fix(#28): zoom requires extract params

README.md

@@ -6,12 +6,11 @@ bimg is designed to be a small and efficient library with a generic and useful s
 It uses internally libvips, which requires a [low memory footprint](http://www.vips.ecs.soton.ac.uk/index.php?title=Speed_and_Memory_Use) 
 and it's 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. 
 
-It can read JPEG, PNG, WEBP and TIFF formats and output to JPEG, PNG and WEBP, including conversion betweem them. It supports common [image operations](#supported-image-operations) such as crop, resize, rotate, zoom, watermark... 
+It can read JPEG, PNG, WEBP and TIFF formats and output to JPEG, PNG and WEBP, including conversion between them. It supports common [image operations](#supported-image-operations) such as crop, resize, rotate, zoom, watermark... 
 
 For getting started, take a look to 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), 
-its homologous package built for node.js by [Lovell Fuller](https://github.com/lovell).
+bimg was heavily inspired in [sharp](https://github.com/lovell/sharp), its homologous package built for node.js by [Lovell Fuller](https://github.com/lovell).
 
 **Note**: bimg is still beta. Do not use in production yet
 
@@ -653,3 +652,5 @@ type Watermark struct {
 ## License
 
 MIT - Tomas Aparicio
+
+[![views](https://sourcegraph.com/api/repos/github.com/h2non/bimg/.counters/views.svg)](https://sourcegraph.com/github.com/h2non/bimg)

image.go

@@ -81,9 +81,10 @@ func (i *Image) Watermark(w Watermark) ([]byte, error) {
 	return i.Process(options)
 }
 
-// Zoom the image by the given factor
-func (i *Image) Zoom(level int) ([]byte, error) {
-	options := Options{Zoom: level}
+// Zoom the image by the given factor.
+// You should probably call Extract() before
+func (i *Image) Zoom(factor int) ([]byte, error) {
+	options := Options{Zoom: factor}
 	return i.Process(options)
 }
 

image_test.go

@@ -23,7 +23,7 @@ func TestImageResize(t *testing.T) {
 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)
+		t.Errorf("Cannot process the image: %s", err)
 	}
 
 	err = assertSize(buf, 300, 300)
@@ -51,7 +51,7 @@ func TestImageEnlarge(t *testing.T) {
 func TestImageCrop(t *testing.T) {
 	buf, err := initImage("test.jpg").Crop(800, 600, NORTH)
 	if err != nil {
-		t.Errorf("Cannot process the image: %#v", err)
+		t.Errorf("Cannot process the image: %s", err)
 	}
 
 	err = assertSize(buf, 800, 600)
@@ -65,7 +65,7 @@ func TestImageCrop(t *testing.T) {
 func TestImageCropByWidth(t *testing.T) {
 	buf, err := initImage("test.jpg").CropByWidth(600)
 	if err != nil {
-		t.Errorf("Cannot process the image: %#v", err)
+		t.Errorf("Cannot process the image: %s", err)
 	}
 
 	err = assertSize(buf, 600, 375)
@@ -79,7 +79,7 @@ func TestImageCropByWidth(t *testing.T) {
 func TestImageCropByHeight(t *testing.T) {
 	buf, err := initImage("test.jpg").CropByHeight(300)
 	if err != nil {
-		t.Errorf("Cannot process the image: %#v", err)
+		t.Errorf("Cannot process the image: %s", err)
 	}
 
 	err = assertSize(buf, 480, 300)
@@ -93,7 +93,7 @@ func TestImageCropByHeight(t *testing.T) {
 func TestImageThumbnail(t *testing.T) {
 	buf, err := initImage("test.jpg").Thumbnail(100)
 	if err != nil {
-		t.Errorf("Cannot process the image: %#v", err)
+		t.Errorf("Cannot process the image: %s", err)
 	}
 
 	err = assertSize(buf, 100, 100)
@@ -138,7 +138,7 @@ func TestImageWatermarkNoReplicate(t *testing.T) {
 	image := initImage("test.jpg")
 	_, err := image.Crop(800, 600, NORTH)
 	if err != nil {
-		t.Errorf("Cannot process the image: %#v", err)
+		t.Errorf("Cannot process the image: %s", err)
 	}
 
 	buf, err := image.Watermark(Watermark{
@@ -166,12 +166,19 @@ func TestImageWatermarkNoReplicate(t *testing.T) {
 }
 
 func TestImageZoom(t *testing.T) {
-	buf, err := initImage("test.jpg").Zoom(1)
+	image := initImage("test.jpg")
+
+	_, err := image.Extract(100, 100, 400, 300)
 	if err != nil {
-		t.Errorf("Cannot process the image: %#v", err)
+		t.Errorf("Cannot extract the image: %s", err)
+	}
+
+	buf, err := image.Zoom(1)
+	if err != nil {
+		t.Errorf("Cannot process the image: %s", err)
 	}
 
-	err = assertSize(buf, 3360, 2100)
+	err = assertSize(buf, 800, 600)
 	if err != nil {
 		t.Error(err)
 	}