检测输入法的输入状态

ImmStatus.cs

public class MainWindow {
    /// <summary>
    ///     输入法的输入框被打开，已有文本在内
    /// </summary>
    /// <returns>若有文本正在输入则为 true，否则为 false</returns>
    private bool IsImeCompositionWindowOpened() {
        var helper = new WindowInteropHelper(this);
        var hImc = NativeMethods.ImmGetContext(helper.Handle);
        const int readType = NativeMethods.GCS_COMPSTR;
        try {
            var opened = NativeMethods.ImmGetOpenStatus(hImc);
            if(opened) {
                return NativeMethods.ImmGetCompositionStringW(hImc, readType, null, 0) > 0;
            }
            return false;
        } finally {
            NativeMethods.ImmReleaseContext(helper.Handle, hImc);
        }
    }
}   

NativeMethods.cs

using System;
using System.Runtime.InteropServices;

internal static class NativeMethods {
    #region IME

    [DllImport("imm32.dll")]
    public static extern IntPtr ImmGetContext(IntPtr hWnd);

    [DllImport("Imm32.dll")]
    public static extern bool ImmReleaseContext(IntPtr hWnd, IntPtr hImc);

    [DllImport("imm32.dll")]
    public static extern bool ImmGetOpenStatus(IntPtr hImc);

    [DllImport("imm32.dll")]
    public static extern bool ImmGetConversionStatus(IntPtr hImc, ref int conversion, ref int sentence);

    [DllImport("Imm32.dll", CharSet = CharSet.Unicode)]
    public static extern int ImmGetCompositionStringW(IntPtr hImc, int index, byte[] buffer, int bufferLen);

    public const int IME_CMODE_ALPHANUMERIC = 0x0;
    public const int IME_CMODE_NATIVE = 0x1;
    public const int IME_CMODE_KATAKANA = 0x2;
    public const int IME_CMODE_LANGUAGE = 0x3;
    public const int IME_CMODE_FULLSHAPE = 0x8;
    public const int IME_CMODE_ROMAN = 0x10;
    public const int IME_CMODE_CHARCODE = 0x20;
    public const int IME_CMODE_HANJACONVERT = 0x40;
    public const int IME_CMODE_SOFTKBD = 0x80;
    public const int IME_CMODE_NOCONVERSION = 0x100;
    public const int IME_CMODE_EUDC = 0x200;
    public const int IME_CMODE_SYMBOL = 0x400;
    public const int GCS_COMPSTR = 8;

    #endregion
}