Question

I have a WinForm application, I’m trying to move a pictureBox in a Form using MouseMove Event, but i can’t figure out what’s the right calculation should i do on MouseMove, when i first the pictureBox , its location changes in a senseless way then on moving the pictureBox Location moves correctly.

It’s a Panel name OuterPanel which contains the pictureBox picBox, here the code im using :

private void picBox_MouseMove(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        Point p = OuterPanel.PointToClient(MousePosition);
        picBox.Location = this.PointToClient(p);
    }
}

P.S : the goal is moving image after zooming in, like windows photo viewer

Update : ConvertFromChildToForm method

private Point ConvertFromChildToForm(int x, int y,Control control)
{
    Point p = new Point(x, y);
    control.Location = p;
    return p;
}

Answer 1

You have to Manage three Events to get it done correctly :

• MouseDown
• MouseMove
• MouseUp

Here is a Related SO Question..

Your Code for picBox :

private void picBox_MouseDown(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        Point p = ConvertFromChildToForm(e.X, e.Y, picBox);
        iOldX = p.X;
        iOldY = p.Y;
        iClickX = e.X;
        iClickY = e.Y;
        clicked = true;
    }
}

private void picBox_MouseMove(object sender, MouseEventArgs e)
{
    if (clicked)
    {
        Point p = new Point(); // New Coordinate
        p.X =  e.X + picBox.Left;
        p.Y =  e.Y + picBox.Top;
        picBox.Left = p.X - iClickX;
        picBox.Top = p.Y - iClickY;
    }
}

private void picBox_MouseUp(object sender, MouseEventArgs e)
{
    clicked = false;   
}

private Point ConvertFromChildToForm(int x, int y, Control control)
{
    Point p = new Point(x, y);
    control.Location = p;
    return p;
}

ConvertFromChildToForm method from Mur Haf Soz