LiveCode Builder Extensions

In this lesson we will create a minimal LiveCode Builder library which extends the set of commands and functions available in LiveCode.

We will

• Install and configure an appropriate text editor for developing in LiveCode Builder.
• Create a Hello World library which extends LiveCode with a single function, which returns the string “Hello World!”. Compile the library.
• Install the library into the LiveCode IDE.
• Include the library in a standalone.

LiveCode Builder Extensions

LiveCode 8.0 is the most exciting release in the history of the technology. It provides a simple way to extend the functionality or control set of LiveCode.

Our focus in LiveCode 8.0 is extensibility. You can now build and share widgets (custom controls) and libraries that are treated by LiveCode as engine level elements.

To make it possible to create extensions and plug them into the LiveCode engine we’ve created a new flavour of our language called LiveCode Builder. LiveCode Builder looks a lot like LiveCode Script so should feel familiar for any seasoned LiveCode developer. There is lots of new syntax which exposes parts of the LiveCode engine that were only previously available to those who were skilled C/C++ developers.

Note: LiveCode Builder is a different flavour of LiveCode so it is not possible to edit LiveCode Builder source code in the main LiveCode Script IDE.

Libraries and Widgets

There are two types of extensions that can be created with LiveCode Builder:

Libraries: A library can be used to extend the set of commands and functions available in LiveCode. The public handlers in a library are added at the bottom of the Message Path.

Widgets: A widget is a custom control that is treated as an engine level element. Widgets appear in the Tools Palette and can be added as controls to any LiveCode stack.

A widget and a library are identical, except that a widget draws to a canvas. As a result, the authoring process is much the same for both extension types.

When to use LiveCode Builder

Why write widgets?

Encapsulation – Widgets are ‘black boxes’ whose behavior can only be changed from LiveCode apps via predefined API Features – Access to drawing / low-level / native APIs Performance – Can control what recalculations are made when a control is redrawn

What are (LCB) libraries?

Libraries are scripts written in LiveCode Builder, whose public handlers are placed at the back of the message path when installed.

LCB libraries make LCB features available to LiveCode apps directly. They can also be used as support code for widgets.

LiveCode Builder API

The API for LiveCode Builder is available in the Dictionary stack. You may find it useful to have this open while you are writing your extension.

• Open the Dictionary from the Menubar.
• Ensure you are on the API pane.
• Select LiveCode Builder from the drop down menu.