小编给大家分享一下golang中如何实现给gif、png、jpeg图片添加文字水印，希望大家阅读完这篇文章之后都有所收获，下面让我们一起去探讨吧！
什么是golang
golang 是Google开发的一种静态强类型、编译型、并发型，并具有垃圾回收功能的编程语言，其语法与 C语言相近，但并不包括如枚举、异常处理、继承、泛型、断言、虚函数等功能。
添加水印示例
添加main文件：“watermark/main.go”
package mainimport ( "fmt" "watermark/textwatermark" )func main() { SavePath := "./kaf" str := textwatermark.FontInfo{18, "努力向上", textwatermark.TopLeft, 20, 20, 255, 255, 0, 255} arr := make([]textwatermark.FontInfo, 0) arr = append(arr, str) str2 := textwatermark.FontInfo{Size: 24, Message: "努力向上，涨工资", Position: textwatermark.TopLeft, Dx: 20, Dy: 40, R: 255, G: 255, B: 0, A: 255} arr = append(arr, str2) //加水印图片路径 // fileName := "123123.jpg" fileName := "17.gif" w := new(textwatermark.Water) w.Pattern = "2006/01/02" textwatermark.Ttf = "./wrzh.ttf" //字体路径 err := w.New(SavePath, fileName, arr) if err != nil { fmt.Println(err) }}golang添加水印包文件"watermark/textwatermark.go"
package textwatermarkimport ("errors""fmt""image""image/color""image/draw""image/gif""image/jpeg""image/png""io/ioutil""math/rand""os""time""github.com/golang/freetype")// 水印的位置const (TopLeft int = iotaTopRightBottomLeftBottomRightCenter)//字体路径var Ttf stringtype Water struct {Pattern string //增加按时间划分的子目录：默认没有时间划分的子目录}func (w *Water) New(SavePath, fileName string, typeface []FontInfo) error {var subPath stringsubPath = w.Patterndirs, err := createDir(SavePath, subPath)if err != nil {return err}imgfile, _ := os.Open(fileName)defer imgfile.Close()_, str, err := image.DecodeConfig(imgfile)if err != nil {return err}newName := fmt.Sprintf("%s%s.%s", dirs, getRandomString(10), str)if str == "gif" {err = gifFontWater(fileName, newName, typeface)} else {err = staticFontWater(fileName, newName, str, typeface)}return err}//gif图片水印func gifFontWater(file, name string, typeface []FontInfo) (err error) {imgfile, _ := os.Open(file)defer imgfile.Close()var err2 errorgifimg2, _ := gif.DecodeAll(imgfile)gifs := make([]*image.Paletted, 0)x0 := 0y0 := 0yuan := 0for k, gifimg := range gifimg2.Image {img := image.NewNRGBA(gifimg.Bounds())if k == 0 {x0 = img.Bounds().Dx()y0 = img.Bounds().Dy()}fmt.Printf("%v, %v\n", img.Bounds().Dx(), img.Bounds().Dy())if k == 0 && gifimg2.Image[k+1].Bounds().Dx() > x0 && gifimg2.Image[k+1].Bounds().Dy() > y0 {yuan = 1break}if x0 == img.Bounds().Dx() && y0 == img.Bounds().Dy() {for y := 0; y < img.Bounds().Dy(); y++ {for x := 0; x < img.Bounds().Dx(); x++ {img.Set(x, y, gifimg.At(x, y))}}img, err2 = common(img, typeface) //添加文字水印if err2 != nil {break}//定义一个新的图片调色板img.Bounds()：使用原图的颜色域，gifimg.Palette：使用原图的调色板p1 := image.NewPaletted(gifimg.Bounds(), gifimg.Palette)//把绘制过文字的图片添加到新的图片调色板上draw.Draw(p1, gifimg.Bounds(), img, image.ZP, draw.Src)//把添加过文字的新调色板放入调色板slicegifs = append(gifs, p1)} else {gifs = append(gifs, gifimg)}}if yuan == 1 {return errors.New("gif: image block is out of bounds")} else {if err2 != nil {return err2}//保存到新文件中newfile, err := os.Create(name)if err != nil {return err}defer newfile.Close()g1 := &gif.GIF{Image: gifs,Delay: gifimg2.Delay,LoopCount: gifimg2.LoopCount,}err = gif.EncodeAll(newfile, g1)return err}}//png,jpeg图片水印func staticFontWater(file, name, status string, typeface []FontInfo) (err error) {//需要加水印的图片imgfile, _ := os.Open(file)defer imgfile.Close()var staticImg image.Imageif status == "png" {staticImg, _ = png.Decode(imgfile)} else {staticImg, _ = jpeg.Decode(imgfile)}img := image.NewNRGBA(staticImg.Bounds())for y := 0; y < img.Bounds().Dy(); y++ {for x := 0; x < img.Bounds().Dx(); x++ {img.Set(x, y, staticImg.At(x, y))}}img, err = common(img, typeface) //添加文字水印if err != nil {return err}//保存到新文件中newfile, err := os.Create(name)if err != nil {return err}defer newfile.Close()if status == "png" {err = png.Encode(newfile, img)} else {err = jpeg.Encode(newfile, img, &jpeg.Options{100})}return err}//添加文字水印函数func common(img *image.NRGBA, typeface []FontInfo) (*image.NRGBA, error) {var err2 error//拷贝一个字体文件到运行目录fontBytes, err := ioutil.ReadFile(Ttf)if err != nil {err2 = errreturn nil, err2}font, err := freetype.ParseFont(fontBytes)if err != nil {err2 = errreturn nil, err2}errNum := 1Loop:for _, t := range typeface {info := t.Messagef := freetype.NewContext()f.SetDPI(108)f.SetFont(font)f.SetFontSize(t.Size)f.SetClip(img.Bounds())f.SetDst(img)f.SetSrc(image.NewUniform(color.RGBA{R: t.R, G: t.G, B: t.B, A: t.A}))//第一行的文字// pt := freetype.Pt(img.Bounds().Dx()-len(info)*4-20, img.Bounds().Dy()-100)first := 0two := 0switch int(t.Position) {case 0:first = t.Dxtwo = t.Dy + int(f.PointToFixed(t.Size)>>6)case 1:first = img.Bounds().Dx() - len(info)*4 - t.Dxtwo = t.Dy + int(f.PointToFixed(t.Size)>>6)case 2:first = t.Dxtwo = img.Bounds().Dy() - t.Dycase 3:first = img.Bounds().Dx() - len(info)*4 - t.Dxtwo = img.Bounds().Dy() - t.Dycase 4:first = (img.Bounds().Dx() - len(info)*4) / 2two = (img.Bounds().Dy() - t.Dy) / 2default:errNum = 0break Loop}// fmt.Printf("%v, %v, %v\n", first, two, info)pt := freetype.Pt(first, two)_, err = f.DrawString(info, pt)if err != nil {err2 = errbreak}}if errNum == 0 {err2 = errors.New("坐标值不对")}return img, err2}//定义添加的文字信息type FontInfo struct {Size float64 //文字大小Message string //文字内容Position int //文字存放位置Dx int //文字x轴留白距离Dy int //文字y轴留白距离R uint8 //文字颜色值RGBA中的R值G uint8 //文字颜色值RGBA中的G值B uint8 //文字颜色值RGBA中的B值A uint8 //文字颜色值RGBA中的A值}//生成图片名字func getRandomString(lenght int) string {str := "0123456789abcdefghijklmnopqrstuvwxyz"bytes := []byte(str)bytesLen := len(bytes)result := []byte{}r := rand.New(rand.NewSource(time.Now().UnixNano()))for i := 0; i < lenght; i++ {result = append(result, bytes[r.Intn(bytesLen)])}return string(result)}//检查并生成存放图片的目录func createDir(SavePath, subPath string) (string, error) {var dirs stringif subPath == "" {dirs = fmt.Sprintf("%s/", SavePath)} else {dirs = fmt.Sprintf("%s/%s/", SavePath, time.Now().Format(subPath))}_, err := os.Stat(dirs)if err != nil {err = os.MkdirAll(dirs, os.ModePerm)if err != nil {return "", err}}return dirs, nil}补充：golang基础--image/draw渲染图片、利用golang/freetype库在图片上生成文字
需求
在一张A4纸上，利用image/draw标准库生成4张二维码，和该二维码的客户信息
二维码生成利用到的库就是image/draw，通过draw.Draw进行写入
然后字体渲染利用了golang/freetype开源库
https://github.com/golang/freetype/blob/master/example/freetype/main.go
安装依赖
"github.com/golang/freetype""golang.org/x/image/font"以上的golang.org/x/image/font需要翻墙，如果不能翻墙利用如下方法也可以：
逻辑
通过os.Create("dst.jpg")生成一个最终的图片，该图片上画了4个二维码，和头部文字渲染
通过os.Open("/Users/zhiliao/zhiliao/gopro/go_safly/src/qr.png")去获取本地的一个二维码图片路径，然后通过png.Decode(file1)生成图片
修改二维码图片的尺寸resize.Resize(314, 314, img, resize.Lanczos3)
通过image.NewRGBA(image.Rect(0, 0, 827, 1169))生成一个RGBA结构体的矩形框，就好比是画布的概念
选渲染头部的客户信息字体，需要一个中文字体库，这个可以用Mac系统库的中文字体，或者自行下载ttf字体库，然后加载该字体
draw.Draw(jpg, jpg.Bounds(), bg, image.ZP, draw.Src)是进行设置渲染的参数，参数是画布、渲染开始的地方、图片来源、图片参数、渲染模式
然后就是设置baseline，我这里去掉了，然后就是划线，最后就是渲染字体，通过c.DrawString(s, pt)
接下来就是画4个二维码
draw.Draw(jpg, img.Bounds().Add(image.Pt(60, 150)), img, img.Bounds().Min, draw.Src) //截取图片的一部分draw.Draw(jpg, img.Bounds().Add(image.Pt(435, 150)), img, img.Bounds().Min, draw.Src) //截取图片的一部分draw.Draw(jpg, img.Bounds().Add(image.Pt(60, 610)), img, img.Bounds().Min, draw.Src) //截取图片的一部分draw.Draw(jpg, img.Bounds().Add(image.Pt(435, 610)), img, img.Bounds().Min, draw.Src) //截取图片的一部分最后通过png.Encode(file, jpg)输出到我们最终生成的图片
效果图
实例
package mainimport ("flag""fmt""github.com/gin-gonic/gin""github.com/golang/freetype""github.com/nfnt/resize""golang.org/x/image/font""image""image/draw""image/png""io/ioutil""log""net/http""os""strings")var (dpi = flag.Float64("dpi", 72, "screen resolution in Dots Per Inch")fontfile = flag.String("fontfile", "/Users/zhiliao/Downloads/ffffonts/simsun.ttf", "filename of the ttf font")hinting = flag.String("hinting", "none", "none | full")size = flag.Float64("size", 30, "font size in points")spacing = flag.Float64("spacing", 1.5, "line spacing (e.g. 2 means double spaced)")wonb = flag.Bool("whiteonblack", false, "white text on a black background"))var text = []string{"地支：沈阳市某区某镇某街道某楼某","姓名：王永飞","电话：1232131231232",}func main() {file, err := os.Create("dst.jpg")if err != nil {fmt.Println(err)}defer file.Close()file1, err := os.Open("/Users/zhiliao/zhiliao/gopro/go_safly/src/qr.png")if err != nil {fmt.Println(err)}defer file1.Close()img, _ := png.Decode(file1)//尺寸img = resize.Resize(314, 314, img, resize.Lanczos3)jpg := image.NewRGBA(image.Rect(0, 0, 827, 1169))fontRender(jpg)draw.Draw(jpg, img.Bounds().Add(image.Pt(60, 150)), img, img.Bounds().Min, draw.Src) //截取图片的一部分draw.Draw(jpg, img.Bounds().Add(image.Pt(435, 150)), img, img.Bounds().Min, draw.Src) //截取图片的一部分draw.Draw(jpg, img.Bounds().Add(image.Pt(60, 610)), img, img.Bounds().Min, draw.Src) //截取图片的一部分draw.Draw(jpg, img.Bounds().Add(image.Pt(435, 610)), img, img.Bounds().Min, draw.Src) //截取图片的一部分png.Encode(file, jpg)}func fontRender(jpg *image.RGBA) {flag.Parse()fontBytes, err := ioutil.ReadFile(*fontfile)if err != nil {log.Println(err)return}f, err := freetype.ParseFont(fontBytes)if err != nil {log.Println(err)return}fg, bg := image.Black, image.White//ruler := color.RGBA{0xdd, 0xdd, 0xdd, 0xff}//if *wonb {//fg, bg = image.White, image.Black//ruler = color.RGBA{0x22, 0x22, 0x22, 0xff}//}draw.Draw(jpg, jpg.Bounds(), bg, image.ZP, draw.Src)c := freetype.NewContext()c.SetDPI(*dpi)c.SetFont(f)c.SetFontSize(*size)c.SetClip(jpg.Bounds())c.SetDst(jpg)c.SetSrc(fg)switch *hinting {default:c.SetHinting(font.HintingNone)case "full":c.SetHinting(font.HintingFull)}//Draw the guidelines.//for i := 0; i < 200; i++ {//jpg.Set(10, 10+i, ruler)//jpg.Set(10+i, 10, ruler)//}// Draw the text.pt := freetype.Pt(200, 10+int(c.PointToFixed(*size)>>6))for _, s := range text {_, err = c.DrawString(s, pt)if err != nil {log.Println(err)return}pt.Y += c.PointToFixed(*size * *spacing)}}func Cors() gin.HandlerFunc {return func(c *gin.Context) {method := c.Request.Method //请求方法origin := c.Request.Header.Get("Origin") //请求头部var headerKeys []string // 声明请求头keysfor k, _ := range c.Request.Header {headerKeys = append(headerKeys, k)}headerStr := strings.Join(headerKeys, ", ")if headerStr != "" {headerStr = fmt.Sprintf("access-control-allow-origin, access-control-allow-headers, %s", headerStr)} else {headerStr = "access-control-allow-origin, access-control-allow-headers"}if origin != "" {c.Writer.Header().Set("Access-Control-Allow-Origin", "*")c.Header("Access-Control-Allow-Origin", "*") // 这是允许访问所有域c.Header("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE,UPDATE") //服务器支持的所有跨域请求的方法,为了避免浏览次请求的多次'预检'请求// header的类型c.Header("Access-Control-Allow-Headers", "Authorization, Content-Length, X-CSRF-Token, Token,session,X_Requested_With,Accept, Origin, Host, Connection, Accept-Encoding, Accept-Language,DNT, X-CustomHeader, Keep-Alive, User-Agent, X-Requested-With, If-Modified-Since, Cache-Control, Content-Type, Pragma")// 允许跨域设置 可以返回其他子段c.Header("Access-Control-Expose-Headers", "Content-Length, Access-Control-Allow-Origin, Access-Control-Allow-Headers,Cache-Control,Content-Language,Content-Type,Expires,Last-Modified,Pragma,FooBar") // 跨域关键设置 让浏览器可以解析c.Header("Access-Control-Max-Age", "172800") // 缓存请求信息 单位为秒c.Header("Access-Control-Allow-Credentials", "false") // 跨域请求是否需要带cookie信息 默认设置为truec.Set("content-type", "application/json") // 设置返回格式是json}//放行所有OPTIONS方法if method == "OPTIONS" {c.JSON(http.StatusOK, "Options Request!")}// 处理请求c.Next() // 处理请求}}看完了这篇文章，相信你对“golang中如何实现给gif、png、jpeg图片添加文字水印”有了一定的了解，如果想了解更多相关知识，欢迎关注编程网行业资讯频道，感谢各位的阅读！
