GetDIBits：位图修改，但崩溃了？
GetDIBits：尝试修改位图，但不确定如何操作？我尝试了 lpvBits，但它在“猪”区域的比较中崩溃了。我该怎么做？谢谢
LPVOID lpvBits=NULL; // pointer to bitmap bits array
BITMAPINFO bi;
ZeroMemory(&bi.bmiHeader, sizeof(BITMAPINFOHEADER));
bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
if (!GetDIBits(dc, m_bmp, 0, 400, lpvBits, &bi, DIB_RGB_COLORS))
AfxMessageBox("1");
char *pig = (char*)lpvBits;
for (int m=0;m<100;m++)
{
if (pig[m] > 100)
{
pig[m] = 250;
}
}
SetDIBits( dc, m_bmp, 0, 400, (void *)pig, &bi, DIB_RGB_COLORS );
GetDIBits: trying to modify the bitmap, but not sure how to go about it? I tried lpvBits but it crashes out in the comparison in the "pig" area. How should I do this? thx
LPVOID lpvBits=NULL; // pointer to bitmap bits array
BITMAPINFO bi;
ZeroMemory(&bi.bmiHeader, sizeof(BITMAPINFOHEADER));
bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
if (!GetDIBits(dc, m_bmp, 0, 400, lpvBits, &bi, DIB_RGB_COLORS))
AfxMessageBox("1");
char *pig = (char*)lpvBits;
for (int m=0;m<100;m++)
{
if (pig[m] > 100)
{
pig[m] = 250;
}
}
SetDIBits( dc, m_bmp, 0, 400, (void *)pig, &bi, DIB_RGB_COLORS );
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http://msdn.microsoft.com/en- us/library/dd144879(v=vs.85).aspx
lpvBits [输出]
指向接收位图数据的缓冲区的指针。如果该参数为NULL，则该函数将位图的尺寸和格式传递给lpbi参数指向的BITMAPINFO结构。
在这里找到的例子：
http://msdn.microsoft.com/en- us/library/dd183402(v=vs.85).aspx
http://msdn.microsoft.com/en-us/library/ms969901.aspx
http://www.codeproject.com/KB/graphics/drawing2bitmap.aspx
http://www.cplusplus.com/forum/general/28469/
http://msdn.microsoft.com/en-us/library/dd144879(v=vs.85).aspx
lpvBits [out]
A pointer to a buffer to receive the bitmap data. If this parameter is NULL, the function passes the dimensions and format of the bitmap to the BITMAPINFO structure pointed to by the lpbi parameter.
example found here:
http://msdn.microsoft.com/en-us/library/dd183402(v=vs.85).aspx
http://msdn.microsoft.com/en-us/library/ms969901.aspx
http://www.codeproject.com/KB/graphics/drawing2bitmap.aspx
http://www.cplusplus.com/forum/general/28469/
仔细阅读 GetDIBits 的文档 - lpvBits 指针不会返回给您 - 您需要为要获取的位图数据分配足够的内存，并将其传递给 GetDIBits 以用图像数据填充它。
Read the documentation for GetDIBits carefully - the lpvBits pointer is not returned to you - you need to allocate enough memory for the bitmap data you want to fetch, and pass it to GetDIBits to fill it in with image data.