github.com/neohugo/neohugo@v0.123.8/resources/images/auto_orient.go (about)

     1  // Copyright 2024 The Hugo Authors. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package images
    15  
    16  import (
    17  	"image"
    18  	"image/draw"
    19  
    20  	"github.com/disintegration/gift"
    21  	"github.com/neohugo/neohugo/resources/images/exif"
    22  )
    23  
    24  var _ gift.Filter = (*autoOrientFilter)(nil)
    25  
    26  var transformationFilters = map[int]gift.Filter{
    27  	2: gift.FlipHorizontal(),
    28  	3: gift.Rotate180(),
    29  	4: gift.FlipVertical(),
    30  	5: gift.Transpose(),
    31  	6: gift.Rotate270(),
    32  	7: gift.Transverse(),
    33  	8: gift.Rotate90(),
    34  }
    35  
    36  type autoOrientFilter struct{}
    37  
    38  type ImageFilterFromOrientationProvider interface {
    39  	AutoOrient(exifInfo *exif.ExifInfo) gift.Filter
    40  }
    41  
    42  func (f autoOrientFilter) Draw(dst draw.Image, src image.Image, options *gift.Options) {
    43  	panic("not supported")
    44  }
    45  
    46  func (f autoOrientFilter) Bounds(srcBounds image.Rectangle) image.Rectangle {
    47  	panic("not supported")
    48  }
    49  
    50  func (f autoOrientFilter) AutoOrient(exifInfo *exif.ExifInfo) gift.Filter {
    51  	if exifInfo != nil {
    52  		if orientation, ok := exifInfo.Tags["Orientation"].(int); ok {
    53  			if filter, ok := transformationFilters[orientation]; ok {
    54  				return filter
    55  			}
    56  		}
    57  	}
    58  
    59  	return nil
    60  }