WIP: Use vips_thumbnail_buffer() to resize

image.go

@@ -129,6 +129,21 @@ func (i *Image) Thumbnail(pixels int) ([]byte, error) {
 	return i.Process(options)
 }
 
+func (i *Image) ThumbnailOptions(o Options) ([]byte, error) {
+	vipsImage, err := imageThumbnail(i.buffer, o.Width, o.Height, o.NoAutoRotate, o.Crop)
+	if err != nil {
+		return nil, err
+	}
+
+	image, err := saveImage(vipsImage, o)
+	if err != nil {
+		return nil, err
+	}
+
+	i.buffer = image
+	return image, nil
+}
+
 // Watermark adds text as watermark on the given image.
 func (i *Image) Watermark(w Watermark) ([]byte, error) {
 	options := Options{Watermark: w}

image_test.go

@@ -212,6 +212,43 @@ func TestImageThumbnail(t *testing.T) {
 	Write("testdata/test_thumbnail_out.jpg", buf)
 }
 
+func TestImageThumbnailOptions(t *testing.T) {
+	buf, err := initImage("test.jpg").ThumbnailOptions(Options{
+		Height:         100,
+		Width:          100,
+		Quality:        50,
+		Type:           JPEG,
+	})
+	if err != nil {
+		t.Errorf("Cannot process the image: %s", err)
+	}
+
+	err = assertSize(buf, 100, 62)
+	if err != nil {
+		t.Error(err)
+	}
+
+	Write("testdata/test_thumbnail_options_out.jpg", buf)
+
+	buf, err = initImage("test.jpg").ThumbnailOptions(Options{
+		Height:         100,
+		Width:          100,
+		Quality:        50,
+		Type:           JPEG,
+		Crop:						true,
+	})
+	if err != nil {
+		t.Errorf("Cannot process the image: %s", err)
+	}
+
+	err = assertSize(buf, 100, 100)
+	if err != nil {
+		t.Error(err)
+	}
+
+	Write("testdata/test_thumbnail_options_crop_out.jpg", buf)
+}
+
 func TestImageWatermark(t *testing.T) {
 	image := initImage("test.jpg")
 	_, err := image.Crop(800, 600, GravityNorth)

resizer.go

@@ -148,6 +148,14 @@ func loadImage(buf []byte) (*C.VipsImage, ImageType, error) {
 	return image, imageType, nil
 }
 
+func imageThumbnail(buf []byte, width, height int, noRotate, crop bool) (*C.VipsImage, error) {
+	if len(buf) == 0 {
+		return nil, errors.New("Image buffer is empty")
+	}
+
+	return vipsThumbnail(buf, width, height, noRotate, crop)
+}
+
 func applyDefaults(o Options, imageType ImageType) Options {
 	if o.Quality == 0 {
 		o.Quality = Quality

vips.go

@@ -317,6 +317,25 @@ func vipsRead(buf []byte) (*C.VipsImage, ImageType, error) {
 	return image, imageType, nil
 }
 
+func vipsThumbnail(buf []byte, width, height int, noAutoRotate, crop bool) (*C.VipsImage, error) {
+	var image *C.VipsImage
+
+	noRotateParam := C.int(boolToInt(noAutoRotate))
+	cropParam := C.int(boolToInt(crop))
+
+	length := C.size_t(len(buf))
+	imageBuf := unsafe.Pointer(&buf[0])
+
+	err := C.vips_thumbnail_bridge(imageBuf, length, &image,
+		C.int(width), C.int(height), noRotateParam, cropParam,
+	)
+	if int(err) != 0 {
+		return nil, catchVipsError()
+	}
+
+	return image, nil
+}
+
 func vipsColourspaceIsSupportedBuffer(buf []byte) (bool, error) {
 	image, _, err := vipsRead(buf)
 	if err != nil {
@@ -733,4 +752,4 @@ func vipsGamma(image *C.VipsImage, Gamma float64) (*C.VipsImage, error) {
 		return nil, catchVipsError()
 	}
 	return out, nil
-}
+}

vips.h

@@ -354,6 +354,23 @@ vips_is_16bit (VipsInterpretation interpretation) {
 	return interpretation == VIPS_INTERPRETATION_RGB16 || interpretation == VIPS_INTERPRETATION_GREY16;
 }
 
+int
+vips_thumbnail_bridge(void *buf, size_t len, VipsImage **out, int width, int height, int no_rotate, int crop) {
+	if (crop) {
+		return vips_thumbnail_buffer(buf, len, out, width,
+			"height", height,
+			"no_rotate", INT_TO_GBOOLEAN(no_rotate),
+			"crop", VIPS_INTERESTING_CENTRE,
+			NULL
+		);
+	}
+	return vips_thumbnail_buffer(buf, len, out, width,
+		"height", height,
+		"no_rotate", INT_TO_GBOOLEAN(no_rotate),
+		NULL
+	);
+}
+
 int
 vips_flatten_background_brigde(VipsImage *in, VipsImage **out, double r, double g, double b) {
 	if (vips_is_16bit(in->Type)) {