BitBlt The BitBlt function performs a bit-block transfer of the color data corresponding to a rectangle of pixels from the specified source device context into a destination device context. BOOL BitBlt( HDC 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 HDC hdcSrc, // handle to source DC int nXSrc, // x-coordinate of source upper-left corner int nYSrc, // y-coordinate of source upper-left corner DWORD dwRop // raster operation code ); Parameters hdcDest [in] Handle to the destination device context. nXDest [in] Specifies the x-coordinate, in logical units, of the upper-left corner of the destination rectangle. nYDest [in] Specifies the y-coordinate, in logical units, of the upper-left corner of the destination rectangle. nWidth [in] Specifies the width, in logical units, of the source and destination rectangles. nHeight [in] Specifies the height, in logical units, of the source and the destination rectangles. hdcSrc [in] Handle to the source device context. nXSrc [in] Specifies the x-coordinate, in logical units, of the upper-left corner of the source rectangle. nYSrc [in] Specifies the y-coordinate, in logical units, of the upper-left corner of the source rectangle. dwRop [in] Specifies a raster-operation code. These codes define how the color data for the source rectangle is to be combined with the color data for the destination rectangle to achieve the final color.
VB声明 Declare Function BitBlt Lib "gdi32" Alias "BitBlt" (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long 说明 将一幅位图从一个设备场景复制到另一个。源和目标DC相互间必须兼容
BitBlt Picture1.hDC, 98, 0, 16, 23, Picture2.hDC, 16 * Int(Mid$(Time, 8, 1)), 0, SRCCOPY
End Sub
上面的代码无法测试.
BitBlt Picture1.hDC, 98, 0, 16, 23, Picture2.hDC, 0, 16 * Int(Mid$(Time, 8, 1)), SRCCOPY
下面这是横向截取的代码:
BitBlt Picture1.hDC, 98, 0, 16, 23, Picture2.hDC, 16 * Int(Mid$(Time, 8, 1)), 0, SRCCOPY代码的所在不同之处是最后的"0"放到了中间就可以实现纵向截取,能不能告诉我这个"0"所在位置的意义呢?
The BitBlt function performs a bit-block transfer of the color data corresponding to a rectangle of pixels from the specified source device context into a destination device context. BOOL BitBlt(
HDC 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
HDC hdcSrc, // handle to source DC
int nXSrc, // x-coordinate of source upper-left corner
int nYSrc, // y-coordinate of source upper-left corner
DWORD dwRop // raster operation code
);
Parameters
hdcDest
[in] Handle to the destination device context.
nXDest
[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the destination rectangle.
nYDest
[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the destination rectangle.
nWidth
[in] Specifies the width, in logical units, of the source and destination rectangles.
nHeight
[in] Specifies the height, in logical units, of the source and the destination rectangles.
hdcSrc
[in] Handle to the source device context.
nXSrc
[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the source rectangle.
nYSrc
[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the source rectangle.
dwRop
[in] Specifies a raster-operation code. These codes define how the color data for the source rectangle is to be combined with the color data for the destination rectangle to achieve the final color.
Declare Function BitBlt Lib "gdi32" Alias "BitBlt" (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long 说明
将一幅位图从一个设备场景复制到另一个。源和目标DC相互间必须兼容
返回值
Long,非零表示成功,零表示失败。会设置GetLastError 参数表
参数 类型及说明
hDestDC Long,目标设备场景
x,y Long,对目标DC中目标矩形左上角位置进行描述的那个点。用目标DC的逻辑坐标表示
nWidth,nHeight Long,欲传输图象的宽度和高度
hSrcDC Long,源设备场景。如光栅运算未指定源,则应设为0
xSrc,ySrc Long,对源DC中源矩形左上角位置进行描述的那个点。用源DC的逻辑坐标表示
dwRop Long,传输过程要执行的光栅运算 注解
在NT环境下,如在一次世界传输中要求在源设备场景中进行剪切或旋转处理,这个函数的执行会失败
如目标和源DC的映射关系要求矩形中像素的大小必须在传输过程中改变,那么这个函数会根据需要自动伸缩、旋转、折叠、或切断,以便完成最终的传输过程