C# 實現類 Spy++ 功能：捕捉桌面滑鼠下的窗口信息與縮略圖

功能

滑鼠移動時實時顯示目標坐標下窗口的：標題、句柄、類名、矩形區域縮略圖。

核心 Win32 API

[DllImport("User32.dll")] public static extern IntPtr WindowFromPoint(int x, int y);
[DllImport("User32.dll")] public static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString, int nMaxCount);
[DllImport("User32.dll")] public static extern int GetClassName(IntPtr hWnd, StringBuilder lpString, int nMaxCount);
[DllImport("User32.dll")] public static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);

[StructLayout(LayoutKind.Sequential)]
public struct RECT { public int left, top, right, bottom; }

實現邏輯

• 用 Timer (300ms) 輪詢 Cursor.Position 獲取滑鼠坐標
• WindowFromPoint 取得窗口句柄
• GetWindowText/GetClassName 取標題/類名
• GetWindowRect 取矩形，Graphics.CopyFromScreen 截取縮略圖顯示在 PictureBox

核心代碼

private void Timer_Tick(object sender, EventArgs e) {
    IntPtr hWnd = WindowFromPoint(Cursor.Position.X, Cursor.Position.Y);
    if (hWnd != IntPtr.Zero) {
        var sbText = new StringBuilder(260);
        var sbClass = new StringBuilder(256);
        GetWindowText(hWnd, sbText, sbText.Capacity);
        GetClassName(hWnd, sbClass, sbClass.Capacity);

        lblLocation.Text = $"{Cursor.Position.X}, {Cursor.Position.Y}";
        lblHandle.Text = hWnd.ToString();
        lblTitle.Text = sbText.ToString();
        lblClass.Text = sbClass.ToString();

        DrawThumbnail(hWnd);
    }
}

private Bitmap _bmp;
private void DrawThumbnail(IntPtr hWnd) {
    if (_bmp != null) _bmp.Dispose();
    if (GetWindowRect(hWnd, out RECT rect)) {
        _bmp = new Bitmap(rect.right - rect.left, rect.bottom - rect.top);
        using (var g = Graphics.FromImage(_bmp))
            g.CopyFromScreen(rect.left, rect.top, 0, 0, _bmp.Size, CopyPixelOperation.SourceCopy);
        pictureBox1.Image = _bmp;
    }
}

效果展示

可見視窗標題、句柄、類名、縮略圖隨滑鼠移動即時刷新，類似 Spy++ 但更輕量。