Add interactive form example

ChangeLog

@@ -1,5 +1,8 @@
 2018-06-21  Jay Berkenbilt  <ejb@ql.org>
 
+	* Create examples/pdf-set-form-values.cc to illustrate use of
+	interactive form helpers.
+
 	* Added methods QPDFAcroFormDocumentHelper::setNeedAppearances and
 	added methods to QPDFFormFieldObjectHelper to set a field's value,
 	optionally updating the document to indicate that appearance

examples/build.mk

@@ -8,7 +8,8 @@ BINS_examples = \
 	pdf-parse-content \
 	pdf-split-pages \
 	pdf-filter-tokens \
-	pdf-count-strings
+	pdf-count-strings \
+	pdf-set-form-values
 CBINS_examples = pdf-linearize
 
 TARGETS_examples = $(foreach B,$(BINS_examples) $(CBINS_examples),examples/$(OUTPUT_DIR)/$(call binname,$(B)))

examples/pdf-set-form-values.cc

@@ -0,0 +1,108 @@
+#include <iostream>
+#include <stdlib.h>
+#include <qpdf/QPDF.hh>
+#include <qpdf/QPDFPageDocumentHelper.hh>
+#include <qpdf/QPDFAcroFormDocumentHelper.hh>
+#include <qpdf/QPDFWriter.hh>
+#include <qpdf/QUtil.hh>
+
+static char const* whoami = 0;
+
+void usage()
+{
+    std::cerr << "Usage: " << whoami << " infile.pdf outfile.pdf value"
+	      << std::endl
+	      << "Set the value of all text fields to a specified value"
+              << std::endl;
+    exit(2);
+}
+
+
+int main(int argc, char* argv[])
+{
+    whoami = QUtil::getWhoami(argv[0]);
+
+    // For libtool's sake....
+    if (strncmp(whoami, "lt-", 3) == 0)
+    {
+	whoami += 3;
+    }
+
+    if (argc != 4)
+    {
+        usage();
+    }
+
+    char const* infilename = argv[1];
+    char const* outfilename = argv[2];
+    char const* value = argv[3];
+
+    // This is a contrived example that just goes through a file page
+    // by page and sets the value of any text fields it finds to a
+    // fixed value as given on the command line. The purpose here is
+    // to illustrate use of the helper classes around interactive
+    // forms.
+
+    try
+    {
+	QPDF qpdf;
+	qpdf.processFile(infilename);
+
+        // We will iterate through form fields by starting at the page
+        // level and looking at each field for each page. We could
+        // also called QPDFAcroFormDocumentHelper::getFormFields to
+        // iterate at the field level, but doing it as below
+        // illustrates how we can map from annotations to fields.
+
+        QPDFAcroFormDocumentHelper afdh(qpdf);
+        QPDFPageDocumentHelper pdh(qpdf);
+        std::vector<QPDFPageObjectHelper> pages = pdh.getAllPages();
+        for (std::vector<QPDFPageObjectHelper>::iterator page_iter =
+                 pages.begin();
+             page_iter != pages.end(); ++page_iter)
+        {
+            // Get all widget annotations for each page. Widget
+            // annotations are the ones that contain the details of
+            // what's in a form field.
+            std::vector<QPDFAnnotationObjectHelper> annotations =
+                afdh.getWidgetAnnotationsForPage(*page_iter);
+            for (std::vector<QPDFAnnotationObjectHelper>::iterator annot_iter =
+                     annotations.begin();
+                 annot_iter != annotations.end(); ++annot_iter)
+            {
+                // For each annotation, find its associated field. If
+                // it's a text field, set its value. This will
+                // automatically update the document to indicate that
+                // appearance streams need to be regenerated. At the
+                // time of this writing, qpdf doesn't have any helper
+                // code to assist with appearance stream generation,
+                // though there's nothing that prevents it from being
+                // possible.
+                QPDFFormFieldObjectHelper ffh =
+                    afdh.getFieldForAnnotation(*annot_iter);
+                if (ffh.getFieldType() == "/Tx")
+                {
+                    // Set the value. This will automatically set
+                    // /NeedAppearances to true. If you don't want to
+                    // do that, pass false as the second argument. For
+                    // details see comments in
+                    // QPDFFormFieldObjectHelper.hh.
+                    ffh.setV(value);
+                }
+            }
+        }
+
+	// Write out a new file
+	QPDFWriter w(qpdf, outfilename);
+        w.setStaticID(true); // for testing only
+	w.write();
+    }
+    catch (std::exception &e)
+    {
+	std::cerr << whoami << " processing file " << infilename << ": "
+		  << e.what() << std::endl;
+	exit(2);
+    }
+
+    return 0;
+}

examples/qtest/set-form-values.test

@@ -0,0 +1,28 @@
+#!/usr/bin/env perl
+require 5.008;
+BEGIN { $^W = 1; }
+use strict;
+
+chdir("set-form-values");
+
+require TestDriver;
+
+my $td = new TestDriver('pdf-set-form-values');
+
+cleanup();
+
+$td->runtest("set form values",
+	     {$td->COMMAND => "pdf-set-form-values form-in.pdf a.pdf soup"},
+	     {$td->STRING => "", $td->EXIT_STATUS => 0});
+$td->runtest("compare files",
+	     {$td->FILE => "a.pdf"},
+	     {$td->FILE => "form-out.pdf"});
+
+cleanup();
+
+$td->report(2);
+
+sub cleanup
+{
+    unlink("a.pdf");
+}