Add invert image step

README.md

@@ -248,6 +248,18 @@ Scales down the image to fit the specified maximum width and height.
 }
 ```
 
+#### Invert
+
+Invert image colors.
+
+**Step definition**:
+
+```json
+{
+  "type": 5
+}
+```
+
 ## Authors
 
 - [Fabian Vowie](https://gogs.informatik.hs-fulda.de/FabianVowie)

pipelines/executable_step.go

@@ -89,3 +89,14 @@ func (s FitImageStep) Execute(src image.Image) (image.Image, error) {
 	src = imaging.Fit(src, s.Options.Width, s.Options.Height, imaging.Lanczos)
 	return src, nil
 }
+
+// Invert image
+
+type InvertImageStep struct {
+	Step
+}
+
+func (s InvertImageStep) Execute(src image.Image) (image.Image, error) {
+	src = imaging.Invert(src)
+	return src, nil
+}

pipelines/pipeline_test.go

@@ -364,6 +364,51 @@ func TestExecuteSteps(t *testing.T) {
 		os.Remove(storageProvider.GetPath(Bucket, "source.jpg"))
 		os.Remove(storageProvider.GetPath(Bucket, dest))
 	})
+
+	t.Run("Image invert step is successful", func(t *testing.T) {
+		const Bucket string = "pipeline_test_09"
+		const Payload string = `{
+			"name": "example pipeline",
+			"type": 1,
+			"removeMetadata": false,
+			"steps": [
+				{
+					"name": "invert",
+					"type": 5
+				}
+			]
+		}`
+
+		wd, _ := os.Getwd()
+		pipe := DeserializePipelines([][]byte{[]byte(Payload)})[0]
+
+		storageProvider := storage.GetFileSystemStorageProvider("test", "..")
+
+		// copy test file to storage bucket
+		_, err := storageProvider.StoreExisting(Bucket, "source.jpg", filepath.Join(wd, "../tests/files/900x900.jpg"))
+		assert.Nil(t, err, "Test file should be readable")
+		assert.FileExists(t, storageProvider.GetPath(Bucket, "source.jpg"))
+
+		// run pipeline steps
+		dest, err := pipe.Run("source.jpg", Bucket, storageProvider)
+		assert.Nil(t, err)
+		assert.FileExists(t, storageProvider.GetPath(Bucket, dest))
+
+		// read image config
+		file, err := storageProvider.OpenFile(Bucket, dest)
+		assert.Nil(t, err)
+
+		imgConf, _, err := image.DecodeConfig(file)
+		assert.Nil(t, err)
+
+		assert.Equal(t, 900, imgConf.Width)
+		assert.Equal(t, 900, imgConf.Height)
+
+		// clean up
+		os.Remove(storageProvider.GetPath(Bucket, "source.jpg"))
+		os.Remove(storageProvider.GetPath(Bucket, dest))
+	})
+
 }
 
 // output options

pipelines/step.go

@@ -13,6 +13,7 @@ const (
 	TypeFlipImageStep
 	TypeGrayscaleImageStep
 	TypeFitImageStep
+	TypeInvertImageStep
 )
 
 type Step struct {
@@ -52,6 +53,9 @@ func (s Step) GetExecutable() (IExecutableStep, error) {
 		}
 		return step, nil
 
+	case TypeInvertImageStep:
+		return InvertImageStep{}, nil
+
 	case TypeGrayscaleImageStep:
 		return GrayscaleImageStep{}, nil
 	}