Creating scrollbars

Creating scrollbars is simple, right? Well, building one from scratch requires some head scratching and a feeling of deja vu. The best advise is to do it once and never again. However, in a recent project, the graphics for the scrollbar were quite unique and didn’t easily fit into any prebuilt component. The thumb track was a fixed size and the gutter was a little bit…well… bendy.

The key thing in a scrollbar is to work out the ratio that is needed to move the target movieclip (which typically would sit underneath a mask with the same bounds of the scrollbox). This needs to account for the size of the scrollbox. When the thumb track is at the top of the box, we want the position to be relative to the top of the movieclip. However, when the thumb track is at the bottom of the scrollbox, we want it to be relative to the foot of the movieclip. So some maths is involved which I will run through tomorrow.