97 lines
2.9 KiB
Dart
97 lines
2.9 KiB
Dart
import 'dart:async';
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import 'dart:ui';
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import 'package:aves/model/settings/settings.dart';
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import 'package:aves_model/aves_model.dart';
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import 'package:aves_utils/aves_utils.dart';
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import 'package:collection/collection.dart';
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import 'package:flutter/foundation.dart';
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import 'package:flutter/material.dart';
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enum HistogramChannel { red, green, blue, luminance }
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typedef HistogramLevels = Map<HistogramChannel, List<double>>;
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mixin HistogramMixin {
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HistogramLevels _levels = {};
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Future<void>? _loader;
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static const int bins = 256;
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Future<HistogramLevels> getHistogramLevels(ImageInfo info, bool forceUpdate) async {
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if (_levels.isEmpty || forceUpdate) {
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_loader ??= _getLevels(info);
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await _loader;
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_loader = null;
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}
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return _levels;
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}
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Future<void> _getLevels(ImageInfo info) async {
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final data = (await info.image.toByteData(format: ImageByteFormat.rawStraightRgba))!;
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_levels = switch (settings.overlayHistogramStyle) {
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OverlayHistogramStyle.rgb => await compute<ByteData, HistogramLevels>(_computeRgbLevels, data),
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OverlayHistogramStyle.luminance => await compute<ByteData, HistogramLevels>(_computeLuminanceLevels, data),
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_ => <HistogramChannel, List<double>>{},
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};
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}
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static HistogramLevels _computeRgbLevels(ByteData data) {
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final redLevels = List.filled(bins, 0);
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final greenLevels = List.filled(bins, 0);
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final blueLevels = List.filled(bins, 0);
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final view = Uint8List.view(data.buffer);
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final viewSize = view.length;
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for (var i = 0; i < viewSize; i += 4) {
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final a = view[i + 3];
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if (a > 0) {
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redLevels[view[i + 0]]++;
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greenLevels[view[i + 1]]++;
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blueLevels[view[i + 2]]++;
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}
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}
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final max = [
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redLevels.max,
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greenLevels.max,
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blueLevels.max,
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].max;
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if (max == 0) return {};
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final f = 1.0 / max;
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return {
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HistogramChannel.red: redLevels.map((v) => v * f).toList(),
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HistogramChannel.green: greenLevels.map((v) => v * f).toList(),
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HistogramChannel.blue: blueLevels.map((v) => v * f).toList(),
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};
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}
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static HistogramLevels _computeLuminanceLevels(ByteData data) {
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final lumLevels = List.filled(bins, 0);
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const normMax = bins - 1;
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final view = Uint8List.view(data.buffer);
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final viewSize = view.length;
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for (var i = 0; i < viewSize; i += 4) {
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final a = view[i + 3];
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if (a > 0) {
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final r = view[i + 0];
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final g = view[i + 1];
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final b = view[i + 2];
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// `Color.computeLuminance()` is more accurate, but slower
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// and photo software typically use the simpler formula
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final l = ColorUtils.luma(r, g, b);
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lumLevels[(l * normMax).round()]++;
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}
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}
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final max = lumLevels.max;
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if (max == 0) return {};
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final f = 1.0 / max;
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return {
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HistogramChannel.luminance: lumLevels.map((v) => v * f).toList(),
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};
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}
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}
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