求助ArgumentException参数错误
我的源代码是using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace Example024
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
[System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
private static extern bool BitBlt(
IntPtr hdcDest, //目标设备的句柄
int nxDest, //目标对象的左上角的X坐标
int nyDest, //目标对象的左上角的Y左边
int nwidth, //目标对象的矩形宽度
int nHeight, //目标对象的矩形长度
IntPtr hdcSrc, //源设备的句柄
int nXSrc, //源对象的左上角X坐标
int nYSrc, //源对象的左上角Y坐标
System.Int32 dwRop //光栅的操作值
);
[System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
private static extern IntPtr CreateDC(
string lpszDriver, //驱动名称
string lpszDevice, //设备名称
string lpszOutput, //无用，可以设定为null
IntPtr lpIntData //任意的打印机数据
);
private void button1_Click(object sender, EventArgs e)
{
this.Hide();
System.Threading.Thread.Sleep(1000);
IntPtr dc1=CreateDC("DISPLAY",null,null,(IntPtr)null);
System.Drawing.Graphics g1 = System.Drawing.Graphics.FromHdc(dc1);
Bitmap MyImage = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, g1);
Graphics g2 = Graphics.FromImage(MyImage);
IntPtr dc2 = g2.GetHdc();
BitBlt(dc2, 0, 0, Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, dc1, 0, 0, 0xCC0020);
g1.ReleaseHdc( dc1 );
g2.ReleaseHdc( dc2 );
MyImage.Save("d:\\C#\\hong.jpg",ImageFormat.Jpeg);
MessageBox.Show("已经把当前屏幕保存到d:\\hong.jpg文件中！");
this.Show();
}
}
}
运行后老是提示g1.ReleaseHdc( dc1 )有ArgumentException参数错误 --------------------编程问答-------------------- d1不能用这样释放，需要声明api，用ReleaseDC
例如
[System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
private static extern bool BitBlt(
IntPtr hdcDest, //目标设备的句柄
int nxDest, //目标对象的左上角的X坐标
int nyDest, //目标对象的左上角的Y左边
int nwidth, //目标对象的矩形宽度
int nHeight, //目标对象的矩形长度
IntPtr hdcSrc, //源设备的句柄
int nXSrc, //源对象的左上角X坐标
int nYSrc, //源对象的左上角Y坐标
System.Int32 dwRop //光栅的操作值
);
[System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
private static extern IntPtr CreateDC(
string lpszDriver, //驱动名称
string lpszDevice, //设备名称
string lpszOutput, //无用，可以设定为null
IntPtr lpIntData //任意的打印机数据
);
[DllImport("user32.dll", EntryPoint = "ReleaseDC")]
public static extern int ReleaseDC(
IntPtr hwnd,
IntPtr hdc
);
private void button5_Click(object sender, EventArgs e)
{
this.Hide();
System.Threading.Thread.Sleep(1000);
IntPtr dc1 = CreateDC("DISPLAY", null, null, (IntPtr)null);
System.Drawing.Graphics g1 = System.Drawing.Graphics.FromHdc(dc1);
Bitmap MyImage = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, g1);
Graphics g2 = Graphics.FromImage(MyImage);
IntPtr dc2 = g2.GetHdc();
BitBlt(dc2, 0, 0, Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, dc1, 0, 0, 0xCC0020);
ReleaseDC(IntPtr.Zero, dc1);
g2.ReleaseHdc(dc2);
MyImage.Save("d:\\C#\\hong.jpg", ImageFormat.Jpeg);
MessageBox.Show("已经把当前屏幕保存到d:\\hong.jpg文件中！");
this.Show();
}
关键的就是：
声明
[DllImport("user32.dll", EntryPoint = "ReleaseDC")]
public static extern int ReleaseDC(
IntPtr hwnd,
IntPtr hdc
);
替换：
g1.ReleaseHdc( dc1 );
换为：
ReleaseDC(IntPtr.Zero, dc1); --------------------编程问答-------------------- 参数异常
dc1是否为null
补充：.NET技术 , C#
