drafting

tracker/gioui/focus.go

@@ -0,0 +1,60 @@
+package gioui
+
+import (
+	"gioui.org/io/event"
+	"gioui.org/io/key"
+)
+
+type TagYieldFunc func(level int, tag event.Tag) bool
+
+func (t *Tracker) FocusNext(gtx C, maxLevel int) {
+	var focused, first, next event.Tag
+	yield := func(level int, tag event.Tag) bool {
+		if first == nil {
+			first = tag // remember the first tag
+		}
+		if focused != nil && level <= maxLevel {
+			next = tag
+			return false // we're done
+		}
+		if gtx.Source.Focused(tag) {
+			focused = tag
+		}
+		return true
+	}
+	if t.Tags(0, yield) {
+		t.Tags(0, yield) // run it twice to ensure we find the next tag after the focused one
+	}
+	if next == nil {
+		next = first // if we didn't find a next tag, use the first one
+	}
+	if next != nil {
+		gtx.Execute(key.FocusCmd{Tag: next})
+	}
+}
+
+func (t *Tracker) FocusPrev(gtx C, maxLevel int) {
+	var prev, first event.Tag
+	yield := func(level int, tag event.Tag) bool {
+		if first == nil {
+			first = tag // remember the first tag
+		}
+		if gtx.Source.Focused(tag) {
+			if prev != nil {
+				return false // we're done
+			}
+		} else if level <= maxLevel {
+			prev = tag
+		}
+		return true
+	}
+	if t.Tags(0, yield) {
+		t.Tags(0, yield) // run it twice to ensure we find the previous tag before the focused one
+	}
+	if prev == nil {
+		prev = first // if we didn't find a next tag, use the first one
+	}
+	if prev != nil {
+		gtx.Execute(key.FocusCmd{Tag: prev})
+	}
+}