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package gocui
import "math"
// returns start and height of scrollbar
// `max` is the maximum possible value of `position`
func calcScrollbar(listSize int, pageSize int, position int, scrollAreaSize int) (int, int) {
height := calcScrollbarHeight(listSize, pageSize, scrollAreaSize)
// assume we can't scroll past the last item
maxPosition := listSize - pageSize
if maxPosition <= 0 {
return 0, height
}
if position == maxPosition {
return scrollAreaSize - height, height
}
// we only want to show the scrollbar at the top or bottom positions if we're at the end. Hence the .Ceil (for moving the scrollbar once we scroll down) and the -1 (for pretending there's a smaller range than we actually have, with the above condition ensuring we snap to the bottom once we're at the end of the list)
start := int(math.Ceil(((float64(position) / float64(maxPosition)) * float64(scrollAreaSize-height-1))))
return start, height
}
func calcScrollbarHeight(listSize int, pageSize int, scrollAreaSize int) int {
if pageSize >= listSize {
return scrollAreaSize
}
return int((float64(pageSize) / float64(listSize)) * float64(scrollAreaSize))
}
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