Adding packages using the IDE
Adding known packages
Open "Package -> Install/Uninstall Packages". The list on the left shows already installed packages or packages marked for installation (which have a green plus sign in their icon). The list to the right shows packages that you can install. Simply double-click on a package in either list to move them to the other - and mark them for installation/uninstall.
Finally, click "Save and Rebuild" to rebuild the IDE and the packages.
You can also compile and install packages the IDE knows nothing about. See below.
Adding new packages
The package should have come with a number of source files, especially one with a .lpk extension. To install this package one goes to "Package -> Open Package File (.lpk)". Navigate to the folder containing the .lpk file and open it. If everything works out as planned you will see the Package Manager. The Package Manager shows a treeview with the files in the package and the required packages.
If you don't want to install the component into the IDE, e.g. because it is a non graphical component, press Compile. Otherwise you should press Use >> and then choose Install. Next we get a warning about Lazarus only supporting static linked libraries and the question if you want to rebuild Lazarus. Just press Yes and sit back. Lazarus will be rebuilt, and depending on your configuration restarted.
If the package was a graphical component, and you selected the Use >> option, you should now have a new tab in your IDE by which you can add that component to your project.
When receiving a new source version of an already installed package, you must
- overwrite the previous source version with the new version
- either open the new .lpk and press Use >> and then choose Install as above,
or rebuild the IDE using the menu "Tools" -> "Build Lazarus with Profile [...]" if you want more control on how the package is compiled.
Compile an IDE with packages at command line
You can use lazbuild to compile and install your package, and add --build-ide to rebuild the IDE.
If you have any questions, go to the lazarus forum or post it to the Lazarus mailing list.