ToolKit: added PlayImageUntil and now Animation uses PlayImageUntil

examples/animation/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"flag"
 	"image"
+	"image/color"
 	"time"
 
 	"github.com/fogleman/gg"
@@ -57,16 +58,16 @@ func NewAnimation(sz image.Point) *Animation {
 	}
 }
 
-func (a *Animation) Next() (image.Image, time.Duration, error) {
+func (a *Animation) Next() (image.Image, <-chan time.Time, error) {
 	defer a.updatePosition()
 
-	a.ctx.SetRGB(0, 0, 0)
+	a.ctx.SetColor(color.Black)
 	a.ctx.Clear()
 
 	a.ctx.DrawCircle(float64(a.position.X), float64(a.position.Y), float64(a.stroke))
-	a.ctx.SetRGB(1, 0, 0)
+	a.ctx.SetColor(color.RGBA{255, 0, 0, 0})
 	a.ctx.Fill()
-	return a.ctx.Image(), time.Millisecond * 50, nil
+	return a.ctx.Image(), time.After(time.Millisecond * 50), nil
 }
 
 func (a *Animation) updatePosition() {

toolkit.go

@@ -44,7 +44,7 @@ func (tk *ToolKit) PlayImage(i image.Image, delay time.Duration) error {
 }
 
 type Animation interface {
-	Next() (image.Image, time.Duration, error)
+	Next() (image.Image, <-chan time.Time, error)
 }
 
 // PlayAnimation play the image during the delay returned by Next, until an err
@@ -52,15 +52,15 @@ type Animation interface {
 func (tk *ToolKit) PlayAnimation(a Animation) error {
 	var err error
 	var i image.Image
-	var d time.Duration
+	var n <-chan time.Time
 
 	for {
-		i, d, err = a.Next()
+		i, n, err = a.Next()
 		if err != nil {
 			break
 		}
 
-		if err := tk.PlayImage(i, d); err != nil {
+		if err := tk.PlayImageUntil(i, n); err != nil {
 			return err
 		}
 	}
@@ -72,6 +72,20 @@ func (tk *ToolKit) PlayAnimation(a Animation) error {
 	return err
 }
 
+// PlayImageUntil draws the given image until is notified to stop
+func (tk *ToolKit) PlayImageUntil(i image.Image, notify <-chan time.Time) error {
+	defer func() {
+		<-notify
+	}()
+
+	if tk.Transform != nil {
+		i = tk.Transform(i)
+	}
+
+	draw.Draw(tk.Canvas, tk.Canvas.Bounds(), i, image.ZP, draw.Over)
+	return tk.Canvas.Render()
+}
+
 // PlayImages draws a sequence of images during the given delays, the len of
 // images should be equal to the len of delay. If loop is true the function
 // loops over images until a true is sent to the returned chan