入左上角的点。此点相对于 <see cref="IIMETextEditor"/> 所在元素坐标
        /// </summary>
        /// <returns></returns>
        Point GetCaretLeftTop();
    }

    internal class IMESupporter<T> where T : UIElement, IIMETextEditor
    {
        // ReSharper disable InconsistentNaming
        public IMESupporter(T editor)
        {
            Editor = editor;
            // 忽略代码
        }
    }

        public IMESupporter(T editor)
        {
            Editor = editor;
            Editor.GotKeyboardFocus += Editor_GotKeyboardFocus;
            Editor.LostKeyboardFocus += Editor_LostKeyboardFocus;
        }

        private T Editor { get; }

            InputMethod.SetIsInputMethodSuspended(editor, true);

            _defaultImeWnd = IMENative.ImmGetDefaultIMEWnd(IntPtr.Zero);

        private T Editor { get; }

        private IntPtr _defaultImeWnd;
        private IntPtr _currentContext;
        private IntPtr _previousContext;
        private HwndSource? _hwndSource;

        private bool _isUpdatingCompositionWindow;

            if (_defaultImeWnd == IntPtr.Zero)
            {
                // 如果拿到了空的默认 IME 窗口了，那么此时也许是作为嵌套窗口放入到另一个进程的窗口
                // 拿不到就需要刷新一下。否则微软拼音输入法将在屏幕的左上角上
                RefreshInputMethodEditors();

                // 忽略代码
            }

        /// <summary>
        /// 刷新 IME 的 ITfThreadMgr 状态，用于修复打开 Win32Dialog 之后关闭，输入法无法输入中文问题
        /// </summary>
        /// 原因是在打开 Win32Dialog 之后，将会让 ITfThreadMgr 失去焦点。因此需要使用本方法刷新，通过 InputMethod 的 IsInputMethodEnabledProperty 属性调用到 InputMethod 的 EnableOrDisableInputMethod 方法，在这里面调用到 TextServicesContext.DispatcherCurrent.SetFocusOnDefaultTextStore 方法，从而调用到 SetFocusOnDim(DefaultTextStore.Current.DocumentManager) 的代码，将 DefaultTextStore.Current.DocumentManager 设置为 ITfThreadMgr 的焦点，重新绑定 IME 输入法
        /// 但是即使如此，依然拿不到 <see cref="_defaultImeWnd"/> 的初始值。依然需要重新打开和关闭 WPF 窗口才能拿到
        /// [Can we public the `DefaultTextStore.Current.DocumentManager` property to create custom TextEditor with IME · Issue #6139 · dotnet/wpf](https://github.com/dotnet/wpf/issues/6139 )
        private void RefreshInputMethodEditors()
        {
            if (InputMethod.GetIsInputMethodEnabled(Editor))
            {
                InputMethod.SetIsInputMethodEnabled(Editor, false);
            }

            if (InputMethod.GetIsInputMethodSuspended(Editor))
            {
                InputMethod.SetIsInputMethodSuspended(Editor, false);
            }

            InputMethod.SetIsInputMethodEnabled(Editor, true);
            InputMethod.SetIsInputMethodSuspended(Editor, true);
        }

            _hwndSource = (HwndSource) (PresentationSource.FromVisual(Editor) ??
                                       throw new ArgumentNullException(nameof(Editor)));

            if (_defaultImeWnd == IntPtr.Zero)
            {
                // 如果拿到了空的默认 IME 窗口了，那么此时也许是作为嵌套窗口放入到另一个进程的窗口
                // 拿不到就需要刷新一下。否则微软拼音输入法将在屏幕的左上角上
                RefreshInputMethodEditors();

                // 尝试通过 _hwndSource 也就是文本所在的窗口去获取
                _defaultImeWnd = IMENative.ImmGetDefaultIMEWnd(_hwndSource.Handle);

                // 忽略代码
            }

                _defaultImeWnd = IMENative.ImmGetDefaultIMEWnd(_hwndSource.Handle);

                if (_defaultImeWnd == IntPtr.Zero)
                {
                    // 如果依然获取不到，那么使用当前激活的窗口，在准备输入的时候
                    // 当前的窗口大部分都是对的
                    // 进入这里，是尽可能恢复输入法，拿到的 GetForegroundWindow 虽然预计是不对的
                    // 也好过没有输入法
                    _defaultImeWnd = IMENative.ImmGetDefaultIMEWnd(Win32.User32.GetForegroundWindow());
                }

            // 使用 DefaultIMEWnd 可以比较好解决微软拼音的输入法到屏幕左上角的问题
            _currentContext = IMENative.ImmGetContext(_defaultImeWnd);

            _currentContext = IMENative.ImmGetContext(_defaultImeWnd);
            if (_currentContext == IntPtr.Zero)
            {
                _currentContext = IMENative.ImmGetContext(_hwndSource.Handle);
            }

            // 对 Win32 使用第二套输入法框架的输入法，可以采用 ImmAssociateContext 关联
            // 但是对实现 TSF 第三套输入法框架的输入法，在应用程序对接第三套输入法框架
            // 就需要调用 ITfThreadMgr 的 SetFocus 方法。刚好 WPF 对接了
            _previousContext = IMENative.ImmAssociateContext(_hwndSource.Handle, _currentContext);

            _previousContext = IMENative.ImmAssociateContext(_hwndSource.Handle, _currentContext);
            _hwndSource.AddHook(WndProc);

            // 尽管文档说传递null是无效的，但这似乎有助于在与WPF共享的默认输入上下文中激活IME输入法
            // 这里需要了解的是，在 WPF 的逻辑，是需要传入 DefaultTextStore.Current.DocumentManager 才符合预期
            IMENative.ITfThreadMgr? threadMgr = IMENative.GetTextFrameworkThreadManager();
            threadMgr?.SetFocus(IntPtr.Zero);

            var textEditorLeftTop = Editor.GetTextEditorLeftTop();
            var caretLeftTop = Editor.GetCaretLeftTop();

            var hIMC = _currentContext;
            HwndSource source = _hwndSource;

            var textEditorLeftTop = Editor.GetTextEditorLeftTop();
            var caretLeftTop = Editor.GetCaretLeftTop();

            var transformToAncestor = Editor.TransformToAncestor(source.RootVisual);

            var textEditorLeftTopForRootVisual = transformToAncestor.Transform(textEditorLeftTop);
            var caretLeftTopForRootVisual = transformToAncestor.Transform(caretLeftTop);

            //解决surface上输入法光标位置不正确
            //现象是surface上光标的位置需要乘以2才能正确，普通电脑上没有这个问题
            //且此问题与DPI无关，目前用CaretWidth可以有效判断
            caretLeftTopForRootVisual = new Point(caretLeftTopForRootVisual.X / SystemParameters.CaretWidth,
                caretLeftTopForRootVisual.Y / SystemParameters.CaretWidth);

            //const int CFS_DEFAULT = 0x0000;
            //const int CFS_RECT = 0x0001;
            const int CFS_POINT = 0x0002;
            //const int CFS_FORCE_POSITION = 0x0020;
            //const int CFS_EXCLUDE = 0x0080;
            //const int CFS_CANDIDATEPOS = 0x0040;

            var form = new IMENative.CompositionForm();
            form.dwStyle = CFS_POINT;
            form.ptCurrentPos.x = (int) Math.Max(caretLeftTopForRootVisual.X, textEditorLeftTopForRootVisual.X);
            form.ptCurrentPos.y = (int) Math.Max(caretLeftTopForRootVisual.Y, textEditorLeftTopForRootVisual.Y);
            //if (_isSoftwarePinYinOverWin7)
            //{
            //    form.ptCurrentPos.y += (int) characterBounds.Height;
            //}

            IMENative.ImmSetCompositionWindow(hIMC, ref form);

        private IntPtr WndProc(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            switch (msg)
            {
              // 忽略代码
                case IMENative.WM_INPUTLANGCHANGE:
                    if (_hwndSource != null)
                    {
                        CreateContext();
                    }

              // 忽略代码
                    break;
            }

            return IntPtr.Zero;
        }

        private IntPtr WndProc(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            switch (msg)
            {
              // 忽略代码
                case IMENative.WM_IME_COMPOSITION:
                    UpdateCompositionWindow();
                    break;
              // 忽略代码
            }

            return IntPtr.Zero;
        }

    public partial class TextEditor : FrameworkElement, IIMETextEditor
    {
        // 忽略代码

        protected override void OnRender(DrawingContext drawingContext)
        {
            drawingContext.DrawRectangle(Brushes.Black,null,new Rect(MouseDownPoint,new Size(3,30)));
            base.OnRender(drawingContext);
        }

        protected override HitTestResult HitTestCore(PointHitTestParameters hitTestParameters)
        {
          // 让控件接收点击
            return new PointHitTestResult(this, hitTestParameters.HitPoint);
        }

        protected override void OnMouseDown(MouseButtonEventArgs e)
        {
            MouseDownPoint = e.GetPosition(this);
            Focus();
            InvalidateVisual();
        }

        private Point MouseDownPoint { get; set; }

        string IIMETextEditor.GetFontFamilyName()
        {
            return "微软雅黑";
        }

        int IIMETextEditor.GetFontSize()
        {
            return 30;
        }

        Point IIMETextEditor.GetTextEditorLeftTop()
        {
            // 相对于当前输入框的坐标
            return new Point(0, 0);
        }

        Point IIMETextEditor.GetCaretLeftTop()
        {
            return MouseDownPoint;
        }
    }

        static TextEditor()
        {
            // 用于接收 Tab 按键，而不是被切换焦点
            KeyboardNavigation.IsTabStopProperty.OverrideMetadata(typeof(TextEditor),
                new FrameworkPropertyMetadata(true));
            KeyboardNavigation.TabNavigationProperty.OverrideMetadata(typeof(TextEditor),
                new FrameworkPropertyMetadata(KeyboardNavigationMode.None));

            // 用于获取焦点逻辑
            FocusableProperty.OverrideMetadata(typeof(TextEditor),
                new FrameworkPropertyMetadata(true));
        }

        public TextEditor()
        {
            // 忽略代码

            _imeSupporter = new IMESupporter<TextEditor>(this);
        }

        private readonly IMESupporter<TextEditor> _imeSupporter;

git init
git remote add origin https://gitee.com/lindexi/lindexi_gd.git
git pull origin b3a1fffece8284d0b84407aa13d949de6a2f1536

git remote remove origin
git remote add origin https://github.com/lindexi/lindexi_gd.git