github.com/shohhei1126/hugo@v0.42.2-0.20180623210752-3d5928889ad7/tpl/images/images.go (about)

     1  // Copyright 2017 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  	"errors"
    18  	"image"
    19  	"sync"
    20  
    21  	// Importing image codecs for image.DecodeConfig
    22  	_ "image/gif"
    23  	_ "image/jpeg"
    24  	_ "image/png"
    25  
    26  	// Import webp codec
    27  	_ "golang.org/x/image/webp"
    28  
    29  	"github.com/gohugoio/hugo/deps"
    30  	"github.com/spf13/cast"
    31  )
    32  
    33  // New returns a new instance of the images-namespaced template functions.
    34  func New(deps *deps.Deps) *Namespace {
    35  	return &Namespace{
    36  		cache: map[string]image.Config{},
    37  		deps:  deps,
    38  	}
    39  }
    40  
    41  // Namespace provides template functions for the "images" namespace.
    42  type Namespace struct {
    43  	cacheMu sync.RWMutex
    44  	cache   map[string]image.Config
    45  
    46  	deps *deps.Deps
    47  }
    48  
    49  // Config returns the image.Config for the specified path relative to the
    50  // working directory.
    51  func (ns *Namespace) Config(path interface{}) (image.Config, error) {
    52  	filename, err := cast.ToStringE(path)
    53  	if err != nil {
    54  		return image.Config{}, err
    55  	}
    56  
    57  	if filename == "" {
    58  		return image.Config{}, errors.New("config needs a filename")
    59  	}
    60  
    61  	// Check cache for image config.
    62  	ns.cacheMu.RLock()
    63  	config, ok := ns.cache[filename]
    64  	ns.cacheMu.RUnlock()
    65  
    66  	if ok {
    67  		return config, nil
    68  	}
    69  
    70  	f, err := ns.deps.Fs.WorkingDir.Open(filename)
    71  	if err != nil {
    72  		return image.Config{}, err
    73  	}
    74  	defer f.Close()
    75  
    76  	config, _, err = image.DecodeConfig(f)
    77  	if err != nil {
    78  		return config, err
    79  	}
    80  
    81  	ns.cacheMu.Lock()
    82  	ns.cache[filename] = config
    83  	ns.cacheMu.Unlock()
    84  
    85  	return config, nil
    86  }