add : add fadeInImage

Runtime/widgets/fade_in_image.cs

+using System;
+using Unity.UIWidgets.animation;
+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.painting;
+using Unity.UIWidgets.ui;
+using UnityEngine;
+using Color = Unity.UIWidgets.ui.Color;
+
+namespace Unity.UIWidgets.widgets {
+    public class FadeInImage : StatefulWidget {
+        public FadeInImage(
+            ImageProvider placeholder,
+            ImageProvider image,
+            TimeSpan? fadeOutDuration = null,
+            Curve fadeOutCurve = null,
+            TimeSpan? fadeInDuration = null,
+            Curve fadeInCurve = null,
+            float? width = null,
+            float? height = null,
+            BoxFit? fit = null,
+            Alignment alignment = null,
+            ImageRepeat repeat = ImageRepeat.noRepeat,
+            bool matchTextDirection = false,
+            Key key = null
+        ) : base(key) {
+            D.assert(placeholder != null);
+            D.assert(image != null);
+            D.assert(fadeOutDuration != null);
+            D.assert(fadeOutCurve != null);
+            D.assert(fadeInDuration != null);
+            D.assert(fadeInCurve != null);
+            D.assert(alignment != null);
+            this.placeholder = placeholder;
+            this.image = image;
+            this.width = width;
+            this.height = height;
+            this.fit = fit;
+            this.fadeOutDuration = fadeOutDuration ?? TimeSpan.FromMilliseconds(300);
+            this.fadeOutCurve = fadeOutCurve ?? Curves.easeOut;
+            this.fadeInDuration = fadeInDuration ?? TimeSpan.FromMilliseconds(700);
+            this.fadeInCurve = fadeInCurve ?? Curves.easeIn;
+            this.alignment = alignment ?? Alignment.center;
+            this.repeat = repeat;
+            this.matchTextDirection = matchTextDirection;
+        }
+
+        public static FadeInImage memoryNetwork(
+            byte[] placeholder,
+            string image,
+            float placeholderScale = 1.0f,
+            float imageScale = 1.0f,
+            TimeSpan? fadeOutDuration = null,
+            Curve fadeOutCurve = null,
+            TimeSpan? fadeInDuration = null,
+            Curve fadeInCurve = null,
+            float? width = null,
+            float? height = null,
+            BoxFit? fit = null,
+            Alignment alignment = null,
+            ImageRepeat repeat = ImageRepeat.noRepeat,
+            bool matchTextDirection = false,
+            Key key = null
+        ) {
+            D.assert(placeholder != null);
+            D.assert(image != null);
+            D.assert(fadeOutDuration != null);
+            D.assert(fadeOutCurve != null);
+            D.assert(fadeInDuration != null);
+            D.assert(fadeInCurve != null);
+            D.assert(alignment != null);
+            var memoryImage = new MemoryImage(placeholder, placeholderScale);
+            var networkImage = new NetworkImage(image, imageScale);
+            return new FadeInImage(
+                memoryImage,
+                networkImage,
+                fadeOutDuration,
+                fadeOutCurve,
+                fadeInDuration,
+                fadeInCurve,
+                width, height,
+                fit,
+                alignment,
+                repeat,
+                matchTextDirection
+            );
+        }
+
+        public static FadeInImage assetNetwork(
+            string placeholder,
+            string image,
+            AssetBundle bundle = null,
+            float placeholderScale = 0.0f,
+            float imageScale = 1.0f,
+            TimeSpan? fadeOutDuration = null,
+            Curve fadeOutCurve = null,
+            TimeSpan? fadeInDuration = null,
+            Curve fadeInCurve = null,
+            float? width = null,
+            float? height = null,
+            BoxFit? fit = null,
+            Alignment alignment = null,
+            ImageRepeat repeat = ImageRepeat.noRepeat,
+            bool matchTextDirection = false,
+            Key key = null
+        ) {
+            D.assert(placeholder != null);
+            D.assert(image != null);
+            D.assert(fadeOutDuration != null);
+            D.assert(fadeOutCurve != null);
+            D.assert(fadeInDuration != null);
+            D.assert(fadeInCurve != null);
+            D.assert(alignment != null);
+            var imageProvider = placeholderScale != null
+                ? new ExactAssetImage(placeholder, bundle: bundle, scale: placeholderScale)
+                : (ImageProvider) new AssetImage(placeholder, bundle: bundle);
+
+            var networkImage = new NetworkImage(image, imageScale);
+            return new FadeInImage(
+                imageProvider,
+                networkImage,
+                fadeOutDuration,
+                fadeOutCurve,
+                fadeInDuration,
+                fadeInCurve,
+                width, height,
+                fit,
+                alignment,
+                repeat,
+                matchTextDirection
+            );
+        }
+
+        public readonly ImageProvider placeholder;
+        public readonly ImageProvider image;
+        public readonly TimeSpan fadeOutDuration;
+        public readonly Curve fadeOutCurve;
+        public readonly TimeSpan fadeInDuration;
+        public readonly Curve fadeInCurve;
+        public readonly float? width;
+        public readonly float? height;
+        public readonly BoxFit? fit;
+        public readonly Alignment alignment;
+        public readonly ImageRepeat repeat;
+        public readonly bool matchTextDirection;
+
+
+        public override State createState() {
+            return new _FadeInImageState();
+        }
+    }
+
+    enum FadeInImagePhase {
+        start,
+        waiting,
+        fadeOut,
+        fadeIn,
+        completed
+    }
+
+    delegate void _ImageProviderResolverListener();
+
+    class _ImageProviderResolver {
+        public _ImageProviderResolver(
+            _FadeInImageState state,
+            _ImageProviderResolverListener listener
+        ) {
+            this.state = state;
+            this.listener = listener;
+        }
+
+        readonly _FadeInImageState state;
+        readonly _ImageProviderResolverListener listener;
+
+        FadeInImage widget {
+            get { return this.state.widget; }
+        }
+
+        public ImageStream _imageStream;
+        public ImageInfo _imageInfo;
+
+        public void resolve(ImageProvider provider) {
+            ImageStream oldImageStream = this._imageStream;
+            Size size = null;
+            if (this.widget.width != null && this.widget.height != null) {
+                size = new Size(Convert.ToSingle(this.widget.width), Convert.ToSingle(this.widget.height));
+            }
+
+            this._imageStream = provider.resolve(ImageUtils.createLocalImageConfiguration(this.state.context, size));
+            D.assert(this._imageStream != null);
+
+            if (this._imageStream.key != oldImageStream?.key) {
+                oldImageStream?.removeListener(this._handleImageChanged);
+                this._imageStream.addListener(this._handleImageChanged);
+            }
+        }
+
+        void _handleImageChanged(ImageInfo imageInfo, bool synchronousCall) {
+            this._imageInfo = imageInfo;
+            this.listener();
+        }
+
+        public void stopListening() {
+            this._imageStream?.removeListener(this._handleImageChanged);
+        }
+    }
+
+
+    class _FadeInImageState : TickerProviderStateMixin<FadeInImage> {
+        _ImageProviderResolver _imageResolver;
+        _ImageProviderResolver _placeholderResolver;
+
+        AnimationController _controller;
+        Animation<float> _animation;
+
+        FadeInImagePhase _phase = FadeInImagePhase.start;
+
+        public override void initState() {
+            this._imageResolver = new _ImageProviderResolver(state: this, this._updatePhase);
+            this._placeholderResolver = new _ImageProviderResolver(state: this, listener: () => {
+                this.setState(() => {
+                    // Trigger rebuild to display the placeholder image
+                });
+            });
+            this._controller = new AnimationController(
+                value: 1.0f,
+                vsync: this
+            );
+            this._controller.addListener(() => {
+                this.setState(() => {
+                    // Trigger rebuild to update opacity value.
+                });
+            });
+            this._controller.addStatusListener(status => { this._updatePhase(); });
+            base.initState();
+        }
+
+        public override void didChangeDependencies() {
+            this._resolveImage();
+            base.didChangeDependencies();
+        }
+
+        public override void didUpdateWidget(StatefulWidget oldWidget) {
+            base.didUpdateWidget(oldWidget);
+            FadeInImage fadeInImage = oldWidget as FadeInImage;
+            if (this.widget.image != fadeInImage.image || this.widget.placeholder != fadeInImage.placeholder) {
+                this._resolveImage();
+            }
+        }
+
+        void _resolveImage() {
+            this._imageResolver.resolve(this.widget.image);
+
+            if (this._isShowingPlaceholder) {
+                this._placeholderResolver.resolve(this.widget.placeholder);
+            }
+
+            if (this._phase == FadeInImagePhase.start) {
+                this._updatePhase();
+            }
+        }
+
+        void _updatePhase() {
+            this.setState(() => {
+                switch (this._phase) {
+                    case FadeInImagePhase.start:
+                        if (this._imageResolver._imageInfo != null) {
+                            this._phase = FadeInImagePhase.completed;
+                        }
+                        else {
+                            this._phase = FadeInImagePhase.waiting;
+                        }
+
+                        break;
+                    case FadeInImagePhase.waiting:
+                        if (this._imageResolver._imageInfo != null) {
+                            this._controller.duration = this.widget.fadeOutDuration;
+                            this._animation = new CurvedAnimation(
+                                parent: this._controller,
+                                curve: this.widget.fadeOutCurve
+                            );
+                            this._phase = FadeInImagePhase.fadeOut;
+                            this._controller.reverse(1.0f);
+                        }
+
+                        break;
+                    case FadeInImagePhase.fadeOut:
+                        if (this._controller.status == AnimationStatus.dismissed) {
+                            // Done fading out placeholder. Begin target image fade-in.
+                            this._controller.duration = this.widget.fadeInDuration;
+                            this._animation = new CurvedAnimation(
+                                parent: this._controller,
+                                curve: this.widget.fadeInCurve
+                            );
+                            this._phase = FadeInImagePhase.fadeIn;
+                            this._placeholderResolver.stopListening();
+                            this._controller.forward(0.0f);
+                        }
+
+                        break;
+                    case FadeInImagePhase.fadeIn:
+                        if (this._controller.status == AnimationStatus.completed) {
+                            // Done finding in new image.
+                            this._phase = FadeInImagePhase.completed;
+                        }
+
+                        break;
+                    case FadeInImagePhase.completed:
+                        // Nothing to do.
+                        break;
+                }
+            });
+        }
+
+        public override void dispose() {
+            this._imageResolver.stopListening();
+            this._placeholderResolver.stopListening();
+            this._controller.dispose();
+            base.dispose();
+        }
+
+        bool _isShowingPlaceholder {
+            get {
+                switch (this._phase) {
+                    case FadeInImagePhase.start:
+                    case FadeInImagePhase.waiting:
+                    case FadeInImagePhase.fadeOut:
+                        return true;
+                    case FadeInImagePhase.fadeIn:
+                    case FadeInImagePhase.completed:
+                        return false;
+                }
+
+                return true;
+            }
+        }
+
+        ImageInfo _imageInfo {
+            get {
+                return this._isShowingPlaceholder
+                    ? this._placeholderResolver._imageInfo
+                    : this._imageResolver._imageInfo;
+            }
+        }
+
+        public override Widget build(BuildContext context) {
+            D.assert(this._phase != FadeInImagePhase.start);
+            ImageInfo imageInfo = this._imageInfo;
+            return new RawImage(
+                image: imageInfo?.image,
+                width: this.widget.width,
+                height: this.widget.height,
+                scale: imageInfo?.scale ?? 1.0f,
+                color: Color.fromRGBO(255, 255, 255, this._animation?.value ?? 1.0f),
+                colorBlendMode: BlendMode.modulate,
+                fit: this.widget.fit,
+                alignment: this.widget.alignment,
+                repeat: this.widget.repeat
+            );
+        }
+
+        public override void debugFillProperties(DiagnosticPropertiesBuilder properties) {
+            base.debugFillProperties(properties);
+            properties.add(new EnumProperty<FadeInImagePhase>("phase", this._phase));
+            properties.add(new DiagnosticsProperty<ImageInfo>("pixels", this._imageInfo));
+            properties.add(new DiagnosticsProperty<ImageStream>("image stream", this._imageResolver._imageStream));
+            properties.add(new DiagnosticsProperty<ImageStream>("placeholder stream",
+                this._placeholderResolver._imageStream));
+        }
+    }
+}

Runtime/widgets/fade_in_image.cs.meta

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