C#调用Windows API函数截图

界面如下：

下面放了一个PictureBox

首先是声明函数：

 //这里是调用 Windows API函数来进行截图
         //首先导入库文件
         [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]

         //声明函数
         private static extern IntPtr CreateDC
         (
             string Driver,   //驱动名称
             string Device,   //设备名称
             string Output,   //无用，可以设定为null
             IntPtr PrintData //任意的打印机数据
          );

         [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
         private static extern bool BitBlt(
             IntPtr hdcDest,     //目标设备的句柄
             int XDest,          //目标对象的左上角X坐标
             int YDest,          //目标对象的左上角的Y坐标
             int Width,          //目标对象的宽度
             int Height,         //目标对象的高度
             IntPtr hdcScr,      //源设备的句柄
             int XScr,           //源设备的左上角X坐标
             int YScr,           //源设备的左上角Y坐标
             Int32 drRop         //光栅的操作值

             );

截图按钮事件代码：

 private void button1_Click(object sender, EventArgs e)
         {
             //创建显示器的DC
             IntPtr dcScreen = CreateDC("DISPLAY", null, null, (IntPtr)null);

             //由一个指定设备的句柄创建一个新的Graphics对象
             Graphics g1 = Graphics.FromHdc(dcScreen);
             int tmpWidth, tmpHeigth;

             //获得保存图片的质量
             long level = long.Parse(this.textBox5.Text);

             //如果是全屏捕获
             if(this.radioButton1.Checked == true)
             {
                 tmpWidth = Screen.PrimaryScreen.Bounds.Width;
                 tmpHeigth = Screen.PrimaryScreen.Bounds.Height;
                 Image MyImage = new Bitmap(tmpWidth, tmpHeigth, g1);

                 //创建位图图形对象
                 Graphics g2 = Graphics.FromImage(MyImage);
                 //获得窗体的上下文设备
                 IntPtr dc1 = g1.GetHdc();
                 //获得位图文件的上下文设备
                 IntPtr dc2 = g2.GetHdc();

                 //写入到位图
                 BitBlt(dc2, , , tmpWidth, tmpHeigth, dc1, , , );

                 //释放窗体的上下文设备
                 g1.ReleaseHdc(dc1);
                 //释放位图的上下文设备
                 g2.ReleaseHdc(dc2);

                 //保存图像并显示
                 SaveImageWithQuality(MyImage,level);
                 this.pictureBox1.Image = MyImage;

             }
             else
             {
                 int X = Convert.ToInt32(this.textBox1.Text);
                 int Y = Convert.ToInt32(this.textBox2.Text);
                 int Width = Convert.ToInt32(this.textBox3.Text);
                 int Height = Convert.ToInt32(this.textBox4.Text);

                 Image Myimage = new Bitmap(Width, Height,g1);
                 Graphics g2 = Graphics.FromImage(Myimage);
                 IntPtr dc1 = g1.GetHdc();
                 IntPtr dc2 = g2.GetHdc();

                 BitBlt(dc2,,,Width,Height,dc1,X,Y,);
                 g1.ReleaseHdc(dc1);
                 g2.ReleaseHdc(dc2);

                 SaveImageWithQuality(Myimage, level);
                 this.pictureBox1.Image = Myimage;

             }
         }

设置图片质量的函数，详细介绍：http://www.cnblogs.com/zhaotianff/p/5570321.html

  //保存图片时设置质量
         private void SaveImageWithQuality(Image bmp,long level)
         {

             ImageCodecInfo jgpEncoder = GetEncoder(ImageFormat.Jpeg);
             System.Drawing.Imaging.Encoder myEncoder =
                 System.Drawing.Imaging.Encoder.Quality;
             EncoderParameters myEncoderParameters = new EncoderParameters();
             EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder, level);
             myEncoderParameters.Param[] = myEncoderParameter;
             bmp.Save(@"test.jpg", jgpEncoder, myEncoderParameters);

         }

         private ImageCodecInfo GetEncoder(ImageFormat format)
         {

             ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();

             foreach (ImageCodecInfo codec in codecs)
             {
                 if (codec.FormatID == format.Guid)
                 {
                     return codec;
                 }
             }
             return null;
         }

运行效果：

可惜把自己也截出来了，正在寻找方法不把自己截出来，哈哈。