refactor and add focus navigation to genres list

ui/widgets/focuslist.go

@@ -0,0 +1,195 @@
+package widgets
+
+import (
+	"sync"
+	"time"
+
+	"fyne.io/fyne/v2"
+	"fyne.io/fyne/v2/canvas"
+	"fyne.io/fyne/v2/container"
+	"fyne.io/fyne/v2/theme"
+	"fyne.io/fyne/v2/widget"
+)
+
+// FocusList extends List to be disabled so that the focus manager
+// considers it unfocusable, and adds utilities for handling our
+// own focus navigation on the rows directly (with FocusListRow
+type FocusList struct {
+	widget.List
+
+	mutex        sync.Mutex
+	itemForIndex map[widget.ListItemID]FocusListRow
+}
+
+type FocusListRow interface {
+	fyne.Focusable
+	ItemID() widget.ListItemID
+}
+
+func NewFocusList(len func() int, create func() fyne.CanvasObject, update func(widget.GridWrapItemID, fyne.CanvasObject)) *FocusList {
+	g := &FocusList{
+		List: widget.List{
+			Length:     len,
+			CreateItem: create,
+			UpdateItem: update,
+		},
+		itemForIndex: make(map[int]FocusListRow),
+	}
+	g.ExtendBaseWidget(g)
+	return g
+}
+
+var _ fyne.Disableable = (*FocusList)(nil)
+
+func (g *FocusList) Disabled() bool { return true }
+
+func (g *FocusList) Disable() {}
+
+func (g *FocusList) Enable() {}
+
+// MUST be called *before* updating the ListItemID field to the
+// new ItemID this row will be bound to.
+func (g *FocusList) SetItemForID(id widget.ListItemID, item FocusListRow) {
+	g.mutex.Lock()
+	if other, ok := g.itemForIndex[id]; ok && other == item {
+		delete(g.itemForIndex, other.ItemID())
+	}
+	g.itemForIndex[id] = item
+	g.mutex.Unlock()
+}
+
+func (g *FocusList) ClearItemForIDMap() {
+	g.itemForIndex = make(map[int]FocusListRow)
+}
+
+func (g *FocusList) FocusNeighbor(curItem widget.ListItemID, up bool) {
+	focusIdx := curItem + 1
+	if up {
+		focusIdx = curItem - 1
+	}
+	if focusIdx >= 0 && focusIdx < g.Length() {
+		g.ScrollTo(focusIdx)
+	}
+	g.mutex.Lock()
+	other, ok := g.itemForIndex[focusIdx]
+	g.mutex.Unlock()
+	if ok {
+		fyne.CurrentApp().Driver().CanvasForObject(g).Focus(other)
+	}
+}
+
+var _ fyne.Tappable = (*FocusListRowBase)(nil)
+var _ fyne.Widget = (*FocusListRowBase)(nil)
+var _ fyne.Focusable = (*FocusListRowBase)(nil)
+
+// Base type used for all list rows in widgets such as Tracklist, etc.
+type FocusListRowBase struct {
+	widget.BaseWidget
+
+	ListItemID widget.ListItemID
+	Content    fyne.CanvasObject
+	Selected   bool
+	Focused    bool
+
+	OnTapped        func()
+	OnDoubleTapped  func()
+	OnFocusNeighbor func(up bool) //TODO: func(up, selecting bool)
+
+	tappedAt      int64 // unixMillis
+	focusedRect   *canvas.Rectangle
+	selectionRect *canvas.Rectangle
+}
+
+func (l *FocusListRowBase) ItemID() widget.ListItemID {
+	return l.ListItemID
+}
+
+func (l *FocusListRowBase) EnsureUnfocused() {
+	if l.Focused {
+		fyne.CurrentApp().Driver().CanvasForObject(l).Unfocus()
+	}
+	l.Focused = false
+}
+
+// We implement our own double tapping so that the Tapped behavior
+// can be triggered instantly.
+func (l *FocusListRowBase) Tapped(*fyne.PointEvent) {
+	prevTap := l.tappedAt
+	l.tappedAt = time.Now().UnixMilli()
+	if l.tappedAt-prevTap < 300 {
+		if l.OnDoubleTapped != nil {
+			l.OnDoubleTapped()
+		}
+	} else {
+		if l.OnTapped != nil {
+			l.OnTapped()
+		}
+	}
+}
+
+func (l *FocusListRowBase) FocusGained() {
+	l.Focused = true
+	l.Refresh()
+}
+
+func (l *FocusListRowBase) FocusLost() {
+	l.Focused = false
+	l.Refresh()
+}
+
+func (l *FocusListRowBase) TypedKey(e *fyne.KeyEvent) {
+	/**
+	// TODO: enable shift+arrows for selection, but it's complicated to implement in the widgets
+	desktop, ok := fyne.CurrentApp().Driver().(desktop.Driver)
+	isSelecting := func() bool {
+		return ok && desktop.CurrentKeyModifiers()&fyne.KeyModifierShift != 0
+	}
+	*/
+	switch {
+	case e.Name == fyne.KeyUp:
+		if l.OnFocusNeighbor != nil {
+			l.OnFocusNeighbor(true)
+		}
+	case e.Name == fyne.KeyDown:
+		if l.OnFocusNeighbor != nil {
+			l.OnFocusNeighbor(false)
+		}
+	case e.Name == fyne.KeySpace:
+		if l.OnTapped != nil {
+			l.OnTapped()
+		}
+	case e.Name == fyne.KeyReturn || e.Name == fyne.KeyEnter:
+		if l.OnDoubleTapped != nil {
+			l.OnDoubleTapped()
+		} else if l.OnTapped != nil {
+			l.OnTapped()
+		}
+	}
+}
+
+func (l *FocusListRowBase) TypedRune(r rune) {
+}
+
+func (l *FocusListRowBase) Refresh() {
+	l.focusedRect.FillColor = theme.HoverColor()
+	l.focusedRect.Hidden = !l.Focused
+	l.selectionRect.FillColor = theme.SelectionColor()
+	l.selectionRect.Hidden = !l.Selected
+	l.BaseWidget.Refresh()
+}
+
+func (l *FocusListRowBase) CreateRenderer() fyne.WidgetRenderer {
+	if l.selectionRect == nil {
+		l.selectionRect = canvas.NewRectangle(theme.SelectionColor())
+		l.selectionRect.CornerRadius = theme.SelectionRadiusSize()
+		l.selectionRect.Hidden = !l.Selected
+	}
+	if l.focusedRect == nil {
+		l.focusedRect = canvas.NewRectangle(theme.HoverColor())
+		l.focusedRect.CornerRadius = theme.SelectionRadiusSize()
+		l.focusedRect.Hidden = !l.Focused
+	}
+	return widget.NewSimpleRenderer(
+		container.NewStack(l.selectionRect, l.focusedRect, l.Content),
+	)
+}