109 lines
2.9 KiB
Dart
109 lines
2.9 KiB
Dart
import 'dart:ffi';
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import 'dart:io';
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import 'package:ffi/ffi.dart';
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import 'phash_bindings.dart';
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/// Loads the vendored C++ `libphash` for the current platform.
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DynamicLibrary loadPhashLibrary({String? hostLibraryPath}) {
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if (hostLibraryPath != null && hostLibraryPath.isNotEmpty) {
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return DynamicLibrary.open(hostLibraryPath);
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}
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if (Platform.isAndroid) {
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return DynamicLibrary.open('libphash.so');
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}
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if (Platform.isIOS) {
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try {
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return DynamicLibrary.process();
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} catch (_) {
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return DynamicLibrary.open('phash.framework/phash');
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}
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}
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if (Platform.isMacOS) {
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final candidates = <String>[
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'native/phash/build/libphash.dylib',
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'native/phash/build/libphash.so',
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'libphash.dylib',
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'libphash.so',
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];
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for (final path in candidates) {
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final file = File(path);
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if (file.existsSync()) {
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return DynamicLibrary.open(file.absolute.path);
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}
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}
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return DynamicLibrary.open('libphash.dylib');
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}
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if (Platform.isLinux) {
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final candidates = <String>[
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'native/phash/build/libphash.so',
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'libphash.so',
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];
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for (final path in candidates) {
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final file = File(path);
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if (file.existsSync()) {
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return DynamicLibrary.open(file.absolute.path);
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}
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}
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return DynamicLibrary.open('libphash.so');
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}
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throw UnsupportedError('phash FFI is not supported on ${Platform.operatingSystem}');
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}
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/// Thin FFI wrapper around rgb-phash-v1 C API.
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class PhashNative {
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PhashNative._(this._fromBytes, this._hamming);
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factory PhashNative({String? hostLibraryPath}) {
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final lib = loadPhashLibrary(hostLibraryPath: hostLibraryPath);
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return PhashNative._(
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lib.lookupFunction<PhashFromBytesNative, PhashFromBytesDart>(
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'phash_from_bytes',
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),
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lib.lookupFunction<PhashHammingNative, PhashHammingDart>(
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'phash_hamming',
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),
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);
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}
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final PhashFromBytesDart _fromBytes;
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final PhashHammingDart _hamming;
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/// Compute 105-bit ASCII hash from encoded image bytes (JPEG/PNG/…).
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String hashFromBytes(List<int> bytes) {
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if (bytes.isEmpty) {
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throw ArgumentError('image bytes are empty');
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}
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final data = malloc<Uint8>(bytes.length);
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final out = malloc<Uint8>(kPhashBits + 1);
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try {
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data.asTypedList(bytes.length).setAll(0, bytes);
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final rc = _fromBytes(data, bytes.length, out.cast<Char>(), kPhashBits + 1);
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if (rc != 0) {
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throw StateError('phash_from_bytes failed with code $rc');
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}
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return out.cast<Utf8>().toDartString();
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} finally {
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malloc.free(data);
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malloc.free(out);
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}
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}
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int hamming(String a, String b) {
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final pa = a.toNativeUtf8();
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final pb = b.toNativeUtf8();
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try {
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final d = _hamming(pa.cast<Char>(), pb.cast<Char>());
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if (d < 0) {
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throw StateError('phash_hamming failed');
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}
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return d;
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} finally {
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malloc.free(pa);
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malloc.free(pb);
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}
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}
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}
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