export color palette to a file

.vscode/launch.json

@@ -11,7 +11,8 @@
         "SLIDESHOW_INTERVAL": "10",
         "SLIDESHOW_DIRECTORY": "/home/velvettear/images",
         "SLIDESHOW_RESOLUTION": "600x1024",
-        "SLIDESHOW_LOGLEVEL": "debug"
+        "SLIDESHOW_LOGLEVEL": "debug",
+        "SLIDESHOW_PALETTE": "/tmp/slideshow.palette"
       },
       "console": "integratedTerminal"
     }

README.md

@@ -16,6 +16,7 @@ configuration is entirely done via environment variables.
 | SLIDESHOW_INTERVAL   | 60                | the interval of the slideshow in seconds                   |
 | SLIDESHOW_DIRECTORY  | "$HOME"           | path to a directory containing images                      | 
 | SLIDESHOW_RESOLUTION |                   | the resolution to which images are scaled (i.e. 1920x1080) | 
+| SLIDESHOW_PALETTE    |                   | path to a file where the color palette will be stored      |
 | SLIDESHOW_LOGLEVEL   | "info"            | the log level                                              |
 
 **note:**  

internal/config/config.go

@@ -12,6 +12,7 @@ import (
 var Interval time.Duration
 var Directory string
 var Resolution string
+var Palette string
 
 // initialize the config
 func Initialize() {
@@ -50,11 +51,16 @@ func Initialize() {
 		if error != nil {
 			loggo.Fatal("encountered an error parsing the configured height '" + height + "'")
 		}
-		return
 	}
+	Palette = os.Getenv("SLIDESHOW_PALETTE")
 }
 
 // check if a resolution has been specified
 func IsResolutionSet() bool {
 	return len(Resolution) > 0
 }
+
+// check if a socket has been set
+func IsPaletteSet() bool {
+	return len(Palette) > 0
+}

internal/slideshow/palette.go

@@ -3,18 +3,61 @@ package slideshow
 import (
 	"fmt"
 	"image/color"
+	"os"
+	"strconv"
 	"time"
 
 	"git.velvettear.de/velvettear/loggo"
+	"git.velvettear.de/velvettear/slideshow/internal/config"
 	color_thief "github.com/kennykarnama/color-thief"
 )
 
-// extract the color palette from an image
+// write the base16 color palette to a file
-func GetPalette(image string) ([]color.Color, error) {
+func exportPalette() error {
+	if !config.IsPaletteSet() {
+		return nil
+	}
+	var palette string
+	colors, error := getColorPalette(image, 16)
+	if error != nil {
+		return error
+	}
+	for index, color := range colors {
+		if index > 0 {
+			palette += "\n"
+		}
+		tmp := strconv.Itoa(index)
+		if len(tmp) < 2 {
+			tmp = "0" + tmp
+		}
+		tmp = "SLIDESHOW_COLOR" + tmp
+		palette += tmp + "=\"" + rgbToHex(color) + "\""
+	}
+	return os.WriteFile(config.Palette, []byte(palette), 0775)
+}
+
+// get the base16 color palette from an image
+func GetBase16Colors(image string) (string, error) {
+	var base16 string
+	colors, error := getColorPalette(image, 16)
+	if error != nil {
+		return base16, error
+	}
+	for index, color := range colors {
+		if index > 0 {
+			base16 += "\n"
+		}
+		base16 += rgbToHex(color)
+	}
+	return base16, nil
+}
+
+// extract the given amount of dominant colors an image
+func getColorPalette(image string, amount int) ([]color.Color, error) {
 	timestamp := time.Now().UnixMilli()
-	colors, error := color_thief.GetPaletteFromFile(image, 16, 0)
+	colors, error := color_thief.GetPaletteFromFile(image, amount, 0)
 	if error == nil {
-		loggo.DebugTimed("generated color palette from image", timestamp, "image: "+image)
+		loggo.DebugTimed("generated color palette from image", timestamp, "image: "+image, "colors: "+strconv.Itoa(amount))
 	}
 	return colors, error
 }

internal/slideshow/slideshow.go

@@ -13,6 +13,10 @@ import (
 	"git.velvettear.de/velvettear/slideshow/internal/watcher"
 )
 
+// currently set image
+var image string
+
+// remember last shown image
 var previousImage string
 
 // start the slideshow
@@ -23,7 +27,6 @@ func Start() {
 	scaleImages := config.IsResolutionSet()
 	for {
 		var data []byte
-		var image string
 		for {
 			image = watcher.GetRandomImage()
 			if image != previousImage {
@@ -40,6 +43,10 @@ func Start() {
 			data = tmp
 			scaleTime = time.Since(scaleTimestamp)
 		}
+		error := exportPalette()
+		if error != nil {
+			loggo.Error("encountered an error exporting the color palette for image", "image: "+image, error.Error())
+		}
 		if sleepTime > 0 {
 			loggo.Debug("sleeping for " + strconv.FormatInt(sleepTime.Milliseconds(), 10) + "ms")
 			time.Sleep(sleepTime)
@@ -129,3 +136,8 @@ func setBackgroundPiped(data []byte) error {
 	}
 	return nil
 }
+
+// get currently shown image
+func GetImage() string {
+	return image
+}