763149e2f4
Using the Double.compare() method is often preferred over the == comparison operator for comparing double values due to several reasons: Handling NaN (Not-a-Number) values: The Double.compare() method correctly handles NaN values, while the == operator does not. If either of the operands is NaN, the == operator will always return false, regardless of the other operand. In contrast, Double.compare() will correctly evaluate NaN values according to the IEEE 754 floating-point standard. Handling positive and negative zero: The == operator treats positive zero and negative zero as equal, whereas they are distinct values in IEEE 754 floating-point representation. Double.compare() correctly distinguishes between positive and negative zero. Robustness against rounding errors: Floating-point arithmetic can introduce rounding errors, causing two double values that should be equal to differ slightly. Directly comparing them with the == operator might yield unexpected results due to these small differences. Double.compare() allows you to define a tolerance level if necessary, providing more control over how equality is determined. Consistent behavior: The behavior of Double.compare() is consistent and predictable across different platforms and JVM implementations, as it follows the IEEE 754 standard. On the other hand, the behavior of the == operator might vary depending on the platform and compiler optimizations. Suitability for sorting: Double.compare() returns an integer value that can be directly used for sorting double values in ascending or descending order. This makes it convenient for sorting arrays or collections of double values. Overall, while the == operator might work in some cases, using Double.compare() provides more robust and predictable behavior, especially when dealing with floating-point numbers in Java. Change-Id: I5756936a0d2b4fe11b9113ddd33b6ae691f5103f Reviewed-on: https://gerrit.libreoffice.org/c/core/+/166796 Tested-by: Jenkins Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com> Tested-by: Caolán McNamara <caolan.mcnamara@collabora.com> |
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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 and Developers Guide. 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 Build Chain and Runtime Baselines
These are the current minimal operating system and compiler versions to run and compile LibreOffice, also used by the TDF builds:
- Windows:
- Runtime: Windows 7
- Build: Cygwin + Visual Studio 2019 version 16.10
- macOS:
- Runtime: 10.15
- Build: 12 (13 for aarch64) + Xcode 14
- Linux:
- Runtime: RHEL 8 or CentOS 8 and comparable
- Build: either GCC 12; or Clang 12 with libstdc++ 10
- iOS (only for LibreOfficeKit):
- Runtime: 11.4 (only support for newer i devices == 64 bit)
- Build: Xcode 9.3 and iPhone SDK 11.4
- Android:
- Build: NDK r23 and SDK 30.0.3
- Emscripten / WASM:
- Runtime: a browser with SharedMemory support (threads + atomics)
- Build: Qt 5.15 with Qt supported Emscripten 1.39.8
- See README.wasm
Java is required for building many parts of LibreOffice. In TDF Wiki article Development/Java, the exact modules that depend on Java are listed.
The baseline for Java is Java Development Kit (JDK) Version 17 or later.
If you want to use Clang with the LibreOffice compiler plugins, the minimal version of Clang is 12.0.1. Since Xcode doesn't provide the compiler plugin headers, you have to compile your own Clang to use them on macOS.
You can find the TDF configure switches in the distro-configs/ directory.
To setup your initial build environment on Windows and macOS, we provide the LibreOffice Development Environment (LODE) scripts.
For more information see the build instructions for your platform in the TDF wiki.
The Important Bits of Code
Each module should have a README.md 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. |
Rules for #include Directives (C/C++)
Use the "..." form if and only if the included file is found next to the
including file. Otherwise, use the <...> form. (For further details, see the
mail Re: C[++]: Normalizing include syntax ("" vs
<>).)
The UNO API include files should consistently use double quotes, for the benefit of external users of this API.
loplugin:includeform (compilerplugins/clang/includeform.cxx) enforces these rules.
Finding Out More
Beyond this, you can read the README.md 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.libera.chat -
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.