前言
大前天上班的时候,坐在旁边的同事需要一批有水印的图片来测试模型。然后我就主动站出来……
他问我怎么加,我说用golang可以。可为啥我不用更容易实现的Python呢……可能是为了装逼。
代码
WaterMark.go | Gist
package main
import (
"bytes"
"fmt"
"strings"
"io/ioutil"
"os"
"path"
"math"
"math/rand"
"time"
"image"
"image/color"
"image/draw"
"image/jpeg"
"image/png"
"github.com/gonum/plot/vg"
"github.com/gonum/plot/vg/vgimg"
)
func init() {
rand.Seed(time.Now().UnixNano())
}
// WaterMark for adding a watermark on the image
func WaterMark(img image.Image, markText string) (image.Image, error) {
// image's length to canvas's length
bounds := img.Bounds()
w := vg.Length(bounds.Max.X) * vg.Inch / vgimg.DefaultDPI
h := vg.Length(bounds.Max.Y) * vg.Inch / vgimg.DefaultDPI
diagonal := vg.Length(math.Sqrt(float64(w*w + h*h)))
// create a canvas, which width and height are diagonal
c := vgimg.New(diagonal, diagonal)
// draw image on the center of canvas
rect := vg.Rectangle{}
rect.Min.X = diagonal/2 - w/2
rect.Min.Y = diagonal/2 - h/2
rect.Max.X = diagonal/2 + w/2
rect.Max.Y = diagonal/2 + h/2
c.DrawImage(rect, img)
// make a fontStyle, which width is vg.Inch * 0.7
fontStyle, _ := vg.MakeFont("Courier", vg.Inch*0.7)
// repeat the markText
markTextWidth := fontStyle.Width(markText)
unitText := markText
for markTextWidth <= diagonal {
markText += " " + unitText
markTextWidth = fontStyle.Width(markText)
}
// set the color of markText
c.SetColor(color.RGBA{0, 0, 0, 122})
// set a random angle between 0 and π/2
θ := math.Pi * rand.Float64() / 2
c.Rotate(θ)
// set the lineHeight and add the markText
lineHeight := fontStyle.Extents().Height * 1
for offset := -2 * diagonal; offset < 2*diagonal; offset += lineHeight {
c.FillString(fontStyle, vg.Point{X: 0, Y: offset}, markText)
}
// canvas writeto jpeg
// canvas.img is private
// so use a buffer to transfer
jc := vgimg.PngCanvas{Canvas: c}
buff := new(bytes.Buffer)
jc.WriteTo(buff)
img, _, err := image.Decode(buff)
if err != nil {
return nil, err
}
// get the center point of the image
ctp := int(diagonal * vgimg.DefaultDPI / vg.Inch / 2)
// cutout the marked image
size := bounds.Size()
bounds = image.Rect(ctp-size.X/2, ctp-size.Y/2, ctp+size.X/2, ctp+size.Y/2)
rv := image.NewRGBA(bounds)
draw.Draw(rv, bounds, img, bounds.Min, draw.Src)
return rv, nil
}
// MarkingPicture for marking picture with text
func MarkingPicture(filepath, text string) (image.Image, error) {
f, err := os.Open(filepath)
if err != nil {
return nil, err
}
defer f.Close()
img, _, err := image.Decode(f)
if err != nil {
return nil, err
}
img, err = WaterMark(img, text)
if err != nil {
return nil, err
}
return img, nil
}
func writeTo(img image.Image, ext string) (rv *bytes.Buffer, err error) {
ext = strings.ToLower(ext)
rv = new(bytes.Buffer)
switch ext {
case ".jpg", ".jpeg":
err = jpeg.Encode(rv, img, &jpeg.Options{Quality: 100})
case ".png":
err = png.Encode(rv, img)
}
return rv, err
}
func main() {
if len(os.Args) < 3 {
panic(fmt.Errorf("Please using like this:$ %s [file or directory] [text]", os.Args[0]))
}
target := os.Args[1]
text := os.Args[2]
if stat, err := os.Stat(target); err == nil && stat.IsDir() {
files, _ := ioutil.ReadDir(target)
for _, fn := range files {
img, err := MarkingPicture(path.Join(target, fn.Name()), text)
if err != nil {
continue
}
ext := path.Ext(fn.Name())
base := strings.Split(fn.Name(), ".")[0] + "_marked"
f, err := os.Create(base + ext)
if err != nil {
panic(err)
}
buff, err := writeTo(img, ext)
if err != nil {
panic(err)
}
if _, err = buff.WriteTo(f); err != nil {
panic(err)
}
}
} else {
img, err := MarkingPicture(target, text)
if err != nil {
panic(err)
}
ext := path.Ext(target)
base := strings.Split(path.Base(target), ".")[0] + "_marked"
f, err := os.Create(base + ext)
if err != nil {
panic(err)
}
buff, err := writeTo(img, ext)
if err != nil {
panic(err)
}
if _, err = buff.WriteTo(f); err != nil {
panic(err)
}
}
}
图片效果
原文链接:用golang给图片打水印 | linw1995