515a8b56f6
Extract the vertical scrolling ability into its own Scrollable struct that can be embedded and reused across any ui element that relies on scrolling. Signed-off-by: Koni Marti <koni.marti@gmail.com> Acked-by: Robin Jarry <robin@jarry.cc>
68 lines
1.2 KiB
Go
68 lines
1.2 KiB
Go
package widgets
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// Scrollable implements vertical scrolling
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type Scrollable struct {
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scroll int
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height int
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elems int
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}
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func (s *Scrollable) Scroll() int {
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return s.scroll
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}
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func (s *Scrollable) PercentVisible() float64 {
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if s.elems <= 0 {
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return 1.0
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}
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return float64(s.height) / float64(s.elems)
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}
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func (s *Scrollable) PercentScrolled() float64 {
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if s.elems <= 0 {
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return 1.0
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}
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return float64(s.scroll) / float64(s.elems)
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}
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func (s *Scrollable) NeedScrollbar() bool {
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needScrollbar := true
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if s.PercentVisible() >= 1.0 {
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needScrollbar = false
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}
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return needScrollbar
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}
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func (s *Scrollable) UpdateScroller(height, elems int) {
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s.height = height
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s.elems = elems
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}
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func (s *Scrollable) EnsureScroll(selectingIdx int) {
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if selectingIdx < 0 {
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return
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}
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maxScroll := s.elems - s.height
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if maxScroll < 0 {
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maxScroll = 0
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}
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if selectingIdx >= s.scroll && selectingIdx < s.scroll+s.height {
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if s.scroll > maxScroll {
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s.scroll = maxScroll
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}
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return
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}
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if selectingIdx >= s.scroll+s.height {
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s.scroll = selectingIdx - s.height + 1
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} else if selectingIdx < s.scroll {
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s.scroll = selectingIdx
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}
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if s.scroll > maxScroll {
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s.scroll = maxScroll
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}
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}
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