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/* $Id: ScrollableImageControl.cs,v 1.4 2009/06/03 01:10:59 ellson Exp $ $Revision: 1.4 $ */
/* vim:set shiftwidth=4 ts=8: */
/**********************************************************
* This software is part of the graphviz package *
* http://www.graphviz.org/ *
* *
* Copyright (c) 1994-2008 AT&T Corp. *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Corp. *
* *
* Information and Software Systems Research *
* AT&T Research, Florham Park NJ *
**********************************************************/
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;
namespace Graphviz
{
public partial class ScrollableImageControl : ScrollableControl
{
public Image Image
{
get
{
return _image;
}
set
{
_image = value;
UpdateAutoScroll();
}
}
public float Zoom
{
get
{
return _zoom;
}
set
{
_zoom = value;
UpdateAutoScroll();
}
}
public ScrollableImageControl()
{
InitializeComponent();
SetStyle(ControlStyles.AllPaintingInWmPaint |
ControlStyles.DoubleBuffer |
ControlStyles.ResizeRedraw |
ControlStyles.UserMouse |
ControlStyles.UserPaint,
true);
_image = null;
_zoom = 1.0f;
_lastScroll = new Point(0, 0);
}
public void ActualSize()
{
Zoom = 1.0f;
}
public void ZoomToFit()
{
Size imageSize = Image.Size;
Size controlSize = Size;
Zoom = Math.Min((float)controlSize.Width / (float)imageSize.Width, (float)controlSize.Height / (float)imageSize.Height);
}
public void ZoomIn()
{
Zoom *= _squareRootOfTwo;
}
public void ZoomOut()
{
Zoom /= _squareRootOfTwo;
}
protected override void OnMouseDown(MouseEventArgs e)
{
/* if potentially panning with the mouse, record last scroll position */
/* NOTE: Autoscroll should be set to +ve values but always returns -ve values */
if (e.Button == MouseButtons.Left)
_lastScroll = new Point(
e.X - AutoScrollPosition.X,
e.Y - AutoScrollPosition.Y);
base.OnMouseDown(e);
}
protected override void OnMouseMove(MouseEventArgs e)
{
/* if panning with the mouse, scroll to position */
/* NOTE: Autoscroll should be set to +ve values but always returns -ve values */
if (e.Button == MouseButtons.Left)
AutoScrollPosition = new Point(
_lastScroll.X - e.X,
_lastScroll.Y - e.Y);
base.OnMouseMove(e);
}
protected override void OnPaintBackground(PaintEventArgs e)
{
/* fill clip rectangle with background color */
e.Graphics.FillRectangle(new SolidBrush(BackColor), e.ClipRectangle);
}
protected override void OnPaint(PaintEventArgs pe)
{
if (_image != null) {
Matrix oldMatrix = pe.Graphics.Transform;
/* if the zoomed image size is smaller than the control size, center the display */
/* adjust by the scroll position, then scale by the zoom factor */
pe.Graphics.TranslateTransform(
Math.Max((Width - _image.Width * _zoom) / 2.0f, 0.0f) + AutoScrollPosition.X,
Math.Max((Height - _image.Height * _zoom) / 2.0f, 0.0f) + AutoScrollPosition.Y);
pe.Graphics.ScaleTransform(_zoom, _zoom);
/* blit the image onto the graphics */
pe.Graphics.DrawImage(_image, 0.0f, 0.0f);
pe.Graphics.Transform = oldMatrix;
}
base.OnPaint(pe);
}
private void UpdateAutoScroll()
{
if (_image == null)
AutoScrollMinSize = Size;
else
AutoScrollMinSize = new Size(
(int)(_image.Width * _zoom + 0.5f),
(int)(_image.Height * _zoom + 0.5f));
Invalidate();
}
private readonly float _squareRootOfTwo = (float)Math.Sqrt(2.0);
private Image _image;
private float _zoom;
private Point _lastScroll;
}
}
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