CODEWITHSUNDEEP
winformscontrols
I. J. Kennedy
I. J. Kennedy

Reputation: 25809

WinForms Control.Scale Method

The code below shows a small WinForms app which includes a simple Control that draws a circle. I'm trying to understand the behavior of the Control.Scale method.

If I call the Scale method on the Control from Main, as shown in the code, it scales properly. But if I instead call Scale from Circle's constructor, no scaling occurs.

My puzzlement here no doubt indicates a gross misunderstanding on my part regarding what Scale is supposed to do. Can anyone enlighten me?

using System;
using System.Windows.Forms;
using System.Drawing;

class Program
{
    [STAThread]
    public static void Main()
    {
        var circle = new Circle(Color.Orange)
        {
            Size = new Size(23, 23),
            Location = new Point(50, 50)
        };
        circle.Scale(new SizeF(3.0f, 3.0f));      //  <-- scaling here works

        var form = new Form();
        form.Controls.Add(circle);

        Application.Run(form);
    }
}

class Circle : Control
{
    public Circle(Color color)
    {
        ForeColor = color;
        // Scale(new SizeF(3.0f, 3.0f));     //  <-- scaling here DOESN'T work
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        e.Graphics.FillEllipse(new SolidBrush(ForeColor), ClientRectangle);
    }
}

Upvotes: 3

Views: 5005

Answers (1)

Hans Passant
Hans Passant

Reputation: 941257

The Scale() method isn't meant to do this. It is a helper method to implement the AutoScaleMode property. When your control is created by the form's InitializeComponent() method, scaling is suspended with SuspendLayout(). Which is why it has no effect in your constructor. The AutoScaleMode property value is applied when the form handle is created. Which cancels any scaling you applied.

I think you are looking for e.Graphics.ScaleTransform() in your OnPaint method. It doesn't scale the control, it scales the drawing. If you really did mean to scale the control then just change its Size property.

Upvotes: 5

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