added parameters to configure the color palette

.vscode/launch.json

@@ -12,7 +12,9 @@
         "SLIDESHOW_DIRECTORY": "/home/velvettear/images",
         "SLIDESHOW_RESOLUTION": "600x1024",
         "SLIDESHOW_LOGLEVEL": "debug",
-        "SLIDESHOW_PALETTE": "/tmp/slideshow.palette"
+        "SLIDESHOW_PALETTE": "/tmp/.slideshow.palette",
+        "SLIDESHOW_PALETTE_ALGORITHM": "wsm",
+        "SLIDESHOW_PALETTE_COLORS": "32"
       },
       "console": "integratedTerminal"
     },
@@ -26,7 +28,9 @@
         "SLIDESHOW_INTERVAL": "10",
         "SLIDESHOW_DIRECTORY": "/home/velvettear/images",
         "SLIDESHOW_LOGLEVEL": "debug",
-        "SLIDESHOW_PALETTE": "/tmp/slideshow.palette"
+        "SLIDESHOW_PALETTE": "/tmp/.slideshow.palette",
+        "SLIDESHOW_PALETTE_ALGORITHM": "wsm",
+        "SLIDESHOW_PALETTE_COLORS": "16"
       },
       "console": "integratedTerminal"
     }

README.md

@@ -11,13 +11,15 @@ a simple cli application to start a background image slideshow using 'feh'.
 
 configuration is entirely done via environment variables.
 
-| variable             | default           | description                                                |
-| -------------------- | ----------------- | -----------------------------------------------------------|
-| SLIDESHOW_INTERVAL   | 60                | the interval of the slideshow in seconds                   |
-| SLIDESHOW_DIRECTORY  | "$HOME"           | path to a directory containing images                      | 
-| SLIDESHOW_RESOLUTION |                   | the resolution to which images are scaled (i.e. 1920x1080) | 
-| SLIDESHOW_PALETTE    |                   | path to a file where the color palette will be stored      |
-| SLIDESHOW_LOGLEVEL   | "info"            | the log level                                              |
+| variable                    | default           | description                                                |
+| --------------------------- | ----------------- | -----------------------------------------------------------|
+| SLIDESHOW_INTERVAL          | 60                | the interval of the slideshow in seconds                   |
+| SLIDESHOW_DIRECTORY         | "$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_PALETTE_ALGORITHM | "wsm"             | the algorithm used to generate the color palette           |
+| SLIDESHOW_PALETTE_COLORS    | 16                | the amount of colors generated                             |
+| SLIDESHOW_LOGLEVEL          | "info"            | the log level                                              |
 
 **note:**  
 if no resolution is set the images will be displayed as they are (without any scaling).
@@ -28,4 +30,13 @@ if no resolution is set the images will be displayed as they are (without any sc
 - `info`
 - `warning`
 - `error`
-- `fatal`
+- `fatal`
+
+## color palette
+
+**available algorithms:**  
+
+- `wsm`
+- `wu`
+
+for more information regarding the color palette see [color-thief](https://github.com/kennykarnama/color-thief).

internal/config/config.go

@@ -12,16 +12,18 @@ import (
 var Interval time.Duration
 var Directory string
 var Resolution string
-var Palette string
+var PaletteFile string
+var PaletteAlgorithm int
+var PaletteColors int
 
 // initialize the config
 func Initialize() {
 	loggo.SetLogLevelByName(os.Getenv("SLIDESHOW_LOGLEVEL"))
-	tmp, _ := strconv.Atoi(os.Getenv("SLIDESHOW_INTERVAL"))
-	if tmp <= 0 {
-		tmp = 60
+	tmpInt, _ := strconv.Atoi(os.Getenv("SLIDESHOW_INTERVAL"))
+	if tmpInt <= 0 {
+		tmpInt = 60
 	}
-	Interval = time.Duration(tmp) * time.Second
+	Interval = time.Duration(tmpInt) * time.Second
 	Directory = os.Getenv("SLIDESHOW_DIRECTORY")
 	if len(Directory) == 0 {
 		tmp, error := os.UserHomeDir()
@@ -52,7 +54,18 @@ func Initialize() {
 			loggo.Fatal("encountered an error parsing the configured height '" + height + "'")
 		}
 	}
-	Palette = os.Getenv("SLIDESHOW_PALETTE")
+	PaletteFile = os.Getenv("SLIDESHOW_PALETTE")
+	tmpString := os.Getenv("SLIDESHOW_PALETTE_ALGORITHM")
+	if strings.ToLower(tmpString) == "wu" {
+		PaletteAlgorithm = 0
+	} else {
+		PaletteAlgorithm = 1
+	}
+	tmpInt, _ = strconv.Atoi(os.Getenv("SLIDESHOW_PALETTE_COLORS"))
+	if tmpInt <= 0 {
+		tmpInt = 16
+	}
+	PaletteColors = tmpInt
 }
 
 // check if a resolution has been specified
@@ -60,7 +73,7 @@ func IsResolutionSet() bool {
 	return len(Resolution) > 0
 }
 
-// check if a socket has been set
+// check if a color palette should be generated
 func IsPaletteSet() bool {
-	return len(Palette) > 0
+	return len(PaletteFile) > 0
 }

internal/slideshow/palette.go

@@ -32,27 +32,28 @@ func exportPalette(colors []color.Color) {
 		tmp = "SLIDESHOW_COLOR" + tmp
 		palette += tmp + "=\"" + rgbToHex(color) + "\""
 	}
-	error := os.WriteFile(config.Palette, []byte(palette), 0775)
+	error := os.WriteFile(config.PaletteFile, []byte(palette), 0775)
 	if error != nil {
 		loggo.ErrorTimed("encountered an error exporting a color palette", timestamp, error.Error())
 	} else {
-		loggo.DebugTimed("exported color palette to filesystem", timestamp, "path: "+config.Palette)
+		loggo.DebugTimed("exported color palette to filesystem", timestamp, "path: "+config.PaletteFile)
 	}
 }
 
 // extract the given amount of dominant colors of raw image bytes
-func getColorPaletteRaw(data []byte, amount int) ([]color.Color, error) {
+func getColorPaletteRaw(data []byte) ([]color.Color, error) {
 	var colors []color.Color
 	if !config.IsPaletteSet() {
 		return colors, nil
 	}
 	timestamp := time.Now().UnixMilli()
+	amount := config.PaletteColors
 	img, _, error := image.Decode(bytes.NewReader(data))
 	if error != nil {
 		loggo.ErrorTimed("encountered an error decoding the provided raw image bytes to an image", timestamp, error.Error())
 		return colors, error
 	}
-	colors, error = color_thief.GetPalette(img, amount, 0)
+	colors, error = color_thief.GetPalette(img, amount, config.PaletteAlgorithm)
 	if error != nil {
 		loggo.ErrorTimed("encountered an error generating the color palette from raw image bytes", timestamp, "colors: "+strconv.Itoa(amount))
 	} else {
@@ -62,13 +63,14 @@ func getColorPaletteRaw(data []byte, amount int) ([]color.Color, error) {
 }
 
 // extract the given amount of dominant colors of an image
-func getColorPalette(image string, amount int) ([]color.Color, error) {
+func getColorPalette(image string) ([]color.Color, error) {
 	var colors []color.Color
 	if !config.IsPaletteSet() {
 		return colors, nil
 	}
 	timestamp := time.Now().UnixMilli()
-	colors, error := color_thief.GetPaletteFromFile(image, amount, 0)
+	amount := config.PaletteColors
+	colors, error := color_thief.GetPaletteFromFile(image, amount, config.PaletteAlgorithm)
 	if error != nil {
 		loggo.ErrorTimed("encountered an error generating the color palette from image", timestamp, "image: "+image, "colors: "+strconv.Itoa(amount))
 	} else {

internal/slideshow/slideshow.go

@@ -42,9 +42,9 @@ func Start() {
 			}
 			data = tmp
 			scaleTime = time.Since(scaleTimestamp)
-			palette, _ = getColorPaletteRaw(data, 16)
+			palette, _ = getColorPaletteRaw(data)
 		} else {
-			palette, _ = getColorPalette(image, 16)
+			palette, _ = getColorPalette(image)
 		}
 		if sleepTime > 0 {
 			loggo.Debug("sleeping for " + strconv.FormatInt(sleepTime.Milliseconds(), 10) + "ms")

slideshow.service

@@ -10,6 +10,8 @@ Environment="SLIDESHOW_DIRECTORY=$HOME"
 Environment="SLIDESHOW_RESOLUTION=1920x1080"
 Environment="SLIDESHOW_LOGLEVEL=info"
 Environment="SLIDESHOW_PALETTE=/tmp/.slideshow.palette"
+Environment="SLIDESHOW_PALETTE_ALGORITHM=wsm"
+Environment="SLIDESHOW_PALETTE_COLORS=16"
 ExecStart=/opt/slideshow/slideshow
 
 [Install]