This summer I’m going to be working on (hopefully) helping to add Tiled Rendering support to LibreOffice Calc and Impress.
As a first stage I’ve been experimenting with implementing a pure GTK+ tiled rendering app, to allow for active testing of tiled rendering work, i.e. using the existing tiled rendering in writer. (On desktop platforms we already do have a basic testing app, but that’s based on VCL — it shows a background window of the document in addition to wherever the tiled rendering happens.)
This application is being developed on the basis of LibreOfficeKit (formerly liblibreoffice) — i.e. avoiding the need to interact with LO internals — which is being extended with the (currently experimental only) necessary API calls to allow rendering to a bitmap buffer (in the longer run OpenGL would probably be most appropriate, but bitmap rendering is still quite useful for some applications. More importantly support for this already exists whereas OpenGL would require a chunk of extra work). Hopefully we’ll soon also have a simple GTK+ viewer widget to allow for simple reuse in other applications (meaning we can then change the internal implementation at will and upgrade to faster rendering as appropriate), perhaps modelled on the basis of the WebViewGtk widget.
The current tiled viewer looks somewhat like this (there are still problems with document rendering, i.e. portions are not rendered in our test document in odk/examples/java/DocumentHandling/test/test1.odt ):
And if you get the rowstride (and colourspaces) mixed up you can get some more interesting effects such as: