Adds the FL_AUTO_DELETE_EVENT to suppress auto delete.
Language wrappers can have major issues with FLTK auto deleting all children of a group if a group is deleted. This event gives individual widget the opportunity to override auto delete.
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@ -407,7 +407,14 @@ enum Fl_Event { // events
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/** A zoom event (ctrl/+/-/0/ or cmd/+/-/0/) was processed.
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Use Fl::add_handler() to be notified of this event.
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*/
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FL_ZOOM_EVENT = 27
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FL_ZOOM_EVENT = 27,
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/** This event is sent if the parent widget is deleted and the parent is about
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to delete this widget as well. Returning the default value 0 will give the
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parent permission to call the destructor of this widget. Returning 1 will
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preserve this widget, but still remove it from the widget hierarchy.
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\see Fl_Group::clear()
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*/
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FL_AUTO_DELETE_EVENT = 28
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// DEV NOTE: Keep this list in sync with FL/names.h
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};
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@ -73,9 +73,10 @@ const char * const fl_eventnames[] =
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"FL_FULLSCREEN",
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"FL_ZOOM_GESTURE",
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"FL_ZOOM_EVENT",
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"FL_EVENT_28", // not yet defined, just in case it /will/ be defined ...
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"FL_AUTO_DELETE_EVENT",
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"FL_EVENT_29", // not yet defined, just in case it /will/ be defined ...
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"FL_EVENT_30" // not yet defined, just in case it /will/ be defined ...
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"FL_EVENT_30", // not yet defined, just in case it /will/ be defined ...
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"FL_EVENT_31" // not yet defined, just in case it /will/ be defined ...
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};
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/**
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@ -375,6 +375,19 @@ Fl_Group::Fl_Group(int X,int Y,int W,int H,const char *l)
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\internal If the Fl_Group widget contains the Fl::focus() or the
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Fl::pushed() widget these are set to sensible values (other widgets
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or the Fl_Group widget itself).
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\note FLTK's auto-delete feature efficiently manages widget hierarchies in
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C++ applications by automatically cleaning up. However, this feature can
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cause issues when FLTK is used with reference-counting languages like Python,
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where automatic deletion might interfere with reference counting. To address
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this, auto-delete can be disabled for individual widgets. When
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\ref Fl_Group::clear() is called, it sends an \ref FL_AUTO_DELETE event to
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each widget. If a widget returns 1 in response to this event, it will not
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be deleted. In a Python wrapper, this behavior would typically involve
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decrementing the widget's reference count instead of deleting it.
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\see Fl_Group::remove(int), Fl_Group::delete_child(int),
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Fl_Group::~Fl_Group()
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*/
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void Fl_Group::clear() {
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savedfocus_ = 0;
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@ -417,7 +430,8 @@ void Fl_Group::clear() {
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} else { // slow removal
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remove(idx);
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}
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delete w; // delete the child
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if (w->handle(FL_AUTO_DELETE_EVENT)==0)
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delete w; // delete the child
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} else { // should never happen
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remove(idx); // remove it anyway
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}
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