Implement dynamic exec displays

Signed-off-by: Knut Ahlers <knut@ahlers.me>

cmd/streamdeck/display_exec.go

@@ -11,21 +11,25 @@ import (
 	"os"
 	"os/exec"
 	"strings"
+	"time"
 
 	"github.com/golang/freetype"
 	"github.com/golang/freetype/truetype"
 	"github.com/pkg/errors"
+	log "github.com/sirupsen/logrus"
 	"golang.org/x/image/font"
 	"golang.org/x/image/math/fixed"
 )
 
 func init() {
-	registerDisplayElement("exec", displayElementCommand{})
+	registerDisplayElement("exec", &displayElementExec{})
 }
 
-type displayElementCommand struct{}
+type displayElementExec struct {
+	running bool
+}
 
-func (d displayElementCommand) Display(idx int, attributes map[string]interface{}) error {
+func (d displayElementExec) Display(idx int, attributes map[string]interface{}) error {
 	var (
 		err error
 		img draw.Image = image.NewRGBA(image.Rect(0, 0, sd.IconSize(), sd.IconSize()))
@@ -107,7 +111,35 @@ func (d displayElementCommand) Display(idx int, attributes map[string]interface{
 	return errors.Wrap(sd.FillImage(idx, img), "Unable to set image")
 }
 
-func (displayElementCommand) drawText(c *freetype.Context, text string, textColor color.Color, fontsize float64, border int) error {
+func (d *displayElementExec) StartLoopDisplay(idx int, attributes map[string]interface{}) error {
+	d.running = true
+
+	var interval = 5 * time.Second
+	if v, ok := attributes["interval"].(int); ok {
+		interval = time.Duration(v) * time.Second
+	}
+
+	go func() {
+		for tick := time.NewTicker(interval); ; <-tick.C {
+			if !d.running {
+				return
+			}
+
+			if err := d.Display(idx, attributes); err != nil {
+				log.WithError(err).Error("Unable to refresh element")
+			}
+		}
+	}()
+
+	return nil
+}
+
+func (d *displayElementExec) StopLoopDisplay() error {
+	d.running = false
+	return nil
+}
+
+func (displayElementExec) drawText(c *freetype.Context, text string, textColor color.Color, fontsize float64, border int) error {
 	c.SetSrc(image.NewUniform(color.RGBA{0x0, 0x0, 0x0, 0x0})) // Transparent for text size guessing
 
 	var (
@@ -140,7 +172,7 @@ func (displayElementCommand) drawText(c *freetype.Context, text string, textColo
 	return err
 }
 
-func (displayElementCommand) getImageFromDisk(filename string) (image.Image, error) {
+func (displayElementExec) getImageFromDisk(filename string) (image.Image, error) {
 	f, err := os.Open(filename)
 	if err != nil {
 		return nil, errors.Wrap(err, "Unable to open image")
@@ -155,7 +187,7 @@ func (displayElementCommand) getImageFromDisk(filename string) (image.Image, err
 	return img, nil
 }
 
-func (displayElementCommand) loadFont() (*truetype.Font, error) {
+func (displayElementExec) loadFont() (*truetype.Font, error) {
 	fontRaw, err := ioutil.ReadFile(userConfig.RenderFont)
 	if err != nil {
 		return nil, errors.Wrap(err, "Unable to read font file")

cmd/streamdeck/main.go

@@ -23,8 +23,9 @@ var (
 
 	currentBrightness int
 
-	userConfig config
-	activePage page
+	userConfig  config
+	activePage  page
+	activeLoops []refreshingDisplayElement
 
 	sd *streamdeck.Client
 
@@ -130,6 +131,14 @@ func main() {
 }
 
 func togglePage(page string) error {
+	// Reset potentially running looped elements
+	for _, l := range activeLoops {
+		if err := l.StopLoopDisplay(); err != nil {
+			return errors.Wrap(err, "Unable to stop element refresh")
+		}
+	}
+	activeLoops = nil
+
 	activePage = userConfig.Pages[page]
 	sd.ClearAllKeys()
 

cmd/streamdeck/registry.go

@@ -15,6 +15,11 @@ type displayElement interface {
 	Display(idx int, attributes map[string]interface{}) error
 }
 
+type refreshingDisplayElement interface {
+	StartLoopDisplay(idx int, attributes map[string]interface{}) error
+	StopLoopDisplay() error
+}
+
 var (
 	registeredActions             = map[string]reflect.Type{}
 	registeredActionsLock         sync.Mutex
@@ -53,7 +58,17 @@ func callDisplayElement(idx int, kd keyDefinition) error {
 		return errors.Errorf("Unknown display type %q", kd.Display.Type)
 	}
 
-	inst := reflect.New(t).Interface().(displayElement)
+	var inst interface{}
+	if t.Kind() == reflect.Ptr {
+		inst = reflect.New(t.Elem()).Interface()
+	} else {
+		inst = reflect.New(t).Interface()
+	}
 
-	return inst.Display(idx, kd.Display.Attributes)
+	if t.Implements(reflect.TypeOf((*refreshingDisplayElement)(nil)).Elem()) {
+		activeLoops = append(activeLoops, inst.(refreshingDisplayElement))
+		return inst.(refreshingDisplayElement).StartLoopDisplay(idx, kd.Display.Attributes)
+	}
+
+	return inst.(displayElement).Display(idx, kd.Display.Attributes)
 }