67 lines
1.7 KiB
Go
67 lines
1.7 KiB
Go
package media
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import (
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"bytes"
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"context"
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"fmt"
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"os/exec"
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"strings"
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)
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const maxTelegramPhotoSize = 10 * 1024 * 1024 // 10 MB
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// CompressImage compresses an image if it exceeds Telegram's 10 MB photo limit.
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// It uses ImageMagick's magick command to convert via stdin/stdout.
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// Returns the (possibly compressed) data, updated filename, and any error.
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func CompressImage(ctx context.Context, data []byte, filename string) (out []byte, outName string, err error) {
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if len(data) <= maxTelegramPhotoSize {
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return data, filename, nil
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}
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// First attempt: just re-encode as JPEG with quality 85
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out, err = runMagick(ctx, data, "-quality", "85")
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if err != nil {
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return nil, "", fmt.Errorf("compress image: %w", err)
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}
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newFilename := replaceExt(filename, ".jpg")
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if len(out) <= maxTelegramPhotoSize {
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return out, newFilename, nil
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}
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// Second attempt: resize to 50% and quality 85
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out, err = runMagick(ctx, data, "-resize", "50%", "-quality", "85")
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if err != nil {
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return nil, "", fmt.Errorf("compress image with resize: %w", err)
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}
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if len(out) > maxTelegramPhotoSize {
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return nil, "", fmt.Errorf("image still too large after compression (%d bytes)", len(out))
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}
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return out, newFilename, nil
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}
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func runMagick(ctx context.Context, data []byte, args ...string) ([]byte, error) {
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cmdArgs := append([]string{"-"}, args...)
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cmdArgs = append(cmdArgs, "jpeg:-")
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cmd := exec.CommandContext(ctx, "magick", cmdArgs...)
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cmd.Stdin = bytes.NewReader(data)
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out, err := cmd.Output()
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if err != nil {
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return nil, fmt.Errorf("magick: %w", err)
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}
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return out, nil
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}
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func replaceExt(filename, newExt string) string {
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if i := strings.LastIndex(filename, "."); i >= 0 {
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return filename[:i] + newExt
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}
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return filename + newExt
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}
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