Split into category packages; module github.com/ZacharyZhang-NY/MujicaUI

layout/scroll_area.go

@@ -0,0 +1,66 @@
+package layout
+
+import (
+	"github.com/egoist/mygo/ui"
+
+	"github.com/ZacharyZhang-NY/MujicaUI/core"
+	"github.com/ZacharyZhang-NY/MujicaUI/theme"
+)
+
+// ScrollDirection is the way a ScrollArea scrolls. The zero value is vertical.
+type ScrollDirection int
+
+const (
+	ScrollVertical ScrollDirection = iota
+	ScrollHorizontal
+	ScrollBoth
+)
+
+// ScrollAreaOptions configure a ScrollArea.
+type ScrollAreaOptions struct {
+	Direction ScrollDirection
+	// Label names the region for assistive technology.
+	Label string
+}
+
+// ScrollArea scrolls children; state keeps and sets the offset, nil keeps it by place.
+func ScrollArea(c *ui.Context, state *ui.ScrollState, opts ScrollAreaOptions, children func()) *ui.Element {
+	if children == nil {
+		panic("mujica: ScrollArea needs children")
+	}
+	var e *ui.Element
+	switch opts.Direction {
+	case ScrollVertical:
+		e = ui.Scroll(c)
+	case ScrollHorizontal:
+		e = ui.ScrollHorizontal(c)
+	case ScrollBoth:
+		e = ui.ScrollBoth(c)
+	default:
+		panic("mujica: invalid ScrollDirection")
+	}
+	if state == nil {
+		state = ui.Local(e, "scroll_area.state", func() ui.ScrollState { return ui.ScrollState{} })
+	}
+	e.TrackScroll(state)
+	overflow := state.MaxX > 0 || state.MaxY > 0
+	if overflow {
+		e.Focusable()
+	}
+	focus := core.Tokens(c).Focus
+	// The ring goes inside, past the focus gap: areas often fill a clipped pane.
+	e.FocusRing(false).DrawOver(func(p *ui.Painter, r ui.Rect) {
+		if overflow != (state.MaxX > 0 || state.MaxY > 0) {
+			// Layout changed the overflow: rebuild so the focus stop follows it.
+			c.Invalidate()
+		}
+		if e.FocusVisible() {
+			in := theme.FocusGap + theme.FocusWidth/2
+			p.Stroke(ui.Rect{X: r.X + in, Y: r.Y + in, W: r.W - 2*in, H: r.H - 2*in}, focus, theme.ControlRadius, theme.FocusWidth)
+		}
+	})
+	if opts.Label != "" {
+		e.Label(opts.Label)
+	}
+	return e.Children(children)
+}