mcs/class/referencesource/System.Activities.Presentation/System.Activities.Presentation/System/Activities/Presentation/Annotations/AnnotationAdorner.cs

   1 //----------------------------------------------------------------
   2 // <copyright company="Microsoft Corporation">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 //----------------------------------------------------------------
   6
   7 namespace System.Activities.Presentation.Annotations
   8 {
   9     using System.Activities.Presentation.View;
  10     using System.Runtime;
  11     using System.Windows;
  12     using System.Windows.Controls;
  13     using System.Windows.Documents;
  14     using System.Windows.Media;
  15
  16     internal class AnnotationAdorner : Adorner
  17     {
  18         public static readonly DependencyProperty AnchorProperty = DependencyProperty.RegisterAttached("Anchor", typeof(AdornerLocation), typeof(AnnotationAdorner), new FrameworkPropertyMetadata(AdornerLocation.None));
  19         private UIElement content;
  20
  21         public AnnotationAdorner(UIElement adornedElement)
  22             : base(adornedElement)
  23         {
  24         }
  25
  26         internal ScrollViewer ScrollViewer
  27         {
  28             get;
  29             set;
  30         }
  31
  32         internal UIElement Content
  33         {
  34             get
  35             {
  36                 return this.content;
  37             }
  38
  39             set
  40             {
  41                 if (this.content != value)
  42                 {
  43                     if (this.content != null)
  44                     {
  45                         this.RemoveVisualChild(this.content);
  46                     }
  47
  48                     this.content = value;
  49                     if (this.content != null)
  50                     {
  51                         this.AddVisualChild(this.content);
  52                     }
  53                 }
  54             }
  55         }
  56
  57         protected override int VisualChildrenCount
  58         {
  59             get
  60             {
  61                 return 1;
  62             }
  63         }
  64
  65         public static AdornerLocation GetAnchor(DependencyObject obj)
  66         {
  67             return (AdornerLocation)obj.GetValue(AnnotationAdorner.AnchorProperty);
  68         }
  69
  70         public static void SetAnchor(DependencyObject obj, AdornerLocation anchor)
  71         {
  72             obj.SetValue(AnnotationAdorner.AnchorProperty, anchor);
  73         }
  74
  75         // (3)   |   (2)
  76         // ______|______
  77         // (4)   |   (1)
  78         //       |
  79         // canvas is divided into four areas by anchorPoint
  80         // try to figure out which area could fit desiredSize from area1 to area4, if there's no fit, default to area4.
  81         internal static AdornerLocation FindAnchor(Point anchorPoint, Size desiredSize, Rect canvas)
  82         {
  83             Fx.Assert(anchorPoint.X >= canvas.X && anchorPoint.X <= canvas.X + canvas.Width, "X axis of anchorPoint not within canvas");
  84             Fx.Assert(anchorPoint.Y >= canvas.Y && anchorPoint.Y <= canvas.Y + canvas.Height, "Y axis of anchorPoint not within canvas");
  85
  86             AdornerLocation anchor = AdornerLocation.None;
  87
  88             // try area 1 and 2
  89             if (anchorPoint.X + desiredSize.Width <= canvas.X + canvas.Width)
  90             {
  91                 // area 1
  92                 if (anchorPoint.Y + desiredSize.Height <= canvas.Y + canvas.Height)
  93                 {
  94                     anchor = AdornerLocation.BottomRight;
  95                 }
  96
  97                 // area 2
  98                 if (anchor == AdornerLocation.None && anchorPoint.Y - desiredSize.Height >= canvas.Y)
  99                 {
 100                     anchor = AdornerLocation.TopRight;
 101                 }
 102             }
 103
 104             // area 3
 105             if (anchor == AdornerLocation.None && anchorPoint.X - desiredSize.Width >= canvas.X && anchorPoint.Y - desiredSize.Height >= canvas.Y)
 106             {
 107                 anchor = AdornerLocation.TopLeft;
 108             }
 109
 110             // default to area 4
 111             if (anchor == AdornerLocation.None)
 112             {
 113                 anchor = AdornerLocation.BottomLeft;
 114             }
 115
 116             return anchor;
 117         }
 118
 119         protected override Visual GetVisualChild(int index)
 120         {
 121             return this.Content;
 122         }
 123
 124         protected override Size MeasureOverride(Size constraint)
 125         {
 126             this.content.Measure(constraint);
 127             return this.content.DesiredSize;
 128         }
 129
 130         protected override Size ArrangeOverride(Size finalSize)
 131         {
 132             Point anchorPoint = this.AdornedElement.TranslatePoint(new Point(this.AdornedElement.RenderSize.Width, 0), this.ScrollViewer);
 133
 134             AdornerLocation anchor = AnnotationAdorner.GetAnchor(this);
 135             if (anchor == AdornerLocation.None)
 136             {
 137                 // Calculate based on the real size of the adorner, depending on current zoom level
 138                 DesignerView designerView = ((WorkflowViewElement)AdornedElement).Context.Services.GetService<DesignerView>();
 139                 double zoomLevel = designerView.ZoomFactor;
 140                 Size adornerSize = new Size(this.content.DesiredSize.Width * zoomLevel, this.content.DesiredSize.Height * zoomLevel);
 141                 anchor = FindAnchor(anchorPoint, adornerSize, new Rect(0, 0, this.ScrollViewer.ViewportWidth, this.ScrollViewer.ViewportHeight));
 142                 AnnotationAdorner.SetAnchor(this, anchor);
 143             }
 144
 145             Point location = CalculateLocation(anchor, this.AdornedElement.RenderSize, this.content.DesiredSize);
 146
 147             this.content.Arrange(new Rect(location, finalSize));
 148
 149             return finalSize;
 150         }
 151
 152         private static Point CalculateLocation(AdornerLocation anchor, Size adorneeSize, Size adornerSize)
 153         {
 154             Point location = new Point();
 155
 156             switch (anchor)
 157             {
 158                 case AdornerLocation.BottomRight:
 159                     location = new Point(adorneeSize.Width, 0);
 160                     break;
 161                 case AdornerLocation.TopRight:
 162                     location = new Point(adorneeSize.Width, -adornerSize.Height);
 163                     break;
 164                 case AdornerLocation.TopLeft:
 165                     location = new Point(adorneeSize.Width - adornerSize.Width, -adornerSize.Height);
 166                     break;
 167                 case AdornerLocation.BottomLeft:
 168                     location = new Point(adorneeSize.Width - adornerSize.Width, 20);
 169                     break;
 170             }
 171
 172             return location;
 173         }
 174     }
 175 }