refactor(resize): extract

README.md

@@ -1,15 +1,18 @@
 # bimg [![Build Status](https://travis-ci.org/h2non/bimg.png)](https://travis-ci.org/h2non/bimg) [![GitHub release](https://img.shields.io/github/tag/h2non/bimg.svg)]() [![GoDoc](https://godoc.org/github.com/h2non/bimg?status.png)](https://godoc.org/github.com/h2non/bimg)
 
-Go library for blazing fast image processing based on [libvips](https://github.com/jcupitt/libvips) using C bindings. 
+Go small but featured library for blazing fast image processing based on [libvips](https://github.com/jcupitt/libvips) using C bindings.
 
-bimg is designed to be a small and efficient library with a limited by generic specific set of features. 
-Thanks to libvips it's typically 4x faster than using the quickest ImageMagick and GraphicsMagick settings 
-or Go native image processing package, and in some cases it's even 8x faster processing JPEG images. 
-It supports JPEG, PNG, WEBP, TIFF and Magick image formats.
+bimg is designed to be a small and efficient library with a specific but useful and generic set of features. 
+It uses internally libvips, which is typically 4x faster than using the quickest ImageMagick and GraphicsMagick settings or Go  native `image` package, and in some cases it's even 8x faster processing JPEG images. 
+bimg can read JPEG, PNG, WEBP, TIFF and Magick formats and it can output to JPEG, PNG and WEBP.
+
+It support common [image transformation](#supported-image-operations) operations such as crop, resize, rotate... and image conversion into multiple formats. 
+
+To getting started see the [examples](#examples) and [programmatic API](https://godoc.org/github.com/h2non/bimg) documentation.
 
 bimg was heavily inspired in [sharp](https://github.com/lovell/sharp), a great node.js package for image processing build by [Lovell Fuller](https://github.com/lovell).
 
-`Work in progress`
+**Note**: bimg is still a beta package. PR and issues are highly appreciated
 
 ## Prerequisites
 
@@ -38,10 +41,10 @@ The [install script](https://github.com/lovell/sharp/blob/master/preinstall.sh)
 - Enlarge
 - Crop
 - Rotate
-- Flip/Flop
+- Flip 
 - Extract area
-- Extract image metadata (size, format, profile, orientation...)
-- Image conversion to multiple formats
+- EXIF metadata (size, alpha channel, profile, orientation...)
+- Format conversion 
 
 ## Performance
 

file.go

@@ -6,15 +6,20 @@ import (
 )
 
 func Read(path string) ([]byte, error) {
-	data, err := os.Open(path)
+	file, err := os.Open(path)
 	if err != nil {
 		return nil, err
 	}
+	defer file.Close()
 
-	buf, err := ioutil.ReadAll(data)
+	buf, err := ioutil.ReadAll(file)
 	if err != nil {
 		return nil, err
 	}
 
 	return buf, nil
 }
+
+func Write(path string, buf []byte) error {
+	return ioutil.WriteFile(path, buf, 0644)
+}

file_test.go

@@ -19,3 +19,20 @@ func TestRead(t *testing.T) {
 		t.Fatal("Image is not jpeg")
 	}
 }
+
+func TestWrite(t *testing.T) {
+	buf, err := Read("fixtures/test.jpg")
+
+	if err != nil {
+		t.Errorf("Cannot read the image: %#v", err)
+	}
+
+	if len(buf) == 0 {
+		t.Fatal("Empty buffer")
+	}
+
+	err = Write("fixtures/test_write_out.jpg", buf)
+	if err != nil {
+		t.Fatal("Cannot write the file: %#v", err)
+	}
+}

image.go

@@ -4,7 +4,7 @@ type Image struct {
 	buffer []byte
 }
 
-func (i *Image) Resize(width int, height int) ([]byte, error) {
+func (i *Image) Resize(width, height int) ([]byte, error) {
 	options := Options{
 		Width:  width,
 		Height: height,
@@ -12,17 +12,17 @@ func (i *Image) Resize(width int, height int) ([]byte, error) {
 	return i.Process(options)
 }
 
-func (i *Image) Extract(top int, left int, width int, height int) ([]byte, error) {
+func (i *Image) Extract(top, left, width, height int) ([]byte, error) {
 	options := Options{
-		Width:  width,
-		Height: height,
 		Top:        top,
 		Left:       left,
+		AreaWidth:  width,
+		AreaHeight: height,
 	}
 	return i.Process(options)
 }
 
-func (i *Image) Crop(width int, height int) ([]byte, error) {
+func (i *Image) Crop(width, height int) ([]byte, error) {
 	options := Options{
 		Width:  width,
 		Height: height,
@@ -31,14 +31,6 @@ func (i *Image) Crop(width int, height int) ([]byte, error) {
 	return i.Process(options)
 }
 
-func (i *Image) Thumbnail(width int, height int) ([]byte, error) {
-	options := Options{
-		Width:  width,
-		Height: height,
-	}
-	return i.Process(options)
-}
-
 func (i *Image) Rotate(a Angle) ([]byte, error) {
 	options := Options{Rotate: a}
 	return i.Process(options)
@@ -49,11 +41,6 @@ func (i *Image) Flip() ([]byte, error) {
 	return i.Process(options)
 }
 
-func (i *Image) Flop() ([]byte, error) {
-	options := Options{Flip: HORIZONTAL}
-	return i.Process(options)
-}
-
 func (i *Image) Convert(t ImageType) ([]byte, error) {
 	options := Options{Type: t}
 	return i.Process(options)

image_test.go

@@ -1,37 +1,59 @@
 package bimg
 
 import (
-	"io/ioutil"
-	"os"
+	"path"
 	"testing"
 )
 
 func TestImageResize(t *testing.T) {
-	image := readImage()
-	_, err := image.Resize(300, 240)
+	buf, err := initImage("test.jpg").Resize(300, 240)
 	if err != nil {
 		t.Errorf("Cannot process the image: %#v", err)
 	}
+	Write("fixtures/test_resize_out.jpg", buf)
+}
+
+func TestImageExtract(t *testing.T) {
+	buf, err := initImage("test.jpg").Extract(100, 100, 300, 300)
+	if err != nil {
+		t.Errorf("Cannot process the image: %#v", err)
+	}
+	Write("fixtures/test_extract_out.jpg", buf)
 }
 
 func TestImageCrop(t *testing.T) {
-	image := readImage()
-	_, err := image.Crop(800, 600)
+	buf, err := initImage("test.jpg").Crop(800, 600)
 	if err != nil {
 		t.Errorf("Cannot process the image: %#v", err)
 	}
+	Write("fixtures/test_crop_out.jpg", buf)
+}
+
+func TestImageFlip(t *testing.T) {
+	buf, err := initImage("test.jpg").Flip()
+	if err != nil {
+		t.Errorf("Cannot process the image: %#v", err)
+	}
+	Write("fixtures/test_flip_out.jpg", buf)
 }
 
 func TestImageRotate(t *testing.T) {
-	image := readImage()
-	_, err := image.Rotate(D90)
+	buf, err := initImage("test_flip_out.jpg").Rotate(90)
+	if err != nil {
+		t.Errorf("Cannot process the image: %#v", err)
+	}
+	Write("fixtures/test_image_rotate_out.jpg", buf)
+}
+
+func TestImageConvert(t *testing.T) {
+	buf, err := initImage("test_rotate_out.jpg").Convert(PNG)
 	if err != nil {
 		t.Errorf("Cannot process the image: %#v", err)
 	}
+	Write("fixtures/test_image_convert_out.png", buf)
 }
 
-func readImage() *Image {
-	data, _ := os.Open("fixtures/test.jpg")
-	buf, _ := ioutil.ReadAll(data)
+func initImage(file string) *Image {
+	buf, _ := Read(path.Join("fixtures", file))
 	return NewImage(buf)
 }

options.go

@@ -55,6 +55,8 @@ const (
 type Options struct {
 	Height       int
 	Width        int
+	AreaHeight   int
+	AreaWidth    int
 	Top          int
 	Left         int
 	Crop         bool

resize.go

@@ -8,6 +8,7 @@ import "C"
 
 import (
 	"errors"
+	"fmt"
 	"math"
 )
 
@@ -19,7 +20,7 @@ func Resize(buf []byte, o Options) ([]byte, error) {
 		return nil, err
 	}
 
-	// defaults
+	// Defaults
 	if o.Quality == 0 {
 		o.Quality = QUALITY
 	}
@@ -36,7 +37,6 @@ func Resize(buf []byte, o Options) ([]byte, error) {
 
 	debug("Options: %#v", o)
 
-	// get WxH
 	inWidth := int(image.Xsize)
 	inHeight := int(image.Ysize)
 
@@ -58,7 +58,6 @@ func Resize(buf []byte, o Options) ([]byte, error) {
 
 	// Try to use libjpeg shrink-on-load
 	if imageType == JPEG && shrink >= 2 {
-		// Recalculate integral shrink and double residual
 		tmpImage, factor, err := shrinkJpegImage(buf, factor, shrink)
 		if err != nil {
 			return nil, err
@@ -78,6 +77,8 @@ func Resize(buf []byte, o Options) ([]byte, error) {
 		shrink = int(math.Max(float64(math.Floor(factor*3.0/windowSize)), 1))
 	}
 
+	// Transform image if necessary
+	if o.Width != inWidth || o.Height != inHeight {
 		// Use vips_shrink with the integral reduction
 		if shrink > 1 {
 			image, residual, err = shrinkImage(image, o, residual, shrink)
@@ -85,7 +86,6 @@ func Resize(buf []byte, o Options) ([]byte, error) {
 				return nil, err
 			}
 		}
-
 		// Use vips_affine with the remaining float part
 		if residual != 0 {
 			image, err = vipsAffine(image, residual, o.Interpolator)
@@ -93,38 +93,20 @@ func Resize(buf []byte, o Options) ([]byte, error) {
 				return nil, err
 			}
 		}
-
 		debug("factor: %v, shrink: %v, residual: %v", factor, shrink, residual)
 
-	// Extract image
+		// Extract area from image
 		image, err = extractImage(image, o)
 		if err != nil {
 			return nil, err
 		}
-
-	if o.Rotate == 0 {
-		rotation, flip := calculateRotationAndFlip(image, o.Rotate)
-		if flip {
-			o.Flip = HORIZONTAL
-		}
-		if rotation > D0 {
-			o.Rotate = rotation
-		}
-	}
-
-	if o.Rotate > 0 {
-		image, err = vipsRotate(image, getAngle(o.Rotate))
-		if err != nil {
-			return nil, err
-		}
 	}
 
-	if o.Flip > 0 {
-		image, err = vipsFlip(image, o.Flip)
+	// Rotate / flip image if necessary based on EXIF metadata
+	image, err = rotateImage(image, o)
 	if err != nil {
 		return nil, err
 	}
-	}
 
 	saveOptions := vipsSaveOptions{
 		Quality:     o.Quality,
@@ -132,6 +114,7 @@ func Resize(buf []byte, o Options) ([]byte, error) {
 		Compression: o.Compression,
 	}
 
+	// Finally save as buffer
 	buf, err = vipsSave(image, saveOptions)
 	if err != nil {
 		return nil, err
@@ -142,58 +125,130 @@ func Resize(buf []byte, o Options) ([]byte, error) {
 
 func extractImage(image *C.struct__VipsImage, o Options) (*C.struct__VipsImage, error) {
 	var err error = nil
-	affinedWidth := int(image.Xsize)
-	affinedHeight := int(image.Ysize)
-
-	if affinedWidth != o.Width || affinedHeight != o.Height {
-		width := int(math.Min(float64(affinedWidth), float64(o.Width)))
-		height := int(math.Min(float64(affinedHeight), float64(o.Height)))
+	inWidth := int(image.Xsize)
+	inHeight := int(image.Ysize)
 
 	switch {
 	case o.Crop:
-			left, top := calculateCrop(affinedWidth, affinedHeight, o.Width, o.Height, o.Gravity)
+		width := int(math.Min(float64(inWidth), float64(o.Width)))
+		height := int(math.Min(float64(inHeight), float64(o.Height)))
+		left, top := calculateCrop(inWidth, inHeight, o.Width, o.Height, o.Gravity)
 		image, err = vipsExtract(image, left, top, width, height)
 		break
 	case o.Embed:
-			left, top := (o.Width-affinedWidth)/2, (o.Height-affinedHeight)/2
+		left, top := (o.Width-inWidth)/2, (o.Height-inHeight)/2
 		image, err = vipsEmbed(image, left, top, o.Width, o.Height, o.Extend)
 		break
 	case o.Top > 0 && o.Left > 0:
-			image, err = vipsExtract(image, o.Left, o.Top, width, height)
+		if o.AreaWidth == 0 || o.AreaHeight == 0 {
+			err = errors.New(fmt.Sprintf("Invalid area to extract %dx%d", o.AreaWidth, o.AreaHeight))
+		} else {
+			image, err = vipsExtract(image, o.Left, o.Top, o.AreaWidth, o.AreaHeight)
+		}
 		break
 	}
+
+	return image, err
+}
+
+func rotateImage(image *C.struct__VipsImage, o Options) (*C.struct__VipsImage, error) {
+	var err error
+
+	rotation, flip := calculateRotationAndFlip(image, o.Rotate)
+	if flip {
+		o.Flip = HORIZONTAL
+	}
+	if rotation > D0 && o.Rotate == 0 {
+		o.Rotate = rotation
+	}
+
+	if o.Rotate > 0 {
+		image, err = vipsRotate(image, getAngle(o.Rotate))
+	}
+
+	if o.Flip > 0 {
+		image, err = vipsFlip(image, o.Flip)
 	}
 
 	return image, err
 }
 
+func shrinkImage(image *C.struct__VipsImage, o Options, residual float64, shrink int) (*C.struct__VipsImage, float64, error) {
+	// Use vips_shrink with the integral reduction
+	image, err := vipsShrink(image, shrink)
+	if err != nil {
+		return nil, 0, err
+	}
+
+	// Recalculate residual float based on dimensions of required vs shrunk images
+	residualx := float64(o.Width) / float64(image.Xsize)
+	residualy := float64(o.Height) / float64(image.Ysize)
+
+	if o.Crop {
+		residual = math.Max(residualx, residualy)
+	} else {
+		residual = math.Min(residualx, residualy)
+	}
+
+	return image, residual, nil
+}
+
+func shrinkJpegImage(buf []byte, factor float64, shrink int) (*C.struct__VipsImage, float64, error) {
+	var image *C.struct__VipsImage
+	var err error
+	shrinkOnLoad := 1
+
+	// Recalculate integral shrink and double residual
+	switch {
+	case shrink >= 8:
+		factor = factor / 8
+		shrinkOnLoad = 8
+	case shrink >= 4:
+		factor = factor / 4
+		shrinkOnLoad = 4
+	case shrink >= 2:
+		factor = factor / 2
+		shrinkOnLoad = 2
+	}
+
+	// Reload input using shrink-on-load
+	if shrinkOnLoad > 1 {
+		image, err = vipsShrinkJpeg(buf, shrinkOnLoad)
+	}
+
+	return image, factor, err
+}
+
 func imageCalculations(o Options, inWidth, inHeight int) float64 {
 	factor := 1.0
+	xfactor := float64(inWidth) / float64(o.Width)
+	yfactor := float64(inHeight) / float64(o.Height)
 
 	switch {
 	// Fixed width and height
 	case o.Width > 0 && o.Height > 0:
-		xf := float64(inWidth) / float64(o.Width)
-		yf := float64(inHeight) / float64(o.Height)
 		if o.Crop {
-			factor = math.Min(xf, yf)
+			factor = math.Min(xfactor, yfactor)
 		} else {
-			factor = math.Max(xf, yf)
+			factor = math.Max(xfactor, yfactor)
 		}
 	// Fixed width, auto height
 	case o.Width > 0:
-		factor = float64(inWidth) / float64(o.Width)
+		factor = xfactor
 		o.Height = int(math.Floor(float64(inHeight) / factor))
 	// Fixed height, auto width
 	case o.Height > 0:
-		factor = float64(inHeight) / float64(o.Height)
+		factor = yfactor
 		o.Width = int(math.Floor(float64(inWidth) / factor))
-	// Identity transform
 	default:
+		// Identity transform
 		o.Width = inWidth
 		o.Height = inHeight
+		break
 	}
 
+	debug("Resolution %dx%d", o.Width, o.Height)
+
 	return factor
 }
 
@@ -263,53 +318,6 @@ func calculateRotationAndFlip(image *C.struct__VipsImage, angle Angle) (Angle, b
 	return rotate, flip
 }
 
-func shrinkImage(image *C.struct__VipsImage, o Options, residual float64, shrink int) (*C.struct__VipsImage, float64, error) {
-	// Use vips_shrink with the integral reduction
-	image, err := vipsShrink(image, shrink)
-	if err != nil {
-		return nil, 0, err
-	}
-
-	// Recalculate residual float based on dimensions of required vs shrunk images
-	residualx := float64(o.Width) / float64(image.Xsize)
-	residualy := float64(o.Height) / float64(image.Ysize)
-
-	if o.Crop {
-		residual = math.Max(residualx, residualy)
-	} else {
-		residual = math.Min(residualx, residualy)
-	}
-
-	return image, residual, nil
-}
-
-func shrinkJpegImage(buf []byte, factor float64, shrink int) (*C.struct__VipsImage, float64, error) {
-	shrinkOnLoad := 1
-
-	switch {
-	case shrink >= 8:
-		factor = factor / 8
-		shrinkOnLoad = 8
-	case shrink >= 4:
-		factor = factor / 4
-		shrinkOnLoad = 4
-	case shrink >= 2:
-		factor = factor / 2
-		shrinkOnLoad = 2
-	}
-
-	if shrinkOnLoad > 1 {
-		// Reload input using shrink-on-load
-		image, err := vipsShrinkJpeg(buf, shrinkOnLoad)
-		if err != nil {
-			return nil, factor, err
-		}
-		return image, factor, err
-	}
-
-	return nil, factor, nil
-}
-
 func getAngle(angle Angle) Angle {
 	divisor := angle % 90
 	if divisor != 0 {

resize_test.go

@@ -7,18 +7,47 @@ import (
 )
 
 func TestResize(t *testing.T) {
-	options := Options{Width: 800, Height: 600, Crop: false, Rotate: 270}
-	img, err := os.Open("fixtures/test.jpg")
+	options := Options{Width: 800, Height: 600}
+	buf, _ := Read("fixtures/test.jpg")
+
+	newImg, err := Resize(buf, options)
 	if err != nil {
-		t.Fatal(err)
+		t.Errorf("Resize(imgData, %#v) error: %#v", options, err)
 	}
-	defer img.Close()
 
-	buf, err := ioutil.ReadAll(img)
+	if DetermineImageType(newImg) != JPEG {
+		t.Fatal("Image is not jpeg")
+	}
+
+	err = Write("fixtures/test_out.jpg", newImg)
 	if err != nil {
-		t.Fatal(err)
+		t.Fatal("Cannot save the image")
+	}
+}
+
+func TestRotate(t *testing.T) {
+	options := Options{Width: 800, Height: 600, Rotate: 270}
+	buf, _ := Read("fixtures/test.jpg")
+
+	newImg, err := Resize(buf, options)
+	if err != nil {
+		t.Errorf("Resize(imgData, %#v) error: %#v", options, err)
 	}
 
+	if DetermineImageType(newImg) != JPEG {
+		t.Fatal("Image is not jpeg")
+	}
+
+	err = Write("fixtures/test_rotate_out.jpg", newImg)
+	if err != nil {
+		t.Fatal("Cannot save the image")
+	}
+}
+
+func TestInvalidRotate(t *testing.T) {
+	options := Options{Width: 800, Height: 600, Rotate: 111}
+	buf, _ := Read("fixtures/test.jpg")
+
 	newImg, err := Resize(buf, options)
 	if err != nil {
 		t.Errorf("Resize(imgData, %#v) error: %#v", options, err)
@@ -28,7 +57,7 @@ func TestResize(t *testing.T) {
 		t.Fatal("Image is not jpeg")
 	}
 
-	err = ioutil.WriteFile("fixtures/test_out.jpg", newImg, 0644)
+	err = Write("fixtures/test_invalid_rotate_out.jpg", newImg)
 	if err != nil {
 		t.Fatal("Cannot save the image")
 	}
@@ -63,7 +92,7 @@ func TestConvert(t *testing.T) {
 		t.Fatal("Invalid image size")
 	}
 
-	err = ioutil.WriteFile("fixtures/test_out.png", newImg, 0644)
+	err = Write("fixtures/test_out.png", newImg)
 	if err != nil {
 		t.Fatal("Cannot save the image")
 	}
@@ -98,7 +127,7 @@ func TestResizePngWithTransparency(t *testing.T) {
 		t.Fatal("Invalid image size")
 	}
 
-	err = ioutil.WriteFile("fixtures/transparent_out.png", newImg, 0644)
+	err = Write("fixtures/transparent_out.png", newImg)
 	if err != nil {
 		t.Fatal("Cannot save the image")
 	}

vips.h

@@ -157,10 +157,10 @@ vips_init_image(void *buf, size_t len, int imageType, VipsImage **out) {
 #endif
 	}
 
-	if (out != NULL) {
 	// Listen for "postclose" signal to delete input buffer
+	//if (out != NULL) {
 		//g_signal_connect(out, "postclose", G_CALLBACK(vips_malloc_cb), buf);
-	}
+	//}
 
 	return code;
 };