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package gui
import (
"image"
"image/color"
"image/draw"
"git.samanthony.xyz/share"
)
var _ Scheme = Scroller{}
type Scroller struct {
Background color.Color
Length int
ChildHeight int
Offset int
Gap int
Vertical bool
}
func (s Scroller) redraw(drw draw.Image, bounds image.Rectangle) {
col := s.Background
if col == nil {
col = image.Black
}
draw.Draw(drw, bounds, image.NewUniform(col), image.ZP, draw.Src)
}
func clamp(val, a, b int) int {
if a > b {
if val < b {
return b
}
if val > a {
return a
}
} else {
if val > b {
return b
}
if val < a {
return a
}
}
return val
}
func (s Scroller) Partition(bounds image.Rectangle) []image.Rectangle {
items := s.Length
ch := s.ChildHeight
gap := s.Gap
ret := make([]image.Rectangle, items)
Y := bounds.Min.Y + s.Offset + gap
for i := 0; i < items; i++ {
r := image.Rect(bounds.Min.X+gap, Y, bounds.Max.X-gap, Y+ch)
ret[i] = r
Y += ch + gap
}
return ret
}
func (s Scroller) Intercept(parent Env) Env {
lastResize := share.NewVal[image.Rectangle]()
img := share.NewVal[draw.Image]()
mouseOver := share.NewVal[bool]()
lastResize.Set <- image.Rectangle{}
img.Set <- image.NewRGBA(image.Rectangle{})
mouseOver.Set <- false
return newEnv(parent,
func(event Event, events chan<- Event) {
switch event := event.(type) {
case MoMove:
mouseOver.Set <- event.Point.In(lastResize.Get())
case MoScroll:
if !mouseOver.Get() {
break
}
oldoff := s.Offset
v := s.Length*s.ChildHeight + ((s.Length + 1) * s.Gap)
bounds := lastResize.Get()
if s.Vertical {
h := bounds.Dx()
s.Offset = clamp(s.Offset+event.Point.X*16, h-v, 0)
} else {
h := bounds.Dy()
s.Offset = clamp(s.Offset+event.Point.Y*16, h-v, 0)
}
if oldoff != s.Offset {
m := img.Get()
s.redraw(m, m.Bounds())
events <- Resize{bounds}
}
case Resize:
lastResize.Set <- event.Rectangle
m := image.NewRGBA(event.Rectangle)
img.Set <- m
s.redraw(m, m.Bounds())
events <- event
default:
events <- event
}
},
func(drawFunc func(draw.Image) image.Rectangle, drawChan chan<- func(draw.Image) image.Rectangle) {
m := img.Get()
if drawFunc(m).Intersect(m.Bounds()) != image.ZR {
drawChan <- func(drw draw.Image) image.Rectangle {
bounds := lastResize.Get()
draw.Draw(drw, bounds, m, bounds.Min, draw.Over)
return m.Bounds()
}
}
},
func() {
lastResize.Close()
img.Close()
mouseOver.Close()
})
}
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