aerc/lib/ui/stack.go

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package ui
import (
"fmt"
"github.com/gdamore/tcell"
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)
type Stack struct {
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children []Drawable
onInvalidate []func(d Drawable)
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}
func NewStack() *Stack {
return &Stack{}
}
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func (stack *Stack) OnInvalidate(onInvalidate func(d Drawable)) {
stack.onInvalidate = append(stack.onInvalidate, onInvalidate)
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}
func (stack *Stack) Invalidate() {
for _, fn := range stack.onInvalidate {
fn(stack)
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}
}
func (stack *Stack) Draw(ctx *Context) {
if len(stack.children) > 0 {
stack.Peek().Draw(ctx)
} else {
ctx.Fill(0, 0, ctx.Width(), ctx.Height(), ' ', tcell.StyleDefault)
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}
}
func (stack *Stack) Push(d Drawable) {
if len(stack.children) != 0 {
stack.Peek().OnInvalidate(nil)
}
stack.children = append(stack.children, d)
d.OnInvalidate(stack.invalidateFromChild)
stack.Invalidate()
}
func (stack *Stack) Pop() Drawable {
if len(stack.children) == 0 {
panic(fmt.Errorf("Tried to pop from an empty UI stack"))
}
d := stack.children[len(stack.children)-1]
stack.children = stack.children[:len(stack.children)-1]
stack.Invalidate()
d.OnInvalidate(nil)
if len(stack.children) != 0 {
stack.Peek().OnInvalidate(stack.invalidateFromChild)
}
return d
}
func (stack *Stack) Peek() Drawable {
if len(stack.children) == 0 {
panic(fmt.Errorf("Tried to peek from an empty stack"))
}
return stack.children[len(stack.children)-1]
}
func (stack *Stack) invalidateFromChild(d Drawable) {
stack.Invalidate()
}