encode.go

// Copyright (c) 2021 Yamagishi Kazutoshi <ykzts@desire.sh>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package manael

import (
	"bytes"
	"errors"
	"io"

	"github.com/h2non/bimg"
)

// Encode converts the image data in src to the format specified by Content-Type t,
// writing the result to w. resize controls optional resizing/cropping in the same
// bimg pipeline pass; quality controls per-format encoding quality. Either
// parameter may be nil to use the defaults.
func Encode(w io.Writer, src []byte, t string, resize *ResizeOptions, quality *QualityOptions) error {
	var opts bimg.Options

	switch t {
	case "image/webp":
		opts = bimg.Options{
			Type:    bimg.WEBP,
			Quality: quality.forFormat(t, 90),
		}
	case "image/avif":
		opts = bimg.Options{
			Type:    bimg.AVIF,
			Quality: quality.forFormat(t, 60),
			Speed:   8,
		}
	default:
		return errors.New("unsupported image type")
	}

	r := resize

	if r != nil && (r.Width > 0 || r.Height > 0) {
		opts.Width = r.Width
		opts.Height = r.Height
		switch r.Fit {
		case "cover":
			// Crop to fill the target dimensions exactly.
			opts.Crop = true
		case "contain", "":
			// Scale to fit within the target box; allow upscaling smaller images.
			// An empty Fit is treated as "contain" per the ResizeOptions documentation.
			opts.Enlarge = true
		case "scale-down":
			// Scale down to fit within the target box; never upscale.
			// This is the bimg default when neither Crop nor Enlarge is set.
		}
	}

	out, err := bimg.NewImage(src).Process(opts)
	if err != nil {
		return err
	}

	_, err = io.Copy(w, bytes.NewReader(out))
	return err
}