如何获得picturebox里面的image的handle

[fatboyyhc]

这几天正在写一个画线程序，要用到异或线，所以用到了GDI API 里面的setROP2函数，而该函数里面有一个intptr类型的参数，而我的线需要画到picturebox里面的image上，如果我能获得image的handle就可以代入那个参数里面了，无奈是.net中的image是没有handle属性，控件才有。请问我该怎么做才能把线画到picturebox的image上呢？

[net5i]

创建Image的绘图对象就可以了：
Graphics g = Graphics.FromImage(pictureBox1.Image);
IntPtr hdc = g.GetHdc();
。。。调用你的API函数，参数使用hdc
g.ReleaseHdc();

[fatboyyhc]

@net5i：

这种方法我试过了，不行啊

这个类就是用来画线的

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace Win32APIDraw
{
    /// <summary>
    /// 封装交互线效果的类
    /// </summary>
    public class Win32XORPenDrawer : IDisposable
    {
        #region 声明Win32 api
        struct POINTAPI
        {
            public int x;
            public int y;
        }   
        
        [DllImport("user32.dll")]
        private static extern IntPtr GetDC(IntPtr hwnd);
        [DllImport("user32.dll")]
        private static extern IntPtr ReleaseDC(IntPtr hwnd, IntPtr hdc);

        [DllImport("gdi32.dll")]
        private static extern bool MoveToEx(IntPtr hDC,
                          IntPtr x,
                          IntPtr y,
                          ref POINTAPI lpPoint);

        [DllImport("gdi32.dll")]
        private static extern IntPtr LineTo(IntPtr hdc, IntPtr x, IntPtr y);
        [DllImport("gdi32.dll")]
        private static extern IntPtr SetROP2(IntPtr hdc, IntPtr fnDrawMode);

        #endregion

        #region 构造函数
        /// <summary>
        /// 传入创建DC的句柄和绘图模式
        /// </summary>
        /// <param name="hWnd"></param>
        /// <param name="drawMode"></param>
        public Win32XORPenDrawer(int hWnd, int drawMode)
        {
            //GetDC by hwnd
            this.hWnd = hWnd;
            IntPtr res = GetDC(new IntPtr(hWnd));
            hDc = res.ToInt32();
            SetROP2(res, new IntPtr(drawMode));
        }


        ~Win32XORPenDrawer()
        {
            Dispose(false);
        }

        #endregion

        #region 私有成员
        private int hDc;

        private int hWnd;       

        private bool disposed = false;

        private void Dispose(bool disposing)
        {
            if (!this.disposed)
            {
                //ReleaseDC
                ReleaseDC(new IntPtr(hWnd), new IntPtr(hDc));
            }
            disposed = true;
        }
        #endregion

        #region 公共接口
        #region IDisposable 成员

        public void Dispose()
        {
            Dispose(true);
        }

        #endregion

        /// <summary>
        /// 从x1, y1向x2, y2画线
        /// </summary>
        /// <param name="x1"></param>
        /// <param name="y1"></param>
        /// <param name="x2"></param>
        /// <param name="y2"></param>
        public void DrawLine(int x1, int y1, int x2, int y2)
        {
            POINTAPI lpOld = new POINTAPI();
            MoveToEx(new IntPtr(hDc), new IntPtr(x1), new IntPtr(y1), ref lpOld);
            LineTo(new IntPtr(hDc), new IntPtr(x2), new IntPtr(y2));
        }

        public void MoveTo(int x, int y)
        {
            POINTAPI lpOld = new POINTAPI();
            MoveToEx(new IntPtr(hDc), new IntPtr(x), new IntPtr(y), ref lpOld);
        }

        public void LineTo(int x, int y)
        {
            LineTo(new IntPtr(hDc), new IntPtr(x), new IntPtr(y));
        }
        #endregion
    }

   
}

[fatboyyhc]

@net5i：
不过还是要谢谢你

[fatboyyhc]

我画线的API函数，是放到 pictureBox1_MouseClick（）事件里面执行的。

[zgke]

((Bitmap)pictureBox1.Image).GetHbitmap();

[zgke]

((Bitmap)pictureBox1.Image).GetHbitmap();

[net5i]

to 搂主2楼：
应该是搂主代码的问题，这个类的构造函数改成下面的看看呢：

        public Win32XORPenDrawer(int hWnd, int drawMode)
        {
            this.hDc = hWnd;
            SetROP2((IntPtr)hDc, new IntPtr(drawMode));
        }

另外，调用这个类的过程应该是：

Bitmap bmp = new Bitmap(this.pictureBox1.Width, this.pictureBox1.Height);
Graphics g = Graphics.FromImage(bmp);
int hdc = (int)g.GetHdc();
Win32XORPenDrawer drawer = new Win32XORPenDrawer(hdc, 0);
drawer.DrawLine(0, 0, 100, 100);
g.ReleaseHdc();
this.pictureBox1.Image = bmp as Image;

这样应该没问题的，你可以试试

[fatboyyhc]

@zgke
不行，我把intptr hdc=((Bitmap)pictureBox1.Image).GetHbitmap();
再实例化 Win32XORPenDrawer penDrawer=new Win32XORPenDrawer( hdc.toToInt32(),6);
debug的时候，下面的构造函数那里 res是等于0的，也就是GetDC(new IntPtr(hWnd))返回0

  /// <summary>
        /// 传入创建DC的句柄和绘图模式
        /// </summary>
        /// <param name="hWnd"></param>
        /// <param name="drawMode"></param>
        public Win32XORPenDrawer(int hWnd, int drawMode)
        {
            //GetDC by hwnd
            this.hWnd = hWnd;
            IntPtr res = GetDC(new IntPtr(hWnd));
            hDc = res.ToInt32();
            SetROP2(res, new IntPtr(drawMode));
        }

[fatboyyhc]

@net5i:

首先非常感谢你的热心帮助，
明天会公司试试，这几天为了这个问题很烦恼。

[scy251147]

up

[fatboyyhc]

@net5i:

你的方法我试过了，画是能画，但不是异或模式，

Bitmap bmp = new Bitmap(this.pictureBox1.Width, this.pictureBox1.Height);
Graphics g = Graphics.FromImage(bmp);
int hdc = (int)g.GetHdc();
Win32XORPenDrawer drawer = new Win32XORPenDrawer(hdc, 0);
drawer.DrawLine(0, 0, 100, 100);
g.ReleaseHdc();
this.pictureBox1.Image = bmp as Image;

即使我把

Win32XORPenDrawer drawer = new Win32XORPenDrawer(hdc, 6);

参数改成了6，画出来的不是异或线，是一条白色的线。
郁闷当中。。。。