qpdf/include/qpdf/QPDFFormFieldObjectHelper.hh

// Copyright (c) 2005-2023 Jay Berkenbilt
//
// This file is part of qpdf.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software distributed under the License
// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
// or implied. See the License for the specific language governing permissions and limitations under
// the License.
//
// Versions of qpdf prior to version 7 were released under the terms of version 2.0 of the Artistic
// License. At your option, you may continue to consider qpdf to be licensed under those terms.
// Please see the manual for additional information.

#ifndef QPDFFORMFIELDOBJECTHELPER_HH
#define QPDFFORMFIELDOBJECTHELPER_HH

// This object helper helps with form fields for interactive forms. Please see comments in
// QPDFAcroFormDocumentHelper.hh for additional details.

#include <qpdf/QPDFObjectHelper.hh>

#include <qpdf/DLL.h>
#include <vector>

class QPDFAnnotationObjectHelper;

class QPDFFormFieldObjectHelper: public QPDFObjectHelper
{
  public:
    QPDF_DLL
    QPDFFormFieldObjectHelper();
    QPDF_DLL
    QPDFFormFieldObjectHelper(QPDFObjectHandle);
    QPDF_DLL
    ~QPDFFormFieldObjectHelper() override = default;

    QPDF_DLL
    bool isNull();

    // Return the field's parent. A form field object helper whose underlying object is null is
    // returned if there is no parent. This condition may be tested by calling isNull().
    QPDF_DLL
    QPDFFormFieldObjectHelper getParent();

    // Return the top-level field for this field. Typically this will be the field itself or its
    // parent. If is_different is provided, it is set to true if the top-level field is different
    // from the field itself; otherwise it is set to false.
    QPDF_DLL
    QPDFFormFieldObjectHelper getTopLevelField(bool* is_different = nullptr);

    // Get a field value, possibly inheriting the value from an ancestor node.
    QPDF_DLL
    QPDFObjectHandle getInheritableFieldValue(std::string const& name);

    // Get an inherited field value as a string. If it is not a string, silently return the empty
    // string.
    QPDF_DLL
    std::string getInheritableFieldValueAsString(std::string const& name);

    // Get an inherited field value of type name as a string representing the name. If it is not a
    // name, silently return the empty string.
    QPDF_DLL
    std::string getInheritableFieldValueAsName(std::string const& name);

    // Returns the value of /FT if present, otherwise returns the empty string.
    QPDF_DLL
    std::string getFieldType();

    QPDF_DLL
    std::string getFullyQualifiedName();

    QPDF_DLL
    std::string getPartialName();

    // Return the alternative field name (/TU), which is the field name intended to be presented to
    // users. If not present, fall back to the fully qualified name.
    QPDF_DLL
    std::string getAlternativeName();

    // Return the mapping field name (/TM). If not present, fall back to the alternative name, then
    // to the partial name.
    QPDF_DLL
    std::string getMappingName();

    QPDF_DLL
    QPDFObjectHandle getValue();

    // Return the field's value as a string. If this is called with a field whose value is not a
    // string, the empty string will be silently returned.
    QPDF_DLL
    std::string getValueAsString();

    QPDF_DLL
    QPDFObjectHandle getDefaultValue();

    // Return the field's default value as a string. If this is called with a field whose value is
    // not a string, the empty string will be silently returned.
    QPDF_DLL
    std::string getDefaultValueAsString();

    // Return the default appearance string, taking inheritance from the field tree into account.
    // Returns the empty string if the default appearance string is not available (because it's
    // erroneously absent or because this is not a variable text field). If not found in the field
    // hierarchy, look in /AcroForm.
    QPDF_DLL
    std::string getDefaultAppearance();

    // Return the default resource dictionary for the field. This comes not from the field but from
    // the document-level /AcroForm dictionary. While several PDF generates put a /DR key in the
    // form field's dictionary, experimentation suggests that many popular readers, including Adobe
    // Acrobat and Acrobat Reader, ignore any /DR item on the field.
    QPDF_DLL
    QPDFObjectHandle getDefaultResources();

    // Return the quadding value, taking inheritance from the field tree into account. Returns 0 if
    // quadding is not specified. Look in /AcroForm if not found in the field hierarchy.
    QPDF_DLL
    int getQuadding();

    // Return field flags from /Ff. The value is a logical or of pdf_form_field_flag_e as defined in
    // qpdf/Constants.h
    QPDF_DLL
    int getFlags();

    // Methods for testing for particular types of form fields

    // Returns true if field is of type /Tx
    QPDF_DLL
    bool isText();
    // Returns true if field is of type /Btn and flags do not indicate some other type of button.
    QPDF_DLL
    bool isCheckbox();
    // Returns true if field is a checkbox and is checked.
    QPDF_DLL
    bool isChecked();
    // Returns true if field is of type /Btn and flags indicate that it is a radio button
    QPDF_DLL
    bool isRadioButton();
    // Returns true if field is of type /Btn and flags indicate that it is a pushbutton
    QPDF_DLL
    bool isPushbutton();
    // Returns true if fields if of type /Ch
    QPDF_DLL
    bool isChoice();
    // Returns choices as UTF-8 strings
    QPDF_DLL
    std::vector<std::string> getChoices();

    // Set an attribute to the given value. If you have a QPDFAcroFormDocumentHelper and you want to
    // set the name of a field, use QPDFAcroFormDocumentHelper::setFormFieldName instead.
    QPDF_DLL
    void setFieldAttribute(std::string const& key, QPDFObjectHandle value);

    // Set an attribute to the given value as a Unicode string (UTF-16 BE encoded). The input string
    // should be UTF-8 encoded. If you have a QPDFAcroFormDocumentHelper and you want to set the
    // name of a field, use QPDFAcroFormDocumentHelper::setFormFieldName instead.
    QPDF_DLL
    void setFieldAttribute(std::string const& key, std::string const& utf8_value);

    // Set /V (field value) to the given value. If need_appearances is true and the field type is
    // either /Tx (text) or /Ch (choice), set /NeedAppearances to true. You can explicitly tell this
    // method not to set /NeedAppearances if you are going to generate an appearance stream
    // yourself. Starting with qpdf 8.3.0, this method handles fields of type /Btn (checkboxes,
    // radio buttons, pushbuttons) specially.
    QPDF_DLL
    void setV(QPDFObjectHandle value, bool need_appearances = true);

    // Set /V (field value) to the given string value encoded as a Unicode string. The input value
    // should be UTF-8 encoded. See comments above about /NeedAppearances.
    QPDF_DLL
    void setV(std::string const& utf8_value, bool need_appearances = true);

    // Update the appearance stream for this field. Note that qpdf's ability 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:
    QPDFObjectHandle getFieldFromAcroForm(std::string const& name);
    void setRadioButtonValue(QPDFObjectHandle name);
    void setCheckBoxValue(bool value);
    void generateTextAppearance(QPDFAnnotationObjectHelper&);
    QPDFObjectHandle getFontFromResource(QPDFObjectHandle resources, std::string const& font_name);

    class Members
    {
        friend class QPDFFormFieldObjectHelper;

      public:
        QPDF_DLL
        ~Members() = default;

      private:
        Members() = default;
        Members(Members const&) = delete;
    };

    std::shared_ptr<Members> m;
};

#endif // QPDFFORMFIELDOBJECTHELPER_HH