imgproxy/processing/pipeline.go

package processing

import (
	"context"

	"github.com/imgproxy/imgproxy/v3/imagedata"
	"github.com/imgproxy/imgproxy/v3/security"
	"github.com/imgproxy/imgproxy/v3/server"
	"github.com/imgproxy/imgproxy/v3/vips"
)

type Context struct {
	// The context to check for timeouts and cancellations
	Ctx context.Context

	// Current image being processed
	Img *vips.Image

	// Processing options this pipeline runs with
	PO ProcessingOptions

	// Security options this pipeline runs with
	SecOps security.Options

	// Original image data
	ImgData imagedata.ImageData

	SrcWidth  int
	SrcHeight int
	Angle     int
	Flip      bool

	CropWidth   int
	CropHeight  int
	CropGravity GravityOptions

	WScale float64
	HScale float64

	DprScale float64

	// The base shrink factor for vector images.
	// It is used to downscale the input vector image to the maximum allowed resolution
	VectorBaseShrink float64

	// The width we aim to get.
	// Based on the requested width scaled according to processing options.
	// Can be 0 if width is not specified in the processing options.
	TargetWidth int
	// The height we aim to get.
	// Based on the requested height scaled according to processing options.
	// Can be 0 if height is not specified in the processing options.
	TargetHeight int

	// The width of the image after cropping, scaling and rotating
	ScaledWidth int
	// The height of the image after cropping, scaling and rotating
	ScaledHeight int

	// The width of the result crop according to the resizing type
	ResultCropWidth int
	// The height of the result crop according to the resizing type
	ResultCropHeight int

	// The width of the image extended to the requested aspect ratio.
	// Can be 0 if any of the dimensions is not specified in the processing options
	// or if the image already has the requested aspect ratio.
	ExtendAspectRatioWidth int
	// The width of the image extended to the requested aspect ratio.
	// Can be 0 if any of the dimensions is not specified in the processing options
	// or if the image already has the requested aspect ratio.
	ExtendAspectRatioHeight int
}

type Step func(c *Context) error
type Pipeline []Step

// Run runs the given pipeline with the given parameters
func (p Pipeline) Run(
	ctx context.Context,
	img *vips.Image,
	po ProcessingOptions,
	secops security.Options,
	imgdata imagedata.ImageData,
) error {
	pctx := p.newContext(ctx, img, po, secops, imgdata)
	pctx.CalcParams()

	for _, step := range p {
		if err := step(&pctx); err != nil {
			return err
		}

		if err := server.CheckTimeout(ctx); err != nil {
			return err
		}
	}

	img.SetDouble("imgproxy-dpr-scale", pctx.DprScale)

	return nil
}

func (p Pipeline) newContext(
	ctx context.Context,
	img *vips.Image,
	po ProcessingOptions,
	secops security.Options,
	imgdata imagedata.ImageData,
) Context {
	pctx := Context{
		Ctx:     ctx,
		Img:     img,
		PO:      po,
		SecOps:  secops,
		ImgData: imgdata,

		WScale: 1.0,
		HScale: 1.0,

		DprScale:         1.0,
		VectorBaseShrink: 1.0,

		CropGravity: po.CropGravity(),
	}

	// If crop gravity is not set, use the general gravity option
	if pctx.CropGravity.Type == GravityUnknown {
		pctx.CropGravity = po.Gravity()
	}

	return pctx
}