vips crop support (#382)

Signed-off-by: songjiayang <songjiayang1@gmail.com>

vips/conversion.c

@@ -223,6 +223,12 @@ int smartcrop(VipsImage *in, VipsImage **out, int width, int height,
                         NULL);
 }
 
+int crop(VipsImage *in, VipsImage **out, int left, int top,
+              int width, int height) {
+  return vips_crop(in, out, left, top, width, height,
+                        NULL);
+}
+
 int flatten_image(VipsImage *in, VipsImage **out, double r, double g,
                   double b) {
   if (is_16bit(in->Type)) {

vips/conversion.go

@@ -274,6 +274,18 @@ func vipsSmartCrop(in *C.VipsImage, width int, height int, interesting Interesti
 	return out, nil
 }
 
+// http://libvips.github.io/libvips/API/current/libvips-conversion.html#vips-crop
+func vipsCrop(in *C.VipsImage, left int, top int, width int, height int) (*C.VipsImage, error) {
+	incOpCounter("crop")
+	var out *C.VipsImage
+
+	if err := C.crop(in, &out, C.int(left), C.int(top), C.int(width), C.int(height)); err != 0 {
+		return nil, handleImageError(out)
+	}
+
+	return out, nil
+}
+
 // https://libvips.github.io/libvips/API/current/libvips-conversion.html#vips-rot
 func vipsRotate(in *C.VipsImage, angle Angle) (*C.VipsImage, error) {
 	incOpCounter("rot")

vips/conversion.h

@@ -33,6 +33,8 @@ int autorot_image(VipsImage *in, VipsImage **out);
 int zoom_image(VipsImage *in, VipsImage **out, int xfac, int yfac);
 int smartcrop(VipsImage *in, VipsImage **out, int width, int height,
               int interesting);
+int crop(VipsImage *in, VipsImage **out, int left, int top,
+              int width, int height);
 
 int bandjoin(VipsImage **in, VipsImage **out, int n);
 int bandjoin_const(VipsImage *in, VipsImage **out, double constants[], int n);

vips/image.go

@@ -1845,6 +1845,16 @@ func (r *ImageRef) SmartCrop(width int, height int, interesting Interesting) err
 	return nil
 }
 
+// Crop will crop the image based on coordinate and box size
+func (r *ImageRef) Crop(left int, top int, width int, height int) error {
+	out, err := vipsCrop(r.image, left, top, width, height)
+	if err != nil {
+		return err
+	}
+	r.setImage(out)
+	return nil
+}
+
 // Label overlays a label on top of the image
 func (r *ImageRef) Label(labelParams *LabelParams) error {
 	out, err := labelImage(r.image, labelParams)

vips/image_golden_test.go

@@ -565,6 +565,15 @@ func TestImage_SmartCrop(t *testing.T) {
 	}, nil)
 }
 
+func TestImage_Crop(t *testing.T) {
+	goldenTest(t, resources+"jpg-24bit.jpg", func(img *ImageRef) error {
+		return img.Crop(10, 10, 60, 80)
+	}, func(result *ImageRef) {
+		assert.Equal(t, 60, result.Width())
+		assert.Equal(t, 80, result.Height())
+	}, nil)
+}
+
 func TestImage_Replicate(t *testing.T) {
 	goldenTest(t, resources+"jpg-24bit.jpg", func(img *ImageRef) error {
 		return img.Replicate(3, 2)