plevent

is the user's interrupt routine

parameter	type	units	description
xpointer,ypointer	float	uu	position of the mouse cursor at the moment of the interrupt
event_code	int	--	value of the code that caused the interrupt
returns:	void

Description

plevent is the user's interrupt routine. The standard one, delivered with the SIMPLOT-package only shows the position of the mouse cursor, until the q-key is hit which then causes the application to exit. The user should use a copy of plevent and change it to his needs.

Possible values for event_code are the ASCII-values of keys and values predefined in simplot.h with self-explaining names:

ArrowDown	F1	MouseDrag
ArrowLeft	F2	MouseLeftDown
ArrowRight	F3	MouseLeftUp
ArrowUp	F4	MouseMiddleDown
Delete	F5	MouseMiddleUp
End	F6	MouseRightDown
Escape	F7	MouseRightUp
Home	F8
Insert	F9
PageDown	F10
PageUp	F11
	F12

Except for MouseLeftUp, MouseMiddleUp and MouseRightUp, the values are positive and are generated by key/button press actions. Key/button releases generate the opposite values. One can thus discard key/button release actions by discarding negative event codes. Several event classes may be distinguished using plget:

• plget(EVENT_ASCII) is non-zero if the event was caused by an ASCII key
• plget(EVENT_BUTTON) is non-zero if the event was caused by a mouse button
• plget(EVENT_DOWN) is non-zero if the event was caused by a key or button being pressed
• plget(EVENT_FUNCTION) is non-zero if the event was caused by a function key
• plget(EVENT_UP) is non-zero if the event was caused by a key of button release

Examples

Here is the simplest example, using the default versions of plevent and pldraw, It shows an X window with a 'Quit' button and, with one of the mouse buttons pressed, horizontal and vertical hairlines plus the

#include <simplot.h>
int main () {
   plinit(X,"",100,100,10,10,"","");
   plloop();
}

See plloop for a more complex example program using several event codes.

See also

plloop