C# Compositor.CreateScalarKeyFrameAnimation方法代码示例

        public static void Initialize(Compositor compositor)
        {
            // Create keyframes to select and unselect:
            // - Since both Saturation and Opacity use float [0.0 -> 1.0], we can actually use the
            //   same keyframe instances and just bind to different properties.

            NormalOnAnimation = compositor.CreateScalarKeyFrameAnimation();
            NormalOnAnimation.InsertKeyFrame(1.0f, 1.0f /* opaque */);
            NormalOnAnimation.Duration = NormalTime;

            SlowOffAnimation = compositor.CreateScalarKeyFrameAnimation();
            SlowOffAnimation.InsertKeyFrame(1.0f, 0.0f /* transparent */);
            SlowOffAnimation.Duration = SlowTime;
        }

 public static KeyFrameAnimation CreateOpacityAnimation(Compositor compositor, TimeSpan duration)
 {
     ScalarKeyFrameAnimation kf = compositor.CreateScalarKeyFrameAnimation();
     kf.InsertExpressionKeyFrame(1.0f, "this.FinalValue");
     kf.Duration = duration;
     kf.Target = "Opacity";
     return kf;
 }

        public CompositionImage()
        {
            this.DefaultStyleKey = typeof(CompositionImage);
            this.Background = new SolidColorBrush(Colors.Transparent);
            this._stretchMode = CompositionStretch.Uniform;
            this.Loading += CompImage_Loading;
            this.Unloaded += CompImage_Unloaded;
            this.SizeChanged += CompImage_SizeChanged;

            _compositor = ElementCompositionPreview.GetElementVisual(this).Compositor;

            // Intialize the statics as needed
            if (!_staticsInitialized)
            {
                _defaultPlaceholderBrush = _compositor.CreateColorBrush(Colors.DarkGray);

                TimeSpan duration = TimeSpan.FromMilliseconds(1000);
                _fadeOutAnimation = _compositor.CreateScalarKeyFrameAnimation();
                _fadeOutAnimation.InsertKeyFrame(0, 1);
                _fadeOutAnimation.InsertKeyFrame(1, 0);
                _fadeOutAnimation.Duration = duration;

                _scaleAnimation = _compositor.CreateVector2KeyFrameAnimation();
                _scaleAnimation.InsertKeyFrame(0, new Vector2(1.25f, 1.25f));
                _scaleAnimation.InsertKeyFrame(1, new Vector2(1, 1));
                _scaleAnimation.Duration = duration;

                _staticsInitialized = true;
            }

            // Initialize the surface loader if needed
            if (!SurfaceLoader.IsInitialized)
            {
                SurfaceLoader.Initialize(ElementCompositionPreview.GetElementVisual(this).Compositor);
            }

            _placeholderDelay = TimeSpan.FromMilliseconds(50);
            _surfaceBrush = _compositor.CreateSurfaceBrush(null);
        }

        public MainPage()
        {
            this.InitializeComponent();
            ContactsCVS.Source = _list;

            this.Loaded += (s, e) =>
            {
                _scrollViewer = ListView.GetScrollViewer();
                _scrollViewer.DirectManipulationStarted += OnDirectManipulationStarted;
                _scrollViewer.DirectManipulationCompleted += OnDirectManipulationCompleted;

                // Retrieve the ScrollViewer manipulation and the Compositor.
                _scrollerViewerManipulation = ElementCompositionPreview.GetScrollViewerManipulationPropertySet(_scrollViewer);
                _compositor = _scrollerViewerManipulation.Compositor;

                // At the moment there are three things happening when pulling down the list -
                // 1. The Refresh Icon fades in.
                // 2. The Refresh Icon rotates (400°).
                // 3. The Refresh Icon gets pulled down a bit (REFRESH_ICON_MAX_OFFSET_Y)
                // QUESTION 5
                // Can we also have Geometric Path animation so we can also draw the Refresh Icon along the way?
                //

                // Create a rotation expression animation based on the overpan distance of the ScrollViewer.
                _rotationAnimation = _compositor.CreateExpressionAnimation("min(max(0, ScrollManipulation.Translation.Y) * Multiplier, MaxDegree)");
                _rotationAnimation.SetScalarParameter("Multiplier", 10.0f);
                _rotationAnimation.SetScalarParameter("MaxDegree", 400.0f);
                _rotationAnimation.SetReferenceParameter("ScrollManipulation", _scrollerViewerManipulation);

                // Create an opacity expression animation based on the overpan distance of the ScrollViewer.
                _opacityAnimation = _compositor.CreateExpressionAnimation("min(max(0, ScrollManipulation.Translation.Y) / Divider, 1)");
                _opacityAnimation.SetScalarParameter("Divider", 30.0f);
                _opacityAnimation.SetReferenceParameter("ScrollManipulation", _scrollerViewerManipulation);

                // Create an offset expression animation based on the overpan distance of the ScrollViewer.
                _offsetAnimation = _compositor.CreateExpressionAnimation("(min(max(0, ScrollManipulation.Translation.Y) / Divider, 1)) * MaxOffsetY");
                _offsetAnimation.SetScalarParameter("Divider", 30.0f);
                _offsetAnimation.SetScalarParameter("MaxOffsetY", REFRESH_ICON_MAX_OFFSET_Y);
                _offsetAnimation.SetReferenceParameter("ScrollManipulation", _scrollerViewerManipulation);

                // Create a keyframe animation to reset properties like Offset.Y, Opacity, etc.
                _resetAnimation = _compositor.CreateScalarKeyFrameAnimation();
                _resetAnimation.InsertKeyFrame(1.0f, 0.0f);

                // Create a loading keyframe animation (in this case, a rotation animation). 
                _loadingAnimation = _compositor.CreateScalarKeyFrameAnimation();
                _loadingAnimation.InsertKeyFrame(1.0f, 360);
                _loadingAnimation.Duration = TimeSpan.FromMilliseconds(1200);
                _loadingAnimation.IterationBehavior = AnimationIterationBehavior.Forever;

                // Get the RefreshIcon's Visual.
                _refreshIconVisual = ElementCompositionPreview.GetElementVisual(RefreshIcon);
                // Set the center point for the rotation animation.
                _refreshIconVisual.CenterPoint = new Vector3(Convert.ToSingle(RefreshIcon.ActualWidth / 2), Convert.ToSingle(RefreshIcon.ActualHeight / 2), 0);

                // Get the ListView's inner Border's Visual.
                var border = (Border)VisualTreeHelper.GetChild(ListView, 0);
                _borderVisual = ElementCompositionPreview.GetElementVisual(border);

                PrepareExpressionAnimationsOnScroll();
            };

            this.Unloaded += (s, e) =>
            {
                _scrollViewer.DirectManipulationStarted -= OnDirectManipulationStarted;
                _scrollViewer.DirectManipulationCompleted -= OnDirectManipulationCompleted;
            };
        }

        /// <summary>
        /// Initializes the Composition elements
        /// </summary>
        private void InitComposition()
        {
            // Compositor
            _compositor = ElementCompositionPreview.GetElementVisual(this).Compositor;
            // CompositionGenerator
            _generator = CompositionGeneratorFactory.GetCompositionGenerator(_compositor);
            
            // Fade Out Animation
            _fadeOutAnimation = _compositor.CreateScalarKeyFrameAnimation();
            _fadeOutAnimation.InsertKeyFrame(1f, 0);
            _fadeOutAnimation.Duration = TransitionDuration;
            // Fade In Animation
            _fadeInAnimation = _compositor.CreateScalarKeyFrameAnimation();
            _fadeInAnimation.InsertKeyFrame(1f, 1);
            _fadeInAnimation.Duration = TransitionDuration;
            // Color Animation
            _colorAnimation = _compositor.CreateColorKeyFrameAnimation();
            _colorAnimation.Duration = TransitionDuration;
            // Offset Animation
            _offsetAnimation = _compositor.CreateVector3KeyFrameAnimation();
            _offsetAnimation.Target = "Offset";
            _offsetAnimation.Duration = TransitionDuration;
            _offsetAnimation.InsertKeyFrame(1f, Vector3.Zero);
            // Alignment animations
            _alignXAnimation = _compositor.CreateScalarKeyFrameAnimation();
            _alignXAnimation.Duration = AlignmentTransitionDuration;
            _alignYAnimation = _compositor.CreateScalarKeyFrameAnimation();
            _alignYAnimation.Duration = AlignmentTransitionDuration;

            // ZoomIn Animation Group
            _scaleAnimation = _compositor.CreateVector3KeyFrameAnimation();
            _scaleAnimation.Target = "Scale";
            _scaleAnimation.InsertKeyFrame(1f, Vector3.One);
            _scaleAnimation.Duration = TransitionDuration;
            _zoomInAnimationGroup = _compositor.CreateAnimationGroup();
            _zoomInAnimationGroup.Add(_scaleAnimation);
            _zoomInAnimationGroup.Add(_offsetAnimation);

            // Visuals
            _rootContainer = _compositor.CreateContainerVisual();
            _frameLayer = _compositor.CreateLayerVisual();
            _frameBackgroundVisual = _compositor.CreateSpriteVisual();
            _frameContentVisual = _compositor.CreateSpriteVisual();
            _placeholderContentVisual = _compositor.CreateSpriteVisual();
            _placeholderBackgroundVisual = _compositor.CreateSpriteVisual();
            _nextVisualContent = _compositor.CreateSpriteVisual();

            _frameLayer.Children.InsertAtTop(_frameBackgroundVisual);
            _frameLayer.Children.InsertAtTop(_frameContentVisual);
            _frameLayer.Children.InsertAtTop(_placeholderBackgroundVisual);
            _frameLayer.Children.InsertAtTop(_placeholderContentVisual);
            _frameLayer.Children.InsertAtTop(_nextVisualContent);

            // Placeholder content
            _placeholderContentMask = _generator.CreateGeometrySurface(PlaceholderSize, GetPlaceHolderGeometry(),
                PlaceholderColor, PlaceholderBackground);
            _placeholderContentBrush = _compositor.CreateSurfaceBrush(_placeholderContentMask.Surface);
            _placeholderContentVisual.Brush = _placeholderContentBrush;
            // Placeholder background
            _placeholderBackgroundVisual.Brush = _compositor.CreateColorBrush(PlaceholderBackground);

            // By default placeholder visual will not be visible
            HidePlaceholder();

            // Shadow visual
            _shadowVisual = _compositor.CreateSpriteVisual();

            _rootContainer.Children.InsertAtBottom(_shadowVisual);
            _rootContainer.Children.InsertAtTop(_frameLayer);

            _frameBackgroundVisual.Brush = _compositor.CreateColorBrush(FrameBackground);

            // Create the effect to create the opacity mask
            var layerEffect = new CompositeEffect
            {
                // CanvasComposite.DestinationIn - Intersection of source and mask. 
                // Equation: O = MA * S
                // where O - Output pixel, MA - Mask Alpha, S - Source pixel.
                Mode = CanvasComposite.DestinationIn,
                Sources =
                        {
                            new CompositionEffectSourceParameter("source"),
                            new CompositionEffectSourceParameter("mask")
                        }
            };

            var layerEffectFactory = _compositor.CreateEffectFactory(layerEffect);
            _layerEffectBrush = layerEffectFactory.CreateBrush();

            // The mask for the imageFrame
            _frameLayerMask = _generator.CreateMaskSurface(new Size(0, 0), null);
            _layerEffectBrush.SetSourceParameter("mask", _compositor.CreateSurfaceBrush(_frameLayerMask.Surface));
            // Apply the mask effect to the frameLayer
            _frameLayer.Effect = _layerEffectBrush;

            ElementCompositionPreview.SetElementChildVisual(this, _rootContainer);
        }