此函数用于将 bmp 文件加载到内存中。您必须首先声明一个具有 bmp 结构的头文件
BMP* load_BMP(char *filename);
BMP *bmp; // local integer for file loaded
FILE *in; // pointer for file opening
int rowsize;
int row, col, color, i;
unsigned char b;
in=fopen(filename,"rb"); // open binary file
if (in==NULL)
{
printf("Problem in opening file %s.\n",filename);
return NULL;
}
bmp=(BMP*) malloc(sizeof(BMP)); //memory allocation
if (bmp==NULL)
{
printf("Not enough memory to load the image.\n");
return NULL;
}
fread(bmp->BM,2,1,in);
if (bmp->BM[0]!='B' || bmp->BM[1]!='M')
{
printf("Bad BMP image file.\n");
free(bmp);
return NULL;
}
fread(&bmp->fileSize,4,1,in);
fread(&bmp->Reserved1,2,1,in);
fread(&bmp->Reserved2,2,1,in);
fread(&bmp->imageOffset,4,1,in);
fread(&bmp->imageHeaderSize,4,1,in);
fread(&bmp->imageWidth,4,1,in);
rowsize=4*((3*bmp->imageWidth+3)/4); //calculate rowsize because of padding
fread(&bmp->imageHeight,4,1,in);
fread(&bmp->colorPlanes,2,1,in);
fread(&bmp->compressionMethod,4,1,in);
fread(&bmp->imageSize,4,1,in);
fread(&bmp->hPPM,4,1,in);
fread(&bmp->vPPM,4,1,in);
fread(&bmp->paletteColors,4,1,in);
fread(&bmp->paletteImportantColors,4,1,in);
bmp->data=(unsigned char*) malloc(bmp->imageSize); //allocate memory for image data array
if (bmp->data==NULL)
{
printf("There is not enough memory to load the image\n");
free(bmp);
return NULL;
}
for(row=0;row<bmp->imageHeight;row++) //read picture data
{
for(col=0;col<bmp->imageWidth;col++)
for(color=0;color<=2;color++)
fread(&bmp->data[row*rowsize+3*col+color],
sizeof(unsigned char),1,in);
//read extra bytes for end of row padding
for(i=0;i<rowsize-3*bmp->imageWidth;i++)
fread(&b,1,1,in);
}
fclose(in);
return bmp;
}