feat(#92): support Extend param with optional background

options.go

@@ -112,6 +112,27 @@ const (
 	InterpretationXYZ Interpretation = C.VIPS_INTERPRETATION_XYZ
 )
 
+// Extend represents the image extend mode, used when the edges
+// of an image are extended, you can specify how you want the extension done.
+type Extend int
+
+const (
+	// ExtendBlack extend with black (all 0) pixels mode.
+	ExtendBlack Extend = C.VIPS_EXTEND_BLACK
+	// ExtendCopy copy the image edges.
+	ExtendCopy Extend = C.VIPS_EXTEND_COPY
+	// ExtendRepeat repeat the whole image.
+	ExtendRepeat Extend = C.VIPS_EXTEND_REPEAT
+	// ExtendMirro mirror the whole image.
+	ExtendMirror Extend = C.VIPS_EXTEND_MIRROR
+	// ExtendWhite extend with white (all bits set) pixels.
+	ExtendWhite Extend = C.VIPS_EXTEND_WHITE
+	// ExtendBackground with colour from the background property.
+	ExtendBackground Extend = C.VIPS_EXTEND_BACKGROUND
+	// ExtendLast extend with last pixel.
+	ExtendLast Extend = C.VIPS_EXTEND_LAST
+)
+
 // WatermarkFont defines the default watermark font to be used.
 var WatermarkFont = "sans 10"
 
@@ -159,7 +180,6 @@ type Options struct {
 	AreaWidth      int
 	Top            int
 	Left           int
-	Extend         int
 	Quality        int
 	Compression    int
 	Zoom           int
@@ -172,6 +192,7 @@ type Options struct {
 	NoAutoRotate   bool
 	NoProfile      bool
 	Interlace      bool
+	Extend         Extend
 	Rotate         Angle
 	Background     Color
 	Gravity        Gravity

resize.go

@@ -240,7 +240,7 @@ func extractOrEmbedImage(image *C.VipsImage, o Options) (*C.VipsImage, error) {
 		break
 	case o.Embed:
 		left, top := (o.Width-inWidth)/2, (o.Height-inHeight)/2
-		image, err = vipsEmbed(image, left, top, o.Width, o.Height, o.Extend)
+		image, err = vipsEmbed(image, left, top, o.Width, o.Height, o.Extend, o.Background)
 		break
 	case o.Top != 0 || o.Left != 0:
 		if o.AreaWidth == 0 {

resize_test.go

@@ -216,6 +216,40 @@ func TestNoColorProfile(t *testing.T) {
 	}
 }
 
+func TestEmbedExtendColor(t *testing.T) {
+	options := Options{Width: 400, Height: 600, Crop: false, Embed: true, Extend: ExtendWhite, Background: Color{255, 20, 10}}
+	buf, _ := Read("fixtures/test_issue.jpg")
+
+	newImg, err := Resize(buf, options)
+	if err != nil {
+		t.Errorf("Resize(imgData, %#v) error: %#v", options, err)
+	}
+
+	size, _ := Size(newImg)
+	if size.Height != options.Height || size.Width != options.Width {
+		t.Fatalf("Invalid image size: %dx%d", size.Width, size.Height)
+	}
+
+	Write("fixtures/test_extend_white_out.jpg", newImg)
+}
+
+func TestEmbedExtendWithCustomColor(t *testing.T) {
+	options := Options{Width: 400, Height: 600, Crop: false, Embed: true, Extend: 5, Background: Color{255, 20, 10}}
+	buf, _ := Read("fixtures/test_issue.jpg")
+
+	newImg, err := Resize(buf, options)
+	if err != nil {
+		t.Errorf("Resize(imgData, %#v) error: %#v", options, err)
+	}
+
+	size, _ := Size(newImg)
+	if size.Height != options.Height || size.Width != options.Width {
+		t.Fatalf("Invalid image size: %dx%d", size.Width, size.Height)
+	}
+
+	Write("fixtures/test_extend_background_out.jpg", newImg)
+}
+
 func TestGaussianBlur(t *testing.T) {
 	options := Options{Width: 800, Height: 600, GaussianBlur: GaussianBlur{Sigma: 5}}
 	buf, _ := Read("fixtures/test.jpg")

vips.go

@@ -459,11 +459,17 @@ func vipsShrink(input *C.VipsImage, shrink int) (*C.VipsImage, error) {
 	return image, nil
 }
 
-func vipsEmbed(input *C.VipsImage, left, top, width, height, extend int) (*C.VipsImage, error) {
+func vipsEmbed(input *C.VipsImage, left, top, width, height int, extend Extend, background Color) (*C.VipsImage, error) {
 	var image *C.VipsImage
-	defer C.g_object_unref(C.gpointer(input))
 
-	err := C.vips_embed_bridge(input, &image, C.int(left), C.int(top), C.int(width), C.int(height), C.int(extend))
+	// Max extend value, see: http://www.vips.ecs.soton.ac.uk/supported/8.4/doc/html/libvips/libvips-conversion.html#VipsExtend
+	if extend > 5 {
+		extend = ExtendBackground
+	}
+
+	defer C.g_object_unref(C.gpointer(input))
+	err := C.vips_embed_bridge(input, &image, C.int(left), C.int(top), C.int(width),
+		C.int(height), C.int(extend), C.double(background.R), C.double(background.G), C.double(background.B))
 	if err != 0 {
 		return nil, catchVipsError()
 	}

vips.h

@@ -207,7 +207,12 @@ vips_zoom_bridge(VipsImage *in, VipsImage **out, int xfac, int yfac) {
 }
 
 int
-vips_embed_bridge(VipsImage *in, VipsImage **out, int left, int top, int width, int height, int extend) {
+vips_embed_bridge(VipsImage *in, VipsImage **out, int left, int top, int width, int height, int extend, double r, double g, double b) {
+	if (extend == VIPS_EXTEND_BACKGROUND) {
+		double background[3] = {r, g, b};
+		VipsArrayDouble *vipsBackground = vips_array_double_new(background, 3);
+		return vips_embed(in, out, left, top, width, height, "extend", extend, "background", vipsBackground, NULL);
+	}
 	return vips_embed(in, out, left, top, width, height, "extend", extend, NULL);
 }
 
@@ -280,7 +285,7 @@ int
 vips_flatten_background_brigde(VipsImage *in, VipsImage **out, double r, double g, double b) {
 	double background[3] = {r, g, b};
 	VipsArrayDouble *vipsBackground = vips_array_double_new(background, 3);
-	
+
 	return vips_flatten(in, out,
 		"background", vipsBackground,
 		"max_alpha", vips_is_16bit(in->Type) ? 65535.0 : 255.0,