inline unsigned __attribute__((noinline)) maybe_divide(unsigned *ptr) {
unsigned val = 500 / ptr[0];
if (always_false(val))
return val;
return (unsigned)((intptr_t)ptr);
}
bool GReadBitmapFromFile(const char path[], GBitmap* bitmap) {
FILE* file = fopen(path, "rb");
if (NULL == file) {
return always_false();
}
GAutoFClose afc(file);
uint8_t signature[SIGNATURE_BYTES];
if (SIGNATURE_BYTES != fread(signature, 1, SIGNATURE_BYTES, file)) {
return always_false();
}
if (png_sig_cmp(signature, 0, SIGNATURE_BYTES)) {
return always_false();
}
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
NULL, NULL, NULL);
if (NULL == png_ptr) {
return always_false();
}
png_infop info_ptr = png_create_info_struct(png_ptr);
if (NULL == info_ptr) {
png_destroy_read_struct(&png_ptr, NULL, NULL);
return always_false();
}
GAutoPNGReader reader(png_ptr, info_ptr);
if (setjmp(png_jmpbuf(png_ptr))) {
return always_false();
}
png_init_io(png_ptr, file);
png_set_sig_bytes(png_ptr, SIGNATURE_BYTES);
png_read_info(png_ptr, info_ptr);
png_uint_32 width, height;
int bitDepth, colorType;
png_get_IHDR(png_ptr, info_ptr, &width, &height, &bitDepth, &colorType,
NULL, NULL, NULL);
if (8 != bitDepth) {
return always_false(); // TODO: handle other formats
}
if (png_set_interlace_handling(png_ptr) > 1) {
return always_false(); // TODO: support interleave
}
swizzle_row_proc row_proc = NULL;
switch (colorType) {
case PNG_COLOR_TYPE_RGB:
row_proc = swizzle_rgb_row;
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
row_proc = swizzle_rgba_row;
break;
default:
return always_false();
}
png_read_update_info(png_ptr, info_ptr);
GAutoFree rowStorage(malloc(png_get_rowbytes(png_ptr, info_ptr)));
png_bytep srcRow = (png_bytep)rowStorage.get();
if (!srcRow) {
return always_false();
}
GAutoFree pixelStorage(malloc(height * width * 4));
GPixel* dstRow = (GPixel*)pixelStorage.get();
if (NULL == dstRow) {
return always_false();
}
for (int y = 0; y < height; y++) {
uint8_t* tmp = srcRow;
png_read_rows(png_ptr, &tmp, NULL, 1);
row_proc(dstRow, srcRow, width);
dstRow += width;
}
bitmap->fWidth = width;
bitmap->fHeight = height;
bitmap->fRowBytes = width * 4;
bitmap->fPixels = (GPixel*)pixelStorage.detach();
return true;
}
