feat(local): support thumbnail cache (close #4216)

drivers/local/util.go

@@ -7,7 +7,12 @@ import (
 	"os"
 	"path/filepath"
 	"sort"
+	"strings"
 
+	"github.com/alist-org/alist/v3/internal/conf"
+	"github.com/alist-org/alist/v3/internal/model"
+	"github.com/alist-org/alist/v3/pkg/utils"
+	"github.com/disintegration/imaging"
 	ffmpeg "github.com/u2takey/ffmpeg-go"
 )
 
@@ -55,3 +60,52 @@ func readDir(dirname string) ([]fs.FileInfo, error) {
 	sort.Slice(list, func(i, j int) bool { return list[i].Name() < list[j].Name() })
 	return list, nil
 }
+
+func (d *Local) getThumb(file model.Obj) (*bytes.Buffer, *string, error) {
+	fullPath := file.GetPath()
+	thumbPrefix := "alist_thumb_"
+	thumbName := thumbPrefix + utils.GetMD5Encode(fullPath) + ".png"
+	if d.ThumbCacheFolder != "" {
+		// skip if the file is a thumbnail
+		if strings.HasPrefix(file.GetName(), thumbPrefix) {
+			return nil, &fullPath, nil
+		}
+		thumbPath := filepath.Join(d.ThumbCacheFolder, thumbName)
+		if utils.Exists(thumbPath) {
+			return nil, &thumbPath, nil
+		}
+	}
+	var srcBuf *bytes.Buffer
+	if utils.GetFileType(file.GetName()) == conf.VIDEO {
+		videoBuf, err := GetSnapshot(fullPath, 10)
+		if err != nil {
+			return nil, nil, err
+		}
+		srcBuf = videoBuf
+	} else {
+		imgData, err := os.ReadFile(fullPath)
+		if err != nil {
+			return nil, nil, err
+		}
+		imgBuf := bytes.NewBuffer(imgData)
+		srcBuf = imgBuf
+	}
+
+	image, err := imaging.Decode(srcBuf)
+	if err != nil {
+		return nil, nil, err
+	}
+	thumbImg := imaging.Resize(image, 144, 0, imaging.Lanczos)
+	var buf bytes.Buffer
+	err = imaging.Encode(&buf, thumbImg, imaging.PNG)
+	if err != nil {
+		return nil, nil, err
+	}
+	if d.ThumbCacheFolder != "" {
+		err = os.WriteFile(filepath.Join(d.ThumbCacheFolder, thumbName), buf.Bytes(), 0666)
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+	return &buf, nil, nil
+}