CreateDIBSection The CreateDIBSection function creates a device-independent bitmap (DIB) that applications can write to directly. The function gives you a pointer to the location of the bitmap's bit values. You can supply a handle to a file mapping object that the function will use to create the bitmap, or you can let the system allocate the memory for the bitmap.HBITMAP CreateDIBSection( HDC hdc, // handle to device context CONST BITMAPINFO *pbmi, // pointer to structure containing bitmap size, // format, and color data UINT iUsage, // color data type indicator: RGB values or // palette indexes VOID *ppvBits, // pointer to variable to receive a pointer to // the bitmap's bit values HANDLE hSection, // optional handle to a file mapping object DWORD dwOffset // offset to the bitmap bit values within the // file mapping object );
Parameters hdc Handle to a device context. If the value of iUsage is DIB_PAL_COLORS, the function uses this device context's logical palette to initialize the device-independent bitmap's colors. pbmi Pointer to a BITMAPINFO structure that specifies various attributes of the device-independent bitmap, including the bitmap's dimensions and colors. iUsage Specifies the type of data contained in the bmiColors array member of the BITMAPINFO structure pointed to by pbmi (either logical palette indexes or literal RGB values). The following values are defined. Value Meaning DIB_PAL_COLORS The bmiColors member is an array of 16-bit indexes into the logical palette of the device context specified by hdc. DIB_RGB_COLORS The BITMAPINFO structure contains an array of literal RGB values. ppvBits Pointer to a variable that receives a pointer to the location of the device-independent bitmap's bit values. hSection Handle to a file mapping object that the function will use to create the device-independent bitmap. This parameter can be NULL. If hSection is not NULL, it must be a handle to a file mapping object created by calling theCreateFileMapping function with the PAGE_READWRITE or PAGE_WRITECOPY flag. Read-only DIB sections are not supported. Handles created by other means will cause CreateDIBSection to fail. If hSection is not NULL, the CreateDIBSection function locates the bitmap's bit values at offset dwOffset in the file mapping object referred to by hSection. An application can later retrieve the hSection handle by calling the GetObject function with theHBITMAP returned by CreateDIBSection. If hSection is NULL, the system allocates memory for the device-independent bitmap. In this case, the CreateDIBSection function ignores the dwOffset parameter. An application cannot later obtain a handle to this memory. The dshSection member of the DIBSECTION structure filled in by calling the GetObject function will be NULL. dwOffset Specifies the offset from the beginning of the file mapping object referenced by hSection where storage for the bitmap's bit values is to begin. This value is ignored if hSection is NULL. The bitmap's bit values are aligned on doubleword boundaries, so dwOffset must be a multiple of the size of a DWORD. Return Values If the function succeeds, the return value is a handle to the newly created device-independent bitmap, and *ppvBits points to the bitmap's bit values. If the function fails, the return value is NULL, and *ppvBits is NULL. Windows NT: To get extended error information, callGetLastError.Res As noted above, if hSection is NULL, the system allocates memory for the device-independent bitmap. The system closes the handle to that memory when you later delete the device-independent bitmap by calling the DeleteObject function. If hSection is not NULL, you must close the hSection memory handle yourself after calling DeleteObject to delete the bitmap.
Windows NT: You need to guarantee that the GDI subsystem has completed any drawing to a bitmap created by CreateDIBSection before you draw to the bitmap yourself. Access to the bitmap must be synchronized. Do this by calling the GdiFlush function. This applies to any use of the pointer to the bitmap's bit values, including passing the pointer in calls to functions such as SetDIBits. ICM: If the bmiHeader member of BITMAPINFO (pointed to by pbmi) does not contain BITMAPV4HEADER or BITMAPV5HEADER, no color management is done. Otherwise, color management is enabled, and the specified color space is associated with the bitmap.Windows CE: Set the iUsage parameter to DIB_RGB_COLORS, except when an 8 bpp bitmap is used, in which case you set iUsage to DIB_PAL_COLORS. However, if DIB_PAL_COLORS is used, Windows CE ignores the values in the bmiColors array member of the BITMAPINFO structure. In addition, you should set the hSection parameter to NULL. Windows CE ignores the dwOffset parameter; set it to zero.In Windows CE version 1.0, the BITMAPINFO structure pointed to by the pbmi parameter must specify 1 or 2 bits per pixel.In Windows CE version 2.0, the BITMAPINFO structure must include a color table if the images are palettized (usually 1,2,4, and 8 bpp formats). For 16 bpp or 32 bpp non-palettized images, the color table must be three entries long; the entries must specify the values of the red, green, and blue bitmasks. GDI ignores the color table for 24 bpp images; their pixels must be stored in Blue-Green-Red (BGR) format. QuickInfo Windows NT: Requires version 3.1 or later. Windows: Requires Windows 95 or later. Windows CE: Requires version 1.0 or later. Header: Declared in wingdi.h. Import Library: Use gdi32.lib.See Also Bitmaps Overview, Bitmap Functions, BITMAPINFO,CreateFileMapping, DeleteObject, DIBSECTION, GetDIBColorTable, GetObject, GdiFlush,HBITMAP, SetDIBits, SetDIBColorTable
The CreateDIBSection function creates a device-independent bitmap (DIB) that applications can write to directly. The function gives you a pointer to the location of the bitmap's bit values. You can supply a handle to a file mapping object that the function will use to create the bitmap, or you can let the system allocate the memory for the bitmap.HBITMAP CreateDIBSection(
HDC hdc, // handle to device context
CONST BITMAPINFO *pbmi,
// pointer to structure containing bitmap size,
// format, and color data
UINT iUsage, // color data type indicator: RGB values or
// palette indexes
VOID *ppvBits, // pointer to variable to receive a pointer to
// the bitmap's bit values
HANDLE hSection, // optional handle to a file mapping object
DWORD dwOffset // offset to the bitmap bit values within the
// file mapping object
);
Parameters
hdc
Handle to a device context. If the value of iUsage is DIB_PAL_COLORS, the function uses this device context's logical palette to initialize the device-independent bitmap's colors.
pbmi
Pointer to a BITMAPINFO structure that specifies various attributes of the device-independent bitmap, including the bitmap's dimensions and colors.
iUsage
Specifies the type of data contained in the bmiColors array member of the BITMAPINFO structure pointed to by pbmi (either logical palette indexes or literal RGB values). The following values are defined. Value Meaning
DIB_PAL_COLORS The bmiColors member is an array of 16-bit indexes into the logical palette of the device context specified by hdc.
DIB_RGB_COLORS The BITMAPINFO structure contains an array of literal RGB values.
ppvBits
Pointer to a variable that receives a pointer to the location of the device-independent bitmap's bit values.
hSection
Handle to a file mapping object that the function will use to create the device-independent bitmap. This parameter can be NULL.
If hSection is not NULL, it must be a handle to a file mapping object created by calling theCreateFileMapping function with the PAGE_READWRITE or PAGE_WRITECOPY flag. Read-only DIB sections are not supported. Handles created by other means will cause CreateDIBSection to fail. If hSection is not NULL, the CreateDIBSection function locates the bitmap's bit values at offset dwOffset in the file mapping object referred to by hSection. An application can later retrieve the hSection handle by calling the GetObject function with theHBITMAP returned by CreateDIBSection. If hSection is NULL, the system allocates memory for the device-independent bitmap. In this case, the CreateDIBSection function ignores the dwOffset parameter. An application cannot later obtain a handle to this memory. The dshSection member of the DIBSECTION structure filled in by calling the GetObject function will be NULL. dwOffset
Specifies the offset from the beginning of the file mapping object referenced by hSection where storage for the bitmap's bit values is to begin. This value is ignored if hSection is NULL. The bitmap's bit values are aligned on doubleword boundaries, so dwOffset must be a multiple of the size of a DWORD.
Return Values
If the function succeeds, the return value is a handle to the newly created device-independent bitmap, and *ppvBits points to the bitmap's bit values. If the function fails, the return value is NULL, and *ppvBits is NULL. Windows NT: To get extended error information, callGetLastError.Res
As noted above, if hSection is NULL, the system allocates memory for the device-independent bitmap. The system closes the handle to that memory when you later delete the device-independent bitmap by calling the DeleteObject function. If hSection is not NULL, you must close the hSection memory handle yourself after calling DeleteObject to delete the bitmap.
Windows NT: You need to guarantee that the GDI subsystem has completed any drawing to a bitmap created by CreateDIBSection before you draw to the bitmap yourself. Access to the bitmap must be synchronized. Do this by calling the GdiFlush function. This applies to any use of the pointer to the bitmap's bit values, including passing the pointer in calls to functions such as SetDIBits. ICM: If the bmiHeader member of BITMAPINFO (pointed to by pbmi) does not contain BITMAPV4HEADER or BITMAPV5HEADER, no color management is done. Otherwise, color management is enabled, and the specified color space is associated with the bitmap.Windows CE: Set the iUsage parameter to DIB_RGB_COLORS, except when an 8 bpp bitmap is used, in which case you set iUsage to DIB_PAL_COLORS. However, if DIB_PAL_COLORS is used, Windows CE ignores the values in the bmiColors array member of the BITMAPINFO structure. In addition, you should set the hSection parameter to NULL. Windows CE ignores the dwOffset parameter; set it to zero.In Windows CE version 1.0, the BITMAPINFO structure pointed to by the pbmi parameter must specify 1 or 2 bits per pixel.In Windows CE version 2.0, the BITMAPINFO structure must include a color table if the images are palettized (usually 1,2,4, and 8 bpp formats). For 16 bpp or 32 bpp non-palettized images, the color table must be three entries long; the entries must specify the values of the red, green, and blue bitmasks. GDI ignores the color table for 24 bpp images; their pixels must be stored in Blue-Green-Red (BGR) format. QuickInfo
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in wingdi.h.
Import Library: Use gdi32.lib.See Also
Bitmaps Overview, Bitmap Functions, BITMAPINFO,CreateFileMapping, DeleteObject, DIBSECTION, GetDIBColorTable, GetObject, GdiFlush,HBITMAP, SetDIBits, SetDIBColorTable
g_CamInfo[iIndex].HbitMap=CreateDIBSection(NULL,bmi,DIB_RGB_COLORS,NULL,0,0);
if (g_CamInfo[iIndex].HbitMap != NULL)
{
DeleteObject(g_CamInfo[iIndex].HbitMap);
g_CamInfo[iIndex].HbitMap=NULL;
}
但是我应该在什么地方删除呢？
使用vld看下是哪行代码造成的
if(g_CamInfo[iIndex].HbitMap) DeleteObjectg_CamInfo[iIndex].HbitMap;
g_CamInfo[iIndex].HbitMap=CreateDIBSection(NULL,bmi,DIB_RGB_COLORS,NULL,0,0);
意思是先辈删除, 接着 创建 .
使用vld看下是哪行代码造成的
vld我这边要报错。
cvCreateImage之后没有对应cvReleaseImage的？
“Potential Errors Passing CRT Objects Across DLL Boundaries”
cvCreateCameraCapture之后没有对应cvReleaseCapture的？
请注意以上内容和11楼不一样！
别每次都cvCreateCameraCapture，改成只在DllMain中DLL_PROCESS_ATTACH时调用一次并记住其返回值，在DllMain中DLL_PROCESS_DETACH时cvReleaseCapture