Handle fallback font size in text appearances

If we end up using our fallback font size when generating appearances for text fields, reflect that in the Tf operator used in the appearance stream.

Handle fallback font size in text appearances
If we end up using our fallback font size when generating appearances for text fields, reflect that in the Tf operator used in the appearance stream.
Jay Berkenbilt
1 parent 9cb59987
Showing 5 changed files with 393 additions and 355 deletions
ChangeLog
libqpdf/QPDFFormFieldObjectHelper.cc
qpdf/qpdf.testcov
qpdf/qtest/qpdf/appearances-a-more2.pdf
qpdf/qtest/qpdf/need-appearances-more2.pdf
 2019-01-20  Jay Berkenbilt  <ejb@ql.org>
  
+	* Tweak the content code generated for variable text fields to
+	better handle font sizes and multi-line text.
+
 	* When generating appearance streams for variable text
 	annotations, properly handle the cases of there being no
 	appearance dictionary, no appearance stream, or an appearance
@@ -715,17 +715,23 @@ class TfFinder: public QPDFObjectHandle::TokenFilter
     virtual void handleToken(QPDFTokenizer::Token const&);
     double getTf();
     std::string getFontName();
+    std::string getDA();
  
   private:
     double tf;
+    size_t tf_idx;
     std::string font_name;
     double last_num;
+    size_t last_num_idx;
     std::string last_name;
+    std::vector<std::string> DA;
 };
  
 TfFinder::TfFinder() :
     tf(11.0),
-    last_num(0.0)
+    tf_idx(0),
+    last_num(0.0),
+    last_num_idx(0)
 {
 }
  
@@ -734,11 +740,13 @@ TfFinder::handleToken(QPDFTokenizer::Token const&amp; token)
 {
     QPDFTokenizer::token_type_e ttype = token.getType();
     std::string value = token.getValue();
+    DA.push_back(token.getRawValue());
     switch (ttype)
     {
       case QPDFTokenizer::tt_integer:
       case QPDFTokenizer::tt_real:
         last_num = strtod(value.c_str(), 0);
+        last_num_idx = DA.size() - 1;
         break;
  
       case QPDFTokenizer::tt_name:
@@ -754,6 +762,7 @@ TfFinder::handleToken(QPDFTokenizer::Token const&amp; token)
             // insane things or suffering from over/underflow
             tf = last_num;
         }
+        tf_idx = last_num_idx;
         font_name = last_name;
         break;
  
@@ -769,6 +778,30 @@ TfFinder::getTf()
 }
  
 std::string
+TfFinder::getDA()
+{
+    std::string result;
+    size_t n = this->DA.size();
+    for (size_t i = 0; i < n; ++i)
+    {
+        std::string cur = this->DA.at(i);
+        if (i == tf_idx)
+        {
+            double delta = strtod(cur.c_str(), 0) - this->tf;
+            if ((delta > 0.001) || (delta < -0.001))
+            {
+                // tf doesn't match the font size passed to Tf, so
+                // substitute.
+                QTC::TC("qpdf", "QPDFFormFieldObjectHelper fallback Tf");
+                cur = QUtil::double_to_string(tf);
+            }
+        }
+        result += cur;
+    }
+    return result;
+}
+
+std::string
 TfFinder::getFontName()
 {
     return this->font_name;
@@ -843,6 +876,7 @@ QPDFFormFieldObjectHelper::generateTextAppearance(
     tok.write(QUtil::unsigned_char_pointer(DA.c_str()), DA.length());
     tok.finish();
     double tf = tff.getTf();
+    DA = tff.getDA();
  
     std::string (*encoder)(std::string const&, char) = &QUtil::utf8_to_ascii;
     std::string font_name = tff.getFontName();
@@ -425,3 +425,4 @@ QPDFPageDocumentHelper ignore annotation with no appearance 0
 QPDFFormFieldObjectHelper create AS from scratch 0
 QPDFFormFieldObjectHelper create AP from scratch 0
 QPDFFormFieldObjectHelper replaced BMC at EOF 0
+QPDFFormFieldObjectHelper fallback Tf 0