using System;
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using System.Diagnostics;
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using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Input;
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using System.Windows.Media;
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using System.Windows.Media.Imaging;
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namespace Bro.Common.ImageCanvas
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{
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/// <summary>
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/// Image element with the ability to pick out a pixel color value.
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/// </summary>
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/// <remarks>
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/// <see cref="ImageColorPicker"/> element adorns the <see cref="System.Windows.Controls.Image"/>
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/// it's derived from with the facility to pick the image pixel color value at the position
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/// specified by the selector visual.
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/// </remarks>
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public class ImageColorPicker : Image
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{
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#region dependency properties
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/// <summary>
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/// SelectedColor property backing ReadOnly DependencyProperty.
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/// </summary>
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private static readonly DependencyPropertyKey SelectedColorPropertyKey = DependencyProperty.RegisterReadOnly("SelectedColor", typeof(Color),
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typeof(ImageColorPicker), new FrameworkPropertyMetadata(Colors.Transparent, FrameworkPropertyMetadataOptions.AffectsRender));
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public Color SelectedColor => (Color)GetValue(SelectedColorPropertyKey.DependencyProperty);
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/// <summary>
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/// Selector property backing DependencyProperty.
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/// </summary>
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public static readonly DependencyProperty SelectorProperty = DependencyProperty.Register("Selector", typeof(Drawing),
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typeof(ImageColorPicker), new FrameworkPropertyMetadata(new GeometryDrawing(Brushes.White, new Pen(Brushes.Black, 1),
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new EllipseGeometry(new Point(), 3, 3))
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{
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Pen = new Pen(new SolidColorBrush(Color.FromArgb(212, 0, 0, 0)), 1),
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Brush = new SolidColorBrush(Color.FromArgb(80, 255, 255, 255))
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}, FrameworkPropertyMetadataOptions.AffectsRender));
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public Drawing Selector
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{
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get { return (Drawing)GetValue(SelectorProperty); }
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set { SetValue(SelectorProperty, value); }
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}
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/// <summary>
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/// Scaling for the TargetImage
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/// </summary>
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public static readonly DependencyProperty ScaleProperty = DependencyProperty.Register("Scale", typeof(double),
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typeof(ImageColorPicker), new PropertyMetadata(0.0, (d, e) => (d as Image)?.InvalidateVisual()));
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public double Scale { get { return (double)GetValue(ScaleProperty); } set { SetValue(ScaleProperty, value); } }
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#endregion
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#region overridden methods
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/// <summary>
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/// Renders the contents of an <see cref="T:System.Windows.Controls.Image"/> and
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/// the SelectorDrawing.
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/// </summary>
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/// <param name="drawingContext">An instance of <see cref="T:System.Windows.Media.DrawingContext"/>
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/// used to render the control.</param>
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protected override void OnRender(DrawingContext drawingContext)
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{
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base.OnRender(drawingContext);
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if (ActualWidth == 0 || ActualHeight == 0)
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return;
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// Render the SelectorDrawing
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drawingContext.PushTransform(new TranslateTransform(Position.X, Position.Y));
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if (Scale > 0) drawingContext.PushTransform(new ScaleTransform(1 / Scale, 1 / Scale));
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drawingContext.DrawDrawing(Selector);
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drawingContext.Pop();
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}
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/// <summary>
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/// Raises the <see cref="E:System.Windows.FrameworkElement.SizeChanged"/> event,
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/// using the specified information as part of the eventual event data.
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/// </summary>
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/// <param name="sizeInfo">Details of the old and new size involved in the change.</param>
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protected override void OnRenderSizeChanged(SizeChangedInfo sizeInfo)
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{
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base.OnRenderSizeChanged(sizeInfo);
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_cachedTargetBitmap = null; // TargetBitmap cache isn't valid anymore.
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// Adjust the selector position proportionally to size change.
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if (sizeInfo.PreviousSize.Width > 0 && sizeInfo.PreviousSize.Height > 0)
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Position = new Point(Position.X * sizeInfo.NewSize.Width / sizeInfo.PreviousSize.Width
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, Position.Y * sizeInfo.NewSize.Height / sizeInfo.PreviousSize.Height);
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}
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/// <summary>
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/// Invoked whenever the effective value of any dependency property on this
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/// <see cref="T:System.Windows.FrameworkElement"/> has been updated.
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/// The specific dependency property that changed is reported in the arguments parameter.
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/// Overrides <see cref="M:System.Windows.DependencyObject.OnPropertyChanged(System.Windows.DependencyPropertyChangedEventArgs)"/>.
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/// </summary>
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/// <param name="e">The event data that describes the property that changed,
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/// as well as old and new values.</param>
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protected override void OnPropertyChanged(DependencyPropertyChangedEventArgs e)
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{
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if (e.Property.Name == "Source")
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{
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_cachedTargetBitmap = null; // TargetBitmap cache isn't valid anymore.
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Position = new Point(); // Move the selector to the top-left corner.
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}
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base.OnPropertyChanged(e);
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}
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#endregion
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#region Position
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/// <summary>
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/// Gets or sets the Selector Position.
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/// </summary>
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/// <value>The position.</value>
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Point Position
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{
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get { return _position; }
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set
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{
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var newPos = new Point(Clamp(value.X, 0, ActualWidth), Clamp(value.Y, 0, ActualHeight));
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if (_position != newPos)
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{
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_position = newPos;
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Color color = GetColor(_position.X, _position.Y);
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if (color == SelectedColor) InvalidateVisual();
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SetValue(SelectedColorPropertyKey, color);
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}
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}
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}
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Point _position;
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/// <summary>
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/// Sets the <paramref name="pt"/> as the new position if the point falls
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/// into the element bounds.
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/// </summary>
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/// <param name="pt">The point.</param>
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void SetPositionIfInBounds(Point pt)
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{
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if (pt.X >= 0 && pt.X <= ActualWidth && pt.Y >= 0 && pt.Y <= ActualHeight)
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Position = pt;
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}
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#endregion Position
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#region TargetBitmap
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RenderTargetBitmap _cachedTargetBitmap;
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/// <summary>
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/// Gets the target bitmap for the DrawingImage image Source.
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/// </summary>
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/// <value>The target bitmap.</value>
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RenderTargetBitmap TargetBitmap
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{
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get
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{
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if (_cachedTargetBitmap == null)
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{
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var drawingImage = Source as DrawingImage;
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if (drawingImage != null)
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{
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DrawingVisual drawingVisual = new DrawingVisual();
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using (DrawingContext drawingContext = drawingVisual.RenderOpen())
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{
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drawingContext.DrawDrawing(drawingImage.Drawing);
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}
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// Scale the DrawingVisual.
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Rect dvRect = drawingVisual.ContentBounds;
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drawingVisual.Transform = new ScaleTransform(ActualWidth / dvRect.Width
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, ActualHeight / dvRect.Height);
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_cachedTargetBitmap = new RenderTargetBitmap((int)ActualWidth
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, (int)ActualHeight, 96, 96, PixelFormats.Pbgra32);
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_cachedTargetBitmap.Render(drawingVisual);
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}
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}
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return _cachedTargetBitmap;
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}
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}
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#endregion TargetBitmap
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#region Mouse handling
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protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
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{
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base.OnMouseLeftButtonDown(e);
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SetPositionIfInBounds(e.GetPosition(this));
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}
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protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
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{
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base.OnMouseLeftButtonUp(e);
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SetPositionIfInBounds(e.GetPosition(this));
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}
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protected override void OnMouseMove(MouseEventArgs e)
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{
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base.OnMouseMove(e);
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if (e.LeftButton == MouseButtonState.Pressed)
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SetPositionIfInBounds(e.GetPosition(this));
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}
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protected override void OnMouseEnter(MouseEventArgs e)
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{
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base.OnMouseEnter(e);
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if (e.LeftButton == MouseButtonState.Pressed)
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{
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Point mousePoint = e.GetPosition(this);
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Position = new Point(mousePoint.X, mousePoint.Y);
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}
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}
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#endregion Mouse handling
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/// <summary>
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/// Picks the color at the position specified.
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/// </summary>
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/// <param name="x">The x coordinate in WPF pixels.</param>
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/// <param name="y">The y coordinate in WPF pixels.</param>
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/// <returns>The image pixel color at x,y position.</returns>
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/// <remarks>
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/// Input coordinates are scaled according to the underlying image resolution,
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/// so this method doesn't expect exceptions thrown by the
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/// <see cref="M:System.Windows.Media.Imaging.BitmapSource.CopyPixels"/> method.
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/// <para>Color can be picked not only from the
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/// <see cref="T:System.Windows.Media.Imaging.BitmapSource"/>, but also from the
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/// <see cref="T:System.Windows.Media.DrawingImage"/>.</para>
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/// </remarks>
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Color GetColor(double x, double y)
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{
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if (Source == null) throw new InvalidOperationException("Image Source not set");
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BitmapSource bitmapSource = Source as BitmapSource;
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if (bitmapSource != null)
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{ // Get color from bitmap pixel.
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// Convert coopdinates from WPF pixels to Bitmap pixels and restrict them by the Bitmap bounds.
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x *= bitmapSource.PixelWidth / ActualWidth;
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if ((int)x > bitmapSource.PixelWidth - 1)
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x = bitmapSource.PixelWidth - 1;
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else if (x < 0)
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x = 0;
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y *= bitmapSource.PixelHeight / ActualHeight;
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if ((int)y > bitmapSource.PixelHeight - 1)
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y = bitmapSource.PixelHeight - 1;
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else if (y < 0)
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y = 0;
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// Lee Brimelow approach (http://thewpfblog.com/?p=62).
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//byte[] pixels = new byte[4];
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//CroppedBitmap cb = new CroppedBitmap(bitmapSource, new Int32Rect((int)x, (int)y, 1, 1));
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//cb.CopyPixels(pixels, 4, 0);
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//return Color.FromArgb(pixels[3], pixels[2], pixels[1], pixels[0]);
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// Alternative approach
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if (bitmapSource.Format == PixelFormats.Indexed4)
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{
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byte[] pixels = new byte[1];
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int stride = (bitmapSource.PixelWidth * bitmapSource.Format.BitsPerPixel + 3) / 4;
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bitmapSource.CopyPixels(new Int32Rect((int)x, (int)y, 1, 1), pixels, stride, 0);
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//Debug.Assert(bitmapSource.Palette != null, "bitmapSource.Palette != null");
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//Debug.Assert(bitmapSource.Palette.Colors.Count == 16, "bitmapSource.Palette.Colors.Count == 16");
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return bitmapSource.Palette.Colors[pixels[0] >> 4];
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}
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else if (bitmapSource.Format == PixelFormats.Indexed8)
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{
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byte[] pixels = new byte[1];
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int stride = (bitmapSource.PixelWidth * bitmapSource.Format.BitsPerPixel + 7) / 8;
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bitmapSource.CopyPixels(new Int32Rect((int)x, (int)y, 1, 1), pixels, stride, 0);
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//Debug.Assert(bitmapSource.Palette != null, "bitmapSource.Palette != null");
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//Debug.Assert(bitmapSource.Palette.Colors.Count == 256, "bitmapSource.Palette.Colors.Count == 256");
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return bitmapSource.Palette.Colors[pixels[0]];
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}
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else
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{
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byte[] pixels = new byte[4];
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int stride = (bitmapSource.PixelWidth * bitmapSource.Format.BitsPerPixel + 7) / 8;
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bitmapSource.CopyPixels(new Int32Rect((int)x, (int)y, 1, 1), pixels, stride, 0);
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return Color.FromArgb(pixels[3], pixels[2], pixels[1], pixels[0]);
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}
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// TODO There are other PixelFormats which processing should be added if desired.
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}
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DrawingImage drawingImage = Source as DrawingImage;
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if (drawingImage != null)
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{ // Get color from drawing pixel.
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RenderTargetBitmap targetBitmap = TargetBitmap;
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Debug.Assert(targetBitmap != null, "targetBitmap != null");
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// Convert coopdinates from WPF pixels to Bitmap pixels and restrict them by the Bitmap bounds.
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x *= targetBitmap.PixelWidth / ActualWidth;
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if ((int)x > targetBitmap.PixelWidth - 1)
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x = targetBitmap.PixelWidth - 1;
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else if (x < 0)
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x = 0;
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y *= targetBitmap.PixelHeight / ActualHeight;
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if ((int)y > targetBitmap.PixelHeight - 1)
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y = targetBitmap.PixelHeight - 1;
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else if (y < 0)
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y = 0;
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// TargetBitmap is always in PixelFormats.Pbgra32 format.
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// Pbgra32 is a sRGB format with 32 bits per pixel (BPP). Each channel (blue, green, red, and alpha)
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// is allocated 8 bits per pixel (BPP). Each color channel is pre-multiplied by the alpha value.
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byte[] pixels = new byte[4];
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int stride = (targetBitmap.PixelWidth * targetBitmap.Format.BitsPerPixel + 7) / 8;
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targetBitmap.CopyPixels(new Int32Rect((int)x, (int)y, 1, 1), pixels, stride, 0);
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return Color.FromArgb(pixels[3], pixels[2], pixels[1], pixels[0]);
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}
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throw new InvalidOperationException("Unsupported Image Source Type");
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}
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private static T Clamp<T>(T value, T min, T max) where T : IComparable<T>
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{
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return (value.CompareTo(min) < 0) ? min : value.CompareTo(max) > 0 ? max : value;
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}
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}
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}
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