kdenlive/dev-docs/coding.md

Coding and Resources

• Qt5
  • All Qt5 classes
  • Signals and Slots
• MLT introduction.
• The KDE Frameworks
  • XMLGUI Technology (e.g. for the kdenliveui.rc file)

Locale handling

Locales are important e.g. for formatting numbers in a way that the user is familiar with. Some countries would write 12500.42 as 12.000,42, for example.

Since 20.08, Kdenlive follows the following rules:

• When parsing data (by Kdenlive or by other libraries like MLT), the C locale is used. This is especially important for project files. The reason is that for passing data between programs, the format has to be well-defined and not depend on where the user happens to live.
• When presenting data to the user, the user’s locale is used.

MLT uses the C locale which is set by setlocale() and which must be set to C. If it is set to e.g. hu_HU.utf-8, which uses , as decimal separator, properties are converted to this format upon saving the project file, and the project file ends up corrupted.

In Kdenlive, QLocale should only be used in one case: when data is shown to the user or read from the user. Usually that is handled by Qt already. A QDoubleSpinBox, for example, presents the double value in the user’s local number format.

Configuration

Named settings are stored in kdenlivesettings.kcfg. To add a new setting with default value, add an entry in the settings file, for example:

<entry name="logscale" type="Bool">
  <label>Use logarithmic scale</label>
  <default>true</default>
</entry>

The setting can then be read and written as follows:

// Read
bool logScale = KdenliveSettings::logscale();

// Write
KdenliveSettings::setLogscale(true);

Effects and Transitions

Effects and Transitions are stored in subfolders of the data folder. For a detailed description see here.