Calculate and Draw the Shapes

[Pingpink]

I already have a class to do a shape program in window form application , but I don't know how to write a code in Form1.cs to show the area of shapes and draw after choosing the combobox - circle , triangle, square. when click the 'Area button' and draw the shape when click 'draw' , and how to enable and disable textbox of typing number when in use , ie. Circle needs to fill radius only , then change the combobox to triangle needs to fill base and height.

The Shape Class is below:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;

namespace Class_Shape
{
class Shape
{
public string[] GetShape()
{

string []s = {"circle","triangle","square"};
return s;

}
public double CircleArea(double radius)
{
return Math.PI * radius * radius;
}
public double RectangleArea(double width, double height)
{
return width * height;
}
public double TangleArea(double width,double height)
{
return 0.5 * width * height;
}
public void DrawCircle(double r,Form1 f)
{
Pen big = new Pen(Brushes.Red ,5);
f.Refresh ();
f.CreateGraphics().DrawEllipse(big, (float) 110,(float) 160,(float) r,(float) r);
f.CreateGraphics().FillEllipse(Brushes.YellowGreen , (float)110, (float)160, (float)r, (float)r);
}
public void DrawRect(double w,double h, Form1 f)
{
Pen big = new Pen(Brushes.Red, 5);
f.Refresh();
f.CreateGraphics().DrawRectangle (big, (float)110, (float)160, (float)w, (float)h);
f.CreateGraphics().FillRectangle (Brushes.YellowGreen, (float)110, (float)160, (float)w, (float)h);
}
public void DrawTang(double w, double h, Form1 f)
{
Pen big = new Pen(Brushes.Red, 5);
Point [] p = {new Point(120, 160),new Point(120,160+(int)h), new Point(120+(int)w,160+(int)h) } ;
f.Refresh();
f.CreateGraphics().DrawPolygon(big, p);
f.CreateGraphics().FillPolygon(Brushes.YellowGreen , p);
}
}
}

[arie]

To do what you want, you basicly have to handle events of your form and controls. For example, to enable/disable some controls when combobox value is changed, you have to handle SelectedIndexChanged event of your combobox (you just need to double-click it in your design window and the method will be created for you :)) You do enabling/disabling here.

Also, you may want to override OnPaint method of your form to draw your shapes (and set DoubleBuffered property of your form to true to prevent flickering). If you use it, your shape will be redrawn every time your form is redrawn (for example after it was covered by another form)
Here they describe how it's used: msdn.microsoft.com/en-us/library/system.windows.forms.control.onpaint.aspx

Also, in Click event of button "DRAW" you decide if currently chosen shape is drawn instead of the previous one, e.g:

string currentShape = "none";
string chosenShape = "none"
private void cbxChooseShape_SelectedIndexChanged(object sender, EventArgs e)
{
  chosenShape = cbxChooseShape.Text;
  // also disable/enable your controls here
}
private void btnDraw_Click(object sender, EventArgs e)
{
 currentShape = chosenShape;
 
 // read parameters such as shape width, height,radius...
 
 this.Refresh();
}
protected override void OnPaint(PaintEventArgs e)
{
   base.OnPaint(e);
   switch(currentShape)
   {
    case "circle": //draw circle here
      break;
    case "triangle": //draw triangle here
      break;
    case "square": //draw square here
      break;
    default: //don't draw anything if shape not chosen
      break;
   }
}

I also wouldn't pass Form1 objects to your drawing methods, instead pass Graphics object - no need to do CreateGraphics afterwards. Just pass e.Graphic to your drawing method in OnPaint(). Your class will be more universal this way, and when you create new form class called ThisStupidFormClass you won't have to modify your Shape class.