I've created the following control & form for people to see what
exactly I'm trying to do.

Here's the code:

--------------------------------LayoutMainControl.cs------------------------------

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Data;
using System.Text;
using System.Windows.Forms;
using System.Collections;

namespace WindowsApplication1
{
public class LayoutMainControl : UserControl
{
private float _ScaleFactor = 1.0F;
private Rectangle DrawingCanvas = new Rectangle ( 0, 0, 1000, 500
);

public float ScaleFactor
{
get
{
return _ScaleFactor;
}

set
{
_ScaleFactor = value;

RescaleDrawingCanvas ( );

Invalidate ( );
}
}

private System.ComponentModel.IContainer components = null;

protected override void Dispose ( bool disposing )
{
if ( disposing && ( components != null ) )
{
components.Dispose ( );
}
base.Dispose ( disposing );
}

#region Component Designer generated code

private void InitializeComponent ( )
{
this.SuspendLayout ( );
this.AutoScaleDimensions = new System.Drawing.SizeF ( 6F, 13F );
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.AutoScroll = true;
this.BackColor = System.Drawing.Color.White;
this.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
this.DoubleBuffered = true;
this.Margin = new System.Windows.Forms.Padding ( 0 );
this.Name = "LayoutMainControl";
this.Size = new System.Drawing.Size ( 692, 409 );
this.Paint += new System.Windows.Forms.PaintEventHandler (
this.LayoutMainControl_Paint );
this.ResumeLayout ( false );

}

#endregion

public LayoutMainControl ( )
{
InitializeComponent ( );
}

private void RescaleDrawingCanvas ( )
{
AutoScrollMinSize = new Size ( ( int ) ( DrawingCanvas.Width *
_ScaleFactor ), ( int ) ( DrawingCanvas.Height * _ScaleFactor ) );
}

private void LayoutMainControl_Paint ( object sender,
PaintEventArgs e )
{
Graphics deviceContext = e.Graphics;

deviceContext.PageUnit = GraphicsUnit.Pixel;
deviceContext.InterpolationMode =
InterpolationMode.HighQualityBicubic;

deviceContext.ScaleTransform ( _ScaleFactor, _ScaleFactor );

deviceContext.TranslateTransform ( AutoScrollPosition.X /
_ScaleFactor, AutoScrollPosition.Y / _ScaleFactor );

Pen pen = new Pen ( Color.Red, 1 );
Rectangle rectangle = new Rectangle ( 500, 250, 10, 10 );
deviceContext.DrawRectangle ( pen, rectangle );
deviceContext.FillRectangle ( new SolidBrush ( pen.Color ),
rectangle );
}
}
}

--------------------------------Form1.cs------------------------------

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace WindowsApplication1
{
public partial class Form1 : Form
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;

/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main ( )
{
Application.EnableVisualStyles ( );
Application.SetCompatibleTextRenderingDefault ( false );
Application.Run ( new Form1 ( ) );
}

/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be
disposed; otherwise, false.</param>
protected override void Dispose ( bool disposing )
{
if ( disposing && ( components != null ) )
{
components.Dispose ( );
}
base.Dispose ( disposing );
}

#region Windows Form Designer generated code

/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent ( )
{
this.trackBar1 = new System.Windows.Forms.TrackBar ( );
this.layoutMainControl1 = new LayoutMainControl ( );
( ( System.ComponentModel.ISupportInitialize ) ( this.trackBar1 )
).BeginInit ( );
this.SuspendLayout ( );
//
// trackBar1
//
this.trackBar1.Dock = System.Windows.Forms.DockStyle.Bottom;
this.trackBar1.Maximum = 100;
this.trackBar1.Minimum = 1;
this.trackBar1.Name = "trackBar1";
this.trackBar1.TabIndex = 0;
this.trackBar1.Value = 10;
this.trackBar1.ValueChanged += new System.EventHandler (
this.trackBar1_ValueChanged );
//
// layoutMainControl1
//
this.layoutMainControl1.AutoScroll = true;
this.layoutMainControl1.BackColor = System.Drawing.Color.White;
this.layoutMainControl1.BorderStyle =
System.Windows.Forms.BorderStyle.FixedSingle;
this.layoutMainControl1.Dock =
System.Windows.Forms.DockStyle.Fill;
this.layoutMainControl1.Margin = new System.Windows.Forms.Padding
( 0 );
this.layoutMainControl1.Name = "layoutMainControl1";
this.layoutMainControl1.ScaleFactor = 1F;
this.layoutMainControl1.TabIndex = 1;
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF ( 6F, 13F );
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size ( 1020, 550 );
this.Controls.Add ( this.layoutMainControl1 );
this.Controls.Add ( this.trackBar1 );
this.Name = "Form1";
this.Text = "Form1";
( ( System.ComponentModel.ISupportInitialize ) ( this.trackBar1 )
).EndInit ( );
this.ResumeLayout ( false );
this.PerformLayout ( );

}

#endregion

private System.Windows.Forms.TrackBar trackBar1;
private LayoutMainControl layoutMainControl1;

public Form1 ( )
{
InitializeComponent ( );
}

private void trackBar1_ValueChanged ( object sender, EventArgs e )
{
this.layoutMainControl1.ScaleFactor = 0.1F *
this.trackBar1.Value;
}
}
}

<dcopestake (AT) gmail (DOT) com> wrote

In that case I wouldn't use the AutoScroll feature of the control, just
create your own scrollbars.

Michael

Annoying because it has different behaviour depending on whether you zoom in
or out.

Once you have the two cases however, the result is pretty simple.....

Here's the user control (with some inelegant dummy drawing :-) )

public partial class zoom2centerControl : UserControl

{

public zoom2centerControl()

{

InitializeComponent();

_docCenter = new Point(this.ClientRectangle.Width / 2,
this.ClientRectangle.Height / 2);

}

Point _docCenter;

float _zoom = 1.0f;

public float Zoom

{

get { return _zoom; }

set {

_zoom = value;

Invalidate();

this.AutoScrollMinSize = new Size(

(int)(this.ClientRectangle.Width * _zoom),

(int)(this.ClientRectangle.Height * _zoom)

);

this.AutoScrollPosition = new Point(

this.AutoScrollMinSize.Width / 2 - this.ClientSize.Width / 2,

this.AutoScrollMinSize.Height / 2 - this.ClientSize.Height / 2

);

}

}

protected override void OnScroll(ScrollEventArgs se)

{

Invalidate();

base.OnScroll(se);

}

protected override void OnPaint(PaintEventArgs e)

{

Matrix mx=new Matrix();

if (_zoom >= 1)

mx = new Matrix(_zoom, 0, 0, _zoom, this.AutoScrollPosition.X,
this.AutoScrollPosition.Y);

else

mx = new Matrix(_zoom, 0, 0, _zoom, this.ClientRectangle.Width / 2 -
(this.ClientRectangle.Width / 2 * _zoom), this.ClientRectangle.Height / 2 -
(this.ClientRectangle.Height / 2 * _zoom));

e.Graphics.Transform = mx;

e.Graphics.DrawLine(Pens.Red, 0, this.ClientRectangle.Height / 2,
this.ClientRectangle.Width, this.ClientRectangle.Height / 2);

e.Graphics.DrawLine(Pens.Red, this.ClientRectangle.Width/2, 0,
this.ClientRectangle.Width/2, this.ClientRectangle.Height);

for (int x = 0; x < 5; x++)

e.Graphics.DrawEllipse(Pens.Blue, ((this.ClientRectangle.Width / 2) - (1 +
(3 * x))), ((this.ClientRectangle.Height / 2) - (1 + (3 * x))), x * 6, x *
6);

}

}

And here's the form the drives it all.....

partial class Form1 : Form

{

/// <summary>

/// Required designer variable.

/// </summary>

private System.ComponentModel.IContainer components = null;

/// <summary>

/// Clean up any resources being used.

/// </summary>

/// <param name="disposing">true if managed resources should be disposed;
otherwise, false.</param>

protected override void Dispose(bool disposing)

{

if (disposing && (components != null))

{

components.Dispose();

}

base.Dispose(disposing);

}

#region Windows Form Designer generated code

/// <summary>

/// Required method for Designer support - do not modify

/// the contents of this method with the code editor.

/// </summary>

private void InitializeComponent()

{

this.trackBar1 = new System.Windows.Forms.TrackBar();

this.zoom2centerControl1 = new zoom2centre.zoom2centerControl();

((System.ComponentModel.ISupportInitialize)(this.t rackBar1)).BeginInit();

this.SuspendLayout();

//

// trackBar1

//

this.trackBar1.Dock = System.Windows.Forms.DockStyle.Top;

this.trackBar1.Location = new System.Drawing.Point(0, 0);

this.trackBar1.Maximum = 20;

this.trackBar1.Minimum = 1;

this.trackBar1.Name = "trackBar1";

this.trackBar1.Size = new System.Drawing.Size(292, 45);

this.trackBar1.TabIndex = 1;

this.trackBar1.Value = 5;

this.trackBar1.ValueChanged += new
System.EventHandler(this.trackBar1_ValueChanged);

//

// zoom2centerControl1

//

this.zoom2centerControl1.AutoScroll = true;

this.zoom2centerControl1.AutoScrollMinSize = new System.Drawing.Size(584,
452);

this.zoom2centerControl1.Dock = System.Windows.Forms.DockStyle.Fill;

this.zoom2centerControl1.Location = new System.Drawing.Point(0, 45);

this.zoom2centerControl1.Name = "zoom2centerControl1";

this.zoom2centerControl1.Size = new System.Drawing.Size(292, 226);

this.zoom2centerControl1.TabIndex = 2;

this.zoom2centerControl1.Zoom = 2F;

//

// Form1

//

this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);

this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;

this.ClientSize = new System.Drawing.Size(292, 271);

this.Controls.Add(this.zoom2centerControl1);

this.Controls.Add(this.trackBar1);

this.Name = "Form1";

this.Text = "Form1";

((System.ComponentModel.ISupportInitialize)(this.t rackBar1)).EndInit();

this.ResumeLayout(false);

this.PerformLayout();

}

#endregion

private System.Windows.Forms.TrackBar trackBar1;

private zoom2centerControl zoom2centerControl1;

public Form1()

{

InitializeComponent();

}





private void panel1_Paint(object sender, PaintEventArgs e)

{

}

private void trackBar1_ValueChanged(object sender, EventArgs e)

{

if (this.trackBar1.Value > 4)

this.zoom2centerControl1.Zoom = 1 + this.trackBar1.Value - 5;

else

this.zoom2centerControl1.Zoom = 1.0f / (5 - this.trackBar1.Value) * 0.5f;

}

}


--
Bob Powell [MVP]
Visual C#, System.Drawing

Ramuseco Limited .NET consulting
http://www.ramuseco.com

Find great Windows Forms articles in Windows Forms Tips and Tricks
http://www.bobpowell.net/tipstricks.htm

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http://www.bobpowell.net/faqmain.htm

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<dcopestake (AT) gmail (DOT) com> wrote

"Lloyd Dupont" <net.galador@ld> wrote

This doesn't compile. It's missing what I presume is an enum called
Alignment and it is missing a form called DraggingForm

Michael

"Lloyd Dupont" <net.galador@ld> wrote

The dragging form is missing some constants but removing all references to
it fixed the problem. What is this control meant to do? Is it a replacement
for the standard scrolling features of controls?

Michael

This is a ScrollView which also zoom.
It is ideally suited for subclassing, where you could ovewrite OnPaint() as
follow:
/// protected override void OnPaint(PaintEventArgs e)
/// {
/// // prepare the client space (standart in ScrollView)
/// Matrix m = e.Graphics.Transform;
/// m.Multiply(ClientTransform());
/// e.Graphics.Transform = m;
///
/// // ... normal drawing code ...
/// }



"Michael C" <nospam (AT) nospam (DOT) com> wrote

Thank you all very much for your help. Everything is working now!

Cheers
Doug

Lloyd Dupont wrote:

"Lloyd Dupont" <net.galador@ld> wrote

I've have a similar control which I use for a few different things. Instead
of having the onpaint event in the control I inherit from so that there is
no need to copy the code each time it is used.

Michael