int LCUI_ReadBMPHeader(LCUI_ImageReader reader)
{
size_t n;
uint16_t buffer[8];
LCUI_BMPReader bmp_reader = reader->data;
INFOHEADER *info = &bmp_reader->info;
reader->header.type = LCUI_UNKNOWN_IMAGE;
if (reader->type != LCUI_BMP_READER) {
return -EINVAL;
}
n = reader->fn_read(reader->stream_data, buffer, 14);
/* 受到字节对齐影响，直接将读到的写到结构体变量里会让最后一个成员
* 变量的值不正常，因此需要手动为其成员变量赋值 */
BMPHeader_Init(&bmp_reader->header, buffer);
if (n < 14 || bmp_reader->header.type != 0x4D42) {
return -2;
}
n = reader->fn_read(reader->stream_data, info, sizeof(INFOHEADER));
if (n < sizeof(INFOHEADER)) {
return -2;
}
reader->header.width = info->width;
reader->header.height = info->height;
reader->header.type = LCUI_BMP_IMAGE;
if (info->bits == 24) {
reader->header.color_type = LCUI_COLOR_TYPE_RGB;
reader->header.bit_depth = 24;
}
return 0;
}
int LCUI_ReadBMP( LCUI_ImageReader reader, LCUI_Graph *graph )
{
size_t n, row, bytes_per_row;
unsigned char *buffer, *dest;
LCUI_BMPReader bmp_reader = reader->data;
INFOHEADER *info = &bmp_reader->info;
if( reader->type != LCUI_BMP_READER ) {
return -EINVAL;
}
if( reader->header.type == LCUI_UNKNOWN_IMAGE ) {
if( LCUI_ReadBMPHeader( reader ) != 0 ) {
return -ENODATA;
}
}
/* 信息头中的偏移位置是相对于起始处，需要减去当前已经偏移的位置 */
n = bmp_reader->header.offset - bmp_reader->info.size - 14;
reader->fn_skip( reader->stream_data, n );
if( 0 != Graph_Create( graph, info->width, info->height ) ) {
return -ENOMEM;
}
/* 暂时不实现其它色彩类型处理 */
if( info->bits != 24 ) {
return -ENOSYS;
}
bytes_per_row = (info->bits * info->width + 31) / 32 * 4;
if( bytes_per_row < graph->bytes_per_row ) {
return -EINVAL;
}
buffer = malloc( bytes_per_row );
if( !buffer ) {
return -ENOMEM;
}
/* 从最后一行开始保存 */
dest = graph->bytes + graph->bytes_per_row * (graph->height - 1);
for( row = 0; row < info->height; ++row ) {
n = reader->fn_read( reader->stream_data,
buffer, bytes_per_row );
if( n < bytes_per_row ) {
break;
}
memcpy( dest, buffer, graph->bytes_per_row );
dest -= graph->bytes_per_row;
if( reader->fn_prog ) {
reader->fn_prog( reader->prog_arg,
100.0f * row / info->height );
}
}
free( buffer );
return 0;
}