Refactor export functions

- Pass output path as parameter
- Return and handle errors correctly

bin/stitch/export-jpeg.go

@@ -1,16 +1,17 @@
 package main
 
 import (
+	"fmt"
 	"image/jpeg"
 	"log"
 	"os"
 )
 
-func exportJPEG(stitchedImage *StitchedImage) error {
+func exportJPEG(stitchedImage *StitchedImage, outputPath string) error {
-	log.Printf("Creating output file %q.", *flagOutputPath)
+	log.Printf("Creating output file %q.", outputPath)
-	f, err := os.Create(*flagOutputPath)
+	f, err := os.Create(outputPath)
 	if err != nil {
-		log.Panic(err)
+		return fmt.Errorf("failed to create file: %w", err)
 	}
 	defer f.Close()
 
@@ -19,7 +20,7 @@ func exportJPEG(stitchedImage *StitchedImage) error {
 	}
 
 	if err := jpeg.Encode(f, stitchedImage, options); err != nil {
-		log.Panic(err)
+		return fmt.Errorf("failed to encode image %q: %w", outputPath, err)
 	}
 
 	return nil

bin/stitch/export-png.go

@@ -1,16 +1,17 @@
 package main
 
 import (
+	"fmt"
 	"image/png"
 	"log"
 	"os"
 )
 
-func exportPNG(stitchedImage *StitchedImage) error {
+func exportPNG(stitchedImage *StitchedImage, outputPath string) error {
-	log.Printf("Creating output file %q.", *flagOutputPath)
+	log.Printf("Creating output file %q.", outputPath)
-	f, err := os.Create(*flagOutputPath)
+	f, err := os.Create(outputPath)
 	if err != nil {
-		log.Panic(err)
+		return fmt.Errorf("failed to create file: %w", err)
 	}
 	defer f.Close()
 
@@ -19,7 +20,7 @@ func exportPNG(stitchedImage *StitchedImage) error {
 	}
 
 	if err := encoder.Encode(f, stitchedImage); err != nil {
-		log.Panic(err)
+		return fmt.Errorf("failed to encode image %q: %w", outputPath, err)
 	}
 
 	return nil

bin/stitch/main.go

@@ -269,9 +269,13 @@ func main() {
 	fileExtension := strings.ToLower(filepath.Ext(*flagOutputPath))
 	switch fileExtension {
 	case ".png":
-		exportPNG(stitchedImage)
+		if err := exportPNG(stitchedImage, *flagOutputPath); err != nil {
+			log.Panicf("Export of PNG file failed: %v", err)
+		}
 	case ".jpg", ".jpeg":
-		exportJPEG(stitchedImage)
+		if err := exportJPEG(stitchedImage, *flagOutputPath); err != nil {
+			log.Panicf("Export of JPEG file failed: %v", err)
+		}
 	default:
 		log.Panicf("Unknown output format %q.", fileExtension)
 	}