使用C＃和Winforms捕获不同方式的屏幕截图

本文概述

• 活动的Winform窗口截图
• 全屏截图
• 更多信息

为了报告错误, 一个应用程序仅打算获取窗口的屏幕截图等。无论使用什么, 图像都可以说1000多个单词。

在本文中, 你将学习如何对监视器或仅对指定的winform窗口进行屏幕截图。

我们提供2种不同的方法来实现每种屏幕截图类型。如果要使用那些使用ScreenCapture类的方法, 则在项目中需要以下类, 代码如下, 请不要忘记根据更改命名空间你的项目之一：

注意：如果使用不需要ScreenCapture的方法, 则不需要此类, 因为可以使用仅使用CopyFromScreen方法的第二个选项。

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

namespace ChangeThisNamespace
{
    /// <summary>
    /// Provides functions to capture the entire screen, or a particular window, and save it to a file.
    /// </summary>
    public class ScreenCapture
    {
        /// <summary>
        /// Creates an Image object containing a screen shot of the entire desktop
        /// </summary>
        /// <returns></returns>
        public Image CaptureScreen()
        {
            return CaptureWindow(User32.GetDesktopWindow());
        }
        /// <summary>
        /// Creates an Image object containing a screen shot of a specific window
        /// </summary>
        /// <param name="handle">The handle to the window. (In windows forms, this is obtained by the Handle property)</param>
        /// <returns></returns>
        public Image CaptureWindow(IntPtr handle)
        {
            // get te hDC of the target window
            IntPtr hdcSrc = User32.GetWindowDC(handle);
            // get the size
            User32.RECT windowRect = new User32.RECT();
            User32.GetWindowRect(handle, ref windowRect);
            int width = windowRect.right - windowRect.left;
            int height = windowRect.bottom - windowRect.top;
            // create a device context we can copy to
            IntPtr hdcDest = GDI32.CreateCompatibleDC(hdcSrc);
            // create a bitmap we can copy it to, // using GetDeviceCaps to get the width/height
            IntPtr hBitmap = GDI32.CreateCompatibleBitmap(hdcSrc, width, height);
            // select the bitmap object
            IntPtr hOld = GDI32.SelectObject(hdcDest, hBitmap);
            // bitblt over
            GDI32.BitBlt(hdcDest, 0, 0, width, height, hdcSrc, 0, 0, GDI32.SRCCOPY);
            // restore selection
            GDI32.SelectObject(hdcDest, hOld);
            // clean up 
            GDI32.DeleteDC(hdcDest);
            User32.ReleaseDC(handle, hdcSrc);
            // get a .NET image object for it
            Image img = Image.FromHbitmap(hBitmap);
            // free up the Bitmap object
            GDI32.DeleteObject(hBitmap);
            return img;
        }
        /// <summary>
        /// Captures a screen shot of a specific window, and saves it to a file
        /// </summary>
        /// <param name="handle"></param>
        /// <param name="filename"></param>
        /// <param name="format"></param>
        public void CaptureWindowToFile(IntPtr handle, string filename, ImageFormat format)
        {
            Image img = CaptureWindow(handle);
            img.Save(filename, format);
        }
        /// <summary>
        /// Captures a screen shot of the entire desktop, and saves it to a file
        /// </summary>
        /// <param name="filename"></param>
        /// <param name="format"></param>
        public void CaptureScreenToFile(string filename, ImageFormat format)
        {
            Image img = CaptureScreen();
            img.Save(filename, format);
        }

        /// <summary>
        /// Helper class containing Gdi32 API functions
        /// </summary>
        private class GDI32
        {

            public const int SRCCOPY = 0x00CC0020; // BitBlt dwRop parameter
            [DllImport("gdi32.dll")]
            public static extern bool BitBlt(IntPtr hObject, int nXDest, int nYDest, int nWidth, int nHeight, IntPtr hObjectSource, int nXSrc, int nYSrc, int dwRop);
            [DllImport("gdi32.dll")]
            public static extern IntPtr CreateCompatibleBitmap(IntPtr hDC, int nWidth, int nHeight);
            [DllImport("gdi32.dll")]
            public static extern IntPtr CreateCompatibleDC(IntPtr hDC);
            [DllImport("gdi32.dll")]
            public static extern bool DeleteDC(IntPtr hDC);
            [DllImport("gdi32.dll")]
            public static extern bool DeleteObject(IntPtr hObject);
            [DllImport("gdi32.dll")]
            public static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);
        }

        /// <summary>
        /// Helper class containing User32 API functions
        /// </summary>
        private class User32
        {
            [StructLayout(LayoutKind.Sequential)]
            public struct RECT
            {
                public int left;
                public int top;
                public int right;
                public int bottom;
            }
            [DllImport("user32.dll")]
            public static extern IntPtr GetDesktopWindow();
            [DllImport("user32.dll")]
            public static extern IntPtr GetWindowDC(IntPtr hWnd);
            [DllImport("user32.dll")]
            public static extern IntPtr ReleaseDC(IntPtr hWnd, IntPtr hDC);
            [DllImport("user32.dll")]
            public static extern IntPtr GetWindowRect(IntPtr hWnd, ref RECT rect);
        }
    }
}

活动的Winform窗口截图

使用完整的屏幕截图有两种方法, 使用带有Windows图形库的自实现屏幕截图或使用前面提到的类。

要仅从活动窗口中获取屏幕截图, 我们将使用以下类, 该类允许你执行不同类型的屏幕截图。

首先, 不要忘记在类顶部(你将在其中使用方法的地方)添加以下use语句, 以访问必要的方法：

using System.Drawing;
using System.Drawing.Imaging;

现在, 要获取活动窗口的屏幕截图, 请在你的主类中使用以下方法：

/// <summary>
/// Creates a screenshot of the active winform window.
/// It uses the ScreenCapture class.
/// </summary>
/// <param name="filepath"></param>
/// <param name="filename"></param>
/// <param name="format"></param>
private void WindowScreenshot(String filepath, String filename, ImageFormat format)
{
    ScreenCapture sc = new ScreenCapture();

    string fullpath = filepath + "\\" + filename;

    sc.CaptureWindowToFile(this.Handle, fullpath, format);
}

// Use like :

WindowScreenshot(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "window_screenshot.jpg", ImageFormat.Jpeg);

现在另一种方法是使用.NET Graphics类中的CopyFromScreen方法。

使用以下方法无需任何类即可从活动窗口获取屏幕截图：

/// <summary>
/// Take the screenshot of the active window using the CopyFromScreen method relative to the bounds of the form.
/// </summary>
/// <param name="filepath"></param>
/// <param name="filename"></param>
/// <param name="format"></param>
private void WindowScreenshotWithoutClass(String filepath, String filename, ImageFormat format)
{
    Rectangle bounds = this.Bounds;

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

        string fullpath = filepath + "\\" + filename;

        bitmap.Save(fullpath, format);
    }
}


// Use it like : 

WindowScreenshotWithoutClass(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "window_screen_noclass.jpg", ImageFormat.Jpeg);

全屏截图

使用完整的屏幕截图有两种方法, 使用带有Windows图形库的自实现屏幕截图或使用前面提到的类。

第一种方法采用全屏截图, 我们将使用.NET Graphics类中的CopyFromScreen方法。

首先, 不要忘记在类顶部添加以下use语句来访问必要的方法：

using System.Drawing;
using System.Drawing.Imaging;

现在, 要截取屏幕截图并将其保存在指定目录中, 请使用以下方法：

/// <summary>
/// Takes a fullscreen screenshot of the monitor and saves the specified file in a directory with custom name.
/// It expects the Format of the file.
/// </summary>
/// <param name="filepath"></param>
/// <param name="filename"></param>
/// <param name="format"></param>
private void FullScreenshot(String filepath, String filename, ImageFormat format)
{
    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);
        }

        string fullpath = filepath + "\\" + filename;

        bitmap.Save(fullpath, format);
    }
}


// Use it as 

FullScreenshot(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "screenshot.jpg", ImageFormat.Jpeg);

并使用ScreenCapture类创建屏幕截图, 请使用以下方法：

/// <summary>
///  Creates a screenshot using the ScreenCapture class.
/// </summary>
/// <param name="filepath"></param>
/// <param name="filename"></param>
/// <param name="format"></param>
private void FullScreenshotWithClass(String filepath, String filename, ImageFormat format)
{
    ScreenCapture sc = new ScreenCapture();
    Image img = sc.CaptureScreen();

    string fullpath = filepath + "\\" + filename;

    img.Save(fullpath, format);
}


// And use it like 

FullScreenshotWithClass(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "screenshotfull_class.jpg", ImageFormat.Jpeg);

更多信息

• 请记住, 你可以更改扩展名和ImageFormat类型来更改图像的格式。此类支持以下格式：
  • ImageFormat.Jpeg
  • 图片格式
  • ImageFormat.Tiff
  • ImageFormat.Icon
  • ImageFormat.MemoryBmp
  • ImageFormat.Bmp
  • ImageFormat.Exif

玩得开心 。