Initial commit

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

pub/common/imgutil/resize.go

@@ -0,0 +1,151 @@
+package imgutil
+
+import (
+	"bytes"
+	"crypto/sha1"
+	"fmt"
+	"image"
+	_ "image/gif"
+	"image/jpeg"
+	_ "image/png"
+	"net/url"
+	"path"
+	"path/filepath"
+	"strings"
+	"unicode"
+)
+
+const (
+	// CoverResizeLimitKB 与 media utils.Resize 一致：超过该大小才缩放
+	CoverResizeLimitKB = 60
+	// CoverMaxWidth 与 media Thumbnail 一致
+	CoverMaxWidth = 750
+	// CoverMaxHeight 与 media Thumbnail 一致
+	CoverMaxHeight = 1560
+	// CoverJPEGQuality 压缩后统一输出 JPEG
+	CoverJPEGQuality = 75
+)
+
+// IsGIF 按文件头判断是否为 GIF，不依赖扩展名。
+func IsGIF(data []byte) bool {
+	return len(data) >= 3 && bytes.Equal(data[:3], []byte{0x47, 0x49, 0x46})
+}
+
+// NeedCompress 原图是否超过 media Resize 阈值，未超过则无需压缩重传。
+// GIF 保持原格式和动效，不参与压缩。
+func NeedCompress(data []byte) bool {
+	if IsGIF(data) {
+		return false
+	}
+	return int64(len(data))/1024 > CoverResizeLimitKB
+}
+
+// CompressCover 按 media Resize(60KB, 750×1560) 压缩封面。
+// GIF 原样返回；其它格式未超过阈值时原样返回，超过则缩放后统一输出 JPEG。
+func CompressCover(data []byte, fileName string) ([]byte, string, error) {
+	if len(data) == 0 {
+		return nil, "", fmt.Errorf("图片内容为空")
+	}
+	outName := compressFileName(fileName)
+	if IsGIF(data) {
+		return data, withExt(outName, ".gif"), nil
+	}
+	if !NeedCompress(data) {
+		return data, outName, nil
+	}
+	img, _, err := image.Decode(bytes.NewReader(data))
+	if err != nil {
+		return nil, "", fmt.Errorf("解码图片失败: %w", err)
+	}
+	thumb := thumbnail(img, CoverMaxWidth, CoverMaxHeight)
+	var buf bytes.Buffer
+	if err = jpeg.Encode(&buf, thumb, &jpeg.Options{Quality: CoverJPEGQuality}); err != nil {
+		return nil, "", err
+	}
+	return buf.Bytes(), withExt(outName, ".jpg"), nil
+}
+
+// SafeCoverFileName 生成仅含 ASCII 的上传文件名。
+// 原封面路径含中文时，直接用 path.Base 会把中文带进上传名，图床返回地址会异常。
+func SafeCoverFileName(src string) string {
+	src = strings.TrimSpace(src)
+	ext := asciiImageExt(src)
+	if src == "" {
+		return "playlet_cover" + ext
+	}
+	sum := sha1.Sum([]byte(src))
+	return fmt.Sprintf("playlet_cover_%x%s", sum[:8], ext)
+}
+
+func thumbnail(img image.Image, maxW, maxH int) image.Image {
+	b := img.Bounds()
+	w, h := b.Dx(), b.Dy()
+	if w <= maxW && h <= maxH {
+		return img
+	}
+	wr := float64(maxW) / float64(w)
+	hr := float64(maxH) / float64(h)
+	scale := wr
+	if hr < wr {
+		scale = hr
+	}
+	nw := int(float64(w) * scale)
+	nh := int(float64(h) * scale)
+	if nw < 1 {
+		nw = 1
+	}
+	if nh < 1 {
+		nh = 1
+	}
+	dst := image.NewRGBA(image.Rect(0, 0, nw, nh))
+	for y := 0; y < nh; y++ {
+		sy := b.Min.Y + y*h/nh
+		for x := 0; x < nw; x++ {
+			sx := b.Min.X + x*w/nw
+			dst.Set(x, y, img.At(sx, sy))
+		}
+	}
+	return dst
+}
+
+func compressFileName(fileName string) string {
+	fileName = filepath.Base(strings.TrimSpace(fileName))
+	if fileName == "" || fileName == "." || fileName == string(filepath.Separator) || !isASCIIFileName(fileName) {
+		return "playlet_cover.jpg"
+	}
+	return fileName
+}
+
+func asciiImageExt(src string) string {
+	name := src
+	if u, err := url.Parse(src); err == nil && u.Path != "" {
+		name = u.Path
+	}
+	name = strings.Split(path.Base(name), "?")[0]
+	if dec, err := url.PathUnescape(name); err == nil {
+		name = dec
+	}
+	ext := strings.ToLower(filepath.Ext(name))
+	switch ext {
+	case ".jpg", ".jpeg", ".png", ".gif", ".webp":
+		return ext
+	default:
+		return ".jpg"
+	}
+}
+
+func isASCIIFileName(name string) bool {
+	if !strings.Contains(name, ".") {
+		return false
+	}
+	for _, r := range name {
+		if r > unicode.MaxASCII || r < 32 || r == '"' || r == '/' || r == '\\' {
+			return false
+		}
+	}
+	return true
+}
+
+func withExt(fileName, ext string) string {
+	return strings.TrimSuffix(fileName, filepath.Ext(fileName)) + ext
+}