Add files via upload

internal/vision/preprocess.go

@@ -0,0 +1,212 @@
+package vision
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"os"
+	"strings"
+
+	"github.com/disintegration/imaging"
+)
+
+// ImagePayload 送入 VL API 的图片字节与 MIME。
+type ImagePayload struct {
+	Bytes    []byte
+	MIMEType string
+}
+
+// PreprocessMeta 记录缩放与编码结果，供工具输出与排障。
+type PreprocessMeta struct {
+	OriginalPath      string
+	OriginalBytes     int64
+	OriginalWidth     int
+	OriginalHeight    int
+	OutputWidth       int
+	OutputHeight      int
+	OutputBytes       int
+	OutputMIMEType    string
+	JPEGQuality       int // 0 表示未 JPEG 重编码（原图直传）
+	PreprocessMode    string // passthrough | jpeg
+}
+
+// PreprocessOptions 图片预处理参数。
+type PreprocessOptions struct {
+	MaxImageBytes            int64
+	MaxDimension             int
+	JPEGQuality              int
+	MaxPayloadBytes          int64
+	SkipPreprocessBelowBytes int64 // 0 = 始终压缩；>0 时小图+尺寸合规可直传
+}
+
+// PreprocessImageFile 读取图片；大图或超尺寸走 imaging 缩放+JPEG，否则可原图直传。
+func PreprocessImageFile(path string, opt PreprocessOptions) (ImagePayload, PreprocessMeta, error) {
+	var meta PreprocessMeta
+	meta.OriginalPath = path
+
+	st, err := os.Stat(path)
+	if err != nil {
+		return ImagePayload{}, meta, err
+	}
+	meta.OriginalBytes = st.Size()
+	if opt.MaxImageBytes > 0 && st.Size() > opt.MaxImageBytes {
+		return ImagePayload{}, meta, fmt.Errorf("file size %d exceeds max_image_bytes %d", st.Size(), opt.MaxImageBytes)
+	}
+
+	cfgW, cfgH, format, err := imageDimensions(path)
+	if err != nil {
+		return ImagePayload{}, meta, err
+	}
+	meta.OriginalWidth = cfgW
+	meta.OriginalHeight = cfgH
+
+	maxDim := opt.MaxDimension
+	if maxDim <= 0 {
+		maxDim = 2048
+	}
+	maxPayload := opt.MaxPayloadBytes
+	if maxPayload <= 0 {
+		maxPayload = 512 * 1024
+	}
+
+	if payload, meta, ok, err := tryPassthrough(path, st.Size(), cfgW, cfgH, format, opt, maxDim, maxPayload); ok {
+		return payload, meta, err
+	}
+
+	return compressWithImaging(path, opt, maxDim, maxPayload, meta)
+}
+
+func tryPassthrough(path string, size int64, w, h int, format string, opt PreprocessOptions, maxDim int, maxPayload int64) (ImagePayload, PreprocessMeta, bool, error) {
+	var meta PreprocessMeta
+	meta.OriginalPath = path
+	meta.OriginalBytes = size
+	meta.OriginalWidth = w
+	meta.OriginalHeight = h
+
+	threshold := opt.SkipPreprocessBelowBytes
+	if threshold <= 0 {
+		return ImagePayload{}, meta, false, nil
+	}
+	if size > threshold {
+		return ImagePayload{}, meta, false, nil
+	}
+	longEdge := w
+	if h > longEdge {
+		longEdge = h
+	}
+	if longEdge > maxDim {
+		return ImagePayload{}, meta, false, nil
+	}
+	if size > maxPayload {
+		return ImagePayload{}, meta, false, nil
+	}
+
+	raw, err := os.ReadFile(path)
+	if err != nil {
+		return ImagePayload{}, meta, false, err
+	}
+	mime := mimeFromImageFormat(format)
+	if mime == "" {
+		return ImagePayload{}, meta, false, nil
+	}
+
+	meta.OutputWidth = w
+	meta.OutputHeight = h
+	meta.OutputBytes = len(raw)
+	meta.OutputMIMEType = mime
+	meta.PreprocessMode = "passthrough"
+	return ImagePayload{Bytes: raw, MIMEType: mime}, meta, true, nil
+}
+
+func compressWithImaging(path string, opt PreprocessOptions, maxDim int, maxPayload int64, meta PreprocessMeta) (ImagePayload, PreprocessMeta, error) {
+	src, err := imaging.Open(path)
+	if err != nil {
+		return ImagePayload{}, meta, fmt.Errorf("open image: %w", err)
+	}
+	bounds := src.Bounds()
+	meta.OriginalWidth = bounds.Dx()
+	meta.OriginalHeight = bounds.Dy()
+
+	dst := imaging.Fit(src, maxDim, maxDim, imaging.Lanczos)
+	outBounds := dst.Bounds()
+	meta.OutputWidth = outBounds.Dx()
+	meta.OutputHeight = outBounds.Dy()
+
+	quality := opt.JPEGQuality
+	if quality <= 0 || quality > 100 {
+		quality = 82
+	}
+
+	dim := maxDim
+	for attempt := 0; attempt < 6; attempt++ {
+		if attempt > 0 {
+			dim = int(float64(dim) * 0.85)
+			if dim < 256 {
+				dim = 256
+			}
+			dst = imaging.Fit(src, dim, dim, imaging.Lanczos)
+			outBounds = dst.Bounds()
+			meta.OutputWidth = outBounds.Dx()
+			meta.OutputHeight = outBounds.Dy()
+		}
+		q := quality
+		for q >= 60 {
+			var buf bytes.Buffer
+			if err := imaging.Encode(&buf, dst, imaging.JPEG, imaging.JPEGQuality(q)); err != nil {
+				return ImagePayload{}, meta, fmt.Errorf("encode jpeg: %w", err)
+			}
+			if int64(buf.Len()) <= maxPayload {
+				meta.JPEGQuality = q
+				meta.OutputBytes = buf.Len()
+				meta.OutputMIMEType = "image/jpeg"
+				meta.PreprocessMode = "jpeg"
+				return ImagePayload{Bytes: buf.Bytes(), MIMEType: "image/jpeg"}, meta, nil
+			}
+			q -= 5
+		}
+		quality = 75
+	}
+	return ImagePayload{}, meta, fmt.Errorf("could not compress image under max_payload_bytes %d", maxPayload)
+}
+
+func imageDimensions(path string) (w, h int, format string, err error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return 0, 0, "", err
+	}
+	defer f.Close()
+	cfg, format, err := image.DecodeConfig(f)
+	if err != nil {
+		return 0, 0, "", fmt.Errorf("decode image config: %w", err)
+	}
+	return cfg.Width, cfg.Height, format, nil
+}
+
+func mimeFromImageFormat(format string) string {
+	switch strings.ToLower(strings.TrimSpace(format)) {
+	case "jpeg", "jpg":
+		return "image/jpeg"
+	case "png":
+		return "image/png"
+	case "gif":
+		return "image/gif"
+	case "webp":
+		return "image/webp"
+	case "bmp":
+		return "image/bmp"
+	case "tiff":
+		return "image/tiff"
+	default:
+		return ""
+	}
+}
+
+// DecodeImageConfig 用于测试：确认文件可被解码。
+func DecodeImageConfig(path string) (image.Config, string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return image.Config{}, "", err
+	}
+	defer f.Close()
+	return image.DecodeConfig(f)
+}