PDFLayers

1//---------------------------------------------------------------------------------------
2// Copyright (c) 2001-2019 by PDFTron Systems Inc. All Rights Reserved.
3// Consult legal.txt regarding legal and license information.
4//---------------------------------------------------------------------------------------
5
6package com.pdftron.android.pdfnetsdksamples.samples;
7
8import com.pdftron.android.pdfnetsdksamples.OutputListener;
9import com.pdftron.android.pdfnetsdksamples.PDFNetSample;
10import com.pdftron.android.pdfnetsdksamples.R;
11import com.pdftron.android.pdfnetsdksamples.util.Utils;
12import com.pdftron.common.Matrix2D;
13import com.pdftron.common.PDFNetException;
14import com.pdftron.pdf.ColorPt;
15import com.pdftron.pdf.ColorSpace;
16import com.pdftron.pdf.Element;
17import com.pdftron.pdf.ElementBuilder;
18import com.pdftron.pdf.ElementWriter;
19import com.pdftron.pdf.Font;
20import com.pdftron.pdf.GState;
21import com.pdftron.pdf.Image;
22import com.pdftron.pdf.PDFDoc;
23import com.pdftron.pdf.PDFDocViewPrefs;
24import com.pdftron.pdf.PDFDraw;
25import com.pdftron.pdf.Page;
26import com.pdftron.pdf.ocg.Config;
27import com.pdftron.pdf.ocg.Context;
28import com.pdftron.pdf.ocg.Group;
29import com.pdftron.pdf.ocg.OCMD;
30import com.pdftron.sdf.Obj;
31import com.pdftron.sdf.SDFDoc;
32
33import java.util.ArrayList;
34
35/**
36 * This sample demonstrates how to create layers in PDF.
37 * The sample also shows how to extract and render PDF layers in documents
38 * that contain optional content groups (OCGs)
39 * <p>
40 * With the introduction of PDF version 1.5 came the concept of Layers.
41 * Layers, or as they are more formally known Optional Content Groups (OCGs),
42 * refer to sections of content in a PDF document that can be selectively
43 * viewed or hidden by document authors or consumers. This capability is useful
44 * in CAD drawings, layered artwork, maps, multi-language documents etc.
45 * <p>
46 * Couple of notes regarding this sample:
47 * ---------------------------------------
48 * - This sample is using CreateLayer() utility method to create new OCGs.
49 * CreateLayer() is relatively basic, however it can be extended to set
50 * other optional entries in the 'OCG' and 'OCProperties' dictionary. For
51 * a complete listing of possible entries in OC dictionary please refer to
52 * section 4.10 'Optional Content' in the PDF Reference Manual.
53 * - The sample is grouping all layer content into separate Form XObjects.
54 * Although using PDFNet is is also possible to specify Optional Content in
55 * Content Streams (Section 4.10.2 in PDF Reference), Optional Content in
56 * XObjects results in PDFs that are cleaner, less-error prone, and faster
57 * to process.
58 */
59public class PDFLayersTest extends PDFNetSample {
60
61	private static OutputListener mOutputListener;
62
63	private static ArrayList<String> mFileList = new ArrayList<>();
64
65    public PDFLayersTest() {
66        setTitle(R.string.sample_pdflayers_title);
67        setDescription(R.string.sample_pdflayers_description);
68    }
69
70	@Override
71	public void run(OutputListener outputListener) {
72		super.run(outputListener);
73		mOutputListener = outputListener;
74		mFileList.clear();
75		printHeader(outputListener);
76
77        try (PDFDoc doc = new PDFDoc()) {
78            // Create three layers...
79            Group image_layer = createLayer(doc, "Image Layer");
80            Group text_layer = createLayer(doc, "Text Layer");
81            Group vector_layer = createLayer(doc, "Vector Layer");
82
83            // Start a new page ------------------------------------
84            Page page = doc.pageCreate();
85
86            ElementBuilder builder = new ElementBuilder(); // ElementBuilder is used to build new Element objects
87            ElementWriter writer = new ElementWriter(); // ElementWriter is used to write Elements to the page
88            writer.begin(page);        // Begin writing to the page
89
90            // Add new content to the page and associate it with one of the layers.
91            Element element = builder.createForm(createGroup1(doc, image_layer.getSDFObj()));
92            writer.writeElement(element);
93
94            element = builder.createForm(createGroup2(doc, vector_layer.getSDFObj()));
95            writer.writeElement(element);
96
97            // Add the text layer to the page...
98            if (false)  // set to true to enable 'ocmd' example.
99            {
100                // A bit more advanced example of how to create an OCMD text layer that
101                // is visible only if text, image and path layers are all 'ON'.
102                // An example of how to set 'Visibility Policy' in OCMD.
103                Obj ocgs = doc.createIndirectArray();
104                ocgs.pushBack(image_layer.getSDFObj());
105                ocgs.pushBack(vector_layer.getSDFObj());
106                ocgs.pushBack(text_layer.getSDFObj());
107                OCMD text_ocmd = OCMD.create(doc, ocgs, OCMD.e_AllOn);
108                element = builder.createForm(createGroup3(doc, text_ocmd.getSDFObj()));
109            } else {
110                element = builder.createForm(createGroup3(doc, text_layer.getSDFObj()));
111            }
112            writer.writeElement(element);
113
114            // Add some content to the page that does not belong to any layer...
115            // In this case this is a rectangle representing the page border.
116            element = builder.createRect(0, 0, page.getPageWidth(), page.getPageHeight());
117            element.setPathFill(false);
118            element.setPathStroke(true);
119            element.getGState().setLineWidth(40);
120            writer.writeElement(element);
121
122            writer.end();  // save changes to the current page
123            doc.pagePushBack(page);
124
125            // Set the default viewing preference to display 'Layer' tab.
126            PDFDocViewPrefs prefs = doc.getViewPrefs();
127            prefs.setPageMode(PDFDocViewPrefs.e_UseOC);
128
129            doc.save(Utils.createExternalFile("pdf_layers.pdf", mFileList).getAbsolutePath(), SDFDoc.SaveMode.LINEARIZED, null);
130            mOutputListener.println("Done.");
131        } catch (Exception e) {
132            mOutputListener.printError(e.getStackTrace());
133        }
134
135        // The following is a code snippet shows how to selectively render
136        // and export PDF layers.
137        try (PDFDoc doc = new PDFDoc(Utils.createExternalFile("pdf_layers.pdf", mFileList).getAbsolutePath())) {
138            doc.initSecurityHandler();
139
140            if (doc.hasOC() == false) {
141                mOutputListener.println("The document does not contain 'Optional Content'");
142            } else {
143                Config init_cfg = doc.getOCGConfig();
144                Context ctx = new Context(init_cfg);
145
146                PDFDraw pdfdraw = new PDFDraw();
147                pdfdraw.setImageSize(1000, 1000);
148                pdfdraw.setOCGContext(ctx); // Render the page using the given OCG context.
149
150                Page page = doc.getPage(1); // Get the first page in the document.
151                pdfdraw.export(page, Utils.createExternalFile("pdf_layers_default.png", mFileList).getAbsolutePath());
152                // output "pdf_layers_default.png"
153
154                // Disable drawing of content that is not optional (i.e. is not part of any layer).
155                ctx.setNonOCDrawing(false);
156
157                // Now render each layer in the input document to a separate image.
158                Obj ocgs = doc.getOCGs(); // Get the array of all OCGs in the document.
159                if (ocgs != null) {
160                    int i, sz = (int) ocgs.size();
161                    for (i = 0; i < sz; ++i) {
162                        Group ocg = new Group(ocgs.getAt(i));
163                        ctx.resetStates(false);
164                        ctx.setState(ocg, true);
165                        String fname =  "pdf_layers_" + ocg.getName() + ".png";
166                        mOutputListener.println(fname);
167                        pdfdraw.export(page, Utils.createExternalFile(fname, mFileList).getAbsolutePath());
168                        // output "pdf_layers_" + ocg.getName() + ".png"
169                    }
170                }
171
172                // Now draw content that is not part of any layer...
173                ctx.setNonOCDrawing(true);
174                ctx.setOCDrawMode(Context.e_NoOC);
175                pdfdraw.export(page, Utils.createExternalFile("pdf_layers_non_oc.png", mFileList).getAbsolutePath());
176                // output "pdf_layers_non_oc.png"
177            }
178
179            mOutputListener.println("Done.");
180        } catch (Exception e) {
181            mOutputListener.printError(e.getStackTrace());
182        }
183
184		for (String file : mFileList) {
185			addToFileList(file);
186		}
187		printFooter(outputListener);
188	}
189
190    // A utility function used to add new Content Groups (Layers) to the document.
191    static Group createLayer(PDFDoc doc, String layer_name) throws PDFNetException {
192        Group grp = Group.create(doc, layer_name);
193        Config cfg = doc.getOCGConfig();
194        if (cfg == null) {
195            cfg = Config.create(doc, true);
196            cfg.setName("Default");
197        }
198
199        // Add the new OCG to the list of layers that should appear in PDF viewer GUI.
200        Obj layer_order_array = cfg.getOrder();
201        if (layer_order_array == null) {
202            layer_order_array = doc.createIndirectArray();
203            cfg.setOrder(layer_order_array);
204        }
205        layer_order_array.pushBack(grp.getSDFObj());
206
207        return grp;
208    }
209
210    // Creates some content (3 images) and associate them with the image layer
211    static Obj createGroup1(PDFDoc doc, Obj layer) throws PDFNetException {
212        ElementWriter writer = new ElementWriter();
213        writer.begin(doc);
214
215        // Create an Image that can be reused in the document or on the same page.
216        Image img = Image.create(doc.getSDFDoc(), (Utils.getAssetTempFile(INPUT_PATH + "peppers.jpg").getAbsolutePath()));
217
218        ElementBuilder builder = new ElementBuilder();
219        Element element = builder.createImage(img, new Matrix2D(img.getImageWidth() / 2, -145, 20, img.getImageHeight() / 2, 200, 150));
220        writer.writePlacedElement(element);
221
222        GState gstate = element.getGState();    // use the same image (just change its matrix)
223        gstate.setTransform(200, 0, 0, 300, 50, 450);
224        writer.writePlacedElement(element);
225
226        // use the same image again (just change its matrix).
227        writer.writePlacedElement(builder.createImage(img, 300, 600, 200, -150));
228
229        Obj grp_obj = writer.end();
230
231        // Indicate that this form (content group) belongs to the given layer (OCG).
232        grp_obj.putName("Subtype", "Form");
233        grp_obj.put("OC", layer);
234        grp_obj.putRect("BBox", 0, 0, 1000, 1000);  // Set the clip box for the content.
235
236        return grp_obj;
237    }
238
239    // Creates some content (a path in the shape of a heart) and associate it with the vector layer
240    static Obj createGroup2(PDFDoc doc, Obj layer) throws PDFNetException {
241        ElementWriter writer = new ElementWriter();
242        writer.begin(doc);
243
244        // Create a path object in the shape of a heart.
245        ElementBuilder builder = new ElementBuilder();
246        builder.pathBegin();        // start constructing the path
247        builder.moveTo(306, 396);
248        builder.curveTo(681, 771, 399.75, 864.75, 306, 771);
249        builder.curveTo(212.25, 864.75, -69, 771, 306, 396);
250        builder.closePath();
251        Element element = builder.pathEnd(); // the path geometry is now specified.
252
253        // Set the path FILL color space and color.
254        element.setPathFill(true);
255        GState gstate = element.getGState();
256        gstate.setFillColorSpace(ColorSpace.createDeviceCMYK());
257        gstate.setFillColor(new ColorPt(1, 0, 0, 0));  // cyan
258
259        // Set the path STROKE color space and color.
260        element.setPathStroke(true);
261        gstate.setStrokeColorSpace(ColorSpace.createDeviceRGB());
262        gstate.setStrokeColor(new ColorPt(1, 0, 0));  // red
263        gstate.setLineWidth(20);
264
265        gstate.setTransform(0.5, 0, 0, 0.5, 280, 300);
266
267        writer.writeElement(element);
268
269        Obj grp_obj = writer.end();
270
271        // Indicate that this form (content group) belongs to the given layer (OCG).
272        grp_obj.putName("Subtype", "Form");
273        grp_obj.put("OC", layer);
274        grp_obj.putRect("BBox", 0, 0, 1000, 1000);    // Set the clip box for the content.
275
276        return grp_obj;
277    }
278
279    // Creates some text and associate it with the text layer
280    static Obj createGroup3(PDFDoc doc, Obj layer) throws PDFNetException {
281        ElementWriter writer = new ElementWriter();
282        writer.begin(doc);
283
284        // Create a path object in the shape of a heart.
285        ElementBuilder builder = new ElementBuilder();
286
287        // Begin writing a block of text
288        Element element = builder.createTextBegin(Font.create(doc, Font.e_times_roman), 120);
289        writer.writeElement(element);
290
291        element = builder.createTextRun("A text layer!");
292
293        // Rotate text 45 degrees, than translate 180 pts horizontally and 100 pts vertically.
294        Matrix2D transform = Matrix2D.rotationMatrix(-45 * (3.1415 / 180.0));
295        transform.concat(1, 0, 0, 1, 180, 100);
296        element.setTextMatrix(transform);
297
298        writer.writeElement(element);
299        writer.writeElement(builder.createTextEnd());
300
301        Obj grp_obj = writer.end();
302
303        // Indicate that this form (content group) belongs to the given layer (OCG).
304        grp_obj.putName("Subtype", "Form");
305        grp_obj.put("OC", layer);
306        grp_obj.putRect("BBox", 0, 0, 1000, 1000);    // Set the clip box for the content.
307
308        return grp_obj;
309    }
310
311}