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A canvas is a managed plain X (sub)window. It it different from the
free object in that a canvas is guaranteed to be associated with a
window that is not shared with any other object, thus an application
program has more freedom in utilizing a canvas, such as using its own
colormap or rendering double-buffered OpenGL in it etc. A canvas is
also different from a raw application window because a canvas is
decorated differently and its geometry is managed, e.g., you can use
fl_set_object_resize() to control its position and size
after its parent form is resized.
You also should be aware that when using a canvas you’ll
probably mostly program directly using basic Xlib functions,
XForms doesn’t supply much more than a few helper functions.
You’ll rather likely draw to it with Xlib functions and will
be dealing with XEvents yourself (instead having them
taken care of by XForms and cenverted to some simpler to
use events that then just return the object from
fl_do_forms() or invoke an associated callback
function. Thus you will typically need a basic knowledge of how to
program via the X11 Xlib.
| • Adding Canvas Objects: | ||
| • Canvas Types: | ||
| • Canvas Interaction: | ||
| • Other Canvas Routines: | ||
| • Canvas Attributes: | ||
| • OpenGL Canvas: |