我正在使用以下方式从文件加载DIBSection:
HBITMAP bmpIn = (HBITMAP) LoadImage(NULL, _T("c:\\Temp\\Temp.bmp"), IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION | LR_LOADFROMFILE);
根据实际经验,我发现以下是加载位图和我过去使用的位图之间存在的差异,但我找不到任何文档说明应该有什么区别。
- 行在内存中从上到下排序,而不是从下到上。我已经验证了.bmp文件本身是自下而上排序的。
- 行填充是2字节的倍数,而不是4字节。
我还发现,当您使用CreateDIBSection
从头创建DIBSection时,存在已记录的差异。
- 由
GetObject
返回的DIBSECTION.dsHandle和BITMAP.bmBits值将为NULL。
这两个差异的文档在哪里?我有什么遗漏吗?这是在Windows 7上,但我想象其他版本的Windows也不会有所不同。
编辑:一些额外的细节。这是temp.bmp
的十六进制转储;它是一个7x7的图像,右侧有白色条纹,左侧有增加的蓝色值(0x10、0x20等)。您可以看到底部行(00,00,70)是第一行,并且有3个字节的填充。
00: 42 4d de 00 00 00 00 00 00 00 36 00 00 00 28 00
10: 00 00 07 00 00 00 07 00 00 00 01 00 18 00 00 00
20: 00 00 a8 00 00 00 00 00 00 00 00 00 00 00 00 00
30: 00 00 00 00 00 00 70 00 00 00 00 00 00 00 00 00
40: 00 00 00 00 00 00 00 00 ff ff ff 00 00 00 60 00
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
60: ff ff ff 00 00 00 50 00 00 00 00 00 00 00 00 00
70: 00 00 00 00 00 00 00 00 ff ff ff 00 00 00 40 00
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90: ff ff ff 00 00 00 30 00 00 00 00 00 00 00 00 00
a0: 00 00 00 00 00 00 00 00 ff ff ff 00 00 00 20 00
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
c0: ff ff ff 00 00 00 10 00 00 00 00 00 00 00 00 00
d0: 00 00 00 00 00 00 00 00 ff ff ff 00 00 00
这里是一个读取 .bmp 文件并输出内容的示例程序。出于简洁起见,我已删除错误检查。
int _tmain(int argc, _TCHAR* argv[])
{
HBITMAP bmpIn = (HBITMAP) LoadImage(NULL, argv[1], IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION | LR_LOADFROMFILE);
FILE * out = _tfopen(argv[2], _T("wb"));
DIBSECTION obj = {0};
GetObject(bmpIn, sizeof(obj), &obj);
cout << "dsBm.bmHeight = " << obj.dsBm.bmHeight << endl;
cout << "dsBmih.biHeight = " << obj.dsBmih.biHeight << endl;
cout << "sizeof(DIBSECTION) = " << sizeof(DIBSECTION) << endl;
fwrite(&obj, sizeof(DIBSECTION), 1, out);
int stride = (((obj.dsBmih.biWidth * obj.dsBmih.biBitCount) + 15) / 16) * 2;
int bytecount = abs(obj.dsBmih.biHeight) * stride;
vector<BYTE> bits(bytecount);
GetBitmapBits(bmpIn, bytecount, &bits[0]);
fwrite(&bits[0], 1, bytecount, out);
fclose(out);
return 0;
}
以下是上述程序的输出,以及所生成文件的十六进制转储:
dsBm.bmHeight = 7
dsBmih.biHeight = 7
sizeof(DIBSECTION) = 84
00: 00 00 00 00 07 00 00 00 07 00 00 00 18 00 00 00
10: 01 00 18 00 00 00 11 00 28 00 00 00 07 00 00 00
20: 07 00 00 00 01 00 18 00 00 00 00 00 a8 00 00 00
30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
50: 00 00 00 00 10 00 00 00 00 00 00 00 00 00 00 00
60: 00 00 00 00 00 00 ff ff ff 00 20 00 00 00 00 00
70: 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff 00
80: 30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90: 00 00 ff ff ff 00 40 00 00 00 00 00 00 00 00 00
a0: 00 00 00 00 00 00 00 00 ff ff ff 00 50 00 00 00
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff
c0: ff 00 60 00 00 00 00 00 00 00 00 00 00 00 00 00
d0: 00 00 00 00 ff ff ff 00 70 00 00 00 00 00 00 00
e0: 00 00 00 00 00 00 00 00 00 00 ff ff ff 00