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// 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"
"math"
"github.com/disintegration/gift"
"github.com/muesli/smartcrop"
)
const (
// Do not change.
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 (p *ImageProcessor) newSmartCropAnalyzer(filter gift.Resampling) smartcrop.Analyzer {
return smartcrop.NewAnalyzer(imagingResizer{p: p, filter: filter})
}
// Needed by smartcrop
type imagingResizer struct {
p *ImageProcessor
filter gift.Resampling
}
func (r imagingResizer) Resize(img image.Image, width, height uint) image.Image {
// See https://github.com/gohugoio/hugo/issues/7955#issuecomment-861710681
scaleX, scaleY := calcFactorsNfnt(width, height, float64(img.Bounds().Dx()), float64(img.Bounds().Dy()))
if width == 0 {
width = uint(math.Ceil(float64(img.Bounds().Dx()) / scaleX))
}
if height == 0 {
height = uint(math.Ceil(float64(img.Bounds().Dy()) / scaleY))
}
result, _ := r.p.Filter(img, gift.Resize(int(width), int(height), r.filter))
return result
}
func (p *ImageProcessor) smartCrop(img image.Image, width, height int, filter gift.Resampling) (image.Rectangle, error) {
if width <= 0 || height <= 0 {
return image.Rectangle{}, nil
}
srcBounds := img.Bounds()
srcW := srcBounds.Dx()
srcH := srcBounds.Dy()
if srcW <= 0 || srcH <= 0 {
return image.Rectangle{}, nil
}
if srcW == width && srcH == height {
return srcBounds, nil
}
smart := p.newSmartCropAnalyzer(filter)
rect, err := smart.FindBestCrop(img, width, height)
if err != nil {
return image.Rectangle{}, err
}
return img.Bounds().Intersect(rect), nil
}
// Calculates scaling factors using old and new image dimensions.
// Code borrowed from https://github.com/nfnt/resize/blob/83c6a9932646f83e3267f353373d47347b6036b2/resize.go#L593
func calcFactorsNfnt(width, height uint, oldWidth, oldHeight float64) (scaleX, scaleY float64) {
if width == 0 {
if height == 0 {
scaleX = 1.0
scaleY = 1.0
} else {
scaleY = oldHeight / float64(height)
scaleX = scaleY
}
} else {
scaleX = oldWidth / float64(width)
if height == 0 {
scaleY = scaleX
} else {
scaleY = oldHeight / float64(height)
}
}
return
}
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