Table of Contents
Notes and Rules
Notes about things which I learn during experiments with interfaces
Touch Interfaces
Scrolling in Drag mode
Scrolling in drag mode may be provided by a special scrollbar widget.
It indeed has to behave differently from the mouse scrollbar.
Allowing the user a comfortable movement on thick scrollbar
In Drag mode it has to be larger than the usual scrollbar. It may start as a thin line and expand on drag-in. On drag-out it may become thin again.
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Alowing fast and Casual navigation
There are solution where the scrollView is started to scroll down, when user moves to the bottom of the scroll-control and scroll up when the user is moving to the upper end. The speed increases when the user moves closer to the end of control. Those solutions are not good at all, because you always have to wait some time until the control comes to its position. Or the speed may become to large, so you have to react fast when you reach the right position.
Better map the whole widget height to the height of the ScrollView. Compute the positon on scrollControl in percent and scroll to this position. This allows nearly immediate navigation to the chosen point in scrollview. This allows fast and casual navigation depending on the movent-speed of the finger.
Use some offset to not to force the user to move the finger to the last pixel in order to reach the end.
