CTK is a user interface toolkit for host-agnostic audio plugin UIs written in C++ under LGPL 3.0 license.

It comes with a slightly modified pugl library for event and window handling and utilizes cairo graphics library for drawing.

CTK has optimized rendering and compositing and full nesting and stacking capabilities. All widgets own a cairo surface they are drawing on. Container widgets take care of compositing their children onto the surface. All drawing is done on the display managers event call while other calculations are done whenever they appear. Drawing and compositing is limited to the parts/pixels of the UI which really updated.

CTK can handle high resolution screens.

CTK offers callback-based event handling per widget.

Generic events are handled by the UI in dedicated queues which fire the events in correct order of the widgets visibility (z value and order inside its container). Some abstract events like click, dragging and hovering are available. The widget class offers mechanisms for adding, removing and firing custom events.

int clicktest (CTK::Widget *widget, const void *event, void *data) {
    printf("clicked id:%d\n", widget->id);
    return 0;
};
myWidget->addEvent(CTK::EVENT_CLICK, &clicktest);

int customtest (CTK::Widget *widget, void *data) {
    printf("fired id:%d\n", widget->id);
    return 0;
};
myWidget->addEvent(1024, &customtest);
myWidget->fireEvent(1024);

CTK is fully self-contained without using external files. Resource files like style definitions, background images or XML layout files can be linked into the final executable via cmake build process.