NAME

       dtk_process_events, dtk_set_event_handler - Events processing

SYNOPSIS

       #include <dtk_event.h>

       typedef int (*DTKEvtProc)(dtk_hwnd, int, const union dtk_event*);

       void dtk_set_event_handler(dtk_hwnd wnd, DTKEvtProc handler);
       int dtk_process_events(dtk_hwnd wnd);

DESCRIPTION

       dtk_set_event_handler()  set  handler  as  the  current  event  handler  for the window wnd. handler is a
       function that has arguments in the following order:

        * a reference of type dtk_hwnd to the window that has received the event.

        * the type ID of the event.

        * a pointer to a union dtk_event holding event-specific data (if not NULL) defined as follows:

              union dtk_event {
                  struct dtk_keyevent key;
                  struct dtk_mouseevent mouse;
              };

       dtk_process_events() processes pending events in the event queues associated to the window referenced  by
       wnd,   i.e.   for  each  event  in  the  queue,  it  calls  the  event  handler  that  has  been  set  by
       dtk_set_event_handler(). dtk_process_events() returns if a event handler has returned 0 or if there is no
       more pending event in the queue.

       If  dtk_set_event_handler()  has  never  been called or called with handle as NULL, it use a minimalistic
       event handler that returns 0 (i.e. stop the loop) when pressing the close button on the window.

       The type ID of the event can be one of the following:

       DTK_EVT_REDRAW
              This event indicates that the whole window or parts of it must be redrawn.  This may be caused  by
              another  window  has  been  overlapped  it  or  the  window  has been resized. If such an event is
              received, the event pointer passed to the handler will be NULL.

       DTK_EVT_QUIT
              This event indicates that the close button of the window has  been  clicked.   The  event  pointer
              passed will be NULL.

       DTK_EVT_KEYBOARD
              Indicates  that  a key of the keyboard has been pressed or released. If such an event is received,
              the meaningfull member of the union dtk_event will be key which is defined as follows:

                  struct dtk_keyevent {
                      unsigned int state;  /* pressed or released */
                      unsigned int sym;    /* Symbolic code of the key */
                      unsigned int mod;    /* modifiers key */
                  };

       DTK_EVT_MOUSEBUTTON
              This event indicates that one of the mouse buttons has been pressed or released. If such an  event
              is  received,  the  meaningfull  member  of  the union dtk_event will be mouse which is defined as
              follows:

                  struct dtk_mouseevent {
                      unsigned int button; /* button identifier */
                      unsigned int state;  /* pressed or realeased */
                      unsigned int x;   /* x-coordinate of the mouse position */
                      unsigned int y;   /* y-coordinate of the mouse position */
                  };

       DTK_EVT_MOUSEMOTION
              This is similar to the DTK_EVT_MOUSEBUTTON but indicates that the  mouse  has  moved.  Event  data
              should also be accessed through mouse member but its button and state members will be meaningless.

RETURN VALUE

       dtk_set_event_handler() does not return value.

       dtk_process_events()  returns  1  if  there  is  no more pending event in the queue.  It returns 0 if the
       processing loop has been interrupted by an event handler, i.e. the last event handler has returned 0.