Cross platform super fast single header c++ library to get image size and format without loading/decoding.
The imageinfo don't get image format by file ext name, but infer by file header bytes and character.
As few I/O times as possible! Read as few bytes as possible!
Some test image files are from image-size. Many thanks to @netroy.
Rust version: imageinfo-rs
imageinfo has been restructured, if you are using old version, please check v1
branch.
imageinfo is available on vcpkg
vcpgk install imageinfo
cmake -B build .
cmake --build build -- all
cmake --build build -- check
Open Visual Studio Command Prompt and run these command
cmake -G "NMake Makefiles" -B build .
cmake --build build -- all
cmake --build build -- check
const char *file = "images/valid/jpg/sample.jpg";
auto info = imageinfo::parse<imageinfo::FilePathReader>(file);
std::cout << "File: " << file << "\n";
std::cout << " - Error : " << info.error_msg() << "\n";
std::cout << " - Width : " << info.size().width << "\n";
std::cout << " - Height : " << info.size().height << "\n";
std::cout << " - Format : " << info.format() << "\n";
std::cout << " - Ext : " << info.ext() << "\n";
std::cout << " - Full Ext : " << info.full_ext() << "\n";
std::cout << " - Mimetype : " << info.mimetype() << "\n\n";
You can pass a file path and use imageinfo::FilePathReader
,
and there are some builtin reader imageinfo::FileReader
, imageinfo::FileStreamReader
, imageinfo::RawDataReader
FILE *file = fopen("images/valid/jpg/sample.jpg", "rb");
auto info = imageinfo::parse<imageinfo::FileReader>(file);
fclose(file);
std::ifstream file("images/valid/jpg/sample.jpg", std::ios::in | std::ios::binary);
auto info = imageinfo::parse<imageinfo::FileStreamReader>(file);
file.close();
// Suppose we already got data and size
// void *data;
// size_t size;
auto info = imageinfo::parse<imageinfo::RawDataReader>(imageinfo::RawData(data, size));
If you known the file is likely a JPEG, you can provide likely_formats
parameter to improve performance;
auto imageInfo = imageinfo::parse<imageinfo::FilePathReader>("images/valid/jpg/sample.jpg", {II_FORMAT_JPEG});
First, take a look at imageinfo::FileReader
, all your need to do is define a class and implement size
and read
method. (not override)
class FileReader {
public:
explicit FileReader(FILE *file) : file_(file) {}
inline size_t size() {
if (file_ != nullptr) {
fseek(file_, 0, SEEK_END);
return ftell(file_);
} else {
return 0;
}
}
inline void read(void *buf, off_t offset, size_t size) {
fseek(file_, offset, SEEK_SET);
fread(buf, 1, size, file_);
}
private:
FILE *file_ = nullptr;
};
Then, let's try to make a reader for Android assets file
class AndroidAssetFileReader {
public:
explicit AndroidAssetFileReader(AAsset *file) : file_(file) {}
inline size_t size() {
if (file_ != nullptr) {
return AAsset_getLength(file_);
} else {
return 0;
}
}
inline void read(void *buf, off_t offset, size_t size) {
AAsset_seek(file_, offset, SEEK_SET);
AAsset_read(file_, buf, size);
}
private:
AAsset *file_ = nullptr;
};
// Suppose we have a AAssetManager
// AAssetManager *manager;
// Open with AASSET_MODE_RANDOM mode to seek forward and backward
AAsset *file = AAssetManager_open(manager, "test.png", AASSET_MODE_RANDOM);
auto imageInfo = imageinfo::parse<imageinfo::AndroidAssetFileReader>(file);
AAsset_close(file);
Pretty easy?
Don't be stingy with your star : )