[
https://issues.apache.org/jira/browse/PDFBOX-2126?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14047723#comment-14047723
]
Petr Slaby commented on PDFBOX-2126:
------------------------------------
I have removed clippingPath.clone() in my patch, the cloned PDGraphicsState
uses a pointer to the same clipping path then. A new clipping object is only
created in setClippingPath() (resp. intersectClippingPath()). This enables me
to use the lastClip == currentClip condition in PageDrawer.applyClipping() to
avoid applying the clip if it did not change.
After the change from storing GeneralPath to storing Area, I thought the
clippingPath.clone() in PDGraphicsState.clone() would be inevitable, but I can
shift it to intersectClippingPath() as well.
I will post an updated patch again as soon as possible, but unfortunately I am
quite overwhelmed by my daily business right now.
> Optimize clipping
> -----------------
>
> Key: PDFBOX-2126
> URL: https://issues.apache.org/jira/browse/PDFBOX-2126
> Project: PDFBox
> Issue Type: Improvement
> Components: Rendering
> Affects Versions: 2.0.0
> Reporter: Petr Slaby
> Attachments: ClipPath.1.patch, ClipPath.patch, example_010.pdf
>
>
> As already stated in a TODO comment in PageDrawer, the call of
> Graphics2D#setClip() is time and memory consuming. The attached patch
> optimizes clipping by calling Graphics2D#setClip() only if the clipping path
> has changed. The effect depends on the document, e.g. the attached one
> renders in 10.5s without the optimization and in 5.5 seconds in the optimized
> version.
> The clipping has to be re-applied whenever the transform in Graphics2D
> changes. This is not explicitly checked for, the implementation rather
> depends on the cached value being reset manually. Currently this is only
> needed at one place when processing annotations (AcroForms). Also, the
> implementation relies upon the clipping path object stored in PDGraphicsState
> to never change so that a comparison using == can be used. This works fine,
> but needs a bit of awareness in future changes. To make the design more
> clean, the clipping path could be made private to PDGraphcisState and thus
> really "immutable" from outside.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
