C#全屏截图的方法

Question

            //得到屏幕的DC
             IntPtr dc1 = g1.GetHdc();这个得到的是你窗体的GC吧

Answer 1

//得到屏幕的DC
            IntPtr dc1 = g1.GetHdc();屏幕的是IntPtr dc1 = GetDC(0);
GetDC是windowsAPI，Intptr GetDC(IntPtr hwnd);

Answer 2

运行结果 是什么图都没有，为什么呢！！！？？？？？using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
//using DWORD = System.UInt32;
//using HANDLE = System.IntPtr;
//using HDC = System.IntPtr;
namespace SmartDeviceProject3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }        [System.Runtime.InteropServices.DllImportAttribute("coredll.dll")]
        private static extern bool BitBlt(
        IntPtr hdcDest, // 目标 DC的句柄
        int nXDest,
        int nYDest,
        int nWidth,
        int nHeight,
        IntPtr hdcSrc,  // 源DC的句柄
        int nXSrc,
        int nYSrc,
        System.Int32 dwRop  // 光栅的处理数值
        );
        //[System.Runtime.InteropServices.DllImportAttribute("coredll.dll")]
        //public static extern IntPtr FindWindow(String lpClassName, String lpWindowName);
        [System.Runtime.InteropServices.DllImportAttribute("coredll.dll")]
        private static extern IntPtr GetCapture();
        [System.Runtime.InteropServices.DllImportAttribute("coredll.dll")]
        private static extern IntPtr GetDC(IntPtr hWnd);
        private void button1_Click(object sender, EventArgs e)
        {
            //IntPtr hwnd1 = FindWindow(null, "Form1");            this.Capture = true;
            IntPtr hwnd1 = GetCapture();
            this.Capture = false;            IntPtr hDC = GetDC(hwnd1);
            Graphics g1 = Graphics.FromHdc(hDC);            //创建一个以当前屏幕为模板的图象
            //Graphics g1 = Graphics.FromHdc(hwnd2);
            
            //创建以屏幕大小为标准的位图 
            Image bitmap = new Bitmap(800, 600);
            Graphics g2 = Graphics.FromImage(bitmap);
            //得到屏幕的DC
            IntPtr dc1 = g1.GetHdc();
            //得到Bitmap的DC 
            IntPtr dc2 = g2.GetHdc();
            //调用此API函数，实现屏幕捕获
            BitBlt(dc2, 0, 0, 800, 600, dc1, 0, 0, 13369376);            //把当前屏幕拷贝到位图中  
            pictureBox1.Image = bitmap;
            //g1.ReleaseHdc(dc1);            //释放屏幕句柄               g2.ReleaseHdc(dc2);
        }
    }
}