initial commit

main.go

@@ -0,0 +1,113 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"image"
+	"image/draw"
+	_ "image/gif"
+	_ "image/jpeg"
+	"image/png"
+	"os"
+)
+
+func main() {
+	outputPath := flag.String("o", "output.png", "output spritesheet path")
+	direction := flag.String("direction", "h", "join direction: h (horizontal) or v (vertical)")
+	flag.Parse()
+
+	inputPaths := flag.Args()
+	if len(inputPaths) == 0 {
+		fmt.Println("Usage: spritestitch -o output.png [-direction h|v] sheet1.png sheet2.png ...")
+		os.Exit(1)
+	}
+
+	if *direction != "h" && *direction != "v" {
+		fmt.Println("direction must be 'h' (horizontal) or 'v' (vertical)")
+		os.Exit(1)
+	}
+
+	var images []image.Image
+	var bounds []image.Rectangle
+
+	for _, path := range inputPaths {
+		imgFile, err := os.Open(path)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "failed to open %s: %v\n", path, err)
+			os.Exit(1)
+		}
+
+		img, _, err := image.Decode(imgFile)
+		imgFile.Close()
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "failed to decode %s: %v\n", path, err)
+			os.Exit(1)
+		}
+
+		images = append(images, img)
+		bounds = append(bounds, img.Bounds())
+	}
+
+	var totalWidth, totalHeight int
+	if *direction == "h" {
+		maxHeight := 0
+		sumWidth := 0
+		for _, b := range bounds {
+			w := b.Dx()
+			h := b.Dy()
+			sumWidth += w
+			if h > maxHeight {
+				maxHeight = h
+			}
+		}
+		totalWidth = sumWidth
+		totalHeight = maxHeight
+	} else {
+		maxWidth := 0
+		sumHeight := 0
+		for _, b := range bounds {
+			w := b.Dx()
+			h := b.Dy()
+			sumHeight += h
+			if w > maxWidth {
+				maxWidth = w
+			}
+		}
+		totalWidth = maxWidth
+		totalHeight = sumHeight
+	}
+
+	outImg := image.NewRGBA(image.Rect(0, 0, totalWidth, totalHeight))
+
+	offsetX, offsetY := 0, 0
+	for i, img := range images {
+		b := bounds[i]
+		w := b.Dx()
+		h := b.Dy()
+
+		var dstRect image.Rectangle
+		if *direction == "h" {
+			dstRect = image.Rect(offsetX, 0, offsetX+w, h)
+			offsetX += w
+		} else {
+			dstRect = image.Rect(0, offsetY, w, offsetY+h)
+			offsetY += h
+		}
+
+		draw.Draw(outImg, dstRect, img, b.Min, draw.Over)
+	}
+
+	outFile, err := os.Create(*outputPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to create output file: %v\n", err)
+		os.Exit(1)
+	}
+	defer outFile.Close()
+
+	if err := png.Encode(outFile, outImg); err != nil {
+		fmt.Fprintf(os.Stderr, "failed to encode PNG: %v\n", err)
+		os.Exit(1)
+	}
+
+	fmt.Printf("Spritesheet written to %s\n", *outputPath)
+}