Mike Kaganski
08ebcff89f
The shadow of objects must not be scaled: this displaces any internal areas that need blur, e.g. holes. Instead, it needs to dilate the shadow using kernel with radius equal to blur radius: this allows the borders of dilated objects to be in the middle of the blur area. The following blur makes those new margin points to have 50% intensity, and full glow intensity at the point of old object margins. This also removed artifacts when moving objects with glow effect caused by mismatch between scaling and D2D range calculation. The D2D range therefore is not calculated by scaling, but using grow. Blur filter's "extend bitmap by blur radius" option got obsoleted and removed. There's no need to blur the glow color (24-bit RGB). Instead, glow bitmap must be filled by glow color, and have an alpha mask that is blurred accordingly. This makes the glow properly transparent, and also reduces the blur complexity which now only needs to process 8 bits of alpha channel. The object shadow is created using basegfx::BColorModifier_replace inserted into the 2d decomposition of the effect, as before. To make sure that any non-fully-transparent pixel will become black pixel in the shadow, black color is used, and the result is further processed in VclPixelProcessor2D::processGlowPrimitive2D with monochrome filter using threshold 255. Glow transparency attribute is taken into account: the initial value at the margins of the objects. Color replacement filter is used to replace the object shadow with the attribute value before blur pass. Correct blur radius is used, calculated from glow effect radius, instead of hardcoded value of 5 pixels. This makes the glow to fade gradually along the full width of the effect, instead of only fading in narrow outer border previously. Since blur filter is only implemented for radius up to 254 pixels, and since downsampling the shadow before blur increases performance without noticeable quality loss, the image is downsampled before filtering. It should be noted that the glow effect is almost identical to soft shadow effect, likely with the only difference of using dilation in the former, but not in the latter. The code might be reused later to implement soft shadow as well. Change-Id: I728c532f9df7ccf85f353c23c6c7d8352d7b2086 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/93235 Tested-by: Jenkins Reviewed-by: Tomaž Vajngerl <quikee@gmail.com> Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
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 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 16.4
- macOS:
- Runtime: 10.10
- Build: 10.14.4 + Xcode 11.3
- Linux:
- Runtime: RHEL 7 or CentOS 7
- Build: either GCC 7.0.0; or Clang 5.0.2 with libstdc++ 7.3.0
- 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 r19c and SDK 22.6.2
If you want to use Clang with the LibreOffice compiler plugins, the minimal version of Clang is 5.0.2. 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 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 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.