add Root.show_full_animation for overriding app cycle speed (#558)

docs/widgets.md

@@ -328,6 +328,7 @@ displaying stale data in the event of e.g. connectivity issues.
 | `child` | `Widget` | Widget to render | **Y** |
 | `delay` | `int` | Frame delay in milliseconds | N |
 | `max_age` | `int` | Expiration time in seconds | N |
+| `show_full_animation` | `bool` | Request animation is shown in full, regardless of app cycle speed | N |
 
 
 

encode/encode.go

@@ -26,10 +26,11 @@ const (
 )
 
 type Screens struct {
-	roots  []render.Root
-	images []image.Image
-	delay  int32
-	MaxAge int32
+	roots             []render.Root
+	images            []image.Image
+	delay             int32
+	MaxAge            int32
+	ShowFullAnimation bool
 }
 
 type ImageFilter func(image.Image) (image.Image, error)
@@ -47,6 +48,7 @@ func ScreensFromRoots(roots []render.Root) *Screens {
 		if roots[0].MaxAge > 0 {
 			screens.MaxAge = roots[0].MaxAge
 		}
+		screens.ShowFullAnimation = roots[0].ShowFullAnimation
 	}
 	return &screens
 }

encode/encode_test.go

@@ -227,3 +227,27 @@ func TestScreensFromRoots(t *testing.T) {
 	assert.Equal(t, int32(4711), s.delay)
 	assert.Equal(t, int32(42), s.MaxAge)
 }
+
+func TestShowFullAnimation(t *testing.T) {
+	requestFull := `
+load("render.star", "render")
+def main():
+    return render.Root(show_full_animation=True, child=render.Box())
+`
+	app := runtime.Applet{}
+	require.NoError(t, app.Load("test.star", []byte(requestFull), nil))
+	roots, err := app.Run(map[string]string{})
+	assert.NoError(t, err)
+	assert.True(t, ScreensFromRoots(roots).ShowFullAnimation)
+
+	dontRequestFull := `
+load("render.star", "render")
+def main():
+    return render.Root(child=render.Box())
+`
+	app = runtime.Applet{}
+	require.NoError(t, app.Load("test.star", []byte(dontRequestFull), nil))
+	roots, err = app.Run(map[string]string{})
+	assert.NoError(t, err)
+	assert.False(t, ScreensFromRoots(roots).ShowFullAnimation)
+}

render/root.go

@@ -37,11 +37,12 @@ const (
 // DOC(Child): Widget to render
 // DOC(Delay): Frame delay in milliseconds
 // DOC(MaxAge): Expiration time in seconds
-//
+// DOC(ShowFullAnimation): Request animation is shown in full, regardless of app cycle speed
 type Root struct {
-	Child  Widget `starlark:"child,required"`
-	Delay  int32  `starlark:"delay"`
-	MaxAge int32  `starlark:"max_age"`
+	Child             Widget `starlark:"child,required"`
+	Delay             int32  `starlark:"delay"`
+	MaxAge            int32  `starlark:"max_age"`
+	ShowFullAnimation bool   `starlark:"show_full_animation"`
 
 	maxParallelFrames int
 	maxFrameCount     int