diff options
Diffstat (limited to 'Xamarin.Forms.Platform.WinRT/ScrollViewRenderer.cs')
| -rw-r--r-- | Xamarin.Forms.Platform.WinRT/ScrollViewRenderer.cs | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/Xamarin.Forms.Platform.WinRT/ScrollViewRenderer.cs b/Xamarin.Forms.Platform.WinRT/ScrollViewRenderer.cs new file mode 100644 index 00000000..6938a76e --- /dev/null +++ b/Xamarin.Forms.Platform.WinRT/ScrollViewRenderer.cs @@ -0,0 +1,194 @@ +using System; +using System.ComponentModel; +using Windows.Foundation; +using Windows.UI.Xaml; +using Windows.UI.Xaml.Controls; + +#if WINDOWS_UWP + +namespace Xamarin.Forms.Platform.UWP +#else + +namespace Xamarin.Forms.Platform.WinRT +#endif +{ + public class ScrollViewRenderer : ViewRenderer<ScrollView, ScrollViewer> + { + VisualElement _currentView; + + 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 Windows.Foundation.Size ArrangeOverride(Windows.Foundation.Size finalSize) + { + if (Element == null) + return finalSize; + + Element.IsInNativeLayout = true; + + Control?.Arrange(new Rect(0, 0, finalSize.Width, finalSize.Height)); + + Element.IsInNativeLayout = false; + + return finalSize; + } + + protected override void Dispose(bool disposing) + { + if (Control != null) + { + Control.ViewChanged -= OnViewChanged; + } + + base.Dispose(disposing); + } + + protected override Windows.Foundation.Size MeasureOverride(Windows.Foundation.Size availableSize) + { + if (Element == null) + return new Windows.Foundation.Size(0, 0); + + double width = Math.Max(0, Element.Width); + double height = Math.Max(0, Element.Height); + var result = new Windows.Foundation.Size(width, height); + + Control?.Measure(result); + + return result; + } + + 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 { HorizontalScrollBarVisibility = ScrollBarVisibility.Auto, VerticalScrollBarVisibility = ScrollBarVisibility.Auto }); + + Control.ViewChanged += OnViewChanged; + } + + Controller.ScrollToRequested += OnScrollToRequested; + + 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(); + } + + void LoadContent() + { + if (_currentView != null) + { + _currentView.Cleanup(); + } + + _currentView = Element.Content; + + IVisualElementRenderer renderer = null; + if (_currentView != null) + { + renderer = _currentView.GetOrCreateRenderer(); + } + + Control.Content = renderer != null ? renderer.ContainerElement : null; + + UpdateMargins(); + } + + void OnScrollToRequested(object sender, ScrollToRequestedEventArgs e) + { + double x = e.ScrollX, y = e.ScrollY; + + ScrollToMode mode = e.Mode; + if (mode == ScrollToMode.Element) + { + Point pos = Controller.GetScrollPositionForElement((VisualElement)e.Element, e.Position); + x = pos.X; + y = pos.Y; + mode = ScrollToMode.Position; + } + + if (mode == ScrollToMode.Position) + { + Control.ChangeView(x, y, null, !e.ShouldAnimate); + } + } + + void OnViewChanged(object sender, ScrollViewerViewChangedEventArgs e) + { + Controller.SetScrolledPosition(Control.HorizontalOffset, Control.VerticalOffset); + + if (!e.IsIntermediate) + Controller.SendScrollFinished(); + } + + void UpdateMargins() + { + var element = Control.Content as FrameworkElement; + if (element == null) + return; + + switch (Element.Orientation) + { + case ScrollOrientation.Horizontal: + // need to add left/right margins + element.Margin = new Windows.UI.Xaml.Thickness(Element.Padding.Left, 0, Element.Padding.Right, 0); + break; + case ScrollOrientation.Vertical: + // need to add top/bottom margins + element.Margin = new Windows.UI.Xaml.Thickness(0, Element.Padding.Top, 0, Element.Padding.Bottom); + break; + case ScrollOrientation.Both: + // need to add all margins + element.Margin = new Windows.UI.Xaml.Thickness(Element.Padding.Left, Element.Padding.Top, Element.Padding.Right, Element.Padding.Bottom); + break; + } + } + + void UpdateOrientation() + { + if (Element.Orientation == ScrollOrientation.Horizontal || Element.Orientation == ScrollOrientation.Both) + { + Control.HorizontalScrollBarVisibility = ScrollBarVisibility.Auto; + } + else + { + Control.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled; + } + } + } +}
\ No newline at end of file |