- 支持不同格式之间的转换
- 支持图片像素的压缩以及拉长
package main
import (
"bytes"
"errors"
"fmt"
"image"
"image/jpeg"
"image/png"
"io/ioutil"
"os"
"golang.org/x/image/draw"
_ "golang.org/x/image/webp" // for RegisterFormat
)
type imageHelper struct {
img image.Image
fileName string
format string
scale draw.Scaler
}
func NewImageHelper(fileName string, scale ...draw.Scaler) *imageHelper {
var s draw.Scaler
if scale == nil {
s = draw.ApproxBiLinear
} else {
s = scale[0]
}
return &imageHelper{
fileName: fileName,
scale: s,
}
}
func (r *imageHelper) GuessFileFormat() (string, error) {
if r.format != "" && r.img != nil {
return r.format, nil
}
f, err := os.Open(r.fileName)
if err != nil {
return "", err
}
_image, s, err := image.Decode(f)
if err != nil {
return "", err
}
r.img = _image
r.format = s
ss := _image.Bounds()
fmt.Println(ss)
return s, nil
}
func (r *imageHelper) SaveAs(format string) (*bytes.Buffer, error) {
_, err := r.GuessFileFormat()
if err != nil {
return nil, err
}
buf := bytes.Buffer{}
switch format {
case "jpeg", "jpg":
err := jpeg.Encode(&buf, r.img, &jpeg.Options{Quality: 100})
if err != nil {
return nil, err
}
return &buf, nil
case "png":
err := png.Encode(&buf, r.img)
if err != nil {
return nil, err
}
return &buf, nil
default:
return nil, errors.New("invalid format")
}
}
func (r *imageHelper) SaveAsJpeg() (*bytes.Buffer, error) {
return r.SaveAs("jpeg")
}
func (r *imageHelper) GetSize() (int, int) {
point := r.img.Bounds().Size()
return point.X, point.Y
}
func (r *imageHelper) RestSize(x, y int) ([]byte, error) {
// https://github.com/nfnt/resize/blob/master/resize_test.go
rect := image.Rect(0, 0, x, y)
// new img
dst := image.NewRGBA(rect)
buf := bytes.Buffer{}
r.scale.Scale(dst, rect, r.img, r.img.Bounds(), draw.Over, nil)
err := jpeg.Encode(&buf, dst, &jpeg.Options{Quality: 100})
if err != nil {
return nil, err
}
return buf.Bytes(), nil
}
func main() {
obj := NewImageHelper("webp/1.webp")
buf, err := obj.SaveAs("png")
if err != nil {
return
}
ioutil.WriteFile("test1.png", buf.Bytes(), 0644)
buf, err = obj.SaveAs("jpeg")
if err != nil {
return
}
ioutil.WriteFile("test2.jpeg", buf.Bytes(), 0644)
content, _ := obj.RestSize(200, 100)
ioutil.WriteFile("test3.jpeg", content, 0644)
}
