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, 0, 0, tmpWidth, tmpHeigth, dc1, 0, 0, 13369376);
                
                //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(dc2,0,0,Width,Height,dc1,X,Y,13369376);
                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(1);
            EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder, level);
            myEncoderParameters.Param[0] = 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。