From e5ca1c346ef833a92ca7184f425fb3a4f2ee41ad Mon Sep 17 00:00:00 2001
From: Weilin Shi <934587911@qq.com>
Date: Wed, 8 Nov 2017 14:21:40 +0800
Subject: [PATCH] Add writeGIF API

---
 captcha.go      | 13 ++++++++++---
 captcha_test.go | 30 +++++++++++++++++++++++++-----
 2 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/captcha.go b/captcha.go
index 479682f..b885f47 100644
--- a/captcha.go
+++ b/captcha.go
@@ -9,13 +9,14 @@ import (
 	"image"
 	"image/color"
 	"image/draw"
+	"image/gif"
+	"image/jpeg"
 	"image/png"
 	"io"
 	"math"
 	"math/rand"
 	"strconv"
 	"time"
-	"image/jpeg"
 )
 
 const charPreset = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
@@ -76,17 +77,23 @@ type Data struct {
 }
 
 // WriteImage encodes image data and writes to an io.Writer.
-// It returns possible error from PNG encoding
+// It returns possible error from PNG encoding.
 func (data *Data) WriteImage(w io.Writer) error {
 	return png.Encode(w, data.img)
 }
 
 // WriteJPG encodes image data in JPEG format and writes to an io.Writer.
-// It returns possible error from JPEG encoding
+// It returns possible error from JPEG encoding.
 func (data *Data) WriteJPG(w io.Writer, o *jpeg.Options) error {
 	return jpeg.Encode(w, data.img, o)
 }
 
+// WriteGIF encodes image data in GIF format and writes to an io.Writer.
+// It returns possible error from GIF encoding.
+func (data *Data) WriteGIF(w io.Writer, o *gif.Options) error {
+	return gif.Encode(w, data.img, o)
+}
+
 func init() {
 	ttfFont, _ = freetype.ParseFont(ttf)
 }
diff --git a/captcha_test.go b/captcha_test.go
index 5e54cc5..f033346 100644
--- a/captcha_test.go
+++ b/captcha_test.go
@@ -2,13 +2,14 @@ package captcha
 
 import (
 	"bytes"
+	"errors"
 	"golang.org/x/image/font/gofont/goregular"
 	"image/color"
+	"image/gif"
+	"image/jpeg"
 	"math/rand"
 	"os"
 	"testing"
-	"errors"
-	"image/jpeg"
 )
 
 func TestNewCaptcha(t *testing.T) {
@@ -17,7 +18,10 @@ func TestNewCaptcha(t *testing.T) {
 		t.Fatal(err)
 	}
 	buf := new(bytes.Buffer)
-	data.WriteImage(buf)
+	err = data.WriteImage(buf)
+	if err != nil {
+		t.Fatal(err)
+	}
 }
 
 func TestSmallCaptcha(t *testing.T) {
@@ -33,7 +37,22 @@ func TestEncodeJPG(t *testing.T) {
 		t.Fatal(err)
 	}
 	buf := new(bytes.Buffer)
-	data.WriteJPG(buf, &jpeg.Options{70})
+	err = data.WriteJPG(buf, &jpeg.Options{Quality: 70})
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestEncodeGIF(t *testing.T) {
+	data, err := New(150, 50)
+	if err != nil {
+		t.Fatal(err)
+	}
+	buf := new(bytes.Buffer)
+	err = data.WriteGIF(buf, &gif.Options{})
+	if err != nil {
+		t.Fatal(err)
+	}
 }
 
 func TestNewCaptchaOptions(t *testing.T) {
@@ -73,7 +92,8 @@ func TestCovNilFontError(t *testing.T) {
 	ttfFont = temp
 }
 
-type errReader struct {}
+type errReader struct{}
+
 func (errReader) Read(_ []byte) (int, error) {
 	return 0, errors.New("")
 }