Create and return an apply-drawing-object.
Each of the functions
make-draw-arc creates and returns an apply-drawing-object.
make-a-drawing-call, the drawing is done by applying the function
is applied to the "root pane" (see drawing-object) followed by
should typically draw something, but it does not have to, and may do other things. The default value of
The arguments for each of these functions are the same as the arguments of the corresponding Graphics Ports function (but the y is interpreted from the bottom, see below), excluding the first argument ( pane ).
Once created, the drawing object can be used in the drawing-object slot of an objects-displayer or a pinboard-objects-displayer, but more commonly it would be passed to one of the positioning/fitting functions (position-object, fit-object and so on), which will position and scale it with, by drawing the object inside a context of Graphics Ports transformation.
At the top level, the y coordinate is reversed, so the y argument is measured from the bottom of the objects-displayer or pinboard-objects-displayer, as opposed to the default which is from the top down. A fitting object in the hierarchy may change that.
apply-drawing-objects can be used repeatedly and concurrently in the same or different panes. The ones that are created by the
make-draw-* functions are fixed, but for objects created by
make-a-drawing-call, the supplied function may depend on values that change, and hence needs to be redisplayed when these values change. Use force-objects-redraw on the root of the hierarchy (an objects-displayer or a pinboard-objects-displayer) to do that.
See drawing-object for description of the drawing operation.
CAPI User Guide and Reference Manual (Macintosh version) - 3 Aug 2017