diff options
Diffstat (limited to 'Xamarin.Forms.Platform.WP8/ScrollViewRenderer.cs')
| -rw-r--r-- | Xamarin.Forms.Platform.WP8/ScrollViewRenderer.cs | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/Xamarin.Forms.Platform.WP8/ScrollViewRenderer.cs b/Xamarin.Forms.Platform.WP8/ScrollViewRenderer.cs new file mode 100644 index 00000000..6e19d8c4 --- /dev/null +++ b/Xamarin.Forms.Platform.WP8/ScrollViewRenderer.cs @@ -0,0 +1,194 @@ +using System; +using System.ComponentModel; +using System.Windows; +using System.Windows.Controls; + +namespace Xamarin.Forms.Platform.WinPhone +{ + public class ScrollViewRenderer : ViewRenderer<ScrollView, ScrollViewer> + { + Animatable _animatable; + + public ScrollViewRenderer() + { + AutoPackage = false; + } + + protected IScrollViewController Controller + { + get { return Element; } + } + + public override SizeRequest GetDesiredSize(double widthConstraint, double heightConstraint) + { + SizeRequest result = base.GetDesiredSize(widthConstraint, heightConstraint); + result.Minimum = new Size(40, 40); + return result; + } + + protected override System.Windows.Size ArrangeOverride(System.Windows.Size finalSize) + { + if (Element == null) + return finalSize; + + Element.IsInNativeLayout = true; + + if (Control != null) + { + Control.Measure(finalSize); + Control.Arrange(new Rect(0, 0, finalSize.Width, finalSize.Height)); + } + + Element.IsInNativeLayout = false; + + return finalSize; + } + + protected override System.Windows.Size MeasureOverride(System.Windows.Size availableSize) + { + if (Element == null) + return new System.Windows.Size(0, 0); + + double width = Math.Max(0, Element.Width); + double height = Math.Max(0, Element.Height); + return new System.Windows.Size(width, height); + } + + protected override void OnElementChanged(ElementChangedEventArgs<ScrollView> e) + { + base.OnElementChanged(e); + + if (e.OldElement != null) + ((IScrollViewController)e.OldElement).ScrollToRequested -= OnScrollToRequested; + + if (e.NewElement != null) + { + if (Control == null) + { + SetNativeControl(new ScrollViewer { ManipulationMode = ManipulationMode.Control }); + Control.LayoutUpdated += (sender, args) => { UpdateScrollPosition(); }; + } + ((IScrollViewController)e.NewElement).ScrollToRequested += OnScrollToRequested; + } + + SizeChanged += (sender, args) => + { + Control.Width = ActualWidth; + Control.Height = ActualHeight; + }; + + UpdateOrientation(); + + LoadContent(); + } + + protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e) + { + base.OnElementPropertyChanged(sender, e); + + if (e.PropertyName == "Content") + LoadContent(); + else if (e.PropertyName == Layout.PaddingProperty.PropertyName) + UpdateMargins(); + else if (e.PropertyName == ScrollView.OrientationProperty.PropertyName) + UpdateOrientation(); + } + + static double GetDistance(double start, double position, double v) + { + return start + (position - start) * v; + } + + void LoadContent() + { + var lastContent = Control.Content as FrameworkElement; + if (lastContent != null) + lastContent.Margin = new System.Windows.Thickness(); //undo any damage we may have done to this renderer + + View view = Element.Content; + + if (view != null) + Platform.SetRenderer(view, Platform.CreateRenderer(view)); + + Control.Content = view != null ? Platform.GetRenderer(view) : null; + + UpdateMargins(); + } + + void OnScrollToRequested(object sender, ScrollToRequestedEventArgs e) + { + if (_animatable == null && e.ShouldAnimate) + _animatable = new Animatable(); + + ScrollToPosition position = e.Position; + double x = e.ScrollX; + double y = e.ScrollY; + + if (e.Mode == ScrollToMode.Element) + { + Point itemPosition = Controller.GetScrollPositionForElement(e.Element as VisualElement, e.Position); + x = itemPosition.X; + y = itemPosition.Y; + } + + if (Control.VerticalOffset == y && Control.HorizontalOffset == x) + return; + + if (e.ShouldAnimate) + { + var animation = new Animation(v => { UpdateScrollOffset(GetDistance(Control.ViewportWidth, x, v), GetDistance(Control.ViewportHeight, y, v)); }); + + animation.Commit(_animatable, "ScrollTo", length: 500, easing: Easing.CubicInOut, finished: (v, d) => + { + UpdateScrollOffset(x, y); + Controller.SendScrollFinished(); + }); + } + else + { + UpdateScrollOffset(x, y); + Controller.SendScrollFinished(); + } + } + + void UpdateMargins() + { + var element = Control.Content as FrameworkElement; + if (element == null) + return; + + if (Element.Orientation == ScrollOrientation.Horizontal) + { + // need to add left/right margins + element.Margin = new System.Windows.Thickness(Element.Padding.Left, 0, Element.Padding.Right, 0); + } + else + { + // need to add top/bottom margins + element.Margin = new System.Windows.Thickness(0, Element.Padding.Top, 0, Element.Padding.Bottom); + } + } + + void UpdateOrientation() + { + if (Element.Orientation == ScrollOrientation.Horizontal) + Control.HorizontalScrollBarVisibility = ScrollBarVisibility.Auto; + else + Control.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled; + } + + void UpdateScrollOffset(double x, double y) + { + if (Element.Orientation == ScrollOrientation.Horizontal) + Control.ScrollToHorizontalOffset(x); + else + Control.ScrollToVerticalOffset(y); + } + + void UpdateScrollPosition() + { + if (Element != null) + Controller.SetScrolledPosition(Control.HorizontalOffset, Control.VerticalOffset); + } + } +}
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