layer.go

Documentation: github.com/jung-kurt/gofpdf

     1  /*
     2   * Copyright (c) 2014 Kurt Jung (Gmail: kurt.w.jung)
     3   *
     4   * Permission to use, copy, modify, and distribute this software for any
     5   * purpose with or without fee is hereby granted, provided that the above
     6   * copyright notice and this permission notice appear in all copies.
     7   *
     8   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
     9   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
    10   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    11   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    12   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
    13   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    14   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
    15   */
    16  
    17  package gofpdf
    18  
    19  // Routines in this file are translated from
    20  // http://www.fpdf.org/en/script/script97.php
    21  
    22  type layerType struct {
    23  	name    string
    24  	visible bool
    25  	objNum  int // object number
    26  }
    27  
    28  type layerRecType struct {
    29  	list          []layerType
    30  	currentLayer  int
    31  	openLayerPane bool
    32  }
    33  
    34  func (f *Fpdf) layerInit() {
    35  	f.layer.list = make([]layerType, 0)
    36  	f.layer.currentLayer = -1
    37  	f.layer.openLayerPane = false
    38  }
    39  
    40  // AddLayer defines a layer that can be shown or hidden when the document is
    41  // displayed. name specifies the layer name that the document reader will
    42  // display in the layer list. visible specifies whether the layer will be
    43  // initially visible. The return value is an integer ID that is used in a call
    44  // to BeginLayer().
    45  func (f *Fpdf) AddLayer(name string, visible bool) (layerID int) {
    46  	layerID = len(f.layer.list)
    47  	f.layer.list = append(f.layer.list, layerType{name: name, visible: visible})
    48  	return
    49  }
    50  
    51  // BeginLayer is called to begin adding content to the specified layer. All
    52  // content added to the page between a call to BeginLayer and a call to
    53  // EndLayer is added to the layer specified by id. See AddLayer for more
    54  // details.
    55  func (f *Fpdf) BeginLayer(id int) {
    56  	f.EndLayer()
    57  	if id >= 0 && id < len(f.layer.list) {
    58  		f.outf("/OC /OC%d BDC", id)
    59  		f.layer.currentLayer = id
    60  	}
    61  }
    62  
    63  // EndLayer is called to stop adding content to the currently active layer. See
    64  // BeginLayer for more details.
    65  func (f *Fpdf) EndLayer() {
    66  	if f.layer.currentLayer >= 0 {
    67  		f.out("EMC")
    68  		f.layer.currentLayer = -1
    69  	}
    70  }
    71  
    72  // OpenLayerPane advises the document reader to open the layer pane when the
    73  // document is initially displayed.
    74  func (f *Fpdf) OpenLayerPane() {
    75  	f.layer.openLayerPane = true
    76  }
    77  
    78  func (f *Fpdf) layerEndDoc() {
    79  	if len(f.layer.list) > 0 {
    80  		if f.pdfVersion < "1.5" {
    81  			f.pdfVersion = "1.5"
    82  		}
    83  	}
    84  }
    85  
    86  func (f *Fpdf) layerPutLayers() {
    87  	for j, l := range f.layer.list {
    88  		f.newobj()
    89  		f.layer.list[j].objNum = f.n
    90  		f.outf("<</Type /OCG /Name %s>>", f.textstring(utf8toutf16(l.name)))
    91  		f.out("endobj")
    92  	}
    93  }
    94  
    95  func (f *Fpdf) layerPutResourceDict() {
    96  	if len(f.layer.list) > 0 {
    97  		f.out("/Properties <<")
    98  		for j, layer := range f.layer.list {
    99  			f.outf("/OC%d %d 0 R", j, layer.objNum)
   100  		}
   101  		f.out(">>")
   102  	}
   103  
   104  }
   105  
   106  func (f *Fpdf) layerPutCatalog() {
   107  	if len(f.layer.list) > 0 {
   108  		onStr := ""
   109  		offStr := ""
   110  		for _, layer := range f.layer.list {
   111  			onStr += sprintf("%d 0 R ", layer.objNum)
   112  			if !layer.visible {
   113  				offStr += sprintf("%d 0 R ", layer.objNum)
   114  			}
   115  		}
   116  		f.outf("/OCProperties <</OCGs [%s] /D <</OFF [%s] /Order [%s]>>>>", onStr, offStr, onStr)
   117  		if f.layer.openLayerPane {
   118  			f.out("/PageMode /UseOC")
   119  		}
   120  	}
   121  }
   122
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