Add fit image step

README.md

@@ -232,6 +232,22 @@ Convert the colorspace of an image into grayscale.
 }
 ```
 
+#### Fit
+
+Scales down the image to fit the specified maximum width and height.
+
+**Step definition**:
+
+```json
+{
+  "type": 4,
+  "options": {
+    "height": 300,
+    "width": 200
+  }
+}
+```
+
 ## Authors
 
 - [Fabian Vowie](https://gogs.informatik.hs-fulda.de/FabianVowie)

pipelines/executable_step.go

@@ -74,3 +74,18 @@ func (s GrayscaleImageStep) Execute(src image.Image) (image.Image, error) {
 	src = imaging.Grayscale(src)
 	return src, nil
 }
+
+// Fit image
+
+type FitImageStep struct {
+	Step
+	Options struct {
+		Height int `json:"height"`
+		Width  int `json:"width"`
+	} `json:"options"`
+}
+
+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
+}

pipelines/pipeline_test.go

@@ -239,7 +239,7 @@ func TestExecuteSteps(t *testing.T) {
 	})
 
 	t.Run("Image flip step direction validation is successful", func(t *testing.T) {
-		const Bucket string = "pipeline_test_06"
+		const Bucket string = "pipeline_test_07"
 		const Payload string = `{
 			"name": "example pipeline",
 			"type": 1,
@@ -316,6 +316,54 @@ func TestExecuteSteps(t *testing.T) {
 		os.Remove(storageProvider.GetPath(Bucket, "source.jpg"))
 		os.Remove(storageProvider.GetPath(Bucket, dest))
 	})
+
+	t.Run("Image fit step is successful", func(t *testing.T) {
+		const Bucket string = "pipeline_test_08"
+		const Payload string = `{
+			"name": "example pipeline",
+			"type": 1,
+			"removeMetadata": false,
+			"steps": [
+				{
+					"name": "fit",
+					"type": 4,
+					"options": {
+						"width": 300,
+						"height": 200
+					}
+				}
+			]
+		}`
+
+		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, 200, imgConf.Width)
+		assert.Equal(t, 200, imgConf.Height)
+
+		// clean up
+		os.Remove(storageProvider.GetPath(Bucket, "source.jpg"))
+		os.Remove(storageProvider.GetPath(Bucket, dest))
+	})
 }
 
 // output options

pipelines/step.go

@@ -12,6 +12,7 @@ const (
 	TypeRotateImageStep
 	TypeFlipImageStep
 	TypeGrayscaleImageStep
+	TypeFitImageStep
 )
 
 type Step struct {
@@ -44,6 +45,13 @@ func (s Step) GetExecutable() (IExecutableStep, error) {
 		}
 		return step, nil
 
+	case TypeFitImageStep:
+		step := FitImageStep{}
+		if err := json.Unmarshal(s.Options, &step.Options); err != nil {
+			return nil, err
+		}
+		return step, nil
+
 	case TypeGrayscaleImageStep:
 		return GrayscaleImageStep{}, nil
 	}