111 lines
2.3 KiB
Go
111 lines
2.3 KiB
Go
package ui
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import (
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"fmt"
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)
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// A container which arranges its children in a list.
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type List struct {
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Items []*ListItem
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itemHeight int
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onInvalidate func(d Drawable)
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selected int
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}
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type ListItem struct {
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Content Drawable
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invalid bool
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}
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type SelectableDrawable interface {
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Drawable
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DrawWithSelected(ctx *Context, selected bool)
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}
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func NewList() *List {
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return &List{itemHeight: 1, selected: -1}
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}
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func (list *List) OnInvalidate(onInvalidate func(d Drawable)) {
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list.onInvalidate = onInvalidate
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}
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func (list *List) Invalidate() {
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for _, item := range list.Items {
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item.Content.Invalidate()
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}
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if list.onInvalidate != nil {
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list.onInvalidate(list)
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}
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}
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func (list *List) Draw(ctx *Context) {
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for i, item := range list.Items {
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if !item.invalid {
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continue
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}
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subctx := ctx.Subcontext(0, i, ctx.Width(), list.itemHeight)
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if content, ok := item.Content.(SelectableDrawable); ok {
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content.DrawWithSelected(subctx, i == list.selected)
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} else {
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item.Content.Draw(subctx)
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}
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}
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}
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func (list *List) Add(child Drawable) {
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list.Items = append(list.Items, &ListItem{Content: child, invalid: true})
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child.OnInvalidate(list.childInvalidated)
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list.Invalidate()
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}
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func (list *List) Remove(child Drawable) {
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for i, item := range list.Items {
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if item.Content == child {
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list.Items = append(list.Items[:i], list.Items[i+1:]...)
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child.OnInvalidate(nil)
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list.Invalidate()
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return
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}
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}
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panic(fmt.Errorf("Attempted to remove unknown child"))
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}
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func (list *List) Set(items []Drawable) {
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for _, item := range list.Items {
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item.Content.OnInvalidate(nil)
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}
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list.Items = make([]*ListItem, len(items))
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for i, item := range items {
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list.Items[i] = &ListItem{Content: item, invalid: true}
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item.OnInvalidate(list.childInvalidated)
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}
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list.Invalidate()
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}
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func (list *List) Select(index int) {
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if index >= len(list.Items) || index < 0 {
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panic(fmt.Errorf("Attempted to select unknown child"))
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}
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list.selected = index
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list.Invalidate()
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}
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func (list *List) ItemHeight(height int) {
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list.itemHeight = height
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list.Invalidate()
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}
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func (list *List) childInvalidated(child Drawable) {
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for _, item := range list.Items {
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if item.Content == child {
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item.invalid = true
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if list.onInvalidate != nil {
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list.onInvalidate(list)
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}
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return
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}
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}
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panic(fmt.Errorf("Attempted to invalidate unknown child"))
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}
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