Image grayscale processor

examples/filesystem_config.json

@@ -2,7 +2,8 @@
     "server": {
         "port": 8080,
         "read_timeout": 5,
-        "write_timeout": 30
+        "write_timeout": 30,
+        "disable_statsd": true
     },
     "sources": {
         "default": {
@@ -22,11 +23,12 @@
             "maintain_aspect_ratio": true,
             "max_blur_radius_percentage": 0,
             "max_image_height": 0,
-            "max_image_width": 1000
-
+            "max_image_width": 1000,
+            "grayscale": "disabled"
         },
         "profile-photos": {
-            "default_image_width": 120
+            "default_image_width": 120,
+            "grayscale": true
         }
     },
     "routes": {

halfshell/config.go

@@ -38,9 +38,10 @@ type Config struct {
 
 // ServerConfig holds the configuration settings relevant for the HTTP server.
 type ServerConfig struct {
-	Port         uint64
-	ReadTimeout  uint64
-	WriteTimeout uint64
+	Port           uint64
+	ReadTimeout    uint64
+	WriteTimeout   uint64
+	StatsdDisabled bool
 }
 
 // RouteConfig holds the configuration settings for a particular route.
@@ -73,6 +74,8 @@ type ProcessorConfig struct {
 	MaxImageHeight          uint64
 	MaxImageWidth           uint64
 	MaxBlurRadiusPercentage float64
+	GrayscaleByDefault      bool
+	GrayscaleDisabled       bool
 }
 
 // Parses a JSON configuration file and returns a pointer to a new Config object.
@@ -149,9 +152,10 @@ func (c *configParser) parse() *Config {
 
 func (c *configParser) parseServerConfig() *ServerConfig {
 	return &ServerConfig{
-		Port:         c.uintForKeypath("server.port"),
-		ReadTimeout:  c.uintForKeypath("server.read_timeout"),
-		WriteTimeout: c.uintForKeypath("server.write_timeout"),
+		Port:           c.uintForKeypath("server.port"),
+		ReadTimeout:    c.uintForKeypath("server.read_timeout"),
+		WriteTimeout:   c.uintForKeypath("server.write_timeout"),
+		StatsdDisabled: c.boolForKeypath("server.disable_statsd"),
 	}
 }
 
@@ -167,7 +171,7 @@ func (c *configParser) parseSourceConfig(sourceName string) *SourceConfig {
 }
 
 func (c *configParser) parseProcessorConfig(processorName string) *ProcessorConfig {
-	return &ProcessorConfig{
+	config := &ProcessorConfig{
 		Name: processorName,
 		ImageCompressionQuality: c.uintForKeypath("processors.%s.image_compression_quality", processorName),
 		MaintainAspectRatio:     c.boolForKeypath("processors.%s.maintain_aspect_ratio", processorName),
@@ -177,6 +181,10 @@ func (c *configParser) parseProcessorConfig(processorName string) *ProcessorConf
 		MaxImageWidth:           c.uintForKeypath("processors.%s.max_image_width", processorName),
 		MaxBlurRadiusPercentage: c.floatForKeypath("processors.%s.max_blur_radius_percentage", processorName),
 	}
+
+	config.GrayscaleByDefault, config.GrayscaleDisabled = c.onOrDisabledForKeypath("processors.%s.grayscale", processorName)
+
+	return config
 }
 
 func (c *configParser) valueForKeypath(valueType reflect.Kind, keypathFormat string, v ...interface{}) interface{} {
@@ -226,3 +234,16 @@ func (c *configParser) uintForKeypath(keypathFormat string, v ...interface{}) ui
 func (c *configParser) boolForKeypath(keypathFormat string, v ...interface{}) bool {
 	return c.valueForKeypath(reflect.Bool, keypathFormat, v...).(bool)
 }
+
+func (c *configParser) onOrDisabledForKeypath(keypathFormat string, v ...interface{}) (bool, bool) {
+	value := c.valueForKeypath(reflect.String, keypathFormat, v...)
+	switch value.(type) {
+	case bool:
+		return value.(bool), false
+	case string:
+		if value == "disabled" {
+			return false, true
+		}
+	}
+	return false, false
+}

halfshell/image_processor.go

@@ -38,6 +38,7 @@ type ImageProcessor interface {
 type ImageProcessorOptions struct {
 	Dimensions ImageDimensions
 	BlurRadius float64
+	GrayScale  bool
 }
 
 type imageProcessor struct {
@@ -73,7 +74,13 @@ func (ip *imageProcessor) ProcessImage(image *Image, request *ImageProcessorOpti
 		return nil
 	}
 
-	if !scaleModified && !blurModified {
+	err, grayscaleModified := ip.grayscaleWand(wand, request)
+	if err != nil {
+		ip.Logger.Warn("Error grayscaling image: %s", err)
+		return nil
+	}
+
+	if !scaleModified && !blurModified && !grayscaleModified {
 		processedImage.Bytes = image.Bytes
 	} else {
 		processedImage.Bytes = wand.GetImageBlob()
@@ -138,6 +145,16 @@ func (ip *imageProcessor) blurWand(wand *imagick.MagickWand, request *ImageProce
 	return nil, false
 }
 
+func (ip *imageProcessor) grayscaleWand(wand *imagick.MagickWand, request *ImageProcessorOptions) (err error, modified bool) {
+	if !ip.Config.GrayscaleDisabled && (ip.Config.GrayscaleByDefault || request.GrayScale) {
+		if err = wand.TransformImageColorspace(imagick.COLORSPACE_GRAY); err != nil {
+			ip.Logger.Warn("ImageMagick error grayscaling image: %s", err)
+		}
+		return err, true
+	}
+	return nil, false
+}
+
 func (ip *imageProcessor) getScaledDimensions(currentDimensions ImageDimensions, request *ImageProcessorOptions) ImageDimensions {
 	requestDimensions := request.Dimensions
 	if requestDimensions.Width == 0 && requestDimensions.Height == 0 {

halfshell/route.go

@@ -68,9 +68,11 @@ 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)
+	grayScale, _ := strconv.ParseBool(r.FormValue("grayscale"))
 
 	return &ImageSourceOptions{Path: path}, &ImageProcessorOptions{
 		Dimensions: ImageDimensions{width, height},
 		BlurRadius: blurRadius,
+		GrayScale:  grayScale,
 	}
 }

halfshell/server.go

@@ -31,6 +31,7 @@ type Server struct {
 	*http.Server
 	Routes []*Route
 	Logger *Logger
+	Config *ServerConfig
 }
 
 func NewServerWithConfigAndRoutes(config *ServerConfig, routes []*Route) *Server {
@@ -40,7 +41,7 @@ func NewServerWithConfigAndRoutes(config *ServerConfig, routes []*Route) *Server
 		WriteTimeout:   time.Duration(config.WriteTimeout) * time.Second,
 		MaxHeaderBytes: 1 << 20,
 	}
-	server := &Server{httpServer, routes, NewLogger("server")}
+	server := &Server{httpServer, routes, NewLogger("server"), config}
 	httpServer.Handler = server
 	return server
 }
@@ -64,7 +65,9 @@ func (s *Server) ImageRequestHandler(w *HalfshellResponseWriter, r *HalfshellReq
 		return
 	}
 
-	defer func() { go r.Route.Statter.RegisterRequest(w, r) }()
+	if !s.Config.StatsdDisabled {
+		defer func() { go r.Route.Statter.RegisterRequest(w, r) }()
+	}
 
 	s.Logger.Info("Handling request for image %s with dimensions %v",
 		r.SourceOptions.Path, r.ProcessorOptions.Dimensions)

halfshell/source_filesystem.go

@@ -48,7 +48,7 @@ func NewFileSystemImageSourceWithConfig(config *SourceConfig) ImageSource {
 
 	baseDirectory, err := os.Open(source.Config.Directory)
 	if os.IsNotExist(err) {
-		source.Logger.Info(source.Config.Directory, " does not exit. Creating.")
+		source.Logger.Info("%s does not exit. Creating.", source.Config.Directory)
 		_ = os.MkdirAll(source.Config.Directory, 0700)
 		baseDirectory, err = os.Open(source.Config.Directory)
 	}
@@ -59,7 +59,7 @@ func NewFileSystemImageSourceWithConfig(config *SourceConfig) ImageSource {
 
 	fileInfo, err := baseDirectory.Stat()
 	if err != nil || !fileInfo.IsDir() {
-		source.Logger.Fatal("Directory ", source.Config.Directory, " not a directory", err)
+		source.Logger.Fatal("Directory %s not a directory", source.Config.Directory, err)
 	}
 
 	return source