C#

Som Shekhar wrote:

I don't see anything wrong in doing it in Button_Click for learning purposes

private void button1_Click(object sender, EventArgs e)
{
    Random rnd = new Random((int)(DateTime.Now.Ticks % int.MaxValue));
    for (int i = 0; i < 100000; i++)
    {
        Graphics g = this.CreateGraphics();
        g.DrawEllipse(Pens.Blue, new Rectangle(rnd.Next(0, 50),
            rnd.Next(0, 50), rnd.Next(55, 100), rnd.Next(55, 100)));
    }
}

OriginalGriff wrote:

If your code executed only once a second, it would execute 100000 Graphics object creations in just over a day.

OriginalGriff wrote:

they also allocate GDI handles, which are a limited system resource

aspdotnetdev wrote:

Did you see the for loop?

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

public partial class FormFlowCalcs : Form
{
    private RectangleWithEllipseUnfilled rectangleWithEllipseUnfilled;
    private Point rectangleWithEllipseUnfilledLocation;
    private bool rectangleWithEllipseUnfilledVisible;

    public FormFlowCalcs()
    {
        InitializeComponent();
        Size = new Size(800, 600);
        rectangleWithEllipseUnfilled = new RectangleWithEllipseUnfilled(
            Color.Black, Color.Red, new Size(200, 200));
        rectangleWithEllipseUnfilledLocation = new Point(200, 200);
        rectangleWithEllipseUnfilledVisible = false;
    }

    private void buttonToggle_Click(object sender, EventArgs e)
    {
        rectangleWithEllipseUnfilledVisible = !rectangleWithEllipseUnfilledVisible;
        Invalidate();
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);
        if (rectangleWithEllipseUnfilledVisible)
            rectangleWithEllipseUnfilled.Draw(rectangleWithEllipseUnfilledLocation, e.Graphics);
    }
}

public struct RectangleWithEllipseUnfilled
{
    private Color ellipseColor;
    private Color rectangleColor;
    private Size size;

    public RectangleWithEllipseUnfilled(Color ellipseColor, Color rectangleColor, Size size)
    {
        this.ellipseColor = ellipseColor;
        this.rectangleColor = rectangleColor;
        this.size = size;
    }

    public Color EllipseColor
    {
        get { return ellipseColor; }
    }
    public Color RectangleColor
    {
        get { return rectangleColor; }
    }
    public Size Size
    {
        get { return size; }
    }

    public void Draw(Point location, Graphics graphics)
    {
        Rectangle drawBounds = new Rectangle(location, size);
        using (Pen ellipsePen = new Pen(ellipseColor))
        {
            graphics.DrawEllipse(ellipsePen, drawBounds);
        }
        using (Pen rectanglePen = new Pen(rectangleColor))
        {
            graphics.DrawRectangle(rectanglePen, drawBounds);
        }
    }
}

Henry Minute wrote:

Secondly a question. Will your DataGridView only have one row or will it have, possibly, many rows where the user can perform this operation differently on each row? e.g. user selects 2 on row1 combo1 and selects 1 on row2 combo1 and so on.