Added tool to crop & resize images.

cmd/imadapt/args.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+func atois(s ...string) ([]int, error) {
+	ints := make([]int, len(s))
+	for i, s := range s {
+		value, err := strconv.Atoi(s)
+		if err != nil {
+			return nil, fmt.Errorf("couldn't convert '%s' to a number; error: %v", s, err)
+		}
+		ints[i] = value
+	}
+	return ints, nil
+}
+
+func scanDir(dir string) ([]string, error) {
+	var files []string
+	err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if path == dir || info.IsDir() {
+			return nil
+		}
+		files = append(files, path)
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return files, nil
+}
+
+type point struct {
+	x, y int
+}
+
+func parsePoint(s string) (point, error) {
+	components := strings.Split(s, ",")
+	if len(components) != 2 {
+		return point{}, errors.New("expected two components separated by a comma")
+	}
+	ints, err := atois(components...)
+	if err != nil {
+		return point{}, err
+	}
+	return point{x: ints[0], y: ints[1]}, nil
+}
+
+type rect struct {
+	min, max point
+}
+
+func parseRect(s string) (rect, error) {
+	components := strings.Split(s, ",")
+	if len(components) != 4 {
+		return rect{}, errors.New("expected four components separated by a comma")
+	}
+	ints, err := atois(components...)
+	if err != nil {
+		return rect{}, err
+	}
+	return rect{min: point{x: ints[0], y: ints[1]}, max: point{x: ints[2], y: ints[3]}}, nil
+}

cmd/imadapt/crop.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"image"
+	"image/draw"
+
+	"github.com/nfnt/resize"
+)
+
+func crop(path string, crop rect, size *point) error {
+	src, err := decodeImage(path)
+	if err != nil {
+		return err
+	}
+	srcRect := image.Rect(crop.min.x, crop.min.y, crop.max.x, crop.max.y)
+	dstRect := image.Rect(0, 0, crop.max.x-crop.min.x, crop.max.y-crop.min.y)
+	dst := image.NewRGBA(dstRect)
+	draw.Draw(dst, dstRect, src, srcRect.Min, draw.Src)
+	if size == nil {
+		return encodePNG(path, dst)
+	}
+
+	resized := resize.Resize(uint(size.x), uint(size.y), dst, resize.Bilinear)
+	return encodePNG(path, resized)
+}

cmd/imadapt/gray.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"image"
+	"image/color"
+)
+
+func convertToGray(path string) error {
+	src, err := decodeImage(path)
+	if err != nil {
+		return err
+	}
+	bounds := src.Bounds()
+	dst := image.NewRGBA(bounds)
+	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x++ {
+			c := src.At(x, y)
+			rgba := color.NRGBAModel.Convert(c).(color.NRGBA)
+			if rgba.A > 0 {
+				gray := color.GrayModel.Convert(c).(color.Gray)
+				rgba.R, rgba.G, rgba.B = gray.Y, gray.Y, gray.Y
+				dst.Set(x, y, rgba)
+			} else {
+				dst.Set(x, y, c)
+			}
+		}
+	}
+	return encodePNG(path, dst)
+}

cmd/imadapt/imadapt.go

@@ -4,11 +4,7 @@ import (
 	"errors"
 	"flag"
 	"fmt"
-	"image"
-	"image/color"
-	"image/png"
 	"log"
-	"os"
 )
 
 func run() error {
@@ -33,76 +29,54 @@ func run() error {
 		flags := flag.NewFlagSet("gray", flag.ContinueOnError)
 		flags.Parse(args[1:])
 		for _, path := range flags.Args() {
-			err := gray(path)
+			err := convertToGray(path)
 			if err != nil {
 				return fmt.Errorf("couldn't convert to grayscale of '%s'; error: %v", path, err)
 			}
 		}
+	case "crop":
+		flags := flag.NewFlagSet("crop", flag.ContinueOnError)
+		var rect string
+		var resize string
+		var dir string
+		flags.StringVar(&rect, "crop", "", "sets the crop rectangle \"x1,y1,y1,y2\"")
+		flags.StringVar(&resize, "resize", "", "sets the target size, \"width,height\", if not specified the crop rectangle size is used")
+		flags.StringVar(&dir, "dir", "", "crops all images in the specified directory (recursively)")
+		flags.Parse(args[1:])
+
+		cropRect, err := parseRect(rect)
+		if err != nil {
+			return fmt.Errorf("crop rectangle is invalid: error: %v", err)
+		}
+		var size *point
+		if len(resize) != 0 {
+			p, err := parsePoint(resize)
+			if err != nil {
+				return fmt.Errorf("resize parameter is invalid: error: %v", err)
+			}
+			size = &p
+		}
+
+		var files []string
+		if len(dir) == 0 {
+			files = flags.Args()
+		} else {
+			files, err = scanDir(dir)
+			if err != nil {
+				return fmt.Errorf("couldn't find files to crop; error: %v", err)
+			}
+		}
+
+		for _, path := range files {
+			err := crop(path, cropRect, size)
+			if err != nil {
+				return fmt.Errorf("couldn't crop '%s'; error: %v", path, err)
+			}
+		}
 	}
 	return nil
 }
 
-func setAlpha(path string, alpha int) error {
-	src, err := os.Open(path)
-	if err != nil {
-		return err
-	}
-	defer src.Close()
-	im, _, err := image.Decode(src)
-	if err != nil {
-		return err
-	}
-	bounds := im.Bounds()
-	dst := image.NewNRGBA(bounds)
-	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
-		for x := bounds.Min.X; x < bounds.Max.X; x++ {
-			c := color.NRGBAModel.Convert(im.At(x, y)).(color.NRGBA)
-			if c.A > 0 {
-				c.A = uint8(alpha)
-			}
-			dst.Set(x, y, c)
-		}
-	}
-	return encodePNG(path, dst)
-}
-
-func gray(path string) error {
-	src, err := os.Open(path)
-	if err != nil {
-		return err
-	}
-	defer src.Close()
-	im, _, err := image.Decode(src)
-	if err != nil {
-		return err
-	}
-	bounds := im.Bounds()
-	dst := image.NewRGBA(bounds)
-	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
-		for x := bounds.Min.X; x < bounds.Max.X; x++ {
-			c := im.At(x, y)
-			rgba := color.NRGBAModel.Convert(c).(color.NRGBA)
-			if rgba.A > 0 {
-				gray := color.GrayModel.Convert(c).(color.Gray)
-				rgba.R, rgba.G, rgba.B = gray.Y, gray.Y, gray.Y
-				dst.Set(x, y, rgba)
-			} else {
-				dst.Set(x, y, c)
-			}
-		}
-	}
-	return encodePNG(path, dst)
-}
-
-func encodePNG(path string, im image.Image) error {
-	dst, err := os.Create(path)
-	if err != nil {
-		return err
-	}
-	defer dst.Close()
-	return png.Encode(dst, im)
-}
-
 func main() {
 	if err := run(); err != nil {
 		log.Fatal(err)

cmd/imadapt/io.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"image"
+	"image/png"
+	"os"
+)
+
+func encodePNG(path string, im image.Image) error {
+	dst, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+	defer dst.Close()
+	return png.Encode(dst, im)
+}
+
+func decodeImage(path string) (image.Image, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	im, _, err := image.Decode(f)
+	if err != nil {
+		return nil, err
+	}
+	return im, nil
+}

cmd/imadapt/setalpha.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"image"
+	"image/color"
+)
+
+func setAlpha(path string, alpha int) error {
+	src, err := decodeImage(path)
+	if err != nil {
+		return err
+	}
+	bounds := src.Bounds()
+	dst := image.NewNRGBA(bounds)
+	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x++ {
+			c := color.NRGBAModel.Convert(src.At(x, y)).(color.NRGBA)
+			if c.A > 0 {
+				c.A = uint8(alpha)
+			}
+			dst.Set(x, y, c)
+		}
+	}
+	return encodePNG(path, dst)
+}