com.unity.uiwidgets/com.unity.uiwidgets/Runtime/widgets/image.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using Unity.UIWidgets.async;
using Unity.UIWidgets.foundation;
using Unity.UIWidgets.painting;
using Unity.UIWidgets.scheduler;
using Unity.UIWidgets.ui;
using UnityEngine;
using Color = Unity.UIWidgets.ui.Color;
using Rect = Unity.UIWidgets.ui.Rect;

namespace Unity.UIWidgets.widgets {
    public class ImageUtils {
        public static ImageConfiguration createLocalImageConfiguration(BuildContext context, Size size = null) {
            return new ImageConfiguration(
                DefaultAssetBundle.of(context: context),
                MediaQuery.of(context: context, true)?.devicePixelRatio ?? 1.0f,
                Localizations.localeOf(context: context, true),
                size: size,
                platform: Application.platform
            );
        }

        public static Future precacheImage(
            ImageProvider provider,
            BuildContext context,
            Size size = null,
            ImageErrorListener onError = null
        ) {
            var config = createLocalImageConfiguration(context: context, size: size);
            var completer = Completer.create();
            var stream = provider.resolve(configuration: config);
            ImageStreamListener listener = null;
            listener = new ImageStreamListener(
                (image, sync) => {
                    if (!completer.isCompleted) {
                        completer.complete();
                    }

                    SchedulerBinding.instance.addPostFrameCallback(timeStamp => {
                        stream.removeListener(listener: listener);
                    });
                },
                onError: error => {
                    if (!completer.isCompleted) {
                        completer.complete();
                    }

                    stream.removeListener(listener: listener);
                    UIWidgetsError.reportError(new UIWidgetsErrorDetails(
                        context: new ErrorDescription("image failed to precache"),
                        library: "image resource service",
                        silent: true));
                }
            );
            stream.addListener(listener: listener);
            return completer.future;
        }
    }

    public delegate Widget ImageFrameBuilder(
        BuildContext context,
        Widget child,
        int frame,
        bool wasSynchronouslyLoaded
    );

    public delegate Widget ImageLoadingBuilder(
        BuildContext context,
        Widget child,
        ImageChunkEvent loadingProgress
    );

    public delegate Widget ImageErrorWidgetBuilder(
        BuildContext context,
        object error,
        StackTrace stackTrace
    );

    public class Image : StatefulWidget {
        public readonly AlignmentGeometry alignment;
        public readonly Rect centerSlice;
        public readonly Color color;
        public readonly BlendMode colorBlendMode;
        public readonly ImageErrorWidgetBuilder errorBuilder;
        public readonly FilterQuality filterQuality;
        public readonly BoxFit? fit;
        public readonly ImageFrameBuilder frameBuilder;
        public readonly bool gaplessPlayback;
        public readonly float? height;

        public readonly ImageProvider image;
        public readonly ImageLoadingBuilder loadingBuilder;
        public readonly bool matchTextDirection;
        public readonly ImageRepeat repeat;
        public readonly float? width;

        public Image(
            Key key = null,
            ImageProvider image = null,
            ImageFrameBuilder frameBuilder = null,
            ImageLoadingBuilder loadingBuilder = null,
            ImageErrorWidgetBuilder errorBuilder = null,
            float? width = null,
            float? height = null,
            Color color = null,
            BlendMode colorBlendMode = BlendMode.srcIn,
            BoxFit? fit = null,
            AlignmentGeometry alignment = null,
            ImageRepeat repeat = ImageRepeat.noRepeat,
            Rect centerSlice = null,
            bool matchTextDirection = false,
            bool gaplessPlayback = false,
            FilterQuality filterQuality = FilterQuality.low
        ) : base(key: key) {
            D.assert(image != null);
            this.image = image;
            this.frameBuilder = frameBuilder;
            this.loadingBuilder = loadingBuilder;
            this.errorBuilder = errorBuilder;
            this.width = width;
            this.height = height;
            this.color = color;
            this.colorBlendMode = colorBlendMode;
            this.fit = fit;
            this.alignment = alignment ?? Alignment.center;
            this.repeat = repeat;
            this.centerSlice = centerSlice;
            this.gaplessPlayback = gaplessPlayback;
            this.filterQuality = filterQuality;
            this.matchTextDirection = matchTextDirection;
        }

        public static Image network(
            string src,
            Key key = null,
            float scale = 1.0f,
            ImageFrameBuilder frameBuilder = null,
            ImageLoadingBuilder loadingBuilder = null,
            ImageErrorWidgetBuilder errorBuilder = null,
            float? width = null,
            float? height = null,
            Color color = null,
            BlendMode colorBlendMode = BlendMode.srcIn,
            BoxFit? fit = null,
            AlignmentGeometry alignment = null,
            ImageRepeat repeat = ImageRepeat.noRepeat,
            Rect centerSlice = null,
            bool gaplessPlayback = false,
            bool matchTextDirection = false,
            FilterQuality filterQuality = FilterQuality.low,
            IDictionary<string, string> headers = null,
            int? cacheWidth = null,
            int? cacheHeight = null
        ) {
            var image = ResizeImage.resizeIfNeeded(cacheWidth: cacheWidth, cacheHeight: cacheHeight,
                new NetworkImage(url: src, scale: scale, headers: headers));
            return new Image(
                key: key,
                image: image,
                frameBuilder: frameBuilder,
                loadingBuilder: loadingBuilder,
                errorBuilder: errorBuilder,
                width: width,
                height: height,
                color: color,
                colorBlendMode: colorBlendMode,
                fit: fit,
                alignment: alignment,
                repeat: repeat,
                centerSlice: centerSlice,
                matchTextDirection: matchTextDirection,
                gaplessPlayback: gaplessPlayback,
                filterQuality: filterQuality
            );
        }

        public static Image file(
            string file,
            Key key = null,
            float scale = 1.0f,
            ImageFrameBuilder frameBuilder = null,
            ImageErrorWidgetBuilder errorBuilder = null,
            float? width = null,
            float? height = null,
            Color color = null,
            BlendMode colorBlendMode = BlendMode.srcIn,
            BoxFit? fit = null,
            AlignmentGeometry alignment = null,
            ImageRepeat repeat = ImageRepeat.noRepeat,
            bool matchTextDirection = false,
            Rect centerSlice = null,
            bool gaplessPlayback = false,
            FilterQuality filterQuality = FilterQuality.low,
            int? cacheWidth = null,
            int? cacheHeight = null
        ) {
            var fileImage = ResizeImage.resizeIfNeeded(cacheWidth: cacheWidth, cacheHeight: cacheHeight,
                new FileImage(file: file, scale: scale));
            return new Image(
                key: key,
                image: fileImage,
                frameBuilder: frameBuilder,
                null,
                errorBuilder: errorBuilder,
                width: width,
                height: height,
                color: color,
                colorBlendMode: colorBlendMode,
                fit: fit,
                alignment: alignment,
                repeat: repeat,
                centerSlice: centerSlice,
                matchTextDirection: matchTextDirection,
                gaplessPlayback: gaplessPlayback,
                filterQuality: filterQuality
            );
        }

        public static Image asset(
            string name,
            Key key = null,
            AssetBundle bundle = null,
            ImageFrameBuilder frameBuilder = null,
            ImageErrorWidgetBuilder errorBuilder = null,
            float? scale = null,
            float? width = null,
            float? height = null,
            Color color = null,
            BlendMode colorBlendMode = BlendMode.srcIn,
            BoxFit? fit = null,
            Alignment alignment = null,
            ImageRepeat repeat = ImageRepeat.noRepeat,
            Rect centerSlice = null,
            bool matchTextDirection = false,
            bool gaplessPlayback = false,
            string package = null,
            FilterQuality filterQuality = FilterQuality.low,
            int? cacheWidth = default,
            int? cacheHeight = null
        ) {
            var _scale = scale ?? 1.0f;
            var _image = scale != null
                ? (AssetBundleImageProvider) new ExactAssetImage(assetName: name, bundle: bundle, scale: _scale)
                : new AssetImage(assetName: name, bundle: bundle);
            var _Image = ResizeImage.resizeIfNeeded(cacheWidth: cacheWidth, cacheHeight: cacheHeight, provider: _image);

            return new Image(
                key: key,
                image: _Image,
                frameBuilder: frameBuilder,
                null,
                errorBuilder: errorBuilder,
                width: width,
                height: height,
                color: color,
                colorBlendMode: colorBlendMode,
                fit: fit,
                alignment: alignment,
                repeat: repeat,
                centerSlice: centerSlice,
                matchTextDirection: matchTextDirection,
                gaplessPlayback: gaplessPlayback,
                filterQuality: filterQuality
            );
        }

        public static Image memory(
            byte[] bytes,
            Key key = null,
            float scale = 1.0f,
            ImageFrameBuilder frameBuilder = null,
            ImageErrorWidgetBuilder errorBuilder = null,
            float? width = null,
            float? height = null,
            Color color = null,
            BlendMode colorBlendMode = BlendMode.srcIn,
            BoxFit? fit = null,
            Alignment alignment = null,
            ImageRepeat repeat = ImageRepeat.noRepeat,
            Rect centerSlice = null,
            bool matchTextDirection = false,
            bool gaplessPlayback = false,
            FilterQuality filterQuality = FilterQuality.low,
            int? cacheWidth = default,
            int? cacheHeight = null
        ) {
            // ResizeImage.resizeIfNeeded(cacheWidth, cacheHeight, MemoryImage(bytes, scale: scale));
            var memoryImage = new MemoryImage(bytes: bytes, scale: scale);
            return new Image(
                key: key,
                ResizeImage.resizeIfNeeded(cacheWidth: cacheWidth, cacheHeight: cacheHeight,
                    new MemoryImage(bytes: bytes, scale: scale)),
                frameBuilder: frameBuilder,
                null,
                errorBuilder: errorBuilder,
                width: width,
                height: height,
                color: color,
                colorBlendMode: colorBlendMode,
                fit: fit,
                alignment: alignment,
                repeat: repeat,
                centerSlice: centerSlice,
                matchTextDirection: matchTextDirection,
                gaplessPlayback: gaplessPlayback,
                filterQuality: filterQuality
            );
        }

        public override State createState() {
            return new _ImageState();
        }

        public override void debugFillProperties(DiagnosticPropertiesBuilder properties) {
            base.debugFillProperties(properties: properties);

            properties.add(new DiagnosticsProperty<ImageProvider>("image", value: image));
            properties.add(new DiagnosticsProperty<ImageFrameBuilder>("frameBuilder", value: frameBuilder));
            properties.add(new DiagnosticsProperty<ImageLoadingBuilder>("loadingBuilder", value: loadingBuilder));
            properties.add(new FloatProperty("width", value: width, defaultValue: foundation_.kNullDefaultValue));
            properties.add(new FloatProperty("height", value: height, defaultValue: foundation_.kNullDefaultValue));
            properties.add(new ColorProperty("color", value: color,
                defaultValue: foundation_.kNullDefaultValue));
            properties.add(new EnumProperty<BlendMode>("colorBlendMode", value: colorBlendMode,
                defaultValue: foundation_.kNullDefaultValue));
            properties.add(new EnumProperty<BoxFit?>("fit", value: fit, defaultValue: foundation_.kNullDefaultValue));
            properties.add(new DiagnosticsProperty<AlignmentGeometry>("alignment", value: alignment,
                defaultValue: foundation_.kNullDefaultValue));
            properties.add(new EnumProperty<ImageRepeat>("repeat", value: repeat, defaultValue: ImageRepeat.noRepeat));
            properties.add(new DiagnosticsProperty<Rect>("centerSlice", value: centerSlice,
                defaultValue: foundation_.kNullDefaultValue));
            properties.add(new EnumProperty<FilterQuality>("filterQuality", value: filterQuality,
                defaultValue: foundation_.kNullDefaultValue));
            properties.add(new FlagProperty("matchTextDirection", value: matchTextDirection, "match text direction"));
        }
    }

    public class _ImageState : State<Image>, WidgetsBindingObserver {
        int _frameNumber;

        ImageInfo _imageInfo;
        ImageStream _imageStream;
        bool _invertColors;
        bool _isListeningToStream;
        object _lastException;
        StackTrace _lastStack;

        ImageChunkEvent _loadingProgress;
        DisposableBuildContext<State<Image>> _scrollAwareContext;
        bool _wasSynchronouslyLoaded;


        public void didChangeAccessibilityFeatures() {
            setState(() => { _updateInvertColors(); });
        }


        public void didChangeMetrics() {
            setState();
        }

        public void didChangeTextScaleFactor() {
            setState();
        }

        public void didChangePlatformBrightness() {
            setState();
        }

        public void didChangeLocales(List<Locale> locale) {
            setState();
        }

        public Future<bool> didPopRoute() {
            return Future.value(false).to<bool>();
        }

        public Future<bool> didPushRoute(string route) {
            return Future.value(false).to<bool>();
        }

        public override void initState() {
            base.initState();
            WidgetsBinding.instance.addObserver(this);
            _scrollAwareContext = new DisposableBuildContext<State<Image>>(this);
        }

        public override void dispose() {
            D.assert(_imageStream != null);
            WidgetsBinding.instance.removeObserver(this);
            _stopListeningToStream();
            _scrollAwareContext.dispose();
            base.dispose();
        }

        public override void didChangeDependencies() {
            _updateInvertColors();
            _resolveImage();

            if (TickerMode.of(context: context)) {
                _listenToStream();
            }
            else {
                _stopListeningToStream();
            }

            base.didChangeDependencies();
        }

        public override void didUpdateWidget(StatefulWidget oldWidget) {
            base.didUpdateWidget(oldWidget: oldWidget);
            var image = (Image) oldWidget;
            if (_isListeningToStream &&
                widget.loadingBuilder == null != (image.loadingBuilder == null)) {
                _imageStream.removeListener(_getListener(loadingBuilder: image.loadingBuilder));
                _imageStream.addListener(_getListener());
            }

            if (widget.image != ((Image) oldWidget).image) {
                _resolveImage();
            }
        }

        public override void reassemble() {
            _resolveImage(); // in case the image cache was flushed
            base.reassemble();
        }


        void _updateInvertColors() {
            _invertColors = MediaQuery.of(context: context, true)?.invertColors
                            ?? false;
        }

        void _resolveImage() {
            //TODO: why refactoring this code? we need a PR to fix it!
            /*ScrollAwareImageProvider<object> provider = new ScrollAwareImageProvider<object>(
                context: _scrollAwareContext,
                imageProvider: widget.image);*/
            var newStream =
                widget.image.resolve(ImageUtils.createLocalImageConfiguration(
                    context: context,
                    widget.width != null && widget.height != null
                        ? new Size(width: widget.width.Value, height: widget.height.Value)
                        : null
                ));
            D.assert(newStream != null);
            _updateSourceStream(newStream: newStream);
        }

        void _onError(Exception error) {
            setState(() => {
                _lastException = error;
                // _lastStack = stackTrace;
            });
        }

        ImageStreamListener _getListener(ImageLoadingBuilder loadingBuilder = null) {
            loadingBuilder = loadingBuilder ?? widget.loadingBuilder;
            _lastException = null;
            _lastStack = null;
            ImageChunkListener onChunk = null;
            if (loadingBuilder == null) {
                onChunk = _handleImageChunk;
            }

            ImageErrorListener onError = null;
            if (widget.errorBuilder != null) {
                onError = error => {
                    setState(() => {
                        _lastException = error;
                        // _lastStack = stackTrace;
                    });
                };
            }

            return new ImageStreamListener(
                onImage: _handleImageFrame,
                onChunk: onChunk,
                onError: onError
            );
        }


        void _handleImageFrame(ImageInfo imageInfo, bool synchronousCall) {
            setState(() => {
                _imageInfo = imageInfo;
                _loadingProgress = null;
                _frameNumber = _frameNumber == null ? 0 : _frameNumber + 1;
                _wasSynchronouslyLoaded |= synchronousCall;
            });
        }

        void _handleImageChunk(ImageChunkEvent _event) {
            D.assert(widget.loadingBuilder != null);
            setState(() => { _loadingProgress = _event; });
        }

        void _handleImageChanged(ImageInfo imageInfo, bool synchronousCall) {
            setState(() => { _imageInfo = imageInfo; });
        }

        void _updateSourceStream(ImageStream newStream) {
            if (_imageStream?.key == newStream?.key) {
                return;
            }

            if (_isListeningToStream) {
                _imageStream.removeListener(_getListener());
            }

            if (!widget.gaplessPlayback) {
                setState(() => { _imageInfo = null; });
            }

            setState(() => {
                _loadingProgress = null;
                _frameNumber = 0;
                _wasSynchronouslyLoaded = false;
            });

            _imageStream = newStream;
            if (_isListeningToStream) {
                _imageStream.addListener(_getListener());
            }
        }

        void _listenToStream() {
            if (_isListeningToStream) {
                return;
            }

            _imageStream.addListener(_getListener());
            _isListeningToStream = true;
        }

        void _stopListeningToStream() {
            if (!_isListeningToStream) {
                return;
            }

            _imageStream.removeListener(_getListener());
            _isListeningToStream = false;
        }

        public override Widget build(BuildContext context) {
            if (_lastException != null) {
                D.assert(widget.errorBuilder != null);
                return widget.errorBuilder(context: context, error: _lastException, stackTrace: _lastStack);
            }

            Widget image = new RawImage(
                image: _imageInfo?.image,
                width: widget.width,
                height: widget.height,
                scale: _imageInfo?.scale ?? 1.0f,
                color: widget.color,
                colorBlendMode: widget.colorBlendMode,
                fit: widget.fit,
                alignment: widget.alignment,
                repeat: widget.repeat,
                centerSlice: widget.centerSlice,
                matchTextDirection: widget.matchTextDirection,
                invertColors: _invertColors,
                filterQuality: widget.filterQuality
            );
            if (widget.frameBuilder != null) {
                image = widget.frameBuilder(context: context, child: image, frame: _frameNumber,
                    wasSynchronouslyLoaded: _wasSynchronouslyLoaded);
            }

            if (widget.loadingBuilder != null) {
                image = widget.loadingBuilder(context: context, child: image, loadingProgress: _loadingProgress);
            }

            return image;
        }

        public override void debugFillProperties(DiagnosticPropertiesBuilder description) {
            base.debugFillProperties(properties: description);
            description.add(new DiagnosticsProperty<ImageStream>("stream", value: _imageStream));
            description.add(new DiagnosticsProperty<ImageInfo>("pixels", value: _imageInfo));
            description.add(new DiagnosticsProperty<ImageChunkEvent>("loadingProgress", value: _loadingProgress));
            description.add(new DiagnosticsProperty<int>("frameNumber", value: _frameNumber));
            description.add(new DiagnosticsProperty<bool>("wasSynchronouslyLoaded", value: _wasSynchronouslyLoaded));
        }
    }
}