1b98f38cfa
In the Java interface it was reportedly copied from, getValue can return null to indicate a missing attribute, but in UNOIDL that's not possible. The workaround that implementations of the UNOIDL interface resorted to is apparently to return an empty string (another option would have been to throw an exception). But the code in xmlsecurity appears to be written under the ill assumption that getValueByName would return null for a missing attribute. What the code as written actually did check was whether the return value is an empty string (because it picks the operator ==(OUString const &, sal_Unicode const *) overload, which happens to treat a null second argument like an empty string). Ideally, the code in xmlsecurity would have some way to tell a missing attribute from an empty one (via some extended XAttributeList2, or by iterating over all getNameByIndex, or ...). But for none of the affected attributes it seems expected that the attribute's value could be an empty string, so checking for an empty string seems to work reasonably well in practice. So keep it simple and just check for an empty string properly. Thanks to Tor for spotting that odd xmlsecurity code. Change-Id: Ib068ee98ef818683a43309ab4d7c3a4731e8deff
LibreOffice
LibreOffice is an integrated office suite based on copyleft licenses and compatible with most document formats and standards. Libreoffice is backed by The Document Foundation, which represents a large independent community of enterprises, developers and other volunteers moved by the common goal of bringing to the market the best software for personal productivity. LibreOffice is open source, and free to download, use and distribute.
A quick overview of the LibreOffice code structure.
Overview
You can develop for LibreOffice in one of two ways, one recommended and one much less so. First the somewhat less recommended way: it is possible to use the SDK to develop an extension, for which you can read the API docs here and here. This re-uses the (extremely generic) UNO APIs that are also used by macro scripting in StarBasic.
The best way to add a generally useful feature to LibreOffice is to work on the code base however. Overall this way makes it easier to compile and build your code, it avoids any arbitrary limitations of our scripting APIs, and in general is far more simple and intuitive - if you are a reasonably able C++ programmer.
The important bits of code
Each module should have a README file inside it which has some
degree of documentation for that module; patches are most welcome to
improve those. We have those turned into a web page here:
However, there are two hundred modules, many of them of only peripheral interest for a specialist audience. So - where is the good stuff, the code that is most useful. Here is a quick overview of the most important ones:
| Module | Description |
|---|---|
| sal/ | this provides a simple System Abstraction Layer |
| tools/ | this provides basic internal types: 'Rectangle', 'Color' etc. |
| vcl/ | this is the widget toolkit library and one rendering abstraction |
| framework | UNO framework, responsible for building toolbars, menus, status bars, and the chrome around the document using widgets from VCL, and XML descriptions from /uiconfig/ files |
| sfx2/ | legacy core framework used by Writer/Calc/Draw: document model / load/save / signals for actions etc. |
| svx/ | drawing model related helper code, including much of Draw/Impress |
Then applications
| Module | Description |
|---|---|
| desktop/ | this is where the 'main' for the application lives, init / bootstrap. the name dates back to an ancient StarOffice that also drew a desktop |
| sw/ | Writer |
| sc/ | Calc |
| sd/ | Draw / Impress |
There are several other libraries that are helpful from a graphical perspective:
| Module | Description |
|---|---|
| basegfx/ | algorithms and data-types for graphics as used in the canvas |
| canvas/ | new (UNO) canvas rendering model with various backends |
| cppcanvas/ | C++ helper classes for using the UNO canvas |
| drawinglayer/ | View code to render drawable objects and break them down into primitives we can render more easily. |
Finding out more
Beyond this, you can read the README files, send us patches, ask
on the mailing list libreoffice@lists.freedesktop.org (no subscription
required) or poke people on IRC #libreoffice-dev on irc.freenode.net -
we're a friendly and generally helpful mob. We know the code can be
hard to get into at first, and so there are no silly questions.