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Posted to dev@pdfbox.apache.org by "Jonathan (JIRA)" <ji...@apache.org> on 2019/05/09 12:22:00 UTC
[jira] [Comment Edited] (PDFBOX-4540) COSWriter sometimes retrieves
wrong ObjectKey
[ https://issues.apache.org/jira/browse/PDFBOX-4540?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16836327#comment-16836327 ]
Jonathan edited comment on PDFBOX-4540 at 5/9/19 12:21 PM:
-----------------------------------------------------------
Frankly, after revisiting the issue in more detail, I'm not sure if an issue would ever arise during normal use of PDFBox. We have a rather special case here, as we use PDFBox's infrastructure to write linearized pdfs. We have the following method which assigns object numbers to every object contained in the pdf:
{code:java}
private void setObjectNumbers(final PDFObjectQueue queue, final LinearizedPDFWriter writer)
{
for (final Map.Entry<COSBase, ObjectMetaData> entry : queue.entrySet())
{
writer.getObjectKeys().put(entry.getKey(), new COSObjectKey(entry.getValue().objNumber, 0)); // always gen 0
if (entry.getKey() instanceof COSObject)
{
writer.getObjectKeys().put(((COSObject)entry.getKey()).getObject(), new COSObjectKey(entry.getValue().objNumber, 0)); // always gen 0
}
}
}
{code}
Later, when we then write the pdf, `COSWriter.doWriteObject(COSBase)` calls `COSWriter.getObjectKey(COSBase)` to obtain the `currentObjectKey` for the element to be written. Without my fix, the object will be assigned a new number, even though it was already defined previously.
I've uploaded a pdf which displays the issue when used as input.
was (Author: rahn2):
Frankly, after revisiting the issue in more detail, I'm not sure if an issue would ever arise during normal use of PDFBox. We have a rather special case here, as we use PDFBox's infrastructure to write linearized pdfs. We have the following method which assigns object numbers to every object contained in the pdf:
{code:java}
private void setObjectNumbers(final PDFObjectQueue queue, final LinearizedPDFWriter writer)
{
for (final Map.Entry<COSBase, ObjectMetaData> entry : queue.entrySet())
{
writer.getObjectKeys().put(entry.getKey(), new COSObjectKey(entry.getValue().objNumber, 0)); // always gen 0
if (entry.getKey() instanceof COSObject)
{
writer.getObjectKeys().put(((COSObject)entry.getKey()).getObject(), new COSObjectKey(entry.getValue().objNumber, 0)); // always gen 0
}
}
}
{code}
Later, when we then write the pdf, `COSWriter.doWriteObject(COSBase)` calls `COSWriter.getObjectKey(COSBase)` to obtain the `currentObjectKey` for the element to be written. Without my fix, the object will be assigned a new number, even though it was already defined previously.
> COSWriter sometimes retrieves wrong ObjectKey
> ---------------------------------------------
>
> Key: PDFBOX-4540
> URL: https://issues.apache.org/jira/browse/PDFBOX-4540
> Project: PDFBox
> Issue Type: Bug
> Components: Writing
> Affects Versions: 2.0.14
> Reporter: Jonathan
> Priority: Major
> Labels: patch, pull-request-available
> Attachments: sample.pdf
>
>
> If a COSBase is directly embedded in a COSObject, it should not be assigned a new object number by the writer. We suggest the following implementation for `COSWriter.getObjectKey(COSBase)`:
> {code:java}
> /**
> * This will get the object key for the object.
> *
> * @param obj The object to get the key for.
> *
> * @return The object key for the object.
> */
> protected COSObjectKey getObjectKey( COSBase obj )
> {
> COSBase actual = obj;
> if( actual instanceof COSObject )
> {
> actual = ((COSObject)obj).getObject();
> }
> COSObjectKey key = null;
> key = objectKeys.get(obj);
> if( key == null && actual != null )
> {
> key = objectKeys.get(actual);
> }
> if (key == null)
> {
> setNumber(getNumber()+1);
> key = new COSObjectKey(getNumber(),0);
> objectKeys.put(obj, key);
> if( actual != null )
> {
> objectKeys.put(actual, key);
> }
> }
> return key;
> }
> {code}
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