feat(formatconverter): add formatconverter method using inkscape

pkg/format/formatconverter.go

@@ -0,0 +1,97 @@
+package format
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"tomatentum.net/svg-templater/pkg/svg"
+)
+
+type ConversionParameters struct {
+	Format        string
+	Width, Height int
+}
+
+func ConvertByte(svgblob []byte, param ConversionParameters) ([]byte, error) {
+	reader, err := ConvertReader(svgblob, param)
+	if err != nil {
+		return nil, err
+	}
+	defer reader.Close()
+
+	result, err := io.ReadAll(reader)
+	if err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+func ConvertReader(svgblob []byte, param ConversionParameters) (io.ReadCloser, error) {
+	if param.Format == "svg" {
+		return io.NopCloser(bytes.NewReader(svgblob)), nil
+	}
+	file, err := svg.CreateTemp(bytes.NewReader(svgblob), "svg")
+	if err != nil {
+		return nil, err
+	}
+	defer os.Remove(file)
+
+	return runCommand(file, param)
+}
+
+func runCommand(input string, param ConversionParameters) (io.ReadCloser, error) {
+	var args []string
+
+	var outExt string
+	switch param.Format {
+	case "png":
+		args = append(args, "--export-type=png")
+		outExt = ".png"
+	case "jpg":
+		args = append(args, "--export-type=png") // inkscape doesn't export jpg directly
+		outExt = ".png"
+	case "pdf":
+		args = append(args, "--export-type=pdf")
+		outExt = ".pdf"
+	default:
+		return nil, fmt.Errorf("format not supported: %s", param.Format)
+	}
+
+	if param.Width > 0 {
+		args = append(args, "-w", strconv.Itoa(param.Width))
+	}
+	if param.Height > 0 {
+		args = append(args, "-h", strconv.Itoa(param.Height))
+	}
+
+	outFile := strings.TrimSuffix(input, filepath.Ext(input)) + outExt
+	args = append(args, "-o", outFile)
+	args = append(args, input)
+
+	cmd := exec.Command("/opt/homebrew/bin/inkscape", args...)
+	cmd.Dir = svg.TempDir
+
+	out, err := cmd.CombinedOutput()
+
+	if err != nil {
+		return nil, fmt.Errorf("inkscape failed: %w: %s", err, string(out))
+	}
+
+	file, err := os.Open(outFile)
+	if err != nil {
+		return nil, err
+	}
+
+	return file, nil
+}
+
+func CheckInkscape() bool {
+	_, err := exec.LookPath("inkscape")
+	return err == nil
+}