Moving an image in C#

 
Boolean isPositionCurseurImageSet = false;

Point positionCurseurImage = new Point(0, 0);

private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
   if (e.Button == MouseButtons.Left)
   {
      this.pictureBox1.Top += e.Y - this.positionCurseurImage.Y;
      this.pictureBox1.Left += e.X - this.positionCurseurImage.X;
   }
}
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
   if (!isPositionCurseurImageSet)
      this.positionCurseurImage = this.pictureBox1.PointToClient(Cursor.Position);
      isPositionCurseurImageSet = true;
   }
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
   isPositionCurseurImageSet = false;
}