Dynamic shape graphic c#

Question

I want to draw graphics (shapes) onto the panel to the top left. The shape will be drawn depending on the shape chosen and the value given by the track bar. The track bar values aren't specific i.e aren't pixels or millimeters, so basically when the track bar increases in number the shape should get larger. enter image description here

This is the my main code. Other classes such as Circle, Square and Triangle also exist.

public partial class drawShape : Form
{

    Graphics drawArea;
    public decimal area;
    double myBoundary = 0;
    double myArea = 0;
    public double length = 100;

    public drawShape()
    {
        InitializeComponent();
        drawArea = pnlDrawArea.CreateGraphics();
    }

    public void updateShape()
    {
        if(rbCircle.Checked)
        {
            drawCircle();
        }

        if(rbSquare.Checked)
        {
            drawSquare();
        }

        if(rbTriangle.Checked)
        {
            drawTriangle();
        }

        if(rb2DecimalPlaces.Checked)
        {
            lblBoundaryLength.Text = myBoundary.ToString("#,0.00");
            lblAreaResult.Text = myArea.ToString("#,0.00");
        }

        if(rb3DecimalPlaces.Checked)
        {
            lblBoundaryLength.Text = myBoundary.ToString("#,0.000");
            lblAreaResult.Text = myArea.ToString("#,0.000");
        }

        if(rb4DecimalPlaces.Checked)
        {
            lblBoundaryLength.Text = myBoundary.ToString("#,0.0000");
            lblAreaResult.Text = myArea.ToString("#,0.0000");
        }
    }

    public void drawCircle()
    {
        Circle myCircle = new Circle(length);
        myArea = myCircle.GetArea(length);
        myBoundary = myCircle.GetCircumference();
        lblAreaResult.Text = myArea.ToString();
        lblBoundaryLength.Text = myBoundary.ToString();
    }

    public void drawSquare()
    {
        Square mySquare = new Square(length);
        myArea = mySquare.GetArea();
        myBoundary = mySquare.GetBoundLength(length);
        lblAreaResult.Text = myArea.ToString();
        lblBoundaryLength.Text = myBoundary.ToString();
    }

    public void drawTriangle()
    {
        Triangle myTriangle = new Triangle(length);
        myArea = myTriangle.GetArea();
        myBoundary = myTriangle.GetBoundLength();
        lblAreaResult.Text = myArea.ToString();
        lblBoundaryLength.Text = myBoundary.ToString();
    }

How do I go about drawing the shapes onto the panel using values from the track bar. — TonyQuig
Drawing in WinForms is event driven. Hook onto the Paint event of the panel and draw there. — John Alexiou
Did you get it to work? If my answer was useful, please consider marking it as accepted. — TaW

TaW TaW · Accepted Answer · 2015-02-25T13:26:06

You should use the Panel's Paint event like this:

private void pnlDrawArea_Paint(object sender, PaintEventArgs e)
{
        int offset = 20;
        Rectangle bounding = new Rectangle(offset, offset, 
                            (int)myBoundary.Value, (int)myBoundary.Value);

        if (rbSquare.Checked)
        {
           e.Graphics.DrawRectangle(Pens.Red, bounding);
        }
        else if (rbCircle.Checked)
        {
           e.Graphics.DrawEllipse(Pens.Red, bounding);
        }
        // else if...

}

and in your updateShape simply call the Paint event by coding: pnlDrawArea.Invalidate();

For the triangle you will

use the DrawLines methos and
have to calculate three Points for it
add them to an array or a list..

Don't forget to hook up the Paint event!!

Dynamic shape graphic c#

1 Answers