feat: support resize and enlarge images

README.md

@@ -1,17 +1,34 @@
 # 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 library for blazing fast image processing based on [libvips](https://github.com/jcupitt/libvips) using C bindings. 
+
+**bimg** was focused on performance, resizing an image with libvips is typically 4x faster than using the quickest ImageMagick and GraphicsMagick settings.
+
+**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`
 
+## Prerequisites
+
+- [libvips](https://github.com/jcupitt/libvips) v7.40.0+ (7.42.0+ recommended)
+- C++11 compatible compiler such as gcc 4.6+ or clang 3.0+
+
 ## Installation
 
 ```bash
 go get gopkg.in/h2non/bimg.v0
 ```
-
 Requires Go 1.3+
 
+### libvips
+
+Run the following script as `sudo` (supports OSX, Debian/Ubuntu, Redhat, Fedora, Amazon Linux):
+```bash
+curl -s https://raw.githubusercontent.com/lovell/sharp/master/preinstall.sh | sudo bash -
+```
+
+The [install script](https://github.com/lovell/sharp/blob/master/preinstall.sh) requires `curl` and `pkg-config`.
+
 ## API
 
 ```go

resize.go

@@ -44,20 +44,142 @@ func Resize(buf []byte, o Options) ([]byte, error) {
 		o.Type = imageType
 	}
 
+	if IsTypeSupported(o.Type) == false {
+		return nil, errors.New("Unsupported image output type")
+	}
+
 	// get WxH
 	inWidth := int(image.Xsize)
 	inHeight := int(image.Ysize)
 
-	if o.Crop {
-		left, top := calculateCrop(inWidth, inHeight, o.Width, o.Height, o.Gravity)
-		o.Width = int(math.Min(float64(inWidth), float64(o.Width)))
-		o.Height = int(math.Min(float64(inHeight), float64(o.Height)))
-		image, err = vipsExtract(image, left, top, o.Width, o.Height)
+	// prepare for factor
+	factor := 0.0
+
+	// image calculations
+	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)
+		} else {
+			factor = math.Max(xf, yf)
+		}
+	// Fixed width, auto height
+	case o.Width > 0:
+		factor = float64(inWidth) / float64(o.Width)
+		o.Height = int(math.Floor(float64(inHeight) / factor))
+	// Fixed height, auto width
+	case o.Height > 0:
+		factor = float64(inHeight) / float64(o.Height)
+		o.Width = int(math.Floor(float64(inWidth) / factor))
+	// Identity transform
+	default:
+		factor = 1
+		o.Width = inWidth
+		o.Height = inHeight
+	}
+
+	debug("transform from %dx%d to %dx%d", inWidth, inHeight, o.Width, o.Height)
+
+	shrink := int(math.Max(math.Floor(factor), 1))
+	residual := float64(shrink) / factor
+
+	// Do not enlarge the output if the input width *or* height are already less than the required dimensions
+	if o.Enlarge == false {
+		if inWidth < o.Width && inHeight < o.Height {
+			factor = 1
+			shrink = 1
+			residual = 0
+			o.Width = inWidth
+			o.Height = inHeight
+		}
+	}
+
+	debug("factor: %v, shrink: %v, residual: %v", factor, shrink, residual)
+
+	// Try to use libjpeg shrink-on-load
+	shrinkOnLoad := 1
+	if imageType == JPEG && shrink >= 2 {
+		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 {
+			// Recalculate integral shrink and double residual
+			factor = math.Max(factor, 1.0)
+			shrink = int(math.Floor(factor))
+			residual = float64(shrink) / factor
+			// Reload input using shrink-on-load
+			image, err = vipsShrinkJpeg(buf, shrinkOnLoad)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	if shrink > 1 {
+		debug("shrink %d", shrink)
+		// Use vips_shrink with the integral reduction
+		image, err = vipsShrink(image, shrink)
+		if err != nil {
+			return nil, err
+		}
+
+		// Recalculate residual float based on dimensions of required vs shrunk images
+		shrunkWidth := int(image.Xsize)
+		shrunkHeight := int(image.Ysize)
+
+		residualx := float64(o.Width) / float64(shrunkWidth)
+		residualy := float64(o.Height) / float64(shrunkHeight)
+		if o.Crop {
+			residual = math.Max(residualx, residualy)
+		} else {
+			residual = math.Min(residualx, residualy)
+		}
+	}
+
+	// Use vips_affine with the remaining float part
+	if residual != 0 {
+		debug("residual %.2f", residual)
+		image, err = vipsAffine(image, residual, o.Interpolator)
 		if err != nil {
 			return nil, err
 		}
 	}
 
+	// Crop/embed
+	affinedWidth := int(image.Xsize)
+	affinedHeight := int(image.Ysize)
+
+	if affinedWidth != o.Width || affinedHeight != o.Height {
+		if o.Crop {
+			left, top := calculateCrop(inWidth, inHeight, o.Width, o.Height, o.Gravity)
+			o.Width = int(math.Min(float64(inWidth), float64(o.Width)))
+			o.Height = int(math.Min(float64(inHeight), float64(o.Height)))
+			image, err = vipsExtract(image, left, top, o.Width, o.Height)
+			if err != nil {
+				return nil, err
+			}
+		} else if o.Embed {
+			left := (o.Width - affinedWidth) / 2
+			top := (o.Height - affinedHeight) / 2
+			image, err = vipsEmbed(image, left, top, o.Width, o.Height, o.Extend)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
 	rotation, flip := calculateRotationAndFlip(image, o.Rotate)
 	if flip {
 		o.Flip = HORIZONTAL
@@ -81,10 +203,6 @@ func Resize(buf []byte, o Options) ([]byte, error) {
 		}
 	}
 
-	if IsTypeSupported(o.Type) == false {
-		return nil, errors.New("Unsupported image output type")
-	}
-
 	saveOptions := vipsSaveOptions{
 		Quality:     o.Quality,
 		Type:        o.Type,

vips.go

@@ -19,13 +19,17 @@ func init() {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 
+	if C.VIPS_MAJOR_VERSION <= 7 && C.VIPS_MINOR_VERSION < 40 {
+		panic("unsupported old vips version")
+	}
+
 	err := C.vips_init(C.CString("bimg"))
 	if err != 0 {
 		C.vips_shutdown()
 		panic("unable to start vips!")
 	}
 
-	C.vips_concurrency_set(1)                   // default
+	C.vips_concurrency_set(1)                   // single-thread
 	C.vips_cache_set_max_mem(100 * 1024 * 1024) // 100 MB
 	C.vips_cache_set_max(500)                   // 500 operations
 }
@@ -50,7 +54,7 @@ func vipsRotate(image *C.struct__VipsImage, angle Angle) (*C.struct__VipsImage,
 func vipsFlip(image *C.struct__VipsImage, direction Direction) (*C.struct__VipsImage, error) {
 	var out *C.struct__VipsImage
 
-	err := C.vips_flip_seq(image, &out)
+	err := C.vips_flip_custom(image, &out, C.int(direction))
 	C.g_object_unref(C.gpointer(image))
 	if err != 0 {
 		return nil, catchVipsError()
@@ -81,10 +85,10 @@ func vipsRead(buf []byte) (*C.struct__VipsImage, ImageType, error) {
 	return image, imageType, nil
 }
 
-func vipsExtract(image *C.struct__VipsImage, left int, top int, width int, height int) (*C.struct__VipsImage, error) {
+func vipsExtract(image *C.struct__VipsImage, left, top, width, height int) (*C.struct__VipsImage, error) {
 	var buf *C.struct__VipsImage
 
-	err := C.vips_extract_area_0(image, &buf, C.int(left), C.int(top), C.int(width), C.int(height))
+	err := C.vips_extract_area_custom(image, &buf, C.int(left), C.int(top), C.int(width), C.int(height))
 	C.g_object_unref(C.gpointer(image))
 	if err != 0 {
 		return nil, catchVipsError()
@@ -93,6 +97,59 @@ func vipsExtract(image *C.struct__VipsImage, left int, top int, width int, heigh
 	return buf, nil
 }
 
+func vipsShrinkJpeg(buf []byte, shrink int) (*C.struct__VipsImage, error) {
+	var image *C.struct__VipsImage
+
+	err := C.vips_jpegload_buffer_shrink(unsafe.Pointer(&buf[0]), C.size_t(len(buf)), &image, C.int(shrink))
+	C.g_object_unref(C.gpointer(image))
+	if err != 0 {
+		return nil, catchVipsError()
+	}
+
+	return image, nil
+}
+
+func vipsShrink(input *C.struct__VipsImage, shrink int) (*C.struct__VipsImage, error) {
+	var image *C.struct__VipsImage
+
+	err := C.vips_shrink_0(input, &image, C.double(float64(shrink)), C.double(float64(shrink)))
+	C.g_object_unref(C.gpointer(image))
+	if err != 0 {
+		return nil, catchVipsError()
+	}
+
+	return image, nil
+}
+
+func vipsEmbed(input *C.struct__VipsImage, left, top, width, height, extend int) (*C.struct__VipsImage, error) {
+	var image *C.struct__VipsImage
+
+	err := C.vips_embed_custom(input, &image, C.int(left), C.int(top), C.int(width), C.int(height), C.int(extend))
+	C.g_object_unref(C.gpointer(image))
+	if err != 0 {
+		return nil, catchVipsError()
+	}
+
+	return image, nil
+}
+
+func vipsAffine(input *C.struct__VipsImage, residual float64, i Interpolator) (*C.struct__VipsImage, error) {
+	var image *C.struct__VipsImage
+
+	istring := C.CString(i.String())
+	interpolator := C.vips_interpolate_new(istring)
+
+	// Perform affine transformation
+	err := C.vips_affine_interpolator(input, &image, C.double(residual), 0, 0, C.double(residual), interpolator)
+	C.g_object_unref(C.gpointer(image))
+	C.free(unsafe.Pointer(istring))
+	if err != 0 {
+		return nil, catchVipsError()
+	}
+
+	return image, nil
+}
+
 func vipsImageType(buf []byte) ImageType {
 	imageType := UNKNOWN
 

vips.h

@@ -23,13 +23,6 @@ vips_affine_interpolator(VipsImage *in, VipsImage **out, double a, double b, dou
 	return vips_affine(in, out, a, b, c, d, "interpolate", interpolator, NULL);
 };
 
-VipsImage*
-vips_image_buffer_seq(void *buf, size_t len)
-{
-	// todo: handle postclose callback
-	return vips_image_new_from_buffer(buf, len, "access", VIPS_ACCESS_SEQUENTIAL, NULL);
-};
-
 int
 vips_jpegload_buffer_shrink(void *buf, size_t len, VipsImage **out, int shrink)
 {
@@ -37,9 +30,9 @@ vips_jpegload_buffer_shrink(void *buf, size_t len, VipsImage **out, int shrink)
 };
 
 int
-vips_flip_seq(VipsImage *in, VipsImage **out)
+vips_flip_custom(VipsImage *in, VipsImage **out, int direction)
 {
-	return vips_flip(in, out, VIPS_DIRECTION_HORIZONTAL, NULL);
+	return vips_flip(in, out, direction, NULL);
 };
 
 int
@@ -48,12 +41,6 @@ vips_shrink_0(VipsImage *in, VipsImage **out, double xshrink, double yshrink)
 	return vips_shrink(in, out, xshrink, yshrink, NULL);
 };
 
-int
-vips_copy_0(VipsImage *in, VipsImage **out)
-{
-	return vips_copy(in, out, NULL);
-};
-
 int
 vips_rotate(VipsImage *in, VipsImage **buf, int angle)
 {
@@ -84,19 +71,19 @@ vips_exif_orientation(VipsImage *image) {
 };
 
 int
-vips_embed_extend(VipsImage *in, VipsImage **out, int left, int top, int width, int height, int extend)
+vips_embed_custom(VipsImage *in, VipsImage **out, int left, int top, int width, int height, int extend)
 {
 	return vips_embed(in, out, left, top, width, height, "extend", extend, NULL);
 };
 
 int
-vips_colourspace_0(VipsImage *in, VipsImage **out, VipsInterpretation space)
+vips_colourspace_custom(VipsImage *in, VipsImage **out, VipsInterpretation space)
 {
 	return vips_colourspace(in, out, space, NULL);
 };
 
 int
-vips_extract_area_0(VipsImage *in, VipsImage **out, int left, int top, int width, int height)
+vips_extract_area_custom(VipsImage *in, VipsImage **out, int left, int top, int width, int height)
 {
 	return vips_extract_area(in, out, left, top, width, height, NULL);
 };