Question

I have a winforms app. Inside, I have one panel (panel1), and inside this panel, another panel (panel2) with buttons inside.
I want to move panel2 horizontally inside panel1 when I mousedown in some button.
I’ve made this in each button inside panel2.

this.button4.MouseDown += new System.Windows.Forms.MouseEventHandler(this.btMouseDown);
        this.button4.MouseMove += new System.Windows.Forms.MouseEventHandler(this.btMouseMove);
        this.button4.MouseUp += new System.Windows.Forms.MouseEventHandler(this.btMouseUp);

and

void btMouseMove(object sender, MouseEventArgs e)
    {
        if (_mouseDown)
            panel2.Location = PointToClient(this.panel2.PointToScreen(new Point(e.X - _mousePos.X, e.Y - _mousePos.Y)));            
    }
    void btMouseDown(object sender, MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
            _mouseDown = true;
            _mousePos = new Point(e.X, e.Y);
        }
    }
    void btMouseUp(object sender, MouseEventArgs e)
    {
        if (_mouseDown)
        {
            _mouseDown = false;
        }
    }

This code moves the panel2 correctly inside the panel1, but I want to move the panel only horizontally, and this code moves to mouse location. I tried to put

Point(e.X - _mousePos.X, 3)

Instead of

Point(e.X - _mousePos.X, e.Y - _mousePos.Y)

But panel2 disappears. I would like to know how to move the panel2 inside the panel1 only horizontally.

Thanks a lot.

Answer 1

    void btMouseMove(object sender, MouseEventArgs e) {
        if (_mouseDown) {
            int deltaX = e.X - _mousePos.X;
            int deltaY = e.Y - _mousePos.Y;
            panel2.Location = new Point(panel2.Left + deltaX, panel2.Top /* + deltaY */);
        }
    }