#95 First shot for implementing Focal Point Cropping (#96)

Closes #95 Implementing Focal Point Cropping
* #95 Wrap the filterContext into the ImageFilterContext
* Adding test for FocalPoint cropping
* Address review comments

Author: duergner

README.md

@@ -109,6 +109,7 @@ Skrop provides a set of filters, which you can use within the routes:
 * **blur(sigma, min_ampl)** — blurs the image (for info see [here](http://www.vips.ecs.soton.ac.uk/supported/current/doc/html/libvips/libvips-convolution.html#vips-gaussblur))
 * **imageOverlay(filename, opacity, gravity, opt-top-margin, opt-right-margin, opt-bottom-margin, opt-left-margin)** — puts an image onverlay over the required image
 * **transformFromQueryParams()** - transforms the image based on the request query parameters (supports only crop for now) e.g: localhost:9090/images/S/big-ben.jpg?crop=120,300,500,300.
+* **cropByFocalPoint(targetX, targetY, aspectRatio)** — crops the image based on a focal point on both the source as well as on the target and desired aspect ratio of the target. TargetX and TargetY are the definition of the target image focal point defined as relative values for both width and height, i.e. if the focal point of the target image should be right in the center it would be 0.5 and 0.5. This filter expects two PathParams named **focalPointX** and **focalPointY** which are absolute X and Y coordinates of the focal point in the source image.
 
 ### About filters
 The eskip file defines a list of configuration. Every configuration is composed by a route and a list of filters to

cmd/skrop/main.go

@@ -110,6 +110,7 @@ func main() {
 			skropFilters.NewCrop(),
 			skropFilters.NewCropByWidth(),
 			skropFilters.NewCropByHeight(),
+			skropFilters.NewCropByFocalPoint(),
 			skropFilters.NewResizeByWidth(),
 			skropFilters.NewResizeByHeight(),
 			skropFilters.NewQuality(),

eskip/sample.eskip

@@ -49,6 +49,11 @@ cropByHeight: Path("/images/cropbyheight/:image")
   -> cropByHeight(1000, "south")
   -> "http://localhost:9090";
 
+cropByFocalPoint: Path("/images/cropbyfocalpoint/:focalPointX/:focalPointY/:image")
+  -> modPath("^/images/cropbyfocalpoint/\\d+/\\d+", "/images")
+  -> cropByFocalPoint(0.25,0.25,0.5)
+  -> "http://localhost:9090";
+
 widthAndQuality: Path("/images/waq/:image")
   -> modPath("^/images/waq", "/images")
   -> width(1000)

filters/cropbyfocalpoint.go

@@ -0,0 +1,132 @@
+package filters
+
+import (
+		"github.com/zalando-stups/skrop/parse"
+	"github.com/zalando/skipper/filters"
+	"gopkg.in/h2non/bimg.v1"
+	"strconv"
+)
+
+// CropByFocalPointName is the name of the filter
+const CropByFocalPointName = "cropByFocalPoint"
+
+type cropByFocalPoint struct {
+	targetX     float64
+	targetY     float64
+	aspectRatio float64
+}
+
+// NewCropByFocalPoint creates a new filter of this type
+func NewCropByFocalPoint() filters.Spec {
+	return &cropByFocalPoint{}
+}
+
+func (f *cropByFocalPoint) Name() string {
+	return CropByFocalPointName
+}
+
+func (f *cropByFocalPoint) CreateOptions(imageContext *ImageFilterContext) (*bimg.Options, error) {
+	imageSize, err := imageContext.Image.Size()
+
+	if err != nil {
+		return nil, err
+	}
+
+	focalPointX := imageContext.PathParam("focalPointX")
+	focalPointY := imageContext.PathParam("focalPointY")
+
+	if focalPointX == "" || focalPointY == "" {
+		return nil, filters.ErrInvalidFilterParameters
+	}
+
+	sourceX, err := strconv.Atoi(focalPointX)
+
+	if err != nil {
+		return nil, err
+	}
+
+	sourceY, err := strconv.Atoi(focalPointY)
+
+	if err != nil {
+		return nil, err
+	}
+
+	right := imageSize.Width - sourceX
+	bottom := imageSize.Height - sourceY
+
+	cropLeftWidth := int(float64(sourceX) / f.targetX)
+	cropRightWidth := int(float64(right) / (float64(1) - f.targetX))
+
+	width := cropRightWidth
+
+	if cropLeftWidth < cropRightWidth {
+		width = cropLeftWidth
+	}
+
+	cropTopHeight := int(float64(sourceY) / f.targetY)
+	cropBottomHeight := int(float64(bottom) / (float64(1) - f.targetY))
+
+	height := cropBottomHeight
+
+	if cropTopHeight < cropBottomHeight {
+		height = int(float64(sourceY) / f.targetY)
+	}
+
+	ratio := float64(height) / float64(width)
+
+	if ratio > f.aspectRatio {
+		height = int(float64(width) * f.aspectRatio)
+	} else {
+		width = int(float64(height) / f.aspectRatio)
+	}
+
+	return &bimg.Options{
+		AreaWidth:  width,
+		AreaHeight: height,
+		Top:    sourceY - int(float64(height) * f.targetY),
+		Left:   sourceX - int(float64(width) * f.targetX)}, nil
+}
+
+func (f *cropByFocalPoint) CanBeMerged(other *bimg.Options, self *bimg.Options) bool {
+	return false
+}
+
+func (f *cropByFocalPoint) Merge(other *bimg.Options, self *bimg.Options) *bimg.Options {
+	return self
+}
+
+func (f *cropByFocalPoint) CreateFilter(args []interface{}) (filters.Filter, error) {
+	var err error
+
+	if len(args) < 3 || len(args) > 3 {
+		return nil, filters.ErrInvalidFilterParameters
+	}
+
+	c := &cropByFocalPoint{}
+
+	c.targetX, err = parse.EskipFloatArg(args[0])
+
+	if err != nil {
+		return nil, err
+	}
+
+	c.targetY, err = parse.EskipFloatArg(args[1])
+
+	if err != nil {
+		return nil, err
+	}
+
+	c.aspectRatio, err = parse.EskipFloatArg(args[2])
+
+	if err != nil {
+		return nil, err
+	}
+
+	return c, nil
+}
+
+func (f *cropByFocalPoint) Request(ctx filters.FilterContext) {}
+
+func (f *cropByFocalPoint) Response(ctx filters.FilterContext) {
+	HandleImageResponse(ctx, f)
+}

filters/cropbyfocalpoint_test.go

@@ -0,0 +1,125 @@
+package filters
+
+import (
+	"testing"
+	"github.com/stretchr/testify/assert"
+	"github.com/zalando-stups/skrop/filters/imagefiltertest"
+	"github.com/zalando/skipper/filters"
+)
+
+func TestNewCropByFocalPoint(t *testing.T) {
+	name := NewCropByFocalPoint().Name()
+	assert.Equal(t, "cropByFocalPoint", name)
+}
+
+func TestCropByFocalPoint_Name(t *testing.T) {
+	c := cropByFocalPoint{}
+	assert.Equal(t, "cropByFocalPoint", c.Name())
+}
+
+func TestCropByFocalPoint_CreateOptions(t *testing.T) {
+	c := cropByFocalPoint{targetX: 0.5, targetY: 0.5, aspectRatio: 1.5}
+	image := imagefiltertest.LandscapeImage()
+	fc := createDefaultContext(t, "doesnotmatter.com")
+	fc.FParams = make(map[string]string)
+	fc.FParams["focalPointX"] = "500";
+	fc.FParams["focalPointY"] = "334";
+
+	options, _ := c.CreateOptions(buildParameters(fc, image))
+
+	assert.Equal(t, 445, options.AreaWidth)
+	assert.Equal(t, 668, options.AreaHeight)
+	assert.Equal(t, 0, options.Top)
+	assert.Equal(t, 278, options.Left)
+
+	c = cropByFocalPoint{targetX: 0.5, targetY: 0.25, aspectRatio: 1.5}
+	image = imagefiltertest.LandscapeImage()
+	fc = createDefaultContext(t, "doesnotmatter.com")
+	fc.FParams = make(map[string]string)
+	fc.FParams["focalPointX"] = "500";
+	fc.FParams["focalPointY"] = "334";
+
+	options, _ = c.CreateOptions(buildParameters(fc, image))
+
+	assert.Equal(t, 296, options.AreaWidth)
+	assert.Equal(t, 445, options.AreaHeight)
+	assert.Equal(t, 223, options.Top)
+	assert.Equal(t, 352, options.Left)
+}
+
+func TestCropByFocalPoint_CreateOptions_MissingPathParam(t *testing.T) {
+	c := cropByFocalPoint{targetX: 0.5, targetY: 0.5, aspectRatio: 1.5}
+	image := imagefiltertest.LandscapeImage()
+	fc := createDefaultContext(t, "doesnotmatter.com")
+	fc.FParams = make(map[string]string)
+	fc.FParams["focalPointY"] = "334";
+
+	options, err := c.CreateOptions(buildParameters(fc, image))
+
+	assert.Nil(t, options)
+	assert.Equal(t, filters.ErrInvalidFilterParameters, err)
+
+	fc = createDefaultContext(t, "doesnotmatter.com")
+	fc.FParams = make(map[string]string)
+	fc.FParams["focalPointX"] = "334";
+
+	options, err = c.CreateOptions(buildParameters(fc, image))
+
+	assert.Nil(t, options)
+	assert.Equal(t, filters.ErrInvalidFilterParameters, err)
+}
+
+func TestCropByFocalPoint_CreateOptions_InvalidPathParam(t *testing.T) {
+	c := cropByFocalPoint{targetX: 0.5, targetY: 0.5, aspectRatio: 1.5}
+	image := imagefiltertest.LandscapeImage()
+	fc := createDefaultContext(t, "doesnotmatter.com")
+	fc.FParams = make(map[string]string)
+	fc.FParams["focalPointX"] = "xyz";
+	fc.FParams["focalPointY"] = "abc";
+
+	options, err := c.CreateOptions(buildParameters(fc, image))
+
+	assert.Nil(t, options)
+	assert.NotNil(t, err)
+
+	fc.FParams["focalPointX"] = "100";
+	fc.FParams["focalPointY"] = "abc";
+
+	options, err = c.CreateOptions(buildParameters(fc, image))
+
+	assert.Nil(t, options)
+	assert.NotNil(t, err)
+}
+
+func TestCropByFocalPoint_CanBeMerged(t *testing.T) {
+	ea := transformFromQueryParams{}
+	assert.Equal(t, false, ea.CanBeMerged(nil, nil))
+}
+
+func TestCropByFocalPoint_CreateFilter(t *testing.T) {
+	imagefiltertest.TestCreate(t, NewCropByFocalPoint, []imagefiltertest.CreateTestItem{{
+		Msg:  "less than 3 args",
+		Args: nil,
+		Err:  true,
+	}, {
+		Msg:  "invalid targetX",
+		Args: []interface{}{"xyz", 0.5, 1.5},
+		Err:  true,
+	}, {
+		Msg:  "invalid targetY",
+		Args: []interface{}{0.5, "abc", 1.5},
+		Err:  true,
+	}, {
+		Msg:  "invalid aspectRatio",
+		Args: []interface{}{0.5, 0.5, "qwerty"},
+		Err:  true,
+	}, {
+		Msg:  "3 args",
+		Args: []interface{}{0.5, 0.5, 1.5},
+		Err:  false,
+	}, {
+		Msg:  "more than 3 args",
+		Args: []interface{}{0.5, 0.5, 1.5, 1.0},
+		Err:  true,
+	}})
+}

filters/imagefilter.go

@@ -36,7 +36,7 @@ const (
 var (
 	cropTypeToGravity map[string]bimg.Gravity
 	cropTypes         map[string]bool
-	stripMetadata bool
+	stripMetadata     bool
 )
 
 func init() {
@@ -67,10 +67,13 @@ type ImageFilter interface {
 }
 
 type ImageFilterContext struct {
-	Image      *bimg.Image
-	Parameters map[string][]string
+	Image         *bimg.Image
+	Parameters    map[string][]string
+	filterContext *filters.FilterContext
 }
 
+func (c *ImageFilterContext) PathParam(key string) string { return (*c.filterContext).PathParam(key) }
+
 func errorResponse() *http.Response {
 	return &http.Response{
 		StatusCode: http.StatusInternalServerError,
@@ -83,9 +86,11 @@ func buildParameters(ctx filters.FilterContext, image *bimg.Image) *ImageFilterC
 	if ctx != nil {
 		parameters = ctx.Request().URL.Query()
 	}
+
 	return &ImageFilterContext{
-		Image:      image,
-		Parameters: parameters,
+		Image:         image,
+		Parameters:    parameters,
+		filterContext: &ctx,
 	}
 }
 

filters/transformFromQueryParams.go

@@ -10,6 +10,7 @@ import (
 const (
 	ExtractArea    = "transformFromQueryParams"
 	cropParameters = "crop"
+	focalPointCropParameters = "focal_point_crop"
 )
 
 type transformFromQueryParams struct{}
@@ -30,6 +31,19 @@ func (t *transformFromQueryParams) CreateOptions(ctx *ImageFilterContext) (*bimg
 	// Get crop prams from the request
 	params, ok := ctx.Parameters[cropParameters]
 	if !ok {
+
+		params, ok = ctx.Parameters[focalPointCropParameters]
+
+		if !ok {
+			return &bimg.Options{}, nil
+		}
+
+		params = strings.Split(params[0], ",")
+		if len(params) != 5 {
+			return &bimg.Options{}, nil
+		}
+
+		// TODO do focal point crop
 		return &bimg.Options{}, nil
 	}