Get font and size of an acroform field

I need to get access to the font style and size of an acroform text field. I have access to the Field object via pdfclown but can't work out how to access the font. Anyone know how to do this?

Solution

I'm glad to announce you that today I committed to the PDF Clown's repository the fully-functional implementation of the FormFlattener, both on the current branch (0.1.2-Fix, rev 129, 131, 133) and on trunk (rev 130, 132, 134): I suggest you to download directly from that SVN repo to get the latest features & fixes.

Otherwise, in case you stick with the published release (0.1.2.0), here it is the relevant code (again, I recommend the committed version as it's more refined). First of all, we need some adjustment:

1) in XObject.java replace the wrap method:

public static XObject wrap(
  PdfDirectObject baseObject
  )
{
  if(baseObject == null)
    return null;

  PdfName subtype = (PdfName)((PdfStream)baseObject.resolve()).getHeader().get(PdfName.Subtype);
  if(PdfName.Form.equals(subtype))
    return FormXObject.wrap(baseObject);
  else if(PdfName.Image.equals(subtype))
    return ImageXObject.wrap(baseObject);
  else
    return null;
}

2) in FormXObject.java replace the wrap method:

public static FormXObject wrap(
  PdfDirectObject baseObject
  )
{
  if(baseObject == null)
    return null;

  PdfDictionary header = ((PdfStream)PdfObject.resolve(baseObject)).getHeader();
  PdfName subtype = (PdfName)header.get(PdfName.Subtype);
  /*
    NOTE: Sometimes the form stream's header misses the mandatory Subtype entry; therefore, here
    we force integrity for convenience (otherwise, content resource allocation may fail, for 
    example in case of Acroform flattening).
  */
  if(subtype == null && header.containsKey(PdfName.BBox))
  {header.put(PdfName.Subtype, PdfName.Form);}
  else if(!subtype.equals(PdfName.Form))
    return null;

  return new FormXObject(baseObject);
}

Then we can define the actual form flattener:

3) add FormFlattener.java to org.pdfclown.tools package:

package org.pdfclown.tools;

import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.Map;

import org.pdfclown.documents.Document;
import org.pdfclown.documents.Page;
import org.pdfclown.documents.PageAnnotations;
import org.pdfclown.documents.contents.xObjects.FormXObject;
import org.pdfclown.documents.interaction.annotations.Annotation.FlagsEnum;
import org.pdfclown.documents.interaction.annotations.Widget;
import org.pdfclown.documents.interaction.forms.Field;
import org.pdfclown.documents.interaction.forms.Fields;
import org.pdfclown.documents.interaction.forms.Form;
import org.pdfclown.objects.PdfArray;
import org.pdfclown.objects.PdfDictionary;
import org.pdfclown.objects.PdfDirectObject;
import org.pdfclown.objects.PdfName;
import org.pdfclown.objects.PdfObjectWrapper;
import org.pdfclown.objects.PdfReference;
import org.pdfclown.tools.PageStamper;
import org.pdfclown.util.math.geom.Dimension;

public class FormFlattener
{
  private boolean hiddenRendered;
  private boolean nonPrintableRendered;

  /**
    Replaces the Acroform fields with their corresponding graphics representation.

    @param document Document to flatten.
  */
  public void flatten(
    Document document
    )
  {
    Map<PdfDirectObject,PageStamper> pageStampers = new HashMap<PdfDirectObject,PageStamper>();
    Form form = document.getForm();
    Fields formFields = form.getFields();
    for(Field field : formFields.values())
    {
      for(Widget widget : field.getWidgets())
      {
        Page widgetPage = widget.getPage();
        EnumSet<FlagsEnum> flags = widget.getFlags();
        // Is the widget to be rendered?
        if((!flags.contains(FlagsEnum.Hidden) || hiddenRendered)
          && (flags.contains(FlagsEnum.Print) || nonPrintableRendered))
        {
          // Stamping the current state appearance of the widget...
          PdfName widgetCurrentState = (PdfName)widget.getBaseDataObject().get(PdfName.AS);
          FormXObject widgetCurrentAppearance = widget.getAppearance().getNormal().get(widgetCurrentState);
          if(widgetCurrentAppearance != null)
          {
            PageStamper widgetStamper = pageStampers.get(widgetPage.getBaseObject());
            if(widgetStamper == null)
            {pageStampers.put(widgetPage.getBaseObject(), widgetStamper = new PageStamper(widgetPage));}

            Rectangle2D widgetBox = widget.getBox();
            widgetStamper.getForeground().showXObject(widgetCurrentAppearance, new Point2D.Double(widgetBox.getX(), widgetBox.getY()), new Dimension(widgetBox.getWidth(), widgetBox.getHeight()));
          }
        }

        // Removing the widget from the page annotations...
        PageAnnotations widgetPageAnnotations = widgetPage.getAnnotations();
        widgetPageAnnotations.remove(widget);
        if(widgetPageAnnotations.isEmpty())
        {
          widgetPage.getBaseDataObject().put(PdfName.Annots, null);
          widgetPageAnnotations.delete();
        }

        // Removing the field references relating the widget...
        PdfDictionary fieldPartDictionary = widget.getBaseDataObject();
        while (fieldPartDictionary != null)
        {
          PdfDictionary parentFieldPartDictionary = (PdfDictionary)fieldPartDictionary.resolve(PdfName.Parent);

          PdfArray kidsArray;
          if(parentFieldPartDictionary != null)
          {kidsArray = (PdfArray)parentFieldPartDictionary.resolve(PdfName.Kids);}
          else
          {kidsArray = formFields.getBaseDataObject();}

          kidsArray.remove(fieldPartDictionary.getReference());
          fieldPartDictionary.getReference().delete();

          if(!kidsArray.isEmpty())
            break;

          fieldPartDictionary = parentFieldPartDictionary;
        }
      }
    }
    if(formFields.isEmpty())
    {
      // Removing the Acroform root...
      document.setForm(null);
      form.delete();
    }
    for(PageStamper pageStamper : pageStampers.values())
    {pageStamper.flush();}
  }

  /**
    Gets whether hidden fields have to be rendered.
  */
  public boolean isHiddenRendered(
    )
  {return hiddenRendered;}

  /**
    Gets whether non-printable fields have to be rendered.
  */
  public boolean isNonPrintableRendered(
    )
  {return nonPrintableRendered;}

  /**
    @see #isHiddenRendered()
  */
  public FormFlattener setHiddenRendered(
    boolean value
    )
  {
    hiddenRendered = value;
    return this;
  }

  /**
    @see #isNonPrintableRendered()
  */
  public FormFlattener setNonPrintableRendered(
    boolean value
    )
  {
    nonPrintableRendered = value;
    return this;
  }
}

And this is an example using it:

import java.io.IOException;

import org.pdfclown.documents.Document;
import org.pdfclown.files.File;
import org.pdfclown.tools.FormFlattener;

File file = null;
try
{
  // 1. Opening the PDF file...
  {
    try
    {file = new File(myFilePath);}
    catch(Exception e)
    {throw new RuntimeException(myFilePath + " file access error.",e);}
  }
  Document document = file.getDocument();

  // 2. Flatten the form!
  FormFlattener formFlattener = new FormFlattener();
  formFlattener.flatten(document);

  // 3. Serialize the PDF file!
  try
  {file.save(SerializationModeEnum.Standard);}
  catch(Exception e)
  {
    System.out.println("File writing failed: " + e.getMessage());
    e.printStackTrace();
  }
}
finally
{
  // 4. Closing the PDF file...
  if(file != null)
  {
    try
    {file.close();}
    catch(IOException e)
    {/* NOOP */}
  }
}

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