139 lines
3.4 KiB
Dart
139 lines
3.4 KiB
Dart
import 'dart:typed_data';
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import 'dart:ui' as ui;
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import 'package:flutter/widgets.dart';
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import 'package:flutter_hbb/common.dart';
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Future<ui.Image?> decodeImageFromPixels(
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Uint8List pixels,
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int width,
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int height,
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ui.PixelFormat format, {
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int? rowBytes,
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int? targetWidth,
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int? targetHeight,
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VoidCallback? onPixelsCopied, // must ensure onPixelsCopied is called no matter this function succeeds
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bool allowUpscaling = true,
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}) async {
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if (targetWidth != null) {
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assert(allowUpscaling || targetWidth <= width);
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if (!(allowUpscaling || targetWidth <= width)) {
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print("not allow upscaling but targetWidth > width");
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onPixelsCopied?.call();
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return null;
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}
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}
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if (targetHeight != null) {
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assert(allowUpscaling || targetHeight <= height);
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if (!(allowUpscaling || targetHeight <= height)) {
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print("not allow upscaling but targetHeight > height");
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onPixelsCopied?.call();
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return null;
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}
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}
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final ui.ImmutableBuffer buffer;
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try {
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buffer = await ui.ImmutableBuffer.fromUint8List(pixels);
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onPixelsCopied?.call();
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} catch (e) {
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onPixelsCopied?.call();
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return null;
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}
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final ui.ImageDescriptor descriptor;
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try {
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descriptor = ui.ImageDescriptor.raw(
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buffer,
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width: width,
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height: height,
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rowBytes: rowBytes,
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pixelFormat: format,
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);
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if (!allowUpscaling) {
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if (targetWidth != null && targetWidth > descriptor.width) {
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targetWidth = descriptor.width;
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}
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if (targetHeight != null && targetHeight > descriptor.height) {
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targetHeight = descriptor.height;
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}
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}
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} catch (e) {
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print("ImageDescriptor.raw failed: $e");
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buffer.dispose();
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return null;
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}
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final ui.Codec codec;
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try {
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codec = await descriptor.instantiateCodec(
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targetWidth: targetWidth,
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targetHeight: targetHeight,
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);
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} catch (e) {
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print("instantiateCodec failed: $e");
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buffer.dispose();
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descriptor.dispose();
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return null;
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}
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final ui.FrameInfo frameInfo;
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try {
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frameInfo = await codec.getNextFrame();
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} catch (e) {
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print("getNextFrame failed: $e");
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codec.dispose();
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buffer.dispose();
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descriptor.dispose();
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return null;
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}
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codec.dispose();
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buffer.dispose();
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descriptor.dispose();
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return frameInfo.image;
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}
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class ImagePainter extends CustomPainter {
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ImagePainter({
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required this.image,
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required this.x,
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required this.y,
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required this.scale,
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});
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ui.Image? image;
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double x;
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double y;
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double scale;
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@override
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void paint(Canvas canvas, Size size) {
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if (image == null) return;
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if (x.isNaN || y.isNaN) return;
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canvas.scale(scale, scale);
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// https://github.com/flutter/flutter/issues/76187#issuecomment-784628161
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// https://api.flutter-io.cn/flutter/dart-ui/FilterQuality.html
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var paint = Paint();
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if ((scale - 1.0).abs() > 0.001) {
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paint.filterQuality = FilterQuality.medium;
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if (scale > 10.00000) {
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paint.filterQuality = FilterQuality.high;
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}
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}
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// It's strange that if (scale < 0.5 && paint.filterQuality == FilterQuality.medium)
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// The canvas.drawImage will not work on web
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if (isWeb) {
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paint.filterQuality = FilterQuality.high;
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}
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canvas.drawImage(
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image!, Offset(x.toInt().toDouble(), y.toInt().toDouble()), paint);
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}
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@override
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bool shouldRepaint(CustomPainter oldDelegate) {
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return oldDelegate != this;
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}
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}
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