Focalpoint

halfshell/image.go

@@ -25,13 +25,15 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"strconv"
 	"strings"
 
 	"github.com/rafikk/imagick/imagick"
 )
 
 var EmptyImageDimensions = ImageDimensions{}
 var EmptyResizeDimensions = ResizeDimensions{}
+var DefaultFocalPoint = Focalpoint{0.5, 0.5}
 
 type Image struct {
 	Wand      *imagick.MagickWand
@@ -109,3 +111,31 @@ type ResizeDimensions struct {
 	Scale ImageDimensions
 	Crop  ImageDimensions
 }
+
+// Focalpoint is a float pair representing the location of the image subject.
+// (0.5, 0.5) is the middle. (1, 1) is the bottom right. (0, 0) is the top left.
+type Focalpoint struct {
+	X float64
+	Y float64
+}
+
+// NewFocalpointFromString splits the given string into a Focalpoint struct. The
+// string format should be: "X,Y". For example: "0.1,0.1".
+func NewFocalpointFromString(s string) (fp Focalpoint) {
+	pair := strings.Split(s, ",")
+	if len(pair) != 2 {
+		return DefaultFocalPoint
+	}
+
+	x, err := strconv.ParseFloat(pair[0], 64)
+	if err != nil {
+		return DefaultFocalPoint
+	}
+
+	y, err := strconv.ParseFloat(pair[1], 64)
+	if err != nil {
+		return DefaultFocalPoint
+	}
+
+	return Focalpoint{x, y}
+}

halfshell/image_processor.go

@@ -48,6 +48,7 @@ type ImageProcessorOptions struct {
 	Dimensions ImageDimensions
 	BlurRadius float64
 	ScaleMode  uint
+	Focalpoint Focalpoint
 }
 
 type imageProcessor struct {
@@ -153,7 +154,7 @@ func (ip *imageProcessor) resize(img *Image, req *ImageProcessorOptions) error {
 	}
 
 	if resize.Crop != EmptyImageDimensions {
-		err = ip.cropApply(img, resize.Crop)
+		err = ip.cropApply(img, resize.Crop, req.Focalpoint)
 		if err != nil {
 			return err
 		}
@@ -292,17 +293,13 @@ func (ip *imageProcessor) resizeApply(img *Image, dimensions ImageDimensions) er
 	return nil
 }
 
-func (ip *imageProcessor) cropApply(img *Image, reqDimensions ImageDimensions) error {
-	if reqDimensions == EmptyImageDimensions {
-		return nil
-	}
+func (ip *imageProcessor) cropApply(img *Image, reqDimensions ImageDimensions, focalpoint Focalpoint) error {
 	oldDimensions := img.GetDimensions()
-	return img.Wand.CropImage(
-		reqDimensions.Width,
-		reqDimensions.Height,
-		int((oldDimensions.Width-reqDimensions.Width)/2),
-		int((oldDimensions.Height-reqDimensions.Height)/2),
-	)
+	x := int(focalpoint.X * (float64(oldDimensions.Width) - float64(reqDimensions.Width)))
+	y := int(focalpoint.Y * (float64(oldDimensions.Height) - float64(reqDimensions.Height)))
+	w := reqDimensions.Width
+	h := reqDimensions.Height
+	return img.Wand.CropImage(w, h, x, y)
 }
 
 func (ip *imageProcessor) blur(image *Image, request *ImageProcessorOptions) error {

halfshell/route.go

@@ -69,6 +69,7 @@ func (p *Route) SourceAndProcessorOptionsForRequest(r *http.Request) (
 	width, _ := strconv.ParseUint(r.FormValue("w"), 10, 32)
 	height, _ := strconv.ParseUint(r.FormValue("h"), 10, 32)
 	blurRadius, _ := strconv.ParseFloat(r.FormValue("blur"), 64)
+	focalpoint := r.FormValue("focalpoint")
 
 	scaleModeName := r.FormValue("scale_mode")
 	scaleMode, _ := ScaleModes[scaleModeName]
@@ -77,5 +78,6 @@ func (p *Route) SourceAndProcessorOptionsForRequest(r *http.Request) (
 		Dimensions: ImageDimensions{uint(width), uint(height)},
 		BlurRadius: blurRadius,
 		ScaleMode:  uint(scaleMode),
+		Focalpoint: NewFocalpointFromString(focalpoint),
 	}
 }