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

using System;
using System.Collections.Generic;
using System.Diagnostics;
using Unity.UIWidgets.async2;
using Unity.UIWidgets.foundation;
using Unity.UIWidgets.painting;
using Unity.UIWidgets.scheduler2;
using Unity.UIWidgets.ui;
using UnityEngine;
using Color = Unity.UIWidgets.ui.Color;
using Object = System.Object;
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(
                bundle: DefaultAssetBundle.of(context),
                devicePixelRatio: MediaQuery.of(context, nullOk: true)?.devicePixelRatio ?? 1.0f,
                locale: Localizations.localeOf(context, nullOk: true),
                size: size,
                platform: Application.platform
            );
        }

        public static Future precacheImage(
            ImageProvider provider,
            BuildContext context,
            Size size = null,
            ImageErrorListener onError = null
        ) {
            ImageConfiguration config = createLocalImageConfiguration(context, size: size);
            Completer completer = Completer.create();
            ImageStream stream = provider.resolve(config);
            ImageStreamListener listener = null;
            listener = new ImageStreamListener(
                (ImageInfo image, bool sync)=> {
                if (!completer.isCompleted) {
                    completer.complete();
                }
                
                SchedulerBinding.instance.addPostFrameCallback((TimeSpan timeStamp)=> {
                    stream.removeListener(listener);
                });
            },
            onError: (Exception error) =>{
                if (!completer.isCompleted) {
                    completer.complete();
                }
                stream.removeListener(listener);
                UIWidgetsError.reportError(new UIWidgetsErrorDetails(
                    context: new ErrorDescription("image failed to precache"),
                    library: "image resource service",
                    silent: true));
                }
            );
            stream.addListener(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 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, cacheHeight,
                new NetworkImage(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, cacheHeight, new FileImage(file, scale: scale));
            return new Image(
                key: key,
                image: fileImage,
                frameBuilder: frameBuilder,
                loadingBuilder: 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(name, bundle: bundle, scale: _scale)
                : new AssetImage(name, bundle: bundle);
            var _Image = ResizeImage.resizeIfNeeded(cacheWidth, cacheHeight, _image);
            
            return new Image(
                key: key,
                image: _Image,
                frameBuilder: frameBuilder,
                loadingBuilder: 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, scale);
            return new Image(
                key: key,
                image: ResizeImage.resizeIfNeeded(cacheWidth, cacheHeight, new MemoryImage(bytes, scale: scale)),
                frameBuilder: frameBuilder,
                loadingBuilder: 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 readonly ImageProvider image;
        public readonly ImageFrameBuilder frameBuilder;
        public readonly ImageLoadingBuilder loadingBuilder;
        public readonly ImageErrorWidgetBuilder errorBuilder;
        public readonly float? width;
        public readonly float? height;
        public readonly Color color;
        public readonly FilterQuality filterQuality;
        public readonly BlendMode colorBlendMode;
        public readonly BoxFit? fit;
        public readonly AlignmentGeometry alignment;
        public readonly ImageRepeat repeat;
        public readonly Rect centerSlice;
        public readonly bool gaplessPlayback;
        public readonly bool matchTextDirection;

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

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

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

    public class _ImageState : State<Image>, WidgetsBindingObserver {
        ImageStream _imageStream;

        ImageInfo _imageInfo;

        ImageChunkEvent _loadingProgress;
        bool _isListeningToStream = false;
        bool _invertColors;
        int _frameNumber;
        bool _wasSynchronouslyLoaded;
        DisposableBuildContext<State<Image>> _scrollAwareContext;
        Object _lastException;
        StackTrace _lastStack;

        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)) {
                _listenToStream();
            }
            else {
                _stopListeningToStream();
            }

            base.didChangeDependencies();
        }

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

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


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


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

        void _resolveImage() {
            ScrollAwareImageProvider<object> provider = new ScrollAwareImageProvider<object>(
                context: _scrollAwareContext,
                imageProvider: (ImageProvider<object>)widget.image
            );
            ImageStream newStream =
                provider.resolve(ImageUtils.createLocalImageConfiguration(
                    context,
                    size: widget.width != null && widget.height != null
                        ? new Size(widget.width.Value, widget.height.Value)
                        : null
                ));
            D.assert(newStream != null);
            _updateSourceStream(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 = (Exception error) => {
                    setState(() => {
                        _lastException = error;
                        // _lastStack = stackTrace;
                    });
                };
            }

            return new ImageStreamListener(
                _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, _lastException, _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, image, _frameNumber, _wasSynchronouslyLoaded);

            if (widget.loadingBuilder != null)
                image = widget.loadingBuilder(context, image, _loadingProgress);

            return image;
        }

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


        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>();
        }
    }
}