Question

hopefully this is an easy one!

I’m deriving from UserControl, and I am overriding OnPaint. I want this control to be scrollable, but all I want is to be able to get the value of the scroll bars and handle where to draw everything myself. I have set up the following:

// How the hell do I get this scrolling to not return to zero?
this.Scroll += new ScrollEventHandler(TimelineControl_Scroll);

this.HorizontalScroll.Enabled = true;
this.HorizontalScroll.Visible = true;
this.HorizontalScroll.Minimum = 0;

this.VerticalScroll.Enabled = false;
this.VerticalScroll.Visible = true;

this.AutoScroll = false;

I am seeing the new value of the scroll position. However, the scroll bars always return to zero. What am I doing wrong?

Answer 1

I cannot reverse-engineer what that code is trying to do. AutoScroll is your friend. Here’s an example:

public partial class UserControl1 : UserControl {
    public UserControl1() {
        InitializeComponent();
        this.SetStyle(ControlStyles.ResizeRedraw, true);
        this.AutoScroll = true;
        this.AutoScrollMinSize = new Size(1000, 0);
    }
    protected override void OnScroll(ScrollEventArgs se) {
        base.OnScroll(se);
        this.Invalidate();
    }
    protected override void OnPaint(PaintEventArgs e) {
        e.Graphics.TranslateTransform(this.AutoScrollPosition.X, this.AutoScrollPosition.Y);
        e.Graphics.DrawLine(Pens.Black, 0, 0, 1000, this.ClientSize.Height);
        base.OnPaint(e);
    }
}