namespace WindowsFormsApplication1

{

public partial class Form3 : Form

{

bool chieu;

public Form3()

{

InitializeComponent();

}

private void button1_Click(object sender, EventArgs e)

{

timer1.Enabled = true;

}

private void Form3_Load(object sender, EventArgs e)

{

timer1.Enabled = false;

chieu = true;

}

private void timer1_Tick(object sender, EventArgs e)

{

if(chieu==true)

pictureBox1.Top = pictureBox1.Top + 5;

else

pictureBox1.Top=pictureBox1.Top-5;

if((pictureBox1.Top<=0)||(pictureBox1.Top+pictureBox1.Height>=this.Height))

chieu=!chieu;

}

}

}