I have problems trying to load png file into my application. It seems to load headers fine, and recognize that image is png, but for some reason the output has the same values, though image is really not one color. Another thing that bugs me is that 16 bytes are left unread.
My code:
AAsset* pngAsset_ = 0;
AAssetManager* pngAassetManager_ = 0;
void png_asset_read(png_structp png, png_bytep data, png_size_t size) {
//AAsset_seek(pngAsset_, 0, 0);
AAsset_read(pngAsset_, data, size);
int numBytesRemaining = AAsset_getRemainingLength(pngAsset_);
LOGI("Read size: %d, remaining: %d", size, numBytesRemaining);
}
Image* loadPngFile(AAssetManager* assetManager) {
pngAassetManager_ = assetManager;
LOGI("Trying to load image...");
int HEADER_SIZE = 8;
string filename = "skybox.png";
pngAsset_ = AAssetManager_open(pngAassetManager_, filename.c_str(),
AASSET_MODE_UNKNOWN);
if (pngAsset_ == 0) {
LOGW("Asset \"%s\" not found.", filename.c_str());
return 0;
}
off_t bufferSize = AAsset_getLength(pngAsset_);
png_byte* buffer = new png_byte[HEADER_SIZE];
int numBytesRead = AAsset_read(pngAsset_, buffer, HEADER_SIZE);
int numBytesRemaining = AAsset_getRemainingLength(pngAsset_);
int is_png = !png_sig_cmp(buffer, 0, 8);
if (!is_png) {
LOGE("File %s format is not PNG.", filename.c_str());
return 0;
}
LOGI("Size of the file: %d, bytes read: %d, bytes remain: %d",
bufferSize, numBytesRead, numBytesRemaining);
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
NULL, NULL);
if (!png_ptr) {
LOGE("Unable to create PNG structure: %s", filename.c_str());
return 0;
}
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
png_destroy_read_struct(&png_ptr, (png_infopp) NULL, (png_infopp) NULL);
LOGE("Unable to create png info : %s", filename.c_str());
return 0;
}
png_infop end_info = png_create_info_struct(png_ptr);
if (!end_info) {
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
LOGE("Unable to create png end info : %s", filename.c_str());
return 0;
}
if (setjmp(png_jmpbuf(png_ptr))) {
LOGE("Error during setjmp : %s", filename.c_str());
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
return 0;
}
png_set_read_fn(png_ptr, NULL, png_asset_read);
png_set_sig_bytes(png_ptr, 8);
png_read_info(png_ptr, info_ptr);
int bit_depth, color_type;
png_uint_32 twidth, theight;
png_get_IHDR(png_ptr, info_ptr, &twidth, &theight, &bit_depth, &color_type,
NULL, NULL, NULL);
LOGI("Width: %d, height: %d.", twidth, theight);
// Update the png info struct.
png_read_update_info(png_ptr, info_ptr);
// Row size in bytes.
int rowbytes = png_get_rowbytes(png_ptr, info_ptr);
LOGI("Row size: %d bytes.", rowbytes);
// Allocate the image_data as a big block, to be given to opengl
png_byte *image_data = new png_byte[rowbytes * theight];
if (!image_data) {
//clean up memory and close stuff
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
LOGE(
"Unable to allocate image_data while loading %s ", filename.c_str());
}
//row_pointers is for pointing to image_data for reading the png with libpng
png_bytep *row_pointers = new png_bytep[theight];
if (!row_pointers) {
//clean up memory and close stuff
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
delete[] image_data;
LOGE(
"Unable to allocate row_pointer while loading %s ", filename.c_str());
}
// set the individual row_pointers to point at the correct offsets of image_data
for (int i = 0; i < theight; ++i)
row_pointers[theight - 1 - i] = image_data + i * rowbytes;
//read the png into image_data through row_pointers
png_read_image(png_ptr, row_pointers);
for (int i = 0; i < 10; i ++) {
LOGI("Pixel %d: %f %f %f %f",i, image_data[i * 4], image_data[i * 4 + 1],
image_data[i * 4 + 2], image_data[i * 4 + 3]);
}
//Now generate the OpenGL texture object
Image* image = new Image((unsigned char*) image_data, twidth, theight,
twidth * theight * 4, 0);
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
delete[] row_pointers;
AAsset_close(pngAsset_);
return image;
}
Output:
06-30 23:49:00.651: I/Ghost Engine(21279): Trying to load image...
06-30 23:49:00.651: I/Ghost Engine(21279): Size of the file: 529452, bytes read: 8, bytes remain: 529444
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 8, remaining: 529436
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 13, remaining: 529423
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 4, remaining: 529419
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 8, remaining: 529411
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 9, remaining: 529402
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 4, remaining: 529398
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 8, remaining: 529390
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 32, remaining: 529358
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 4, remaining: 529354
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 8, remaining: 529346
06-30 23:49:00.651: I/Ghost Engine(21279): Width: 1024, height: 1024.
06-30 23:49:00.651: I/Ghost Engine(21279): Row size: 4096 bytes.
06-30 23:49:00.651: I/Ghost Engine(21279): Read size: 8192, remaining: 521154
06-30 23:49:00.681: I/Ghost Engine(21279): Read size: 8192, remaining: 512962
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06-30 23:49:00.851: I/Ghost Engine(21279): Read size: 5042, remaining: 16
06-30 23:49:00.861: I/Ghost Engine(21279): Pixel 0: 0.000000 0.000000 1197.166992 1420.242434
06-30 23:49:00.861: I/Ghost Engine(21279): Pixel 1: 0.000000 0.000000 1197.166992 1420.242434
06-30 23:49:00.861: I/Ghost Engine(21279): Pixel 2: 0.000000 0.000000 1197.166992 1420.242434
06-30 23:49:00.861: I/Ghost Engine(21279): Pixel 3: 0.000000 0.000000 1197.166992 1420.242434
06-30 23:49:00.861: I/Ghost Engine(21279): Pixel 4: 0.000000 0.000000 1197.166992 1420.242434
06-30 23:49:00.861: I/Ghost Engine(21279): Pixel 5: 0.000000 0.000000 1197.166992 1420.242434
06-30 23:49:00.861: I/Ghost Engine(21279): Pixel 6: 0.000000 0.000000 1197.166992 1420.242434
06-30 23:49:00.861: I/Ghost Engine(21279): Pixel 7: 0.000000 0.000000 1197.166992 1420.242434
06-30 23:49:00.861: I/Ghost Engine(21279): Pixel 8: 0.000000 0.000000 1197.166992 1420.242434
06-30 23:49:00.861: I/Ghost Engine(21279): Pixel 9: 0.000000 0.000000 1197.166992 1420.242434
06-30 23:49:00.871: I/Ghost Engine(21279): Image id: 1.
06-30 23:49:00.871: I/Ghost Engine(21279): Image dimensions: 1024 x 1024
06-30 23:49:00.871: I/Ghost Engine(21279): Image size: 4194304
Any ideas where everything might start to go wrong? Thanks, Martin.
