我有这条线：
Process.Start("chrome.exe",
"http://www.cnn.com");
它正在打开一个新的 chrome 浏览器窗口。我想做两件事：
- 将 chrome 窗口转换/保存为图像。
- 隐藏此窗口。
这是我现在在一个新类中尝试的代码：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Drawing.Imaging;
using System.Drawing;
namespace GatherLinks
{
class WebSiteScreenShot
{
[DllImport("user32.dll")]
private static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);
[DllImport("user32.dll")]
public static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);
[DllImport("user32.dll")]
public static extern bool PrintWindow(IntPtr hWnd, IntPtr hdcBlt, int nFlags);
public WebSiteScreenShot()
{
}
public void WhateverMethod()
{
//initialize process and get hWnd
Process putty = Process.Start("chrome.exe",
"http://www.cnn.com");
putty.WaitForInputIdle();
IntPtr winHandle = putty.MainWindowHandle;
//print screen
RECT rc;
GetWindowRect(winHandle, out rc);
Bitmap bmp = new Bitmap(rc.Width, rc.Height, PixelFormat.Format32bppArgb);
Graphics gfxBmp = Graphics.FromImage(bmp);
IntPtr hdcBitmap = gfxBmp.GetHdc();
PrintWindow(winHandle, hdcBitmap, 0);
gfxBmp.ReleaseHdc(hdcBitmap);
gfxBmp.Dispose();
bmp.Save("c:\\temp\\test.png", ImageFormat.Png);
//hides window
ShowWindowAsync(winHandle, 0);
}
[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
private int _Left;
private int _Top;
private int _Right;
private int _Bottom;
public RECT(RECT Rectangle)
: this(Rectangle.Left, Rectangle.Top, Rectangle.Right, Rectangle.Bottom)
{
}
public RECT(int Left, int Top, int Right, int Bottom)
{
_Left = Left;
_Top = Top;
_Right = Right;
_Bottom = Bottom;
}
public int X
{
get { return _Left; }
set { _Left = value; }
}
public int Y
{
get { return _Top; }
set { _Top = value; }
}
public int Left
{
get { return _Left; }
set { _Left = value; }
}
public int Top
{
get { return _Top; }
set { _Top = value; }
}
public int Right
{
get { return _Right; }
set { _Right = value; }
}
public int Bottom
{
get { return _Bottom; }
set { _Bottom = value; }
}
public int Height
{
get { return _Bottom - _Top; }
set { _Bottom = value + _Top; }
}
public int Width
{
get { return _Right - _Left; }
set { _Right = value + _Left; }
}
public Point Location
{
get { return new Point(Left, Top); }
set
{
_Left = value.X;
_Top = value.Y;
}
}
public Size Size
{
get { return new Size(Width, Height); }
set
{
_Right = value.Width + _Left;
_Bottom = value.Height + _Top;
}
}
public static implicit operator Rectangle(RECT Rectangle)
{
return new Rectangle(Rectangle.Left, Rectangle.Top, Rectangle.Width, Rectangle.Height);
}
public static implicit operator RECT(Rectangle Rectangle)
{
return new RECT(Rectangle.Left, Rectangle.Top, Rectangle.Right, Rectangle.Bottom);
}
public static bool operator ==(RECT Rectangle1, RECT Rectangle2)
{
return Rectangle1.Equals(Rectangle2);
}
public static bool operator !=(RECT Rectangle1, RECT Rectangle2)
{
return !Rectangle1.Equals(Rectangle2);
}
public override string ToString()
{
return "{Left: " + _Left + "; " + "Top: " + _Top + "; Right: " + _Right + "; Bottom: " + _Bottom + "}";
}
public override int GetHashCode()
{
return ToString().GetHashCode();
}
public bool Equals(RECT Rectangle)
{
return Rectangle.Left == _Left && Rectangle.Top == _Top && Rectangle.Right == _Right && Rectangle.Bottom == _Bottom;
}
public override bool Equals(object Object)
{
if (Object is RECT)
{
return Equals((RECT)Object);
}
else if (Object is Rectangle)
{
return Equals(new RECT((Rectangle)Object));
}
return false;
}
}
}
}
首先，chrome 的窗口是打开的，没有隐藏。第二个我开始上线异常：
Bitmap bmp = new Bitmap(rc.Width, rc.Height, PixelFormat.Format32bppArgb);
例外是：
ArguemntException 参数无效
我看到 bmp 为空，宽度和高度为 0
我在 Form1 中使用了这个代码，如下所示：
WebSiteScreenShot wsss;
然后在构造函数中：
wsss = new WebSiteScreenShot();
wsss.WhateverMethod();
并使用断点并得到异常。
这是异常的完整消息：
System.ArgumentException was unhandled
HResult=-2147024809
Message=Parameter is not valid.
Source=System.Drawing
StackTrace:
at System.Drawing.Bitmap..ctor(Int32 width, Int32 height, PixelFormat format)
at GatherLinks.WebSiteScreenShot.WhateverMethod() in d:\C-Sharp\GatherLinks\GatherLinks-2\GatherLinks\GatherLinks\WebSiteScreenShot.cs:line 38
at GatherLinks.Form1..ctor() in d:\C-Sharp\GatherLinks\GatherLinks-2\GatherLinks\GatherLinks\Form1.cs:line 71
at GatherLinks.Program.Main() in d:\C-Sharp\GatherLinks\GatherLinks-2\GatherLinks\GatherLinks\Program.cs:line 18
at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException: