Fix up some bugs and update to modern go

go.mod

@@ -0,0 +1,7 @@
+module github.com/tardisx/slicerdicer
+
+go 1.22.1
+
+require github.com/disintegration/imaging v1.6.2
+
+require golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8 // indirect

go.sum

@@ -0,0 +1,5 @@
+github.com/disintegration/imaging v1.6.2 h1:w1LecBlG2Lnp8B3jk5zSuNqd7b4DXhcjwek1ei82L+c=
+github.com/disintegration/imaging v1.6.2/go.mod h1:44/5580QXChDfwIclfc/PCwrr44amcmDAg8hxG0Ewe4=
+golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8 h1:hVwzHzIUGRjiF7EcUjqNxk3NCfkPxbDKRdnNE1Rpg0U=
+golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

main.go

@@ -1,109 +1,110 @@
-package main;
+package main
 
-import "image"
-import "image/png"
-import "github.com/disintegration/imaging"
-import "runtime"
-import "flag"
-import "fmt"
-import "os"
+import (
+	"flag"
+	"fmt"
+	"image"
+	"image/png"
+	"os"
+
+	"github.com/disintegration/imaging"
+)
 
 const currentVersion = "0.01"
 
 func main() {
 
-  filenamePtr    := flag.String("filename", "", "filename to open")
-  tileSizePtr    := flag.Int   ("tile-size", 256, "tile size, in pixels")
-  concurrencyPtr := flag.Int ("concurrency", 5, "how many tiles to generate concurrently (threads)")
+	filenamePtr := flag.String("filename", "", "filename to open")
+	tileSizePtr := flag.Int("tile-size", 256, "tile size, in pixels")
+	concurrencyPtr := flag.Int("concurrency", 5, "how many tiles to generate concurrently (threads)")
+	baseName := flag.String("basename", "tile", "base of the output files")
 
-  flag.Parse()
+	flag.Parse()
 
-  if (*filenamePtr == "") {
-    fmt.Println("Error: You must specify a filename with --filename");
-    return;
-  }
+	if *filenamePtr == "" {
+		fmt.Println("Error: You must specify a filename with --filename")
+		return
+	}
 
-  fmt.Println("opening file:", *filenamePtr)
-  src, err := imaging.Open(*filenamePtr)
-  if err != nil {
-    fmt.Println("Error: Could not open file:", err)
-    return;
-  }
+	fmt.Println("opening file:", *filenamePtr)
+	src, err := imaging.Open(*filenamePtr)
+	if err != nil {
+		fmt.Println("Error: Could not open file:", err)
+		return
+	}
 
-  size := src.Bounds().Max
+	size := src.Bounds().Max
 
-  tile_size_x := *tileSizePtr
-  tile_size_y := *tileSizePtr
+	tile_size_x := *tileSizePtr
+	tile_size_y := *tileSizePtr
 
-  // work out maximum zoom
-  var max_zoom int
-  zoom_test_size_x := size.X
-  zoom_test_size_y := size.Y
-  for max_zoom = 0 ; ; max_zoom++ {
-    if zoom_test_size_x < tile_size_x && zoom_test_size_y < tile_size_y {
-      break
-    }
-    zoom_test_size_x = zoom_test_size_x >> 1
-    zoom_test_size_y = zoom_test_size_y >> 1
-  }
+	// work out maximum zoom
+	var max_zoom int
+	zoom_test_size_x := size.X
+	zoom_test_size_y := size.Y
+	for max_zoom = 0; ; max_zoom++ {
+		if zoom_test_size_x <= tile_size_x && zoom_test_size_y <= tile_size_y {
+			break
+		}
+		zoom_test_size_x = zoom_test_size_x >> 1
+		zoom_test_size_y = zoom_test_size_y >> 1
+	}
 
-  z := max_zoom
-  fmt.Println("maximum zoom level is", max_zoom)
+	z := max_zoom
+	fmt.Println("maximum zoom level is", max_zoom)
 
-  concurrency := *concurrencyPtr
-  sem := make(chan bool, concurrency)
+	concurrency := *concurrencyPtr
+	sem := make(chan bool, concurrency)
 
-  fmt.Println("starting tiling with concurrency of", concurrency)
+	fmt.Println("starting tiling with concurrency of", concurrency)
 
-  // outer loop for zoom
-  for {
-    if (z == max_zoom) {
-      // do nothing
-    } else {
-      // halve image size
-      src = imaging.Resize(src, size.X/2, 0, imaging.NearestNeighbor)
-      runtime.GC()
-      // recalculate size
-      size = src.Bounds().Max
-    }
+	// outer loop for zoom
+	for {
+		if z == max_zoom {
+			// do nothing
+		} else {
+			// halve image size
+			src = imaging.Resize(src, size.X/2, 0, imaging.NearestNeighbor)
+			// recalculate size
+			size = src.Bounds().Max
+		}
 
-    fmt.Print(fmt.Sprintf("zoom level: %d (%d x %d)\n", z, size.X, size.Y))
+		fmt.Print(fmt.Sprintf("zoom level: %d (%d x %d)\n", z, size.X, size.Y))
 
-    for y := 0 ; y <= (size.Y / tile_size_y) ; y++ {
-      for x := 0 ; x <= (size.X / tile_size_x) ; x++ {
-        sem <- true
-        go tile(src, z, x, y, tile_size_x, tile_size_y, sem)
-      }
+		for y := 0; y < (size.Y / tile_size_y); y++ {
+			for x := 0; x < (size.X / tile_size_x); x++ {
+				sem <- true
+				go tile(*baseName, src, z, x, y, tile_size_x, tile_size_y, sem)
+			}
 
-    }
+		}
 
-    z--
-    if (z < 0) {
-      break
-    }
-  }
+		z--
+		if z < 0 {
+			break
+		}
+	}
 
-  // drain at the end of each zoom level
-  // since we are about to modify the source image
-  for i := 0; i < cap(sem); i++ {
-    sem <- true
-  }
+	// drain at the end of each zoom level
+	// since we are about to modify the source image in memory
+	for i := 0; i < cap(sem); i++ {
+		sem <- true
+	}
 
-  fmt.Println("done")
+	fmt.Println("done")
 }
 
-func tile (src image.Image, z, x, y int, tile_size_x, tile_size_y int, sem chan bool) {
-  defer func() { <-sem }()
-  output_filename := fmt.Sprintf("tile-%d-%d-%d.png", z, x, y)
-  cropped := imaging.Crop(src, image.Rect(tile_size_x*x, tile_size_y*y, tile_size_x*x+tile_size_x, tile_size_y*y+tile_size_y));
+func tile(basename string, src image.Image, z, x, y int, tile_size_x, tile_size_y int, sem chan bool) {
+	defer func() { <-sem }()
+	output_filename := fmt.Sprintf("%s-%d-%d-%d.png", basename, z, x, y)
+	cropped := imaging.Crop(src, image.Rect(tile_size_x*x, tile_size_y*y, tile_size_x*x+tile_size_x, tile_size_y*y+tile_size_y))
 
-  writer, _ := os.Create(output_filename)
-  err := png.Encode(writer, cropped)
-  if err != nil {
-    fmt.Println(err)
-  }
-  writer.Close()
+	writer, _ := os.Create(output_filename)
+	err := png.Encode(writer, cropped)
+	if err != nil {
+		fmt.Println(err)
+	}
+	writer.Close()
 
-  runtime.GC()
-  return;
+	return
 }