initial commit

.gitignore

@@ -0,0 +1,2 @@
+./slideshow-api
+__debug_bin*

.vscode/launch.json

@@ -0,0 +1,23 @@
+{
+  "version": "0.0.1",
+  "configurations": [
+    {
+      "name": "slideshow-api-scaled",
+      "type": "go",
+      "request": "launch",
+      "mode": "auto",
+      "program": "${workspaceFolder}/main.go",
+      "env":{
+        "SLIDESHOW_ADDRESS": "0.0.0.0",
+        "SLIDESHOW_PORT": "3000",
+        "SLIDESHOW_DIRECTORY": "/home/velvettear/images",
+        "SLIDESHOW_SCANINTERVAL": "10",
+        "SLIDESHOW_RESOLUTION": "600x1024",
+        "SLIDESHOW_LOGLEVEL": "debug",
+        "SLIDESHOW_PALETTE_ALGORITHM": "wsm",
+        "SLIDESHOW_PALETTE_COLORS": "16"
+      },
+      "console": "integratedTerminal"
+    },
+  ]
+}

LICENSE.md

@@ -0,0 +1,20 @@
+# MIT License 
+**Copyright (c) 2023 Daniel Sommer \<daniel.sommer@velvettear.de\>**
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is furnished
+to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice (including the next
+paragraph) shall be included in all copies or substantial portions of the
+Software.
+
+**THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
+OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
+OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.**

README.md

@@ -0,0 +1,42 @@
+# slideshow
+
+a simple web server serving (scaled) images and color palettes for [slideshow](https://git.velvettear.de/velvettear/slideshow).
+
+## requirements
+
+- [ImageMagick](https://imagemagick.org/) (optional)
+
+## configuration
+
+configuration is entirely done via environment variables.
+
+| variable                    | default           | description                                                |
+| --------------------------- | ----------------- | -----------------------------------------------------------|
+| SLIDESHOW_ADDRESS           | "0.0.0.0"         | the listen address of the web server                       |
+| SLIDESHOW_PORT              | 3000              | the port of the web server                                 |
+| SLIDESHOW_DIRECTORY         | "$HOME"           | path to a directory containing images                      |
+| SLIDESHOW_SCANINTERVAL      | 60                | the interval for directory scans in seconds                |
+| SLIDESHOW_RESOLUTION        |                   | the resolution to which images are scaled (i.e. 1920x1080) | 
+| 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 `SLIDESHOW_RESOLUTION` is unset the images will served as they are (without any scaling).  
+
+**available log levels:**
+
+- `debug`
+- `info`
+- `warning`
+- `error`
+- `fatal`
+
+## color palette
+
+**available algorithms:**  
+
+- `wsm`
+- `wu`
+
+for more information regarding the color palette see [color-thief](https://github.com/kennykarnama/color-thief).

go.mod

@@ -0,0 +1,13 @@
+module git.velvettear.de/velvettear/slideshow
+
+go 1.21
+
+require git.velvettear.de/velvettear/loggo v0.0.0-20231113084149-980a00b4e084
+
+require (
+	github.com/fatih/color v1.16.0 // indirect
+	github.com/kennykarnama/color-thief v0.0.0-20230222041546-c1bf65ec0808
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	golang.org/x/sys v0.14.0 // indirect
+)

go.sum

@@ -0,0 +1,15 @@
+git.velvettear.de/velvettear/loggo v0.0.0-20231113084149-980a00b4e084 h1:13S20q+usZ+yJr2cxxOpnPrOd5+4PwCbQg56RuWSkKk=
+git.velvettear.de/velvettear/loggo v0.0.0-20231113084149-980a00b4e084/go.mod h1:Jjjno0vz7v1Y6tCnpQHnq2TVL2+5m7TXkmNNYYREIMo=
+github.com/fatih/color v1.16.0 h1:zmkK9Ngbjj+K0yRhTVONQh1p/HknKYSlNT+vZCzyokM=
+github.com/fatih/color v1.16.0/go.mod h1:fL2Sau1YI5c0pdGEVCbKQbLXB6edEj1ZgiY4NijnWvE=
+github.com/kennykarnama/color-thief v0.0.0-20230222041546-c1bf65ec0808 h1:9JJaKNm4eDnB/ad7rWfejfMw+1ufpchM8Eik9VcQzUQ=
+github.com/kennykarnama/color-thief v0.0.0-20230222041546-c1bf65ec0808/go.mod h1:9qLIEhoYLAXPjhQQpgR0nVnhJxNXBtAqRZAp2Dj87WQ=
+github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
+github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
+github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.14.0 h1:Vz7Qs629MkJkGyHxUlRHizWJRG2j8fbQKjELVSNhy7Q=
+golang.org/x/sys v0.14.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

internal/api/server.go

@@ -0,0 +1,64 @@
+package api
+
+import (
+	"encoding/json"
+	"net/http"
+	"strconv"
+
+	"git.velvettear.de/velvettear/loggo"
+	"git.velvettear.de/velvettear/slideshow/internal"
+	"git.velvettear.de/velvettear/slideshow/internal/config"
+)
+
+// start the web server
+func Run() {
+	address := config.ServerAddress + ":" + strconv.Itoa(config.ServerPort)
+	loggo.Info("starting web server...", "address: "+address)
+	registerHandlers()
+	error := http.ListenAndServe(address, nil)
+	if error != nil {
+		loggo.Fatal("encountered an error starting the web server", "address: "+address, error.Error())
+	}
+}
+
+// register the handlers
+func registerHandlers() {
+	http.HandleFunc("/", handleImageRequest)
+}
+
+// handle the request to '/image'
+func handleImageRequest(writer http.ResponseWriter, request *http.Request) {
+	if !internal.HasFoundImages() {
+		writer.WriteHeader(404)
+		return
+	}
+	name, data, error := internal.GetRandomImage()
+	if error != nil {
+		loggo.Error("encountered an error getting a random image", error.Error())
+		writer.WriteHeader(501)
+		writer.Write([]byte("encountered an internal server error (" + error.Error() + ")\n"))
+		return
+	}
+	palette, error := internal.GetColorPalette(data)
+	if error != nil {
+		writer.WriteHeader(501)
+		writer.Write([]byte("encountered an internal server error (" + error.Error() + ")\n"))
+		return
+	}
+	bytes, error := json.Marshal(struct {
+		Name    string
+		Palette string
+		Data    []byte
+	}{
+		name,
+		palette,
+		data,
+	})
+	if error != nil {
+		loggo.Error("encountered an error marshalling the json response", error.Error())
+		writer.WriteHeader(501)
+		writer.Write([]byte("encountered an internal server error (" + error.Error() + ")\n"))
+		return
+	}
+	writer.Write(bytes)
+}

internal/cache.go

@@ -0,0 +1,44 @@
+package internal
+
+import (
+	"image/color"
+	"strconv"
+)
+
+// the internally pre buffered (and scaled) image
+var cachedImage []byte
+
+// the internally pre buffered color palette
+var cachedPalette []byte
+
+// cache an image
+func cacheImage(image []byte) {
+	cachedImage = image
+}
+
+// cache a color palette
+func cachePalette(colors []color.Color) {
+	var palette string
+	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) + "\""
+	}
+	cachedPalette = []byte(palette)
+}
+
+// check if an image is cached
+func hasCachedImage() bool {
+	return len(cachedImage) > 0
+}
+
+// check if a color palette is cached
+func hasCachedColorPalette() bool {
+	return len(cachedPalette) > 0
+}

internal/config/config.go

@@ -0,0 +1,80 @@
+package config
+
+import (
+	"os"
+	"strconv"
+	"strings"
+	"time"
+
+	"git.velvettear.de/velvettear/loggo"
+)
+
+var ServerAddress string
+var ServerPort int
+var Directory string
+var ScanInterval time.Duration
+var Resolution string
+var PaletteAlgorithm int
+var PaletteColors int
+
+// initialize the config
+func Initialize() {
+	loggo.SetLogLevelByName(os.Getenv("SLIDESHOW_LOGLEVEL"))
+	ServerAddress = os.Getenv("SLIDESHOW_ADDRESS")
+	tmpInt, _ := strconv.Atoi(os.Getenv("SLIDESHOW_PORT"))
+	if tmpInt <= 0 {
+		tmpInt = 3000
+	}
+	ServerPort = tmpInt
+	Directory = os.Getenv("SLIDESHOW_DIRECTORY")
+	if len(Directory) == 0 {
+		tmp, error := os.UserHomeDir()
+		if error != nil {
+			loggo.Fatal("encountered an error getting the current user's home directory", error.Error())
+		}
+		Directory = tmp
+	}
+	stats, error := os.Stat(Directory)
+	if error != nil {
+		loggo.Fatal("encountered an error checking the directory '"+Directory+"'", error.Error())
+	}
+	if !stats.IsDir() {
+		loggo.Fatal("configured directory '" + Directory + "' is not a valid directory")
+	}
+	tmpInt, _ = strconv.Atoi(os.Getenv("SLIDESHOW_SCANINTERVAL"))
+	if tmpInt <= 0 {
+		tmpInt = 60
+	}
+	ScanInterval = time.Duration(tmpInt) * time.Second
+	Resolution = os.Getenv("SLIDESHOW_RESOLUTION")
+	if len(Resolution) > 0 {
+		width, height, found := strings.Cut(Resolution, "x")
+		if !found {
+			loggo.Fatal("encountered an error parsing the configured resolution, make sure to specify the format like '1920x1080'")
+		}
+		_, error = strconv.Atoi(width)
+		if error != nil {
+			loggo.Fatal("encountered an error parsing the configured width '" + width + "'")
+		}
+		_, error = strconv.Atoi(height)
+		if error != nil {
+			loggo.Fatal("encountered an error parsing the configured height '" + height + "'")
+		}
+	}
+	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
+func IsResolutionSet() bool {
+	return len(Resolution) > 0
+}

internal/palette.go

@@ -0,0 +1,65 @@
+package internal
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"image/color"
+	"strconv"
+	"time"
+
+	"git.velvettear.de/velvettear/loggo"
+	"git.velvettear.de/velvettear/slideshow/internal/config"
+	color_thief "github.com/kennykarnama/color-thief"
+)
+
+// extract the given amount of dominant colors of raw image bytes
+func GetColorPalette(data []byte) (string, error) {
+	var palette string
+	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 palette, error
+	}
+	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))
+		return palette, error
+	} else {
+		loggo.DebugTimed("generated color palette from raw image bytes", timestamp, "colors: "+strconv.Itoa(amount))
+	}
+	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 palette, nil
+}
+
+// extract the given amount of dominant colors of an image
+func getColorPalette(image string) ([]color.Color, error) {
+	var colors []color.Color
+	timestamp := time.Now().UnixMilli()
+	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 {
+		loggo.DebugTimed("generated color palette from image", timestamp, "image: "+image, "colors: "+strconv.Itoa(amount))
+	}
+	return colors, error
+}
+
+// parse rgb color values to hex
+func rgbToHex(color color.Color) string {
+	r, g, b, _ := color.RGBA()
+	return fmt.Sprintf("#%02x%02x%02x", uint8(r>>8), uint8(g>>8), uint8(b>>8))
+}

internal/scale.go

@@ -0,0 +1,43 @@
+package internal
+
+import (
+	"errors"
+	"io"
+	"os/exec"
+	"strings"
+	"time"
+
+	"git.velvettear.de/velvettear/loggo"
+	"git.velvettear.de/velvettear/slideshow/internal/config"
+)
+
+// scale an image
+func ScaleImage(image string) ([]byte, error) {
+	timestamp := time.Now().UnixMilli()
+	cmd := exec.Command("convert", image, "-resize", config.Resolution+"^", "-gravity", "center", "-extent", config.Resolution, "-")
+	stdout, stdoutError := cmd.StdoutPipe()
+	stderr, stderrError := cmd.StderrPipe()
+	var data []byte
+	cmd.Start()
+	if stdoutError != nil {
+		return data, stdoutError
+	}
+	if stderrError != nil {
+		return data, stdoutError
+	}
+	data, stdoutError = io.ReadAll(stdout)
+	if stdoutError != nil {
+		return data, stdoutError
+	}
+	errorBytes, stderrError := io.ReadAll(stderr)
+	if stderrError != nil {
+		return data, stdoutError
+	}
+	cmd.Wait()
+	errorMessage := strings.TrimSpace(string(errorBytes))
+	if len(errorMessage) > 0 {
+		return data, errors.New(errorMessage)
+	}
+	loggo.DebugTimed("successfully scaled image", timestamp, "image: "+image, "resolution: "+config.Resolution)
+	return data, nil
+}

internal/scanner.go

@@ -0,0 +1,80 @@
+package internal
+
+import (
+	"errors"
+	"io/fs"
+	"math/rand"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"git.velvettear.de/velvettear/loggo"
+	"git.velvettear.de/velvettear/slideshow/internal/config"
+)
+
+// slice of images
+var images []string
+
+// temporary slice of images
+var tmpImages []string
+
+// Scan the specified directory
+func Scan() {
+	timestamp := time.Now()
+	directory := config.Directory
+	loggo.Info("scanning directory for images and subdirectories...", "interval: "+strconv.FormatFloat(config.ScanInterval.Seconds(), 'f', 0, 64)+" seconds", "directory: "+directory)
+	filepath.WalkDir(directory, checkDirectory)
+	images = tmpImages
+	tmpImages = nil
+	loggo.InfoTimed("found "+strconv.Itoa(len(images))+" image(s)", timestamp.UnixMilli())
+	go scheduleRescan()
+}
+
+// check if images has been found
+func HasFoundImages() bool {
+	return len(images) > 0
+}
+
+// get a random image
+func GetRandomImage() (string, []byte, error) {
+	var name string
+	var data []byte
+	var error error
+	if len(images) == 0 {
+		return name, data, errors.New("no images have been found")
+	}
+	image := images[rand.Intn(len(images))]
+	if config.IsResolutionSet() {
+		data, error = ScaleImage(image)
+	} else {
+		data, error = os.ReadFile(image)
+	}
+	return image, data, error
+}
+
+// sleep the specified interval and then trigger a rescan of the specified directory
+func scheduleRescan() {
+	loggo.Debug("sleeping for " + strconv.FormatInt(config.ScanInterval.Milliseconds(), 10) + "ms before next scan...")
+	time.Sleep(config.ScanInterval)
+	Scan()
+}
+
+// add image files to the slice of images and subdirectoies to the watcher
+func checkDirectory(path string, dir fs.DirEntry, err error) error {
+	if err != nil {
+		return err
+	}
+	if dir.IsDir() || !isImage(path) {
+		return nil
+	}
+	tmpImages = append(tmpImages, path)
+	loggo.Debug("added image to temporary slice of images", path)
+	return nil
+}
+
+// check if a file is an image
+func isImage(file string) bool {
+	return strings.HasSuffix(file, ".jpeg") || strings.HasSuffix(file, ".jpg") || strings.HasSuffix(file, ".png")
+}

main.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"time"
+
+	"git.velvettear.de/velvettear/loggo"
+	"git.velvettear.de/velvettear/slideshow/internal"
+	"git.velvettear.de/velvettear/slideshow/internal/api"
+	"git.velvettear.de/velvettear/slideshow/internal/config"
+)
+
+func main() {
+	timestamp := time.Now().UnixMilli()
+	loggo.Info("slideshow-api is starting now...")
+	config.Initialize()
+	internal.Scan()
+	api.Run()
+	loggo.InfoTimed("slideshow-api is shutting down now!", timestamp)
+}

slideshow-api.service

@@ -0,0 +1,19 @@
+[Unit]
+Description=slideshow-api
+
+[Service]
+Type=simple
+User=velvettear
+Environment="DISPLAY=:0"
+Environment="SLIDESHOW_ADDRESS=0.0.0.0"
+Environment="SLIDESHOW_PORT=3000"
+Environment="SLIDESHOW_DIRECTORY=$HOME"
+Environment="SLIDESHOW_SCANINTERVAL=60"
+Environment="SLIDESHOW_RESOLUTION="
+Environment="SLIDESHOW_PALETTE_ALGORITHM=wsm"
+Environment="SLIDESHOW_PALETTE_COLORS=16"
+Environment="SLIDESHOW_LOGLEVEL=info"
+ExecStart=/opt/slideshow-api/slideshow-api
+
+[Install]
+WantedBy=multi-user.target