Simple Arrow Animation

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Introduction

This simple program explains how simple animations are implemented, using for loops etc.

Background

Actually, this program was made for my Instant Messaging Client - Gaim. I needed to know when my boss come online and when he went offline. Gaim has a feature called "Buddy Pounce" which allows users to trigger events. As per my logic, when a user logs in, my application will give me a signal by flying an arrow from right-bottom to left-top. And when he goes offline, the arrow moves from left-top to right-bottom.

Using the code

The images are stored as resources, and I call them depending on the value of Status:

this.BackgroundImage = Resource1.arrow2;

I have used this code to check whether the user is logged in or logged off. This accepts command line arguments. When Status is true, it means "LogIn", otherwise it means "LogOff".

if (args.Length > 0)
{
    if (args[0].ToString() == "logoff") 
    {
        Status = false;
    }
}

The animation logic is placed inside a Timer_Tick method. Inside the method, the screen width and height are validated, so this program will work under all screen resolutions. An Application.DoEvents(); call is placed in between, to avoid system concentrating on this app only.

private void timer1_Tick(object sender, EventArgs e)
{
    Application.DoEvents();
    
    if (Program.Status)
    {
        if (this.Top <= 0 || this.Left <= 0)
        {
            timer1.Enabled = false;
            Application.Exit();

        }
        this.Left -= 25;
        this.Top -= 15;
    }
    else
    {
        if (this.Top > Screen.GetBounds(this).Height || 
            this.Left > Screen.GetBounds(this).Width)
        {
            timer1.Enabled = false;
            Application.Exit();

        }
        this.Left += 25;
        this.Top += 15;
    }
}

History

This is my second version of this program but, this is my first version of this article.

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