///
/// 截取部分屏幕
///
/// 左上角
/// 右下角
/// 是否全屏幕
/// 返回值Bitmap
public static Bitmap GetPartScreen(Point P1,Point P2,bool Full)
{
IntPtr hscrdc,hmemdc;
IntPtr hbitmap,holdbitmap;
int nx,ny,nx2,ny2;
nx=ny=nx2=ny2=0;
int nwidth, nheight;
int xscrn, yscrn;
hscrdc = CreateDC("DISPLAY", null, null, 0);//创建DC句柄
hmemdc = CreateCompatibleDC(hscrdc);//创建一个内存DC
xscrn = GetDeviceCaps(hscrdc, GetDeviceCapsIndex.HORZRES);//获取屏幕宽度
yscrn = GetDeviceCaps(hscrdc, GetDeviceCapsIndex.VERTRES);//获取屏幕高度
if(Full)//如果是截取整个屏幕
{
nx = 0;
ny = 0;
nx2 = xscrn;
ny2 = yscrn;
}
else
{
nx = P1.X;
ny = P1.Y;
nx2 =P2.X;
ny2 =P2.Y;
//检查数值合法性
if(nx<0)nx = 0;
if(ny<0)ny = 0;
if(nx2>xscrn)nx2 = xscrn;
if(ny2>yscrn)ny2 = yscrn;
}
nwidth = nx2 - nx;//截取范围的宽度
nheight = ny2 - ny;//截取范围的高度
hbitmap = CreateCompatibleBitmap(hscrdc, nwidth, nheight);//从内存DC复制到hbitmap句柄
holdbitmap = SelectObject(hmemdc, hbitmap);
BitBlt(hmemdc, 0, 0, nwidth, nheight,hscrdc, nx, ny,(UInt32)0xcc0020);
hbitmap = SelectObject(hmemdc, holdbitmap);
DeleteDC(hscrdc);//删除用过的对象
DeleteDC(hmemdc);//删除用过的对象
return Bitmap.FromHbitmap(hbitmap);//用Bitmap.FromHbitmap从hbitmap返回Bitmap
所用到的API声明:
| [DllImport("gdi32.dll")]
public static extern IntPtr CreateDC(
string lpszDriver, // driver name
string lpszDevice, // device name
string lpszOutput, // not used; should be NULL
Int64 lpInitData // optional printer data
);
[DllImport("gdi32.dll")]
public static extern IntPtr CreateCompatibleDC(
IntPtr hdc // handle to DC
);
[DllImport("gdi32.dll")]
public static extern int GetDeviceCaps(
IntPtr hdc, // handle to DC
GetDeviceCapsIndex nIndex // index of capability
);
[DllImport("gdi32.dll")]
public static extern IntPtr CreateCompatibleBitmap(
IntPtr hdc, // handle to DC
int nWidth, // width of bitmap, in pixels
int nHeight // height of bitmap, in pixels
);
[DllImport("gdi32.dll")]
public static extern IntPtr SelectObject(
IntPtr hdc, // handle to DC
IntPtr hgdiobj // handle to object
);
[DllImport("gdi32.dll")]
public static extern int BitBlt(
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
IntPtr hdcSrc, // handle to source DC
int nXSrc, // x-coordinate of source upper-left corner
int nYSrc, // y-coordinate of source upper-left corner
UInt32 dwRop // raster operation code
);
[DllImport("gdi32.dll")]
public static extern int DeleteDC(
IntPtr hdc // handle to DC
);
|
