golang image 智能合并图片，自动识别图片类型，合并后缩放。
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package util
import (
"fmt"
"image"
"image/draw"
"image/gif"
"image/jpeg"
"image/png"
"net/http"
"os"
"github.com/nfnt/resize"
)
func CheckImageType2(filePath string) (string, error) {
file, err := os.Open(filePath)
if err != nil {
return "", err
}
defer file.Close()
buff := make([]byte, 512) // why 512 bytes ? see http://golang.org/pkg/net/http/#DetectContentType
_, err = file.Read(buff)
if err != nil {
return "", err
}
filetype := http.DetectContentType(buff)
fmt.Println(filetype)
switch filetype {
case "image/jpeg", "image/jpg":
fmt.Println(filetype)
return "jpg", nil
case "image/gif":
fmt.Println(filetype)
case "image/png":
fmt.Println(filetype)
case "application/pdf": // not image, but application !
fmt.Println(filetype)
default:
fmt.Println("unknown file type uploaded")
}
return "aa", nil
}
func GetImageObj(filePath string) (img image.Image, err error) {
f1Src, err := os.Open(filePath)
if err != nil {
return nil, err
}
defer f1Src.Close()
buff := make([]byte, 512) // why 512 bytes ? see http://golang.org/pkg/net/http/#DetectContentType
_, err = f1Src.Read(buff)
if err != nil {
return nil, err
}
filetype := http.DetectContentType(buff)
fmt.Println(filetype)
fSrc, err := os.Open(filePath)
defer fSrc.Close()
switch filetype {
case "image/jpeg", "image/jpg":
img, err = jpeg.Decode(fSrc)
if err != nil {
fmt.Println("jpeg error")
return nil, err
}
case "image/gif":
img, err = gif.Decode(fSrc)
if err != nil {
return nil, err
}
case "image/png":
img, err = png.Decode(fSrc)
if err != nil {
return nil, err
}
default:
return nil, err
}
return img, nil
}
func MergeImage(worksDir string, file1 string, file2 string, newName string) (string, error) {
src, err := GetImageObj(worksDir + file1)
if err != nil {
return "", err
}
srcB := src.Bounds().Max
src1, err := GetImageObj(worksDir + file2)
if err != nil {
return "", err
}
src1B := src.Bounds().Max
newWidth := srcB.X + src1B.X
newHeight := srcB.Y
if src1B.Y > newHeight {
newHeight = src1B.Y
}
des := image.NewRGBA(image.Rect(0, 0, newWidth, newHeight)) // 底板
draw.Draw(des, des.Bounds(), src, src.Bounds().Min, draw.Over) //首先将一个图片信息存入jpg
draw.Draw(des, image.Rect(srcB.X, 0, newWidth, src1B.Y), src1, image.ZP, draw.Over) //将另外一张图片信息存入jpg
fSave, err := os.Create(worksDir + newName)
if err != nil {
return "", err
}
defer fSave.Close()
var opt jpeg.Options
opt.Quality = 80
newImage := resize.Resize(1024, 0, des, resize.Lanczos3)
err = jpeg.Encode(fSave, newImage, &opt) // put quality to 80%
if err != nil {
return "", err
}
return newName, nil
}