imgproxy/processing/pipeline.go

package processing

import (
	"context"

	"github.com/imgproxy/imgproxy/v3/imagedata"
	"github.com/imgproxy/imgproxy/v3/imagetype"
	"github.com/imgproxy/imgproxy/v3/options"
	"github.com/imgproxy/imgproxy/v3/server"
	"github.com/imgproxy/imgproxy/v3/vips"
)

type pipelineContext struct {
	ctx context.Context

	imgtype imagetype.Type

	trimmed bool

	srcWidth  int
	srcHeight int
	angle     int
	flip      bool

	cropWidth   int
	cropHeight  int
	cropGravity options.GravityOptions

	wscale float64
	hscale float64

	dprScale float64

	// The base scale factor for vector images.
	// It is used to downscale the input vector image to the maximum allowed resolution
	vectorBaseScale 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 pipelineStep func(pctx *pipelineContext, img *vips.Image, po *options.ProcessingOptions, imgdata imagedata.ImageData) error
type pipeline []pipelineStep

func (p pipeline) Run(ctx context.Context, img *vips.Image, po *options.ProcessingOptions, imgdata imagedata.ImageData) error {
	pctx := pipelineContext{
		ctx: ctx,

		wscale: 1.0,
		hscale: 1.0,

		dprScale:        1.0,
		vectorBaseScale: 1.0,

		cropGravity: po.Crop.Gravity,
	}

	if pctx.cropGravity.Type == options.GravityUnknown {
		pctx.cropGravity = po.Gravity
	}

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

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

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

	return nil
}