.NET Compact Framework 1.0 下实现抓屏
.NET Compact Framework 1.x中实现屏幕抓取有些难度，其实还是.net cf 1.x的支持库不够强大，微软在.net cf2.0中已经弥补了此处的不足。但是为什么还非要实现.net cf1.x的屏幕抓取呢？因为目前使用windows mobile 2003的用户还是大多数，即使目前刷了windows moblie 5的玩家，其系统也并未集成.net cf2.0。这就需要自己安装 .net cf2.0，这对一般用户有一定的门槛（我会在以后的文章中介绍如何安装.net cf2.0），高级用户即使安装也是有顾虑的，.net cf2.0会占用大约10M的手机空间。所以，在这里我给出一个.net cf1.x下抓屏的实例。
#region Using directives
using System;
using System.Runtime.InteropServices;
using System.IO;
#endregion
namespace CatchScreen
{
///
/// Summary description for CaptureScreen.
///
public class CaptureScreen
{
public CaptureScreen()
{
}
public class CaptureScreenApplication
{
private const int sizeBFH = 14;
private const int imgHeight = 220;
private const int imgWidth = 176;
private const int SRCCOPY = 0xCC0020;
public static void CaptureScreen()
{
//IntPtr h1 = GDIApi.FindWindow("", "Form1");
IntPtr h1 = GDIApi.GetDesktopWindow();
IntPtr dc1 = GDIApi.GetDC(IntPtr.Zero);
IntPtr InMemoryDC = GDIApi.CreateCompatibleDC(dc1);
IntPtr hBitmap;
IntPtr ppvBits;
GDIApi.BITMAPINFO bmi = new GDIApi.BITMAPINFO();
bmi.biSize = Marshal.SizeOf(bmi);
bmi.biBitCount = 24;
bmi.biPlanes = 1;
bmi.biWidth = imgWidth;
bmi.biHeight = imgHeight;
bmi.biXPelsPerMeter = 0xb12;
bmi.biYPelsPerMeter = 0xb12;
bmi.biSizeImage = bmi.biWidth * bmi.biHeight * bmi.biBitCount / 8;
bmi.biClrUsed = 0;
bmi.biClrImportant = 0;
bmi.biCompression = 0;
hBitmap = GDIApi.CreateDIBSection(new IntPtr(0), bmi, 0, out ppvBits, new IntPtr(0), 0);
IntPtr OldBitmap = GDIApi.SelectObject(InMemoryDC, hBitmap);
IntPtr dc2 = GDIApi.GetWindowDC(h1);
GDIApi.StretchBlt(InMemoryDC, 0, 0, imgWidth, imgHeight, dc2, 0, 0, imgWidth, imgHeight, SRCCOPY);
byte[] rawData = new byte[bmi.biSizeImage];
Marshal.Copy(ppvBits, rawData, 0, bmi.biSizeImage);
GDIApi.DeleteDC(InMemoryDC);
GDIApi.ReleaseDC(IntPtr.Zero, dc1);
GDIApi.ReleaseDC(h1, dc2);
byte[] bitmap = CreateBitmap(imgWidth, imgHeight, rawData, bmi);
FileStream fs = new FileStream(@"/out1.bmp", FileMode.Create, FileAccess.Write);
fs.Write(bitmap, 0, bitmap.Length);
fs.Close();
}
public static byte[] CreateBitmap(int width, int height, byte[] bitmapData, GDIApi.BITMAPINFO bi)
{
if ((width & 1) == 1)
throw new ArgumentException("Width must be an even number");
int nSize = sizeBFH + Marshal.SizeOf(typeof(GDIApi.BITMAPINFO)) + (width << 3) * height;
byte[] data = new byte[nSize];
byte[] bfh = new byte[sizeBFH];
BitConverter.GetBytes((short)0x4d42).CopyTo(data, 0);
BitConverter.GetBytes(nSize).CopyTo(data, 2);
int bfhOffBits = (int)(sizeBFH + Marshal.SizeOf(typeof(GDIApi.BITMAPINFO)));
BitConverter.GetBytes(bfhOffBits).CopyTo(data, 10);
byte[] hdr = GetBytes(bi);
Buffer.BlockCopy(hdr, 0, data, sizeBFH, hdr.Length);
Buffer.BlockCopy(bitmapData, 0, data, (int)bfhOffBits, Math.Min(bitmapData.Length, bi.biSizeImage));
return data;
}
private static byte[] GetBytes(object o)
{
int size = Marshal.SizeOf(o.GetType());
IntPtr p = GDIApi.LocalAlloc(GDIApi.GPTR, size);
Marshal.StructureToPtr(o, p, false);
byte[] ret = new byte[size];
Marshal.Copy(p, ret, 0, size);
GDIApi.LocalFree(p);
return ret;
}
}
public class GDIApi
{
public const int GPTR = 0x40;
public struct BITMAPFILEHEADER
{
public Int16 bfType;
public Int32 bfSize;
public Int16 bfReserved1;
public Int16 bfReserved2;
public Int32 bfOffBits;
}
public class BITMAPINFO
{
public Int32 biSize;
public Int32 biWidth;
public Int32 biHeight;
public Int16 biPlanes;
public Int16 biBitCount;
public Int32 biCompression;
public Int32 biSizeImage;
public Int32 biXPelsPerMeter;
public Int32 biYPelsPerMeter;
public Int32 biClrUsed;
public Int32 biClrImportant;
};
[DllImport("coredll.dll")]
public static extern uint GetLastError();
[DllImport("coredll.dll")]
public static extern IntPtr CreateDIBSection(IntPtr hdc, BITMAPINFO pbmi, uint iUsage, out IntPtr
ppvBits, IntPtr hSection, uint dwOffset);
[DllImport("coredll.dll")]
public static extern uint GetSystemPaletteEntries(IntPtr hdc, uint iStartIndexx,
uint nEntries, IntPtr lppe);
[DllImport("coredll.dll")]
public static extern int GetObject(IntPtr hgdiobj, int cBuffer, IntPtr lp);
[DllImport("coredll.dll")]
public static extern IntPtr DeleteDC(IntPtr hdc);
[DllImport("coredll.dll")]
public static extern IntPtr CreateCompatibleDC(IntPtr hdc);
[DllImport("coredll.dll")]
public static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj);
[DllImport("coredll.dll")]
public static extern IntPtr CreateCompatibleBitmap(IntPtr hdc, int nWidth, int nHeight);
[DllImport("coredll.dll")]
public static extern IntPtr FindWindow(string s1, string s2);
[DllImport("coredll.dll")]
public static extern int GetWindowText(IntPtr handle, char[] c, int len);
[DllImport("coredll.dll")]
public static extern IntPtr GetWindow(IntPtr handle, int cmd);
[DllImportAttribute("coredll.dll")]
public static extern IntPtr GetDC(IntPtr hWnd);
[DllImportAttribute("coredll.dll")]
public static extern IntPtr GetWindowDC(IntPtr hWnd);
[DllImportAttribute("coredll.dll")]
public static extern int GetDeviceCaps(IntPtr hWnd, int nIndex);
[DllImportAttribute("coredll.dll")]
public static extern int DrawText(IntPtr hDC, string lpString, int nCount, ref int[] lpRect, uint uFormat);
[DllImportAttribute("coredll.dll")]
public static extern IntPtr ReleaseDC(IntPtr hWnd, IntPtr hDC);
[DllImportAttribute("coredll.dll")]
public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int x, int Y, int cx, int cy, uint uFlags);
[DllImportAttribute("coredll.dll")]
public static extern bool StretchBlt(
IntPtr hdcDest, // handle to destination DC
int nXDest, // x-coord of destination upper-left corner
int nYDest, // y-coord of destination upper-left corner
int nWidth, // width of destination rectangle
int nHeight, // height of destination rectangle, negative to switch upside down
IntPtr hdcSrc, // handle to source DC
int nXSrc, // x-coordinate of source upper-left corner
int nYSrc, // y-coordinate of source upper-left corner
int nWidthSrc,
int nHeightSrc,
uint dwRop // raster operation code
);
[DllImport("coredll.dll")]
public static extern IntPtr GetDesktopWindow();
[DllImport("coredll.dll")]
public static extern IntPtr LocalAlloc(uint flags, int cb);
[DllImport("coredll.dll")]
public static extern IntPtr LocalFree(IntPtr hMem);
}
}
}
有过c#开发经验的朋友会很容看懂以上的代码，在win32下实现抓屏是很简单的，因为我们可以用ImageFormat类来保存抓取的文件。其实，.net cf 1.x下实现抓屏并不在于抓屏本身难以实现，无非都是调用windows 的api函数，其难点在于如何保存抓取的文件。我是在opennetcf的论坛中找到了一段代码，然后经过自己的修改调试才完成的抓屏功能。这个类并不完善，一些参数我都写死了，有兴趣的朋友可以自己完善一下。Good luck!God bless you!