81 lines
2.2 KiB
Go
81 lines
2.2 KiB
Go
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package ui
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import (
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"opslag.de/schobers/geom"
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)
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type Scrollbar struct {
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ControlBase
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Orientation Orientation
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Content float32
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Offset float32
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handle ScrollbarHandle
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startDragOffset float32
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}
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func BuildScrollbar(o Orientation, fn func(s *Scrollbar)) *Scrollbar {
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var s = &Scrollbar{Orientation: o, Content: 0, Offset: 0}
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s.handle.OnDragStart(func(_ Context, _ Control, _ geom.PointF32) {
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s.startDragOffset = s.Offset
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})
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s.handle.OnDragMove(func(_ Context, _ Control, start, move geom.PointF32) {
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var length = s.Orientation.SizeParallel(s.bounds)
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var handleMaxOffset = length - s.Orientation.SizeParallel(s.handle.bounds)
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var hidden = s.Content - length
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var offset = (s.Orientation.LengthParallel(move) - s.Orientation.LengthParallel(start)) / handleMaxOffset
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s.Offset = geom.Max32(0, geom.Min32(s.startDragOffset+offset*hidden, hidden))
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})
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fn(s)
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return s
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}
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func (s *Scrollbar) Arrange(ctx Context, bounds geom.RectangleF32, offset geom.PointF32) {
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s.ControlBase.Arrange(ctx, bounds, offset)
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s.updateBar(ctx)
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}
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func (s *Scrollbar) DesiredSize(ctx Context) geom.PointF32 {
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return s.Orientation.Pt(geom.NaN32(), ctx.Style().Dimensions.ScrollbarWidth)
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}
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func (s *Scrollbar) Handle(ctx Context, e Event) {
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s.handle.Handle(ctx, e)
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s.ControlBase.Handle(ctx, e)
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}
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func (s *Scrollbar) Render(ctx Context) {
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s.handle.Render(ctx)
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}
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func (s *Scrollbar) updateBar(ctx Context) {
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var length = s.Orientation.SizeParallel(s.bounds)
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var width = ctx.Style().Dimensions.ScrollbarWidth
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var handleLength = length
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var handleOffset = s.Orientation.LengthParallel(s.bounds.Min)
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if s.Content > length {
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handleLength = geom.Max32(2*width, length/s.Content)
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var hidden = s.Content - length
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var offset = geom.Min32(1, s.Offset/hidden)
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handleOffset = handleOffset + offset*(length-handleLength)
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}
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var min = s.Orientation.Pt(handleOffset, s.Orientation.LengthPerpendicular(s.bounds.Max)-width)
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s.handle.Arrange(ctx, s.Orientation.Rect(min, handleLength, width), s.offset)
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}
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type ScrollbarHandle struct {
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ControlBase
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}
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func (h *ScrollbarHandle) Render(ctx Context) {
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h.RenderBackground(ctx)
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p := ctx.Style().Palette
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fill := p.Primary
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if h.over {
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fill = p.PrimaryHighlight
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}
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ctx.Renderer().FillRectangle(h.bounds.Inset(1), fill)
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}
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