source: branches/PersistentDataStructures/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Utils/PixelSnapHelpers.cs

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
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// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
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using System;
using System.Windows;
using System.Windows.Media;

namespace ICSharpCode.AvalonEdit.Utils
{
  /// <summary>
  /// Contains static helper methods for aligning stuff on a whole number of pixels.
  /// </summary>
  public static class PixelSnapHelpers
  {
    /// <summary>
    /// Gets the pixel size on the screen containing visual.
    /// This method does not take transforms on visual into account.
    /// </summary>
    public static Size GetPixelSize(Visual visual)
    {
      if (visual == null)
        throw new ArgumentNullException("visual");
      PresentationSource source = PresentationSource.FromVisual(visual);
      if (source != null) {
        Matrix matrix = source.CompositionTarget.TransformFromDevice;
        return new Size(matrix.M11, matrix.M22);
      } else {
        return new Size(1, 1);
      }
    }
    
    /// <summary>
    /// Aligns <paramref name="value"/> on the next middle of a pixel.
    /// </summary>
    /// <param name="value">The value that should be aligned</param>
    /// <param name="pixelSize">The size of one pixel</param>
    public static double PixelAlign(double value, double pixelSize)
    {
      // 0 -> 0.5
      // 0.1 -> 0.5
      // 0.5 -> 0.5
      // 0.9 -> 0.5
      // 1 -> 1.5
      return pixelSize * (Math.Round((value / pixelSize) + 0.5) - 0.5);
    }
    
    /// <summary>
    /// Aligns the borders of rect on the middles of pixels.
    /// </summary>
    public static Rect PixelAlign(Rect rect, Size pixelSize)
    {
      rect.X = PixelAlign(rect.X, pixelSize.Width);
      rect.Y = PixelAlign(rect.Y, pixelSize.Height);
      rect.Width = Round(rect.Width, pixelSize.Width);
      rect.Height = Round(rect.Height, pixelSize.Height);
      return rect;
    }
    
    /// <summary>
    /// Rounds <paramref name="point"/> to whole number of pixels.
    /// </summary>
    public static Point Round(Point point, Size pixelSize)
    {
      return new Point(Round(point.X, pixelSize.Width), Round(point.Y, pixelSize.Height));
    }
    
    /// <summary>
    /// Rounds val to whole number of pixels.
    /// </summary>
    public static Rect Round(Rect rect, Size pixelSize)
    {
      return new Rect(Round(rect.X, pixelSize.Width), Round(rect.Y, pixelSize.Height),
                      Round(rect.Width, pixelSize.Width), Round(rect.Height, pixelSize.Height));
    }
    
    /// <summary>
    /// Rounds <paramref name="value"/> to a whole number of pixels.
    /// </summary>
    public static double Round(double value, double pixelSize)
    {
      return pixelSize * Math.Round(value / pixelSize);
    }
    
    /// <summary>
    /// Rounds <paramref name="value"/> to an whole odd number of pixels.
    /// </summary>
    public static double RoundToOdd(double value, double pixelSize)
    {
      return Round(value - pixelSize, pixelSize * 2) + pixelSize;
    }
  }
}