Add basic appearance stream generation

2 files changed, 24 insertions, 0 deletions

diff --git a/include/qpdf/QPDFAcroFormDocumentHelper.hh b/include/qpdf/QPDFAcroFormDocumentHelper.hh
index 3a308467..281056b9 100644
--- a/include/qpdf/QPDFAcroFormDocumentHelper.hh
+++ b/include/qpdf/QPDFAcroFormDocumentHelper.hh
@@ -157,6 +157,16 @@ class QPDFAcroFormDocumentHelper: public QPDFDocumentHelper
     QPDF_DLL
     void setNeedAppearances(bool);
 
+    // If /NeedAppearances is false, do nothing. Otherwise generate
+    // appearance streams for all widget annotations that need them.
+    // See comments in QPDFFormFieldObjectHelper.hh for
+    // generateAppearance for limitations. For checkbox and radio
+    // button fields, this code ensures that appearance state is
+    // consistent with the field's value and uses any pre-existing
+    // appearance streams.
+    QPDF_DLL
+    void generateAppearancesIfNeeded();
+
   private:
     void analyze();
     void traverseField(QPDFObjectHandle field,
diff --git a/include/qpdf/QPDFFormFieldObjectHelper.hh b/include/qpdf/QPDFFormFieldObjectHelper.hh
index 7ab9a1c0..a03ce555 100644
--- a/include/qpdf/QPDFFormFieldObjectHelper.hh
+++ b/include/qpdf/QPDFFormFieldObjectHelper.hh
@@ -31,6 +31,8 @@
 #include <qpdf/DLL.h>
 #include <vector>
 
+class QPDFAnnotationObjectHelper;
+
 class QPDFFormFieldObjectHelper: public QPDFObjectHelper
 {
   public:
@@ -179,9 +181,21 @@ class QPDFFormFieldObjectHelper: public QPDFObjectHelper
     QPDF_DLL
     void setV(std::string const& utf8_value, bool need_appearances = true);
 
+    // Update the appearance stream for this field. Note that qpdf's
+    // abilitiy to generate appearance streams is limited. We only
+    // generate appearance streams for streams of type text or choice.
+    // The appearance uses the default parameters provided in the
+    // file, and it only supports ASCII characters. Quadding is
+    // currently ignored. While this functionality is limited, it
+    // should do a decent job on properly constructed PDF files when
+    // field values are restricted to ASCII characters.
+    QPDF_DLL
+    void generateAppearance(QPDFAnnotationObjectHelper&);
+
   private:
     void setRadioButtonValue(QPDFObjectHandle name);
     void setCheckBoxValue(bool value);
+    void generateTextAppearance(QPDFAnnotationObjectHelper&);
 
     class Members
     {