基于C#实现Windows桌面截图功能

在C#中实现Windows桌面截图功能可以通过多种方式实现。下面我将介绍几种常见的方法：

方法一：使用.NET内置的Graphics类

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Windows.Forms;

public class ScreenCapture
{
    public static void CaptureScreen(string filePath)
    {
        try
        {
            // 获取主显示器的大小
            Rectangle bounds = Screen.GetBounds(Point.Empty);

            // 创建位图对象
            using (Bitmap bitmap = new Bitmap(bounds.Width, bounds.Height))
            {
                // 创建Graphics对象
                using (Graphics g = Graphics.FromImage(bitmap))
                {
                    // 截取整个屏幕
                    g.CopyFromScreen(Point.Empty, Point.Empty, bounds.Size);
                }

                // 保存截图
                bitmap.Save(filePath, ImageFormat.Png);
            }

            Console.WriteLine($"截图已保存到: {filePath}");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"截图失败: {ex.Message}");
        }
    }
}

// 使用示例
ScreenCapture.CaptureScreen("screenshot.png");

方法二：使用Windows API (user32.dll)

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;

public class ScreenCapture
{
    [DllImport("user32.dll")]
    private static extern IntPtr GetDesktopWindow();

    [DllImport("user32.dll")]
    private static extern IntPtr GetWindowDC(IntPtr hWnd);

    [DllImport("gdi32.dll")]
    private static extern IntPtr CreateCompatibleBitmap(IntPtr hdc, int nWidth, int nHeight);

    [DllImport("gdi32.dll")]
    private static extern IntPtr CreateCompatibleDC(IntPtr hdc);

    [DllImport("gdi32.dll")]
    private static extern IntPtr SelectObject(IntPtr hdc, IntPtr hObject);

    [DllImport("gdi32.dll")]
    private static extern bool BitBlt(IntPtr hdcDest, int xDest, int yDest, int wDest, int hDest, IntPtr hdcSrc, int xSrc, int ySrc, int rasterOp);

    [DllImport("gdi32.dll")]
    private static extern bool DeleteObject(IntPtr hObject);

    [DllImport("user32.dll")]
    private static extern int ReleaseDC(IntPtr hWnd, IntPtr hdc);

    private const int SRCCOPY = 0x00CC0020;

    public static void CaptureScreen(string filePath)
    {
        IntPtr hWnd = GetDesktopWindow();
        IntPtr hdcSrc = GetWindowDC(hWnd);
        IntPtr hdcDest = CreateCompatibleDC(hdcSrc);

        Rectangle bounds = Screen.GetBounds(Point.Empty);
        IntPtr hBitmap = CreateCompatibleBitmap(hdcSrc, bounds.Width, bounds.Height);
        IntPtr hOld = SelectObject(hdcDest, hBitmap);

        BitBlt(hdcDest, 0, 0, bounds.Width, bounds.Height, hdcSrc, 0, 0, SRCCOPY);
        SelectObject(hdcDest, hOld);

        using (Bitmap bitmap = Image.FromHbitmap(hBitmap))
        {
            bitmap.Save(filePath, ImageFormat.Png);
        }

        DeleteObject(hBitmap);
        ReleaseDC(hWnd, hdcSrc);
        DeleteObject(hdcDest);
    }
}

方法三：捕获特定窗口（需要窗口句柄）

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;

public class WindowCapture
{
    [DllImport("user32.dll")]
    private static extern IntPtr GetWindowRect(IntPtr hWnd, ref Rectangle rect);

    [DllImport("user32.dll")]
    private static extern bool PrintWindow(IntPtr hWnd, IntPtr hdcBlt, int nFlags);

    public static void CaptureWindow(IntPtr handle, string filePath)
    {
        Rectangle rect = new Rectangle();
        GetWindowRect(handle, ref rect);

        using (Bitmap bitmap = new Bitmap(rect.Width, rect.Height))
        {
            using (Graphics g = Graphics.FromImage(bitmap))
            {
                IntPtr hdc = g.GetHdc();
                PrintWindow(handle, hdc, 0);
                g.ReleaseHdc(hdc);
            }

            bitmap.Save(filePath, ImageFormat.Png);
        }
    }
}

高级功能：添加鼠标指针到截图中

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Windows.Forms;

public class ScreenCaptureWithCursor
{
    [StructLayout(LayoutKind.Sequential)]
    struct CURSORINFO
    {
        public int cbSize;
        public int flags;
        public IntPtr hCursor;
        public Point ptScreenPos;
    }

    [DllImport("user32.dll")]
    static extern bool GetCursorInfo(out CURSORINFO pci);

    [DllImport("user32.dll")]
    static extern bool DrawIcon(IntPtr hDC, int X, int Y, IntPtr hIcon);

    const int CURSOR_SHOWING = 0x00000001;

    public static void CaptureScreenWithCursor(string filePath)
    {
        Rectangle bounds = Screen.GetBounds(Point.Empty);

        using (Bitmap bitmap = new Bitmap(bounds.Width, bounds.Height))
        {
            using (Graphics g = Graphics.FromImage(bitmap))
            {
                g.CopyFromScreen(Point.Empty, Point.Empty, bounds.Size);

                // 添加鼠标指针
                CURSORINFO cursorInfo = new CURSORINFO();
                cursorInfo.cbSize = Marshal.SizeOf(typeof(CURSORINFO));

                if (GetCursorInfo(out cursorInfo) && 
                    (cursorInfo.flags & CURSOR_SHOWING) == CURSOR_SHOWING)
                {
                    DrawIcon(g.GetHdc(), cursorInfo.ptScreenPos.X, cursorInfo.ptScreenPos.Y, cursorInfo.hCursor);
                    g.ReleaseHdc();
                }
            }

            bitmap.Save(filePath, ImageFormat.Png);
        }
    }
}

注意事项

1. 这些代码需要在Windows窗体应用程序或控制台应用程序中使用
2. 需要添加对System.Drawing和System.Windows.Forms程序集的引用
3. 对于高DPI显示器，可能需要调整代码以正确处理缩放
4. 如果要捕获多显示器环境中的特定显示器，可以使用Screen.AllScreens数组

以上方法提供了从简单到高级的截图功能实现，你可以根据具体需求选择合适的方法。