97 строки
3.0 KiB
C#
97 строки
3.0 KiB
C#
using System;
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using System.ComponentModel;
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using Windows.UI.Xaml;
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using Windows.UI.Xaml.Controls.Primitives;
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#if WINDOWS_UWP
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namespace Xamarin.Forms.Platform.UWP
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#else
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namespace Xamarin.Forms.Platform.WinRT
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#endif
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{
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public class SliderRenderer : ViewRenderer<Slider, Windows.UI.Xaml.Controls.Slider>
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{
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protected override void OnElementChanged(ElementChangedEventArgs<Slider> e)
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{
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base.OnElementChanged(e);
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if (e.NewElement != null)
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{
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if (Control == null)
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{
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var slider = new Windows.UI.Xaml.Controls.Slider();
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SetNativeControl(slider);
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Control.Minimum = e.NewElement.Minimum;
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Control.Maximum = e.NewElement.Maximum;
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Control.Value = e.NewElement.Value;
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slider.ValueChanged += OnNativeValueChanged;
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// Even when using Center/CenterAndExpand, a Slider has an oddity where it looks
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// off-center in its layout by a smidge. The default templates are slightly different
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// between 8.1/UWP; the 8.1 rows are 17/Auto/32 and UWP are 18/Auto/18. The value of
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// the hardcoded 8.1 rows adds up to 49 (when halved is 24.5) and UWP are 36 (18). Using
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// a difference of about 6 pixels to correct this oddity seems to make them both center
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// more correctly.
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//
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// The VerticalAlignment needs to be set as well since a control would not actually be
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// centered if a larger HeightRequest is set.
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if (Element.VerticalOptions.Alignment == LayoutAlignment.Center && Control.Orientation == Windows.UI.Xaml.Controls.Orientation.Horizontal)
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{
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Control.VerticalAlignment = VerticalAlignment.Center;
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#if WINDOWS_UWP
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slider.Margin = new Windows.UI.Xaml.Thickness(0, 7, 0, 0);
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#else
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slider.Margin = new Windows.UI.Xaml.Thickness(0, 13, 0, 0);
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#endif
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}
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}
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double stepping = Math.Min((e.NewElement.Maximum - e.NewElement.Minimum) / 10, 1);
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Control.StepFrequency = stepping;
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Control.SmallChange = stepping;
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}
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}
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protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
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{
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base.OnElementPropertyChanged(sender, e);
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if (e.PropertyName == Slider.MinimumProperty.PropertyName)
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Control.Minimum = Element.Minimum;
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else if (e.PropertyName == Slider.MaximumProperty.PropertyName)
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Control.Maximum = Element.Maximum;
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else if (e.PropertyName == Slider.ValueProperty.PropertyName)
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{
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if (Control.Value != Element.Value)
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Control.Value = Element.Value;
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}
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}
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protected override void UpdateBackgroundColor()
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{
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if (Control != null)
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{
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Color backgroundColor = Element.BackgroundColor;
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if (!backgroundColor.IsDefault)
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{
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Control.Background = backgroundColor.ToBrush();
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}
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else
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{
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Control.ClearValue(Windows.UI.Xaml.Controls.Control.BackgroundProperty);
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}
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}
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}
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protected override bool PreventGestureBubbling { get; set; } = true;
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void OnNativeValueChanged(object sender, RangeBaseValueChangedEventArgs e)
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{
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((IElementController)Element).SetValueFromRenderer(Slider.ValueProperty, e.NewValue);
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}
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}
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} |