Merge pull request #38 from idoknow/feat-preview-image

feat: 图片压缩预览

backend/controller/postapi.go

@@ -118,10 +118,15 @@ func (pr *PostRouter) DownloadImage(c *gin.Context) {
 	}
 
 	key := c.Param("key")
+	_, isPreview := c.GetQuery("preview")
 
 	buf := bytes.NewBuffer(nil)
 
-	err = pr.PostService.DownloadImage(key, buf)
+	if isPreview {
+		err = pr.PostService.PreviewImage(key, buf)
+	} else {
+		err = pr.PostService.DownloadImage(key, buf)
+	}
 
 	if err != nil {
 		pr.Fail(c, 1, err.Error())

backend/oss/base.go

@@ -4,6 +4,7 @@ import "io"
 
 type BaseOSSProvider interface {
 	UploadFromIO(io.Reader, string) (string, error)
+	UploadFromIOWithKey(io.Reader, string, string) (string, error)
 	DownloadToIO(string, io.Writer) error
 	CheckObjectExist(string) (bool, error)
 }

backend/oss/local.go

@@ -29,18 +29,24 @@ func NewLocalStorage() *LocalStorage {
 func (l *LocalStorage) UploadFromIO(ioReader io.Reader, suffix string) (string, error) {
 	objectName := generateObjectName()
 
+	key, err := l.UploadFromIOWithKey(ioReader, objectName, suffix)
+
+	return key, err
+}
+
+func (l *LocalStorage) UploadFromIOWithKey(ioReader io.Reader, key string, suffix string) (string, error) {
 	if suffix != "" {
-		objectName += "." + suffix
+		key += "." + suffix
 	}
 
-	file, err := os.Create(filepath.Join(l.dir, objectName))
+	file, err := os.Create(filepath.Join(l.dir, key))
 	if err != nil {
 		return "", err
 	}
 	defer file.Close()
 
 	_, err = io.Copy(file, ioReader)
-	return objectName, err
+	return key, err
 }
 
 func (l *LocalStorage) DownloadToIO(objectName string, ioWriter io.Writer) error {

backend/oss/minio.go

@@ -43,15 +43,25 @@ func generateObjectName() string {
 
 // 从io.Reader上传文件
 func (m *MinioClient) UploadFromIO(ioReader io.Reader, suffix string) (string, error) {
-
 	objectName := generateObjectName()
 
+	key, err := m.UploadFromIOWithKey(ioReader, objectName, suffix)
+
+	return key, err
+}
+
+func (m *MinioClient) UploadFromIOWithKey(ioReader io.Reader, key string, suffix string) (string, error) {
 	if suffix != "" {
-		objectName += "." + suffix
+		key += "." + suffix
+	}
+
+	_, err := m.client.PutObject(context.Background(), m.bucket, key, ioReader, -1, minio.PutObjectOptions{})
+
+	if err != nil {
+		return "", err
 	}
 
-	_, err := m.client.PutObject(context.Background(), m.bucket, objectName, ioReader, -1, minio.PutObjectOptions{})
-	return objectName, err
+	return key, nil
 }
 
 // 下载文件到io.Writer

backend/service/post.go

@@ -1,8 +1,10 @@
 package service
 
 import (
+	"bytes"
 	"errors"
 	"io"
+	"strings"
 
 	"github.com/RockChinQ/Campux/backend/database"
 	"github.com/RockChinQ/Campux/backend/mq"
@@ -40,6 +42,48 @@ func (ps *PostService) DownloadImage(key string, ioWriter io.Writer) error {
 	return ps.OSS.DownloadToIO(key, ioWriter)
 }
 
+func (ps *PostService) PreviewImage(key string, ioWriter io.Writer) error {
+	thumbnailKey := strings.Split(key, ".")[0] + "_thumbnail"
+	thumbnailKeySuffix := thumbnailKey + ".jpg"
+
+	exist, err := ps.OSS.CheckObjectExist(thumbnailKeySuffix)
+
+	if err != nil {
+		return err
+	}
+
+	if exist {
+		// download the thumbnail directly
+		return ps.OSS.DownloadToIO(thumbnailKeySuffix, ioWriter)
+	}
+
+	// compress the image and then upload.
+
+	buf := new(bytes.Buffer)
+	err = ps.OSS.DownloadToIO(key, buf)
+
+	if err != nil {
+		return err
+	}
+
+	// compress the image
+	reader, err := util.CompressImage(buf.Bytes(), 10)
+
+	if err != nil {
+		ioWriter.Write(buf.Bytes())
+		return nil
+	}
+
+	// CompressImage() should return a JPEG format image
+	_, err = ps.OSS.UploadFromIOWithKey(reader, thumbnailKey, "jpg")
+
+	if err != nil {
+		return err
+	}
+
+	return ps.OSS.DownloadToIO(thumbnailKeySuffix, ioWriter)
+}
+
 func (ps *PostService) PostNew(uuid string, uin int64, text string, images []string, anon bool) (int, error) {
 
 	// 检查这个用户是否有未过审的帖子

backend/util/image.go

@@ -0,0 +1,26 @@
+package util
+
+import (
+	"bytes"
+	"image"
+	_ "image/gif" // register gif format
+	"image/jpeg"
+	_ "image/png" // register png format
+	"io"
+)
+
+func CompressImage(input []byte, quality int) (io.Reader, error) {
+	img, _, err := image.Decode(bytes.NewReader(input))
+	if err != nil {
+		return nil, err
+	}
+
+	var buf bytes.Buffer
+
+	err = jpeg.Encode(&buf, img, &jpeg.Options{Quality: quality})
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes.NewReader(buf.Bytes()), nil
+}

frontend/src/pages/post.vue

@@ -242,6 +242,8 @@ export default {
             // 将images中的baseurl去掉
             this.post.images = this.post.images.map(image => {
                 return image.replace(this.$store.state.base_url + "/v1/post/download-image/", '')
+                            .replace("?preview=1", "")
+
             })
 
             this.$axios.post('/v1/post/post-new', this.post)
@@ -286,7 +288,7 @@ export default {
                     })
                     .then(res => {
                         if (res.data.code === 0) {
-                            let url = this.$store.state.base_url + '/v1/post/download-image/' + res.data.data.key
+                            let url = this.$store.state.base_url + '/v1/post/download-image/' + res.data.data.key + "?preview=1"
                             console.log(url)
                             this.post.images.push(url)
                             this.fetchLatestImageToImageBlobs(url)

frontend/src/pages/world.vue

@@ -197,7 +197,7 @@ export default {
               p[i].created_at = date.toLocaleString()
               p[i].status = this.$store.state.statusMap[p[i].status]
               for (let j = 0; j < p[i].images.length; j++) {
-                p[i].images[j] = this.$store.state.base_url + "/v1/post/download-image/" + p[i].images[j]
+                p[i].images[j] = this.$store.state.base_url + "/v1/post/download-image/" + p[i].images[j] + "?preview=1"
               }
             }
             console.log(p)
@@ -250,7 +250,7 @@ export default {
               p[i].created_at = date.toLocaleString()
               p[i].status = this.$store.state.statusMap[p[i].status]
               for (let j = 0; j < p[i].images.length; j++) {
-                p[i].images[j] = this.$store.state.base_url + "/v1/post/download-image/" + p[i].images[j]
+                p[i].images[j] = this.$store.state.base_url + "/v1/post/download-image/" + p[i].images[j] + "?preview=1"
               }
             }
             console.log(p)