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package layout
import (
"container/list"
"errors"
"image"
"image/draw"
"github.com/faiface/gui/event"
)
type EventImageFlusher interface {
Event(pattern string, handler func(event string) bool)
Image() *image.RGBA
Flush(r image.Rectangle)
}
type LayerList struct {
event.Dispatch
dst EventImageFlusher
layers list.List
}
func NewLayerList(dst EventImageFlusher) *LayerList {
l := &LayerList{dst: dst}
dst.Event("", l.Happen)
l.Event("resize", func(evt string) bool {
var x1, y1, x2, y2 int
event.Sscan(evt, &x1, &y1, &x2, &y2)
for e := l.layers.Back(); e != nil; e = e.Prev() {
layer := e.Value.(*Layer)
rgba := image.NewRGBA(dst.Image().Bounds())
draw.Draw(rgba, layer.rgba.Bounds(), layer.rgba, layer.rgba.Bounds().Min, draw.Src)
layer.rgba = rgba
}
return false
})
r := dst.Image().Bounds()
l.Happen(event.Sprint("resize", r.Min.X, r.Min.Y, r.Max.X, r.Max.Y))
return l
}
func (l *LayerList) Push() *Layer {
layer := &Layer{
lst: l,
rgba: image.NewRGBA(l.dst.Image().Bounds()),
}
layer.elm = l.layers.PushFront(layer)
return layer
}
func (l *LayerList) Remove(layer *Layer) {
if layer.lst == nil {
panic(errors.New("layer: Remove: layer already removed"))
}
l.layers.Remove(layer.elm)
layer.lst = nil
}
func (l *LayerList) Front(layer *Layer) {
if layer.lst == nil {
panic(errors.New("layer: Front: layer removed"))
}
l.layers.MoveToFront(layer.elm)
}
func (l *LayerList) Flush(r image.Rectangle) {
if l.dst == nil {
panic(errors.New("layer: Flush: no destination"))
}
draw.Draw(l.dst.Image(), r, image.Transparent, r.Min, draw.Src)
for e := l.layers.Back(); e != nil; e = e.Prev() {
layer := e.Value.(*Layer)
draw.Draw(l.dst.Image(), r, layer.rgba, r.Min, draw.Over)
}
l.dst.Flush(r)
}
func (l *LayerList) Happen(event string) bool {
if l.Dispatch.Happen(event) {
return true
}
for e := l.layers.Front(); e != nil; e = e.Next() {
layer := e.Value.(*Layer)
if layer.Happen(event) {
return true
}
}
return false
}
type Layer struct {
event.Dispatch
lst *LayerList
elm *list.Element
rgba *image.RGBA
}
func (l *Layer) List() *LayerList {
return l.lst
}
func (l *Layer) Image() *image.RGBA {
return l.rgba
}
func (l *Layer) Flush(r image.Rectangle) {
if l.lst == nil {
panic(errors.New("layer: Flush: layer removed"))
}
l.lst.Flush(r)
}
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