remove redundant code

captcha.go

@@ -16,16 +16,6 @@
 // base64Captcha is used for fast development of RESTful APIs, web apps and backend services in Go. give a string identifier to the package and it returns with a base64-encoding-png-string
 package base64Captcha
 
-import (
-	"math/rand"
-	"time"
-)
-
-func init() {
-	//init rand seed
-	rand.Seed(time.Now().UnixNano())
-}
-
 // Captcha captcha basic information.
 type Captcha struct {
 	Driver Driver

const.go

@@ -1,5 +1,10 @@
 package base64Captcha
 
+const idLen = 20
+
+// idChars are characters allowed in captcha id.
+var idChars = []byte(TxtNumbers + TxtAlphabet)
+
 const (
 	imageStringDpi = 72.0
 	//TxtNumbers chacters for numbers.

item_digit.go

@@ -32,13 +32,12 @@ type ItemDigit struct {
 //NewItemDigit create a instance of item-digit
 func NewItemDigit(width int, height int, dotCount int, maxSkew float64) *ItemDigit {
 	itemDigit := &ItemDigit{width: width, height: height, dotCount: dotCount, maxSkew: maxSkew}
-
-	itemDigit.Paletted = image.NewPaletted(image.Rect(0, 0, width, height), randomPalette(dotCount))
-
+	//init image.Paletted
+	itemDigit.Paletted = image.NewPaletted(image.Rect(0, 0, width, height), createRandPaletteColors(dotCount))
 	return itemDigit
 }
 
-func randomPalette(dotCount int) color.Palette {
+func createRandPaletteColors(dotCount int) color.Palette {
 	p := make([]color.Color, dotCount+1)
 	// Transparent color.
 	p[0] = color.RGBA{0xFF, 0xFF, 0xFF, 0x00}

random_math.go

@@ -6,8 +6,14 @@ import (
 	"math"
 	"math/rand"
 	"strings"
+	"time"
 )
 
+func init() {
+	//init rand seed
+	rand.Seed(time.Now().UnixNano())
+}
+
 //RandText create random text.
 func RandText(size int, sourceChars string) string {
 	if size >= len(sourceChars) {
@@ -90,3 +96,12 @@ func randBytes(n int) []byte {
 	}
 	return b[:n]
 }
+
+// RandomId returns a new random id key string.
+func RandomId() string {
+	b := randomBytesMod(idLen, byte(len(idChars)))
+	for i, c := range b {
+		b[i] = idChars[c]
+	}
+	return string(b)
+}