# To subscribers of the xforms list from spl@szechuan.ucsd.edu (Steve Lamont) :
> 1)- I have developed, with a previous version of xforms that does
> not support images, some applications using interaction with
> freehandler defined as:
>
> int freeobject_handler(FL_OBJECT *ob, int event, int mx, int my, int key, void *xev)
> {
> switch (event)
> { case FL_PUSH:
>
> printf("mx=%d my=%d\n",mx,my);
> }
> return 0;
> }
>
> This application enables me to read the coordinates of a pixel after
> a mouse click.
> Now that I have used images with canvas, it did not work. I did not
> find out yet a way to read coordinates of a selected point inside a
> canvas.
If you have created a Canvas object to replace your Free object, then
you need to install a button handler. Use
fl_add_canvas_handler( your_canvas,
ButtonPress,
your_button_handler,
your_special_data );
and then create
int your_button_handler( FL_OBJECT *obj, Window window,
int window_width, int window_height,
XEvent *xevent, void *user_data )
{
XButtonEvent *xbutton_event = ( XButtonEvent *) xevent;
int mx = xbutton_event->x;
int my = xbutton_event->y;
[...]
The manual, as always, has the gory details.
spl
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