FurryChat/lib/utils/resize_image.dart

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import 'dart:typed_data';
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import 'dart:ui';
import 'package:famedlysdk/famedlysdk.dart';
import 'package:native_imaging/native_imaging.dart' as native;
import 'run_in_background.dart';
Future<MatrixImageFile> resizeImage(MatrixImageFile file,
{int max = 800}) async {
// we want to resize the image in a separate isolate, because otherwise that can
// freeze up the UI a bit
// we can't do width / height fetching in a separate isolate, as that may use the UI stuff
await native.init();
_IsolateArgs args;
try {
final nativeImg = native.Image();
await nativeImg.loadEncoded(file.bytes);
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file.width = nativeImg.width;
file.height = nativeImg.height;
args = _IsolateArgs(
width: file.width, height: file.height, bytes: file.bytes, max: max);
nativeImg.free();
} on UnsupportedError {
final dartCodec = await instantiateImageCodec(file.bytes);
final dartFrame = await dartCodec.getNextFrame();
file.width = dartFrame.image.width;
file.height = dartFrame.image.height;
final rgbaData = await dartFrame.image.toByteData();
final rgba = Uint8List.view(
rgbaData.buffer, rgbaData.offsetInBytes, rgbaData.lengthInBytes);
dartFrame.image.dispose();
dartCodec.dispose();
args = _IsolateArgs(
width: file.width, height: file.height, bytes: rgba, max: max);
}
final res = await runInBackground(_isolateFunction, args);
file.blurhash = res.blurhash;
final thumbnail = MatrixImageFile(
bytes: res.jpegBytes,
name: file.name != null
? 'scaled_' + file.name.split('.').first + '.jpg'
: 'thumbnail.jpg',
mimeType: 'image/jpeg',
width: res.width,
height: res.height,
);
// only return the thumbnail if the size actually decreased
return thumbnail.size >= file.size ? file : thumbnail;
}
class _IsolateArgs {
final int width;
final int height;
final Uint8List bytes;
final int max;
final String name;
_IsolateArgs({this.width, this.height, this.bytes, this.max, this.name});
}
class _IsolateResponse {
final String blurhash;
final Uint8List jpegBytes;
final int width;
final int height;
_IsolateResponse({this.blurhash, this.jpegBytes, this.width, this.height});
}
Future<_IsolateResponse> _isolateFunction(_IsolateArgs args) async {
await native.init();
var nativeImg = native.Image();
try {
await nativeImg.loadEncoded(args.bytes);
} on UnsupportedError {
nativeImg.loadRGBA(args.width, args.height, args.bytes);
}
if (args.width > args.max || args.height > args.max) {
var w = args.max, h = args.max;
if (args.width > args.height) {
h = args.max * args.height ~/ args.width;
} else {
w = args.max * args.width ~/ args.height;
}
final scaledImg = nativeImg.resample(w, h, native.Transform.lanczos);
nativeImg.free();
nativeImg = scaledImg;
}
final jpegBytes = await nativeImg.toJpeg(75);
final blurhash = nativeImg.toBlurhash(3, 3);
final ret = _IsolateResponse(
blurhash: blurhash,
jpegBytes: jpegBytes,
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width: nativeImg.width,
height: nativeImg.height);
nativeImg.free();
return ret;
}