How could I emulate a visual analogue scale (VAS) in Winforms?

Question

In Psychology, Visual Analogue Scales (VASs) are commonly used to collect subjective responses without overtly quantifying them. They don't have gradations; just end-points. The participant is asked to click a point on the line and the distance from the end is taken to be their response. In some cases, the location on the line is illustrated with a small 'tick' in the form of a perpendicular line, so that the participant may refine their choice before submitting it.

I'm building an experiment in C# and Windows Forms. As a lazy approach, I've used a horizontal scoll bar. This clearly isn't good enough though, so I was wondering what approach people would suggest I take.

Answer 1

Have you considered the Trackbar?

http://msdn.microsoft.com/en-us/library/system.windows.forms.trackbar.aspx

Answer 2

@asawyer's TrackBar solution is somewhat problematic without some extra code, because the control itself jumps LargeChange in the direction of your cursor when you click, so no matter what you set it to, it will never jump to exactly where the user clicked, which is important in a VAS.

For those not familiar with the Visual Analogue Scale, it is generally graded as a point between 0 and 100mm along a horizontal or vertical line.

A decent first cut approach is a TrackBar with a min of 0, max of 100, and a frequency of 1, small/large change of 1, with something like:

this.trackBar1.MouseDown += trackBar1_MouseDown;

// ...

void trackBar1_MouseDown(object sender, MouseEventArgs e)
{
    double leftDelta = e.Location.X - this.trackBar1.Location.X;
    this.trackBar1.Value = (int)(leftDelta / this.trackBar1.Size.Width * 100);
}

You'll probably want to take into account the little gutters on either side of the track bar to make this more exact, but this will get you on your feet. You could include buttons above the TrackBar with the Wong-Baker faces for pediatric patients, the buttons could set the value to various presets.