diff options
| author | Albrecht Schlosser <albrechts.fltk@online.de> | 2023-11-17 15:25:21 +0100 |
|---|---|---|
| committer | Albrecht Schlosser <albrechts.fltk@online.de> | 2023-11-17 15:25:21 +0100 |
| commit | 6f7e1f4fb7e1277b4e28a15874db449cef2d6bfc (patch) | |
| tree | 9f652f4db45dc12e66c85beb35272a798dc06b23 | |
| parent | c5ef206c570f0dd925aeb40f99a914ec40d78a2d (diff) | |
Enhance documentation of event processing
| -rw-r--r-- | FL/Fl_Widget.H | 13 | ||||
| -rw-r--r-- | documentation/src/subclassing.dox | 3 |
2 files changed, 15 insertions, 1 deletions
diff --git a/FL/Fl_Widget.H b/FL/Fl_Widget.H index 55282857a..fb0f32eb0 100644 --- a/FL/Fl_Widget.H +++ b/FL/Fl_Widget.H @@ -259,6 +259,19 @@ public: your overridden method so that you don't short-circuit events that you don't handle. In this last case you should return the callee retval. + One exception to the rule in the previous paragraph is if you really + want to \e override the behavior of the base class. This requires + knowledge of the details of the inherited class. + + In rare cases you may want to return 1 from your handle() method + although you don't really handle the event. The effect would be to + \e filter event processing, for instance if you want to dismiss + non-numeric characters (keypresses) in a numeric input widget. You + may "ring the bell" or show another visual indication or drop the + event silently. In such a case you must not call the handle() method + of the base class and tell FLTK that you \e consumed the event by + returning 1 even if you didn't \e do anything with it. + \param[in] event the kind of event received \retval 0 if the event was not used or understood \retval 1 if the event was used and can be deleted diff --git a/documentation/src/subclassing.dox b/documentation/src/subclassing.dox index 7dfe2909b..bbf750b15 100644 --- a/documentation/src/subclassing.dox +++ b/documentation/src/subclassing.dox @@ -17,7 +17,8 @@ display a value of some sort. A composite widget holds a list of child widgets and handles moving, sizing, showing, or hiding them as needed. Fl_Group is the main composite widget class in FLTK, and all of the other composite widgets -(Fl_Pack, Fl_Scroll, Fl_Tabs, Fl_Tile, and Fl_Window) are subclasses of it. +(Fl_Pack, Fl_Scroll, Fl_Tabs, Fl_Tile, Fl_Window, Fl_Flex, Fl_Grid, etc.) +are subclasses of it. You can also subclass other existing widgets to provide a different look or user-interface. For example, the button widgets are all |