/
list.go
432 lines (370 loc) · 10.9 KB
/
list.go
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package widget
import (
"fmt"
"math"
"sync"
"fyne.io/fyne/v2"
"fyne.io/fyne/v2/canvas"
"fyne.io/fyne/v2/data/binding"
"fyne.io/fyne/v2/driver/desktop"
"fyne.io/fyne/v2/internal/widget"
"fyne.io/fyne/v2/theme"
)
// ListItemID uniquely identifies an item within a list.
type ListItemID = int
// Declare conformity with Widget interface.
var _ fyne.Widget = (*List)(nil)
// List is a widget that pools list items for performance and
// lays the items out in a vertical direction inside of a scroller.
// List requires that all items are the same size.
//
// Since: 1.4
type List struct {
BaseWidget
Length func() int
CreateItem func() fyne.CanvasObject
UpdateItem func(id ListItemID, item fyne.CanvasObject)
OnSelected func(id ListItemID)
OnUnselected func(id ListItemID)
scroller *widget.Scroll
selected []ListItemID
itemMin fyne.Size
offsetY float32
offsetUpdated func(fyne.Position)
}
// NewList creates and returns a list widget for displaying items in
// a vertical layout with scrolling and caching for performance.
//
// Since: 1.4
func NewList(length func() int, createItem func() fyne.CanvasObject, updateItem func(ListItemID, fyne.CanvasObject)) *List {
list := &List{BaseWidget: BaseWidget{}, Length: length, CreateItem: createItem, UpdateItem: updateItem}
list.ExtendBaseWidget(list)
return list
}
// NewListWithData creates a new list widget that will display the contents of the provided data.
//
// Since: 2.0
func NewListWithData(data binding.DataList, createItem func() fyne.CanvasObject, updateItem func(binding.DataItem, fyne.CanvasObject)) *List {
l := NewList(
data.Length,
createItem,
func(i ListItemID, o fyne.CanvasObject) {
item, err := data.GetItem(i)
if err != nil {
fyne.LogError(fmt.Sprintf("Error getting data item %d", i), err)
return
}
updateItem(item, o)
})
data.AddListener(binding.NewDataListener(l.Refresh))
return l
}
// CreateRenderer is a private method to Fyne which links this widget to its renderer.
func (l *List) CreateRenderer() fyne.WidgetRenderer {
l.ExtendBaseWidget(l)
if f := l.CreateItem; f != nil {
if l.itemMin.IsZero() {
l.itemMin = newListItem(f(), nil).MinSize()
}
}
layout := &fyne.Container{}
l.scroller = widget.NewVScroll(layout)
layout.Layout = newListLayout(l)
layout.Resize(layout.MinSize())
objects := []fyne.CanvasObject{l.scroller}
lr := newListRenderer(objects, l, l.scroller, layout)
return lr
}
// MinSize returns the size that this widget should not shrink below.
func (l *List) MinSize() fyne.Size {
l.ExtendBaseWidget(l)
return l.BaseWidget.MinSize()
}
// Select add the item identified by the given ID to the selection.
func (l *List) Select(id ListItemID) {
if len(l.selected) > 0 && id == l.selected[0] {
return
}
length := 0
if f := l.Length; f != nil {
length = f()
}
if id < 0 || id >= length {
return
}
old := l.selected
l.selected = []ListItemID{id}
defer func() {
if f := l.OnUnselected; f != nil && len(old) > 0 {
f(old[0])
}
if f := l.OnSelected; f != nil {
f(id)
}
}()
if l.scroller == nil {
return
}
y := (float32(id) * l.itemMin.Height) + (float32(id) * theme.SeparatorThicknessSize())
if y < l.scroller.Offset.Y {
l.scroller.Offset.Y = y
} else if y+l.itemMin.Height > l.scroller.Offset.Y+l.scroller.Size().Height {
l.scroller.Offset.Y = y + l.itemMin.Height - l.scroller.Size().Height
}
l.offsetUpdated(l.scroller.Offset)
l.Refresh()
}
// Unselect removes the item identified by the given ID from the selection.
func (l *List) Unselect(id ListItemID) {
if len(l.selected) == 0 {
return
}
l.selected = nil
l.Refresh()
if f := l.OnUnselected; f != nil {
f(id)
}
}
// Declare conformity with WidgetRenderer interface.
var _ fyne.WidgetRenderer = (*listRenderer)(nil)
type listRenderer struct {
widget.BaseRenderer
list *List
scroller *widget.Scroll
layout *fyne.Container
}
func newListRenderer(objects []fyne.CanvasObject, l *List, scroller *widget.Scroll, layout *fyne.Container) *listRenderer {
lr := &listRenderer{BaseRenderer: widget.NewBaseRenderer(objects), list: l, scroller: scroller, layout: layout}
lr.scroller.OnScrolled = l.offsetUpdated
return lr
}
func (l *listRenderer) Layout(size fyne.Size) {
l.scroller.Resize(size)
}
func (l *listRenderer) MinSize() fyne.Size {
return l.scroller.MinSize().Max(l.list.itemMin)
}
func (l *listRenderer) Refresh() {
if f := l.list.CreateItem; f != nil {
l.list.itemMin = newListItem(f(), nil).MinSize()
}
l.Layout(l.list.Size())
l.scroller.Refresh()
canvas.Refresh(l.list.super())
}
// Declare conformity with interfaces.
var _ fyne.Widget = (*listItem)(nil)
var _ fyne.Tappable = (*listItem)(nil)
var _ desktop.Hoverable = (*listItem)(nil)
type listItem struct {
BaseWidget
onTapped func()
background *canvas.Rectangle
child fyne.CanvasObject
hovered, selected bool
}
func newListItem(child fyne.CanvasObject, tapped func()) *listItem {
li := &listItem{
child: child,
onTapped: tapped,
}
li.ExtendBaseWidget(li)
return li
}
// CreateRenderer is a private method to Fyne which links this widget to its renderer.
func (li *listItem) CreateRenderer() fyne.WidgetRenderer {
li.ExtendBaseWidget(li)
li.background = canvas.NewRectangle(theme.HoverColor())
li.background.Hide()
objects := []fyne.CanvasObject{li.background, li.child}
return &listItemRenderer{widget.NewBaseRenderer(objects), li}
}
// MinSize returns the size that this widget should not shrink below.
func (li *listItem) MinSize() fyne.Size {
li.ExtendBaseWidget(li)
return li.BaseWidget.MinSize()
}
// MouseIn is called when a desktop pointer enters the widget.
func (li *listItem) MouseIn(*desktop.MouseEvent) {
li.hovered = true
li.Refresh()
}
// MouseMoved is called when a desktop pointer hovers over the widget.
func (li *listItem) MouseMoved(*desktop.MouseEvent) {
}
// MouseOut is called when a desktop pointer exits the widget.
func (li *listItem) MouseOut() {
li.hovered = false
li.Refresh()
}
// Tapped is called when a pointer tapped event is captured and triggers any tap handler.
func (li *listItem) Tapped(*fyne.PointEvent) {
if li.onTapped != nil {
li.selected = true
li.Refresh()
li.onTapped()
}
}
// Declare conformity with the WidgetRenderer interface.
var _ fyne.WidgetRenderer = (*listItemRenderer)(nil)
type listItemRenderer struct {
widget.BaseRenderer
item *listItem
}
// MinSize calculates the minimum size of a listItem.
// This is based on the size of the status indicator and the size of the child object.
func (li *listItemRenderer) MinSize() (size fyne.Size) {
itemSize := li.item.child.MinSize()
size = fyne.NewSize(itemSize.Width+theme.Padding()*3,
itemSize.Height+theme.Padding()*2)
return
}
// Layout the components of the listItem widget.
func (li *listItemRenderer) Layout(size fyne.Size) {
li.item.background.Resize(size)
li.item.child.Move(fyne.NewPos(theme.Padding()*2, theme.Padding()))
li.item.child.Resize(fyne.NewSize(size.Width-theme.Padding()*3, size.Height-theme.Padding()*2))
}
func (li *listItemRenderer) Refresh() {
if li.item.selected {
li.item.background.FillColor = theme.FocusColor()
li.item.background.Show()
} else if li.item.hovered {
li.item.background.FillColor = theme.HoverColor()
li.item.background.Show()
} else {
li.item.background.Hide()
}
li.item.background.Refresh()
canvas.Refresh(li.item.super())
}
// Declare conformity with Layout interface.
var _ fyne.Layout = (*listLayout)(nil)
type listLayout struct {
list *List
separators []fyne.CanvasObject
children []fyne.CanvasObject
itemPool *syncPool
visible map[ListItemID]*listItem
renderLock sync.Mutex
}
func newListLayout(list *List) fyne.Layout {
l := &listLayout{list: list, itemPool: &syncPool{}, visible: make(map[ListItemID]*listItem)}
list.offsetUpdated = l.offsetUpdated
return l
}
func (l *listLayout) Layout([]fyne.CanvasObject, fyne.Size) {
l.updateList()
}
func (l *listLayout) MinSize([]fyne.CanvasObject) fyne.Size {
if f := l.list.Length; f != nil {
separatorThickness := theme.SeparatorThicknessSize()
return fyne.NewSize(l.list.itemMin.Width,
(l.list.itemMin.Height+separatorThickness)*float32(f())-separatorThickness)
}
return fyne.NewSize(0, 0)
}
func (l *listLayout) getItem() *listItem {
item := l.itemPool.Obtain()
if item == nil {
if f := l.list.CreateItem; f != nil {
item = newListItem(f(), nil)
}
}
return item.(*listItem)
}
func (l *listLayout) offsetUpdated(pos fyne.Position) {
if l.list.offsetY == pos.Y {
return
}
l.list.offsetY = pos.Y
l.updateList()
}
func (l *listLayout) setupListItem(li *listItem, id ListItemID) {
previousIndicator := li.selected
li.selected = false
for _, s := range l.list.selected {
if id == s {
li.selected = true
break
}
}
if previousIndicator != li.selected {
li.Refresh()
}
if f := l.list.UpdateItem; f != nil {
f(id, li.child)
}
li.onTapped = func() {
l.list.Select(id)
}
}
func (l *listLayout) updateList() {
l.renderLock.Lock()
defer l.renderLock.Unlock()
separatorThickness := theme.SeparatorThicknessSize()
width := l.list.Size().Width
length := 0
if f := l.list.Length; f != nil {
length = f()
}
visibleItemCount := int(math.Ceil(float64(l.list.scroller.Size().Height)/float64(l.list.itemMin.Height+theme.SeparatorThicknessSize()))) + 1
offY := l.list.offsetY - float32(int(l.list.offsetY)%int(l.list.itemMin.Height+separatorThickness))
minRow := ListItemID(offY / (l.list.itemMin.Height + separatorThickness))
maxRow := ListItemID(fyne.Min(float32(minRow+visibleItemCount), float32(length)))
if l.list.UpdateItem == nil {
fyne.LogError("Missing UpdateCell callback required for List", nil)
}
wasVisible := l.visible
l.visible = make(map[ListItemID]*listItem)
var cells []fyne.CanvasObject
y := offY
size := fyne.NewSize(width, l.list.itemMin.Height)
for row := minRow; row < maxRow; row++ {
c, ok := wasVisible[row]
if !ok {
c = l.getItem()
if c == nil {
continue
}
}
c.Move(fyne.NewPos(0, y))
c.Resize(size)
l.setupListItem(c, row)
y += l.list.itemMin.Height + separatorThickness
l.visible[row] = c
cells = append(cells, c)
}
for id, old := range wasVisible {
if _, ok := l.visible[id]; !ok {
l.itemPool.Release(old)
}
}
l.children = cells
l.updateSeparators()
objects := l.children
objects = append(objects, l.separators...)
l.list.scroller.Content.(*fyne.Container).Objects = objects
}
func (l *listLayout) updateSeparators() {
if len(l.children) > 1 {
if len(l.separators) > len(l.children) {
l.separators = l.separators[:len(l.children)]
} else {
for i := len(l.separators); i < len(l.children); i++ {
l.separators = append(l.separators, NewSeparator())
}
}
} else {
l.separators = nil
}
separatorThickness := theme.SeparatorThicknessSize()
for i, child := range l.children {
if i == 0 {
continue
}
l.separators[i].Move(fyne.NewPos(0, child.Position().Y-separatorThickness))
l.separators[i].Resize(fyne.NewSize(l.list.Size().Width, separatorThickness))
l.separators[i].Show()
}
}