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package image
import (
"bytes"
"encoding/base64"
"fmt"
"image"
_ "image/jpeg"
"image/png"
"io"
"strings"
)
func encodeDataURL(imageBytes []byte, mimeType string) (string, error) {
if len(imageBytes) == 0 {
return "", fmt.Errorf("no image bytes returned")
}
normalizedBytes, err := normalizePNG(imageBytes, mimeType)
if err != nil {
return "", err
}
return geminiDataPrefix + base64.StdEncoding.EncodeToString(normalizedBytes), nil
}
func decodeDataURL(url string) (io.ReadCloser, error) {
header, payload, ok := strings.Cut(url, ",")
if !ok || !strings.HasPrefix(header, "data:") || !strings.Contains(header, ";base64") {
return nil, fmt.Errorf("unsupported data URI: %s", url)
}
data, err := base64.StdEncoding.DecodeString(payload)
if err != nil {
return nil, fmt.Errorf("decode data URI: %w", err)
}
return io.NopCloser(bytes.NewReader(data)), nil
}
func normalizePNG(imageBytes []byte, mimeType string) ([]byte, error) {
if strings.EqualFold(strings.TrimSpace(mimeType), "image/png") {
return append([]byte(nil), imageBytes...), nil
}
img, _, err := image.Decode(bytes.NewReader(imageBytes))
if err != nil {
return nil, fmt.Errorf("decode generated image: %w", err)
}
var buffer bytes.Buffer
if err := png.Encode(&buffer, img); err != nil {
return nil, fmt.Errorf("encode generated image as png: %w", err)
}
return buffer.Bytes(), nil
}
func decodedImageDimensions(imageBytes []byte) (int, int, error) {
cfg, _, err := image.DecodeConfig(bytes.NewReader(imageBytes))
if err != nil {
return 0, 0, fmt.Errorf("decode generated image dimensions: %w", err)
}
return cfg.Width, cfg.Height, nil
}
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