Created
April 11, 2013 14:37
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Helps resize a control to fill its parent. Works only with a Image control but may be enhanced to work with other controls. Works in Windows Phone, may work in Silverlight/WPF. See http://stackoverflow.com/questions/13535022/windows-8-image-uniformfill-centered
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| namespace MyPhoneApp.Behaviors | |
| { | |
| using System; | |
| using System.Collections.Generic; | |
| using System.Linq; | |
| using System.Text; | |
| using System.Threading.Tasks; | |
| using System.Windows; | |
| using System.Windows.Controls; | |
| using System.Windows.Interactivity; | |
| using System.Windows.Media; | |
| using System.Windows.Media.Imaging; | |
| /// <summary> | |
| /// Helps resize a control to fill its parent. | |
| /// Provides a Stretch=UniformToFill behavior. | |
| /// </summary> | |
| public class FillParentBehavior : Behavior<FrameworkElement> | |
| { | |
| /// <summary> | |
| /// The parent element to measure. | |
| /// </summary> | |
| private FrameworkElement parent; | |
| /// <summary> | |
| /// Called after the behavior is attached to an AssociatedObject. | |
| /// </summary> | |
| /// <remarks> | |
| /// Override this to hook up functionality to the AssociatedObject. | |
| /// </remarks> | |
| protected override void OnAttached() | |
| { | |
| base.OnAttached(); | |
| this.parent = VisualTreeHelper.GetParent(this.AssociatedObject) as FrameworkElement; | |
| if (this.parent != null) | |
| { | |
| this.parent.SizeChanged += this.OnParentSizeChanged; | |
| this.OnParentSizeChanged(null, null); | |
| } | |
| } | |
| /// <summary> | |
| /// Called when the behavior is being detached from its AssociatedObject, but before it has actually occurred. | |
| /// </summary> | |
| /// <remarks> | |
| /// Override this to unhook functionality from the AssociatedObject. | |
| /// </remarks> | |
| protected override void OnDetaching() | |
| { | |
| base.OnDetaching(); | |
| if (this.parent != null) | |
| { | |
| this.parent.SizeChanged -= this.OnParentSizeChanged; | |
| } | |
| } | |
| /// <summary> | |
| /// Called when [parent size changed]. | |
| /// </summary> | |
| /// <param name="sender">The sender.</param> | |
| /// <param name="e">The <see cref="SizeChangedEventArgs"/> instance containing the event data.</param> | |
| private void OnParentSizeChanged(object sender, SizeChangedEventArgs e) | |
| { | |
| double width = this.AssociatedObject.Width; | |
| double height = this.AssociatedObject.Height; | |
| var parentSize = new Size(this.parent.ActualWidth, this.parent.ActualHeight); | |
| var parentRatio = parentSize.Width / parentSize.Height; | |
| // determine optimal size | |
| if (this.AssociatedObject is Image) | |
| { | |
| var image = (Image)this.AssociatedObject; | |
| if (image.Source is BitmapImage) | |
| { | |
| var bitmap = (BitmapImage)image.Source; | |
| var imageSize = new Size(bitmap.PixelWidth, bitmap.PixelHeight); | |
| var imageRatio = imageSize.Width / imageSize.Height; | |
| if (parentRatio <= imageRatio) | |
| { | |
| // picture has a greater width than necessary | |
| // use its height | |
| width = double.NaN; | |
| height = parentSize.Height; | |
| } | |
| else | |
| { | |
| // picture has a greater height than necessary | |
| // use its width | |
| width = parentSize.Width; | |
| height = double.NaN; | |
| } | |
| } | |
| } | |
| this.AssociatedObject.Width = width; | |
| this.AssociatedObject.Height = height; | |
| } | |
| } | |
| } |
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