PDFLayers

1//
2// Copyright (c) 2001-2020 by PDFTron Systems Inc. All Rights Reserved.
3//
4
5using System;
6using System.IO;
7using System.Threading.Tasks;
8using Windows.Foundation;
9
10using pdftron.Common;
11using pdftron.PDF;
12using pdftron.PDF.OCG;
13using pdftron.SDF;
14
15using PDFNetUniversalSamples.ViewModels;
16
17namespace PDFNetSamples
18{
19    public sealed class PDFLayersTest : Sample
20    {
21        public PDFLayersTest() :
22            base("PDFLayers", "This sample demonstrates how to create PDF layers (also known as Optional Content Groups - OCGs). The sample also shows how to extract and render PDF layers.")
23        {
24        }
25
26        public override IAsyncAction RunAsync()
27        {
28            return Task.Run(new System.Action(async () => {
29                WriteLine("--------------------------------");
30                WriteLine("Starting PDFLayers Test...");
31                WriteLine("--------------------------------\n");
32			    try
33			    {
34				    PDFDoc doc = new PDFDoc();
35
36				    // Create three layers...
37				    Group image_layer = CreateLayer(doc, "Image Layer");
38				    Group text_layer = CreateLayer(doc, "Text Layer");
39				    Group vector_layer = CreateLayer(doc, "Vector Layer");
40
41				    // Start a new page ------------------------------------
42				    pdftron.PDF.Page page = doc.PageCreate();
43
44				    ElementBuilder builder = new ElementBuilder(); // ElementBuilder is used to build new Element objects
45				    ElementWriter writer = new ElementWriter(); // ElementWriter is used to write Elements to the page
46				    writer.Begin(page);	// begin writing to this page
47
48				    // Add new content to the page and associate it with one of the layers.
49				    Element element = builder.CreateForm(CreateGroup1(doc, image_layer.GetSDFObj()));
50				    writer.WriteElement(element);
51
52				    element = builder.CreateForm(CreateGroup2(doc, vector_layer.GetSDFObj()));
53				    writer.WriteElement(element);
54
55				    // Add the text layer to the page...
56                    bool ocmdSample = false;  // set to 'true' to enable 'ocmd' example.
57                    if (ocmdSample)
58				    {
59					    // A bit more advanced example of how to create an OCMD text layer that 
60					    // is visible only if text, image and path layers are all 'ON'.
61					    // An example of how to set 'Visibility Policy' in OCMD.
62					    Obj ocgs = doc.CreateIndirectArray();
63					    ocgs.PushBack(image_layer.GetSDFObj());
64					    ocgs.PushBack(vector_layer.GetSDFObj());
65					    ocgs.PushBack(text_layer.GetSDFObj());
66					    OCMD text_ocmd = OCMD.Create(doc, ocgs, OCMDVisibilityPolicyType.e_AllOn);
67					    element = builder.CreateForm(CreateGroup3(doc, text_ocmd.GetSDFObj()));
68				    }
69				    else {
70					    element = builder.CreateForm(CreateGroup3(doc, text_layer.GetSDFObj()));
71				    }
72				    writer.WriteElement(element);
73
74				    // Add some content to the page that does not belong to any layer...
75				    // In this case this is a rectangle representing the page border.
76				    element = builder.CreateRect(0, 0, page.GetPageWidth(), page.GetPageHeight());
77				    element.SetPathFill(false);
78				    element.SetPathStroke(true);
79				    element.GetGState().SetLineWidth(40);
80				    writer.WriteElement(element);
81
82                    writer.End();  // save changes to the current page
83				    doc.PagePushBack(page);
84
85				    // Set the default viewing preference to display 'Layer' tab.
86				    PDFDocViewPrefs prefs = doc.GetViewPrefs();
87				    prefs.SetPageMode(PDFDocViewPrefsPageMode.e_UseOC);
88
89                    string output_file_path = Path.Combine(OutputPath, "pdf_layers.pdf");
90                    await doc.SaveAsync(output_file_path, SDFDocSaveOptions.e_linearized);
91				    doc.Destroy();
92                    WriteLine("Done. Results saved in " + output_file_path);
93                    await AddFileToOutputList(output_file_path).ConfigureAwait(false);
94			    }
95			    catch (Exception e)
96			    {
97                    WriteLine(GetExceptionMessage(e));
98			    }
99
100			    // The following is a code snippet shows how to selectively render 
101			    // and export PDF layers.
102			    try  
103			    {	 
104				    PDFDoc doc = new PDFDoc(Path.Combine(OutputPath, "pdf_layers.pdf"));
105				    doc.InitSecurityHandler();
106
107				    if (!doc.HasOC()) 
108				    {
109					    WriteLine("The document does not contain 'Optional Content'");
110				    }
111				    else 
112				    {
113					    Config init_cfg = doc.GetOCGConfig();
114					    Context ctx = new Context(init_cfg);
115
116					    PDFDraw pdfdraw = new PDFDraw();
117					    pdfdraw.SetImageSize(1000, 1000);
118					    pdfdraw.SetOCGContext(ctx); // Render the page using the given OCG context.
119
120					    pdftron.PDF.Page page = doc.GetPage(1); // Get the first page in the document.
121                        string output_file_path = Path.Combine(OutputPath, "pdf_layers_default.png");
122                        pdfdraw.Export(page, output_file_path);
123                        WriteLine("Exporting " + output_file_path);
124                        await AddFileToOutputList(output_file_path).ConfigureAwait(false);
125
126					    // Disable drawing of content that is not optional (i.e. is not part of any layer).
127					    ctx.SetNonOCDrawing(false);
128
129					    // Now render each layer in the input document to a separate image.
130					    Obj ocgs = doc.GetOCGs(); // Get the array of all OCGs in the document.
131					    if (ocgs != null) 
132					    {
133						    int i, sz = ocgs.Size();
134						    for (i=0; i<sz; ++i) 
135						    {
136							    Group ocg = new Group(ocgs.GetAt(i));
137							    ctx.ResetStates(false);
138							    ctx.SetState(ocg, true);
139							    string fname = Path.Combine(OutputPath, "pdf_layers_" + ocg.GetName() + ".png");
140							    WriteLine(fname);
141							    pdfdraw.Export(page, fname);
142                                WriteLine("Exporting " + fname);
143                                await AddFileToOutputList(fname).ConfigureAwait(false);
144						    }
145					    }
146
147					    // Now draw content that is not part of any layer...
148					    ctx.SetNonOCDrawing(true);
149					    ctx.SetOCDrawMode(ContextOCDrawMode.e_NoOC);
150                        output_file_path =  Path.Combine(OutputPath, "pdf_layers_non_oc.png");
151                        pdfdraw.Export(page, output_file_path);
152                        WriteLine("Exporting " + output_file_path);
153                        await AddFileToOutputList(output_file_path).ConfigureAwait(false);
154
155					    doc.Destroy();
156                        WriteLine("Done.");
157				    }
158			    }
159			    catch (Exception e)
160			    {
161                    WriteLine(GetExceptionMessage(e));
162                }
163
164                WriteLine("\n--------------------------------");
165                WriteLine("Done PDFLayers Test.");
166                WriteLine("--------------------------------\n");
167            })).AsAsyncAction();
168		}
169
170		// A utility function used to add new Content Groups (Layers) to the document.
171        Group CreateLayer(PDFDoc doc, String layer_name)
172		{
173			Group grp = Group.Create(doc, layer_name);
174			Config cfg = doc.GetOCGConfig();
175			if (cfg == null) 
176			{
177				cfg = Config.Create(doc, true);
178				cfg.SetName("Default");
179			}
180
181			// Add the new OCG to the list of layers that should appear in PDF viewer GUI.
182			Obj layer_order_array = cfg.GetOrder();
183			if (layer_order_array == null) 
184			{
185				layer_order_array = doc.CreateIndirectArray();
186				cfg.SetOrder(layer_order_array);
187			}
188			layer_order_array.PushBack(grp.GetSDFObj());
189
190			return grp;
191		}
192
193		// Creates some content (3 images) and associate them with the image layer
194        Obj CreateGroup1(PDFDoc doc, Obj layer)
195		{
196			ElementWriter writer = new ElementWriter();
197            writer.Begin(doc.GetSDFDoc());
198
199			// Create an Image that can be reused in the document or on the same page.		
200			pdftron.PDF.Image img = pdftron.PDF.Image.Create(doc.GetSDFDoc(), Path.Combine(InputPath, "peppers.jpg"));
201
202			ElementBuilder builder = new ElementBuilder();
203			Element element = builder.CreateImage(img, new Matrix2D(img.GetImageWidth()/2, -145, 20, img.GetImageHeight()/2, 200, 150));
204			writer.WritePlacedElement(element);
205
206			GState gstate = element.GetGState();	// use the same image (just change its matrix)
207			gstate.SetTransform(200, 0, 0, 300, 50, 450);
208			writer.WritePlacedElement(element);
209
210			// use the same image again (just change its matrix).
211			writer.WritePlacedElement(builder.CreateImage(img, 300, 600, 200, -150));
212
213			Obj grp_obj = writer.End();	
214
215			// Indicate that this form (content group) belongs to the given layer (OCG).
216			grp_obj.PutName("Subtype","Form");
217			grp_obj.Put("OC", layer);	
218			grp_obj.PutRect("BBox", 0, 0, 1000, 1000);  // Set the clip box for the content.
219            
220			// As an example of further configuration, set the image layer to
221			// be visible on screen, but not visible when printed...
222
223			// The AS entry is an auto state array consisting of one or more usage application 
224			// dictionaries that specify how conforming readers shall automatically set the 
225			// state of optional content groups based on external factors.
226			Obj cfg = doc.GetOCGConfig().GetSDFObj();
227			Obj auto_state = cfg.FindObj("AS");
228			if (auto_state == null) auto_state = cfg.PutArray("AS");
229			Obj print_state = auto_state.PushBackDict();
230			print_state.PutArray("Category").PushBackName("Print");
231			print_state.PutName("Event", "Print");
232			print_state.PutArray("OCGs").PushBack(layer);
233
234			Obj layer_usage = layer.PutDict("Usage");
235
236			Obj view_setting = layer_usage.PutDict("View");
237			view_setting.PutName("ViewState", "ON");
238
239			Obj print_setting = layer_usage.PutDict("Print");
240			print_setting.PutName("PrintState", "OFF");
241
242            return grp_obj;
243		}
244
245		// Creates some content (a path in the shape of a heart) and associate it with the vector layer
246        static public Obj CreateGroup2(PDFDoc doc, Obj layer)
247		{
248			ElementWriter writer = new ElementWriter();
249            writer.Begin(doc.GetSDFDoc());
250
251			// Create a path object in the shape of a heart.
252			ElementBuilder builder = new ElementBuilder();
253			builder.PathBegin();		// start constructing the path
254			builder.MoveTo(306, 396);
255			builder.CurveTo(681, 771, 399.75, 864.75, 306, 771);
256			builder.CurveTo(212.25, 864.75, -69, 771, 306, 396);
257			builder.ClosePath();
258			Element element = builder.PathEnd(); // the path geometry is now specified.
259
260			// Set the path FILL color space and color.
261			element.SetPathFill(true);
262			GState gstate = element.GetGState();
263			gstate.SetFillColorSpace(ColorSpace.CreateDeviceCMYK()); 
264			gstate.SetFillColor(new ColorPt(1, 0, 0, 0));  // cyan
265
266			// Set the path STROKE color space and color.
267			element.SetPathStroke(true); 
268			gstate.SetStrokeColorSpace(ColorSpace.CreateDeviceRGB()); 
269			gstate.SetStrokeColor(new ColorPt(1, 0, 0));  // red
270			gstate.SetLineWidth(20);
271
272			gstate.SetTransform(0.5, 0, 0, 0.5, 280, 300);
273
274			writer.WriteElement(element);
275
276            Obj grp_obj = writer.End();	
277
278			// Indicate that this form (content group) belongs to the given layer (OCG).
279			grp_obj.PutName("Subtype","Form");
280			grp_obj.Put("OC", layer);
281			grp_obj.PutRect("BBox", 0, 0, 1000, 1000); 	// Set the clip box for the content.
282
283			return grp_obj;
284		}
285
286		// Creates some text and associate it with the text layer
287        static public Obj CreateGroup3(PDFDoc doc, Obj layer)
288		{
289			ElementWriter writer = new ElementWriter();
290            writer.Begin(doc.GetSDFDoc());
291
292			// Create a path object in the shape of a heart.
293			ElementBuilder builder = new ElementBuilder();
294
295			// Begin writing a block of text
296			Element element = builder.CreateTextBegin(Font.Create(doc.GetSDFDoc(), FontStandardType1Font.e_times_roman), 120);
297			writer.WriteElement(element);
298
299			element = builder.CreateTextRun("A text layer!");
300
301			// Rotate text 45 degrees, than translate 180 pts horizontally and 100 pts vertically.
302			Matrix2D transform = Matrix2D.RotationMatrix(-45 *  (3.1415/ 180.0));
303			transform.Concat(1, 0, 0, 1, 180, 100);  
304			element.SetTextMatrix(transform);
305
306			writer.WriteElement(element);
307			writer.WriteElement(builder.CreateTextEnd());
308
309            Obj grp_obj = writer.End();	
310
311			// Indicate that this form (content group) belongs to the given layer (OCG).
312			grp_obj.PutName("Subtype","Form");
313			grp_obj.Put("OC", layer);
314			grp_obj.PutRect("BBox", 0, 0, 1000, 1000); 	// Set the clip box for the content.
315
316			return grp_obj;
317		}
318	}
319}