I have a pane that contains image content which changes during scrolling. The content is properly updated via a scrollwheel event because I implemented a wheel listener which repaints the image before setting the new scroll value.
However, when the user drags the scrollbar handle with the mouse, the image content was not being updated during the manual drag-scroll. So I implemented a timer which grabs the current scroll value and repaints the content given the new scroll position.
This solution however (despite 10 millisecond adjustments) results in a jumpy scroll experience. The image moves (without the necessary image adjustments) and then gets corrected after-the-fact every 10 milliseconds.
I had originally tried an adjustmentlistener, but it only gets the event after the handle is released. How can I live-update the pane content during a jscrollbar handle drag BEFORE the scrollbar machinery starts to simply move my content as if it was a static image? Can I somehow give the scrollbar machinery a clue that content has changed or something every time it tries to redraw the content? Or can I disable the scrollbar's ability to move the image and just rely on my timer to do it?
I would recommend that you add a ChangeListener to the JScrollBar's model, a BounderedRangeModel, and then based on the value of the model as well as its maximum and minimum, change your image. If you're swapping images, the easiest way to do this is by swapping a JLabel's ImageIcon.