Add color calibration functionality and cleanup a bit

server/einkimage.go

@@ -69,6 +69,40 @@ func ConvertToEInkImage(src image.Image, colorSpace ColorSpace) []byte {
 	return einkImage
 }
 
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func GenerateCalibrationImage(width, height int, colorSpace ColorSpace) []byte {
+	var einkImage []byte
+
+	colorCount := len(colorSpace)
+
+	// calculate number of rows and columns (sideLength)
+	sideLengthFloat := math.Sqrt(float64(colorCount))
+	sideLength := int(sideLengthFloat)
+	if float64(sideLength) != sideLengthFloat {
+		sideLength = sideLength + 1
+	}
+
+	rowSpacing := height / sideLength
+	columnSpacing := width / sideLength
+
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			row := y / rowSpacing
+			column := x / columnSpacing
+			colorIndex := min(colorCount-1, row*sideLength+column)
+			einkImage = append(einkImage, colorSpace[colorIndex].Code)
+		}
+	}
+
+	return packBytesIntoNibbles(einkImage)
+}
+
 func packBytesIntoNibbles(input []byte) []byte {
 	// input length must divisible by 2
 

server/main.go

@@ -63,6 +63,22 @@ type ImageProperties struct {
 	ColorSpace    ColorSpace `json:"color_space"`
 }
 
+func calibrationImage(w http.ResponseWriter, r *http.Request) {
+	var imageProps ImageProperties
+	err := json.NewDecoder(r.Body).Decode(&imageProps)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	data := GenerateCalibrationImage(imageProps.Width, imageProps.Height, imageProps.ColorSpace)
+
+	fmt.Printf("Bytes to send: %+v\n", len(data))
+
+	w.Header().Set("Content-Length", strconv.Itoa(len(data)))
+	w.Write(data)
+}
+
 func fetchImage(w http.ResponseWriter, r *http.Request) {
 	var imageProps ImageProperties
 	err := json.NewDecoder(r.Body).Decode(&imageProps)
@@ -120,8 +136,9 @@ func main() {
 	router.Get("/{name}", requestHandler)
 
 	router.Group(func(r chi.Router) {
-		r.Use(basicAuth)
+		// r.Use(basicAuth)
 		r.Post("/fetchImage", fetchImage)
+		r.Post("/calibrationImage", calibrationImage)
 	})
 
 	// Start the HTTP server on port 8080 and log any errors