Split up Create banner finction

nmslib.CreateBanner() now calls nmslib.GenRawBanner() for the
majority of processing createbanner now just calls the gen func
and saves the file.

GenRawBanner() returns an image.Image type for more processing by
another function. this will be used for upcoming features.

tests have been updated as needed

upddated go.mod and go.sum

glyphbanner.go

@@ -23,19 +23,40 @@ var opt int
 	* note first of the 2 bits sets the layout, the second bit sets the glyph color
 */
 func CreateBanner(portalhex string, savename string, opt int) (err error) {
+	out, err := GenRawBanner(portalhex, opt)
+	if err != nil {
+		return
+	}
+	gg.SavePNG(savename+".png", out)
+	//gg.SaveJPG(savename+".jpg", out, 50)
+	return
+}
+
+/*GenRawBanner - Returns image.Image of genorated image
+Requires 2 vars and returns image.Image (raw image data) and an error
+var portalex string: Portal Glyph hex string
+var opt int
+	00 sets horizontal banner in light mode [ 00 || 0 ]
+	01 sets horizontal banner in dark mode  [ 01 || 1 ]
+	10 sets vertical banner in light mode
+	11 sets vertical banner in dark mode
+
+	* note first of the 2 bits sets the layout, the second bit sets the glyph color
+*/
+func GenRawBanner(portalhex string, layout int) (portalbanner image.Image, err error) {
 	var GlyphHex [12]int64
 	var glyphImg [12]string
 	var mode string
 	var imgArray [12]image.Image
 
 	//Set light or dark mode glyphs
-	if opt == 00 || opt == 10 {
+	if layout == 00 || layout == 10 {
 		mode = "light"
-	} else if opt == 01 || opt == 11 {
+	} else if layout == 01 || layout == 11 {
 		mode = "dark"
 	} else {
-		// if opt is an invalid option (ie. not a 2 bit binary number default to classic mode/layout
-		opt = 0
+		// if layout is an invalid option (ie. not a 2 bit binary number default to classic mode/layout
+		layout = 0
 		mode = "light"
 	}
 
@@ -45,7 +66,7 @@ func CreateBanner(portalhex string, savename string, opt int) (err error) {
 		for i := 0; i < len(portalhex); i++ {
 			GlyphHex[i], err = strconv.ParseInt(portalhex[i:int(i+1)], 16, 16)
 			if err != nil {
-				return errors.New("string provided is not hexadecimal ([0-9][A-F])")
+				return nil, errors.New("string provided is not hexadecimal ([0-9][A-F])")
 			}
 		}
 
@@ -58,11 +79,11 @@ func CreateBanner(portalhex string, savename string, opt int) (err error) {
 		for k := 0; k < len(glyphImg); k++ {
 			data, err := Asset(glyphImg[k])
 			if err != nil {
-				return errors.New("can not load images from assets: " + glyphImg[k])
+				return nil, errors.New("can not load images from assets: " + glyphImg[k])
 			}
 			err = ioutil.WriteFile(NmsTemp+"/"+glyphImg[k], []byte(data), 0644)
 			if err != nil {
-				return errors.New("can not write file to temp directory")
+				return nil, errors.New("can not write file to temp directory")
 			}
 		}
 
@@ -70,7 +91,7 @@ func CreateBanner(portalhex string, savename string, opt int) (err error) {
 		for iter := 0; iter < 12; iter++ {
 			imgArray[iter], err = gg.LoadPNG(NmsTemp + "/" + glyphImg[iter])
 			if err != nil {
-				return errors.New("can not read glyph " + glyphImg[iter])
+				return nil, errors.New("can not read glyph " + glyphImg[iter])
 			}
 		}
 
@@ -78,28 +99,30 @@ func CreateBanner(portalhex string, savename string, opt int) (err error) {
 		// get image size of first glyph, all glyphs have the same X && Y dimension so we only need to measure one.
 		imgDim := imgArray[0].Bounds().Size()
 
+		//Set Layout
 		//classic horizontal layout
-		if opt == 01 || opt == 00 {
+		if layout == 01 || layout == 00 {
 			imgWidth := imgDim.X * 12
 			imgHeight := imgDim.Y
 			concat := gg.NewContext(imgWidth, imgHeight)
 			for a := 0; a < 12; a++ {
 				concat.DrawImage(imgArray[a], imgDim.X*a, 0)
 			}
-			concat.SavePNG(savename)
+			return concat.Image(), nil
 		}
+
 		//Vertical layout
-		if opt == 10 || opt == 11 {
+		if layout == 10 || layout == 11 {
 			imgWidth := imgDim.X
 			imgHeight := imgDim.Y * 12
 			concat := gg.NewContext(imgWidth, imgHeight)
 			for a := 0; a < 12; a++ {
 				concat.DrawImage(imgArray[a], 0, imgDim.Y*a)
 			}
-			concat.SavePNG(savename)
+			return concat.Image(), nil
 		}
 	} else {
-		return errors.New("portalcode must be exactly 12 chars")
+		return nil, errors.New("portalcode must be exactly 12 chars")
 	}
 	return
 }