Lithium/pipelines/executable_step.go

package pipelines

import (
	"errors"
	"fmt"
	"image"

	"github.com/disintegration/imaging"
)

type IExecutableStep interface {
	Execute(src image.Image) (image.Image, error)
}

// Resize image

type ResizeImageStep struct {
	Step
	Options struct {
		Width   int  `json:"width"`
		Height  int  `json:"height"`
		Upscale bool `json:"upscale"`
	} `json:"options"`
}

func (s ResizeImageStep) Execute(src image.Image) (image.Image, error) {
	src = imaging.Resize(src, s.Options.Width, s.Options.Height, imaging.Linear)
	return src, nil
}

// Rotate image

type RotateImageStep struct {
	Step
	Options struct {
		Angle float64 `json:"angle"`
	} `json:"options"`
}

func (s RotateImageStep) Execute(src image.Image) (image.Image, error) {
	src = imaging.Rotate(src, s.Options.Angle, image.Black)
	return src, nil
}

// Flip image

type FlipImageStep struct {
	Step
	Options struct {
		Direction string `json:"direction"`
	} `json:"options"`
}

func (s FlipImageStep) Execute(src image.Image) (image.Image, error) {
	switch s.Options.Direction {
	case "h":
		src = imaging.FlipH(src)
	case "v":
		src = imaging.FlipH(src)
	default:
		return src, errors.New(fmt.Sprintf("invalid flip direction: %s", s.Options.Direction))
	}

	return src, nil
}

// Grayscale image

type GrayscaleImageStep struct {
	Step
}

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
}