pdfbox-trunk/preflight/src/main/java/org/apache/pdfbox/preflight/action/HideAction.java
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package org.apache.pdfbox.preflight.action;

import static org.apache.pdfbox.preflight.PreflightConstants.ERROR_ACTION_HIDE_H_INVALID;
import static org.apache.pdfbox.preflight.PreflightConstants.ERROR_ACTION_INVALID_TYPE;
import static org.apache.pdfbox.preflight.PreflightConstants.ERROR_ACTION_MISING_KEY;

import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.cos.COSBase;
import org.apache.pdfbox.cos.COSDictionary;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.cos.COSString;
import org.apache.pdfbox.preflight.PreflightContext;
import org.apache.pdfbox.preflight.ValidationResult.ValidationError;

/**
 * ActionManager for the Hide action. The Hide action isn't specifically prohibited by PDF/A-1, but should have been. So
 * this action manager isn't an instance of InvalidAction but authorized only the H entry with the false value.
 */
public class HideAction extends AbstractActionManager
{

    /**
     * @param amFact
     *            Instance of ActionManagerFactory used to create ActionManager to check Next actions.
     * @param adict
     *            the COSDictionary of the action wrapped by this class.
     * @param ctx
     *            the DocumentHandler from which the action comes from.
     * @param aaKey
     *            The name of the key which identify the action in a additional action dictionary.
     */
    public HideAction(ActionManagerFactory amFact, COSDictionary adict, PreflightContext ctx, String aaKey)
    {
        super(amFact, adict, ctx, aaKey);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.pdfbox.preflight.action.AbstractActionManager#valid(java.util .List)
     */
    @Override
    protected boolean innerValid()
    {
        COSBase t = this.actionDictionary.getDictionaryObject(COSName.T);
        // ---- T entry is mandatory
        if (t == null)
        {
            context.addValidationError(new ValidationError(ERROR_ACTION_MISING_KEY,
                    "T entry is mandatory for the NamedActions"));
            return false;
        }

        if (!(t instanceof COSDictionary || t instanceof COSArray || t instanceof COSString
                || t instanceof COSName))
        {
            context.addValidationError(new ValidationError(ERROR_ACTION_INVALID_TYPE, "T entry type is invalid"));
            return false;
        }

        /*
         * ---- H entry is optional but the default value is True (annotations of the T entry will be hidden) according
         * to the aim of a PDF/A it should be false (annotations of the T entry will be shown).
         * 
         * We check the H value and we throw an error if it is true because of the PDF/A Application Notes sentence :
         * 
         * The PDF Reference supports a concept whereby something will happen when the user performs an explicit or
         * implicit action in a PDF viewer - these "things" are called Actions. PDF/A-1 permits a limited set of these
         * Actions, which are detailed in section 6.6.1. Specifically, any action that could change the visual
         * representation of the document or is not documented in the PDF Reference is not permitted. This includes the
         * /Hide action which isn't specifically prohibited by PDF/A-1, but should have been.
         */
        boolean h = this.actionDictionary.getBoolean(COSName.H, true);
        if (h)
        {
            context.addValidationError(new ValidationError(ERROR_ACTION_HIDE_H_INVALID, "H entry is \"true\""));
            return false;
        }

        return true;
    }
}
