using System;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media.Animation;
using System.Windows;
using System.Windows.Media;
namespace PanAndZoom
{
public class PanAndZoomViewer : ContentControl
{
public double DefaultZoomFactor { get; set; }
private FrameworkElement source;
private Point ScreenStartPoint = new Point(0, 0);
private TranslateTransform translateTransform;
private ScaleTransform zoomTransform;
private TransformGroup transformGroup;
private Point startOffset;
public PanAndZoomViewer()
{
this.DefaultZoomFactor = 1.4;
}
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
Setup(this);
}
void Setup(FrameworkElement control)
{
this.source = VisualTreeHelper.GetChild(this, 0) as FrameworkElement;
this.translateTransform = new TranslateTransform();
this.zoomTransform = new ScaleTransform();
this.transformGroup = new TransformGroup();
this.transformGroup.Children.Add(this.zoomTransform);
this.transformGroup.Children.Add(this.translateTransform);
this.source.RenderTransform = this.transformGroup;
this.Focusable = true;
this.KeyDown += new KeyEventHandler(source_KeyDown);
this.MouseMove += new MouseEventHandler(control_MouseMove);
this.MouseDown += new MouseButtonEventHandler(source_MouseDown);
this.MouseUp += new MouseButtonEventHandler(source_MouseUp);
this.MouseWheel += new MouseWheelEventHandler(source_MouseWheel);
}
void source_KeyDown(object sender, KeyEventArgs e)
{
// hit escape to reset everything
if (e.Key == Key.Escape) Reset();
}
void source_MouseWheel(object sender, MouseWheelEventArgs e)
{
// zoom into the content. Calculate the zoom factor based on the direction of the mouse wheel.
double zoomFactor = this.DefaultZoomFactor;
if (e.Delta <= 0) zoomFactor = 1.0 / this.DefaultZoomFactor;
// DoZoom requires both the logical and physical location of the mouse pointer
var physicalPoint = e.GetPosition(this);
DoZoom(zoomFactor, this.transformGroup.Inverse.Transform(physicalPoint), physicalPoint);
}
void source_MouseUp(object sender, MouseButtonEventArgs e)
{
if (this.IsMouseCaptured)
{
// we‘re done. reset the cursor and release the mouse pointer
this.Cursor = Cursors.Arrow;
this.ReleaseMouseCapture();
}
}
void source_MouseDown(object sender, MouseButtonEventArgs e)
{
// Save starting point, used later when determining how much to scroll.
this.ScreenStartPoint = e.GetPosition(this);
this.startOffset = new Point(this.translateTransform.X, this.translateTransform.Y);
this.CaptureMouse();
this.Cursor = Cursors.ScrollAll;
}
void control_MouseMove(object sender, MouseEventArgs e)
{
if (this.IsMouseCaptured)
{
// if the mouse is captured then move the content by changing the translate transform.
// use the Pan Animation to animate to the new location based on the delta between the
// starting point of the mouse and the current point.
var physicalPoint = e.GetPosition(this);
this.translateTransform.BeginAnimation(TranslateTransform.XProperty, CreatePanAnimation(physicalPoint.X - this.ScreenStartPoint.X + this.startOffset.X), HandoffBehavior.Compose);
this.translateTransform.BeginAnimation(TranslateTransform.YProperty, CreatePanAnimation(physicalPoint.Y - this.ScreenStartPoint.Y + this.startOffset.Y), HandoffBehavior.Compose);
}
}
/// <summary>Helper to create the panning animation for x,y coordinates.</summary>
/// <param name="toValue">New value of the coordinate.</param>
/// <returns>Double animation</returns>
private DoubleAnimation CreatePanAnimation(double toValue)
{
var da = new DoubleAnimation(toValue, new Duration(TimeSpan.FromMilliseconds(300)));
da.AccelerationRatio = 0.1;
da.DecelerationRatio = 0.9;
da.FillBehavior = FillBehavior.HoldEnd;
da.Freeze();
return da;
}
/// <summary>Helper to create the zoom double animation for scaling.</summary>
/// <param name="toValue">Value to animate to.</param>
/// <returns>Double animation.</returns>
private DoubleAnimation CreateZoomAnimation(double toValue)
{
var da = new DoubleAnimation(toValue, new Duration(TimeSpan.FromMilliseconds(500)));
da.AccelerationRatio = 0.1;
da.DecelerationRatio = 0.9;
da.FillBehavior = FillBehavior.HoldEnd;
da.Freeze();
return da;
}
/// <summary>Zoom into or out of the content.</summary>
/// <param name="deltaZoom">Factor to mutliply the zoom level by. </param>
/// <param name="mousePosition">Logical mouse position relative to the original content.</param>
/// <param name="physicalPosition">Actual mouse position on the screen (relative to the parent window)</param>
public void DoZoom(double deltaZoom, Point mousePosition, Point physicalPosition)
{
double currentZoom = this.zoomTransform.ScaleX;
currentZoom *= deltaZoom;
this.translateTransform.BeginAnimation(TranslateTransform.XProperty, CreateZoomAnimation(-1 * (mousePosition.X * currentZoom - physicalPosition.X)));
this.translateTransform.BeginAnimation(TranslateTransform.YProperty, CreateZoomAnimation(-1 * (mousePosition.Y * currentZoom - physicalPosition.Y)));
this.zoomTransform.BeginAnimation(ScaleTransform.ScaleXProperty, CreateZoomAnimation(currentZoom));
this.zoomTransform.BeginAnimation(ScaleTransform.ScaleYProperty, CreateZoomAnimation(currentZoom));
}
/// <summary>Reset to default zoom level and centered content.</summary>
public void Reset()
{
this.translateTransform.BeginAnimation(TranslateTransform.XProperty, CreateZoomAnimation(0));
this.translateTransform.BeginAnimation(TranslateTransform.YProperty, CreateZoomAnimation(0));
this.zoomTransform.BeginAnimation(ScaleTransform.ScaleXProperty, CreateZoomAnimation(1));
this.zoomTransform.BeginAnimation(ScaleTransform.ScaleYProperty, CreateZoomAnimation(1));
}
}
}
