Add clock example

examples/clock/main.go

@@ -0,0 +1,126 @@
+// Example clock demonstrates the use of goroutines and tomo.Do() to provide
+// live-updating information.
+package main
+
+import "time"
+import "math"
+import "image"
+import "image/color"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/nasin"
+import "git.tebibyte.media/tomo/objects"
+import "git.tebibyte.media/tomo/tomo/theme"
+import "git.tebibyte.media/tomo/tomo/canvas"
+import "git.tebibyte.media/tomo/objects/layouts"
+
+type Application struct {
+	clockFace *ClockFace
+	timeLabel *objects.Label
+}
+
+func (this *Application) Describe () nasin.ApplicationDescription {
+	return nasin.ApplicationDescription {
+		Name: "Clock",
+		ID:   "xyz.holanet.TomoClockExample",
+	}
+}
+
+func (this *Application) Init () error {
+	window, err := nasin.NewApplicationWindow(this, image.Rect(0, 0, 128, 160))
+	if err != nil { return err }
+
+	this.clockFace = NewClockFace()
+	this.timeLabel = objects.NewLabel("")
+	this.timeLabel.SetAlign(tomo.AlignMiddle, tomo.AlignMiddle)
+	container := objects.NewOuterContainer (
+		layouts.NewGrid([]bool { true }, []bool { true, false }),
+		this.clockFace,
+		this.timeLabel)
+	window.SetRoot(container)
+
+	go func () {
+		for {
+			tomo.Do(this.updateTime)
+			time.Sleep(time.Second)
+		}
+	} ()
+
+	window.OnClose(tomo.Stop)
+	window.Show()
+	return nil
+}
+
+func (this *Application) updateTime () {
+	now := time.Now()
+	this.clockFace.SetTime(now)
+	this.timeLabel.SetText(now.Format(time.DateTime))
+}
+
+func main () {
+	nasin.RunApplication(&Application { })
+}
+
+type ClockFace struct {
+	tomo.CanvasBox
+	time time.Time
+}
+
+func NewClockFace () *ClockFace {
+	box := &ClockFace {
+		CanvasBox: tomo.NewCanvasBox(),
+	}
+	theme.Apply(box, theme.R("nasin", "ClockFace", ""))
+	box.SetDrawer(box)
+	return box
+}
+
+// TODO move ClockFace to objects
+
+func (this *ClockFace) SetTime (when time.Time) {
+	this.time = when
+	this.Invalidate()
+}
+
+func (this *ClockFace) Draw (destination canvas.Canvas) {
+	pen := destination.Pen()
+	pen.Fill(color.Transparent)
+	pen.Rectangle(destination.Bounds())
+
+	for hour := 0; hour < 12; hour ++ {
+		radialLine (
+			destination,
+			theme.ColorForeground,
+			0.8, 0.9, float64(hour) / 6 * math.Pi)
+	}
+
+	second := float64(this.time.Second())
+	minute := float64(this.time.Minute()) + second / 60
+	hour   := float64(this.time.Hour())   + minute / 60
+
+	radialLine(destination, theme.ColorForeground, 0, 0.5, (hour   - 3)  / 6  * math.Pi)
+	radialLine(destination, theme.ColorForeground, 0, 0.7, (minute - 15) / 30 * math.Pi)
+	radialLine(destination, theme.ColorAccent,     0, 0.7, (second - 15) / 30 * math.Pi)
+}
+
+func radialLine (
+	destination canvas.Canvas,
+	source color.Color,
+	inner  float64,
+	outer  float64,
+	theta  float64,
+) {
+	pen := destination.Pen()
+	bounds := destination.Bounds()
+	width  := float64(bounds.Dx()) / 2
+	height := float64(bounds.Dy()) / 2
+	min := bounds.Min.Add(image.Pt (
+		int(math.Cos(theta) * inner * width + width),
+		int(math.Sin(theta) * inner * height + height)))
+	max := bounds.Min.Add(image.Pt (
+		int(math.Cos(theta) * outer * width + width),
+		int(math.Sin(theta) * outer * height + height)))
+	
+	pen.Stroke(source)
+	pen.StrokeWeight(1)
+	pen.Path(min, max)
+}