github.com/pdfcpu/pdfcpu@v0.11.1/pkg/pdfcpu/property.go (about)

     1  /*
     2  Copyright 2020 The pdfcpu Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8  	http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package pdfcpu
    18  
    19  import (
    20  	"fmt"
    21  	"sort"
    22  
    23  	"github.com/pdfcpu/pdfcpu/pkg/pdfcpu/model"
    24  	"github.com/pdfcpu/pdfcpu/pkg/pdfcpu/types"
    25  )
    26  
    27  // PropertiesList returns a list of document properties as recorded in the document info dict.
    28  func PropertiesList(ctx *model.Context) ([]string, error) {
    29  	list := make([]string, 0, len(ctx.Properties))
    30  	keys := make([]string, len(ctx.Properties))
    31  	i := 0
    32  	for k := range ctx.Properties {
    33  		keys[i] = k
    34  		i++
    35  	}
    36  	sort.Strings(keys)
    37  	for _, k := range keys {
    38  		v := ctx.Properties[k]
    39  		list = append(list, fmt.Sprintf("%s = %s", k, v))
    40  	}
    41  	return list, nil
    42  }
    43  
    44  // PropertiesAdd adds properties into the document info dict.
    45  // Returns true if at least one property was added.
    46  func PropertiesAdd(ctx *model.Context, properties map[string]string) error {
    47  	if err := ensureInfoDictAndFileID(ctx); err != nil {
    48  		return err
    49  	}
    50  
    51  	d, _ := ctx.DereferenceDict(*ctx.Info)
    52  
    53  	for k, v := range properties {
    54  		s, err := types.EscapedUTF16String(v)
    55  		if err != nil {
    56  			return err
    57  		}
    58  		d[k] = types.StringLiteral(*s)
    59  		ctx.Properties[k] = *s
    60  	}
    61  
    62  	return nil
    63  }
    64  
    65  // PropertiesRemove deletes specified properties.
    66  // Returns true if at least one property was removed.
    67  func PropertiesRemove(ctx *model.Context, properties []string) (bool, error) {
    68  	if ctx.Info == nil {
    69  		return false, nil
    70  	}
    71  
    72  	d, err := ctx.DereferenceDict(*ctx.Info)
    73  	if err != nil || d == nil {
    74  		return false, err
    75  	}
    76  
    77  	if len(properties) == 0 {
    78  		// Remove all properties.
    79  		for k := range ctx.Properties {
    80  			delete(d, types.EncodeName(k))
    81  		}
    82  		ctx.Properties = map[string]string{}
    83  		return true, nil
    84  	}
    85  
    86  	var removed bool
    87  	for _, k := range properties {
    88  		_, ok := d[k]
    89  		if ok && !removed {
    90  			delete(d, k)
    91  			delete(ctx.Properties, k)
    92  			removed = true
    93  		}
    94  	}
    95  
    96  	return removed, nil
    97  }