Okular is the multiplatform document viewer developed by the KDE community and based on Qt and KDE Frameworks libraries. It is distributed as part of the KDE Applications bundle. It was originally based on KPDF and it replaced KPDF, KGhostView, KFax, KFaxview and KDVI in KDE 4. Its functionality can be easily embedded in other applications.
Okular showing a PDF in KDE SC 4
|Original author(s)||Piotr Szymański|
|Developer(s)||The Okular Team|
1.4 / 19 April 2018
|Operating system||Linux, Unix-like|
|Type||Universal document viewer|
|License||GNU General Public License|
Okular was identified as a success story of the 2007 Season of Usability. In this season the Okular toolbar mockup was created based on an analysis of other popular document viewers and a usage survey.
When it was ported to Qt 5 in December 2016, the version numbering jumped from 0.26 to 1.0.
Okular's annotation features include commenting on PDF documents, highlighting and drawing lines, geometric shapes, adding textboxes, and stamps. Annotations are stored separately from the unmodified PDF file, or (since version 0.15 with Poppler 0.20) can be saved in the document as standard PDF annotations.
Text can be extracted to a text file. It is possible to select parts of the document and copy the text or image to the clipboard. Other features include reading text aloud using the Qt Speech module part of Qt since Qt 5 (previously using the Jovie,), trimming of white page borders and setting of bookmarks.
File format supportEdit
It supports the following file formats:
- Portable Document Format (PDF) with the Poppler backend
- PostScript with the libspectre backend
- Tagged Image File Format (TIFF) with the libTIFF backend
- Microsoft Compiled HTML Help (CHM) with the libCHM backend
- DjVu with the DjVuLibre backend
- Device independent file format (DVI)
- XML Paper Specification (XPS)
- OpenDocument format (ODF) (only OpenDocument Text)
- FictionBook (*.fb2)
- Various image formats, such as JPG
The official version obeys the DRM restrictions of PDF files by default, which may prevent copying, printing, or converting some PDF files. This can be turned off in the options under "Obey DRM limitations", however.
- KDE Developer's Corner - Google Summer of Code 2005 Projects Archived 2006-06-28 at the Wayback Machine.
- KDE Developer's Corner - Okular Archived 2005-12-11 at the Wayback Machine.
- Season of Usability Published on September 30th, 2007 by Ellen Reitmayr » Okular
- "Bug 151614 - store annotations with documents". Archived from the original on 2014-08-19.
- 3 Alternatives to the Adobe PDF Reader on Linux - The Linux Foundation
- Jovie on KDE.org
- Okular - Document format handlers status
- KDE Applications 17.12.0 Full Log Page
- Okular and DRM
- Okular, PDF and file permissions
- Okular, Debian, and copy restrictions
- Debian Bug report logs - #531221 okular: Arbitrarily enforces DRM by default