hugo/resources/images/smartcrop.go
Bjørn Erik Pedersen f9978ed164
Image resource refactor
This commit pulls most of the image related logic into its own package, to make it easier to reason about and extend.

This is also a rewrite of the transformation logic used in Hugo Pipes, mostly to allow constructs like the one below:

    {{ ($myimg | fingerprint ).Width }}

Fixes #5903
Fixes #6234
Fixes #6266
2019-08-26 15:00:44 +02:00

76 lines
2 KiB
Go

// Copyright 2019 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package images
import (
"image"
"github.com/disintegration/imaging"
"github.com/muesli/smartcrop"
)
const (
// Do not change.
// TODO(bep) image unexport
SmartCropIdentifier = "smart"
// This is just a increment, starting on 1. If Smart Crop improves its cropping, we
// need a way to trigger a re-generation of the crops in the wild, so increment this.
smartCropVersionNumber = 1
)
func newSmartCropAnalyzer(filter imaging.ResampleFilter) smartcrop.Analyzer {
return smartcrop.NewAnalyzer(imagingResizer{filter: filter})
}
// Needed by smartcrop
type imagingResizer struct {
filter imaging.ResampleFilter
}
func (r imagingResizer) Resize(img image.Image, width, height uint) image.Image {
return imaging.Resize(img, int(width), int(height), r.filter)
}
func smartCrop(img image.Image, width, height int, anchor imaging.Anchor, filter imaging.ResampleFilter) (*image.NRGBA, error) {
if width <= 0 || height <= 0 {
return &image.NRGBA{}, nil
}
srcBounds := img.Bounds()
srcW := srcBounds.Dx()
srcH := srcBounds.Dy()
if srcW <= 0 || srcH <= 0 {
return &image.NRGBA{}, nil
}
if srcW == width && srcH == height {
return imaging.Clone(img), nil
}
smart := newSmartCropAnalyzer(filter)
rect, err := smart.FindBestCrop(img, width, height)
if err != nil {
return nil, err
}
b := img.Bounds().Intersect(rect)
cropped := imaging.Crop(img, b)
return imaging.Resize(cropped, width, height, filter), nil
}