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https://github.com/fltk/fltk.git
synced 2026-06-07 17:35:39 +08:00
Added the helper class Fl_Watch to simplify safe handling of widget deletion
in callbacks. This is used e.g. in Fl_Widget::do_callback() to prevent accessing widgets after deletion in the callback. Documentation adjusted, Fl_Menu_Button.cxx changed to use Fl_Watch instead of Fl::watch_widget_pointer. Fl::watch_widget_pointer() and Fl::release_widget_pointer() have been modified to use an array without "holes" (NULL pointers) for storing the widget pointers for faster access: Fl::release_widget_pointer() now shifts pointers to close gaps of freed pointers. git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@6651 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
This commit is contained in:
Albrecht Schlosser
@@ -1,9 +1,12 @@
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CHANGES IN FLTK 1.3.0
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- Fl_Help_View handles HTML2 font color specification (STR#890)
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- Copyright dates are now updated to 2009 (STR#2036)
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- New helper class Fl_Watch to simplify safe handling of widget
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deletion in callbacks. This is used in Fl_Widget::do_callback()
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to prevent accessing widgets after deletion in the callback.
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- Fl_Help_View handles HTML2 font color specification (STR #890)
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- Copyright dates are now updated to 2009 (STR #2036)
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- Copy/Paste operations should now work as expected,
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with utf8,16 support and fltk1.1 compatibility. (STR#2104,2121).
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with utf8,16 support and fltk1.1 compatibility. (STR #2104,2121).
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- Widgets now remove themselves from their parent group (if any),
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when destroyed (STR #1894)
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- Added flexible gap size for text buffer (STR #2046)
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@@ -72,7 +75,7 @@ CHANGES IN FLTK 1.1.9
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CHANGES IN FLTK 1.1.8
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- Documentation fixes (STR #1454, STR #1455, STR #1456,
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- Documentation fixes (STR #1454, STR #1455, STR #1456,
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STR #1457, STR #1458, STR #1460, STR #1481, STR #1578,
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STR #1639, STR #1645, STR #1644, STR #1792, STR #1793,
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STR #1742, STR #1777, STR #1794, STR #1827, STR #1843,
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@@ -849,17 +849,31 @@ public:
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/** \defgroup fl_del_widget Safe widget deletion support functions
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These functions support deletion of widgets inside callbacks.
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These functions support deletion of widgets inside callbacks.
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There are two groups of related methods:
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Fl::delete_widget() should be called when deleting widgets
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or complete widget trees (Fl_Group, Fl_Window, ...) inside
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callbacks.
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-# scheduled widget deletion
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- Fl::delete_widget() schedules widgets for deletion
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- Fl::do_widget_deletion() deletes all scheduled widgets
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-# widget watch list ("smart pointers")
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- Fl::watch_widget_pointer() adds a widget pointer to the watch list
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- Fl::release_widget_pointer() removes a widget pointer from the watch list
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- Fl::clear_widget_pointer() clears a widget pointer \e in the watch list
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The other functions are intended for internal use. The preferred
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way to use them is by using the helper class Fl_Watch.
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The following is to show how it works ...
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There are three groups of related methods:
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-# scheduled widget deletion
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- Fl::delete_widget() schedules widgets for deletion
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- Fl::do_widget_deletion() deletes all scheduled widgets
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-# widget watch list ("smart pointers")
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- Fl::watch_widget_pointer() adds a widget pointer to the watch list
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- Fl::release_widget_pointer() removes a widget pointer from the watch list
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- Fl::clear_widget_pointer() clears a widget pointer \e in the watch list
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-# the class Fl_Watch:
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- the constructor calls Fl::watch_widget_pointer()
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- the destructor calls Fl::release_widget_pointer()
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- the access methods can be used to test, if a widget has been deleted
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\see Fl_Watch.
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@{ */
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// Widget deletion:
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@@ -919,6 +933,86 @@ public:
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};
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/**
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This class should be used to control safe widget deletion.
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You can use an Fl_Watch object to watch another widget, if you
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need to know, if this widget has been deleted during a callback.
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This simplifies the use of the "safe widget deletion" methods
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Fl::watch_widget_pointer() and Fl::release_widget_pointer() and
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makes their use more reliable, because the destructor autmatically
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releases the widget pointer from the widget watch list.
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It is intended to be used as an automatic (local/stack) variable,
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such that the automatic destructor is called when the object's
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scope is left. This ensures that no stale widget pointers are
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left in the widget watch list (see example below).
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You can also create Fl_Watch objects with \e \b new, but then it
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is your responsibility to delete the object (and thus remove the
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widget pointer from the watch list) when it is not needed any more.
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Example:
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\code
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int MyClass::handle (int event) {
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if (...) {
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Fl_Watch wp(this); // watch myself
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do_callback(); // call the callback
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if (wp.deleted()) return 1; // exit, if deleted
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// Now we are sure that the widget has not been deleted.
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// It is safe to access the widget
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clear_changed(); // access the widget
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}
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}
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\endcode
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*/
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class FL_EXPORT Fl_Watch {
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Fl_Widget* wp_;
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public:
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Fl_Watch(Fl_Widget *wi);
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~Fl_Watch();
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/**
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returns a pointer to the watched widget.
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This pointer is NULL, if the widget has been deleted.
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*/
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Fl_Widget *widget() {return wp_;}
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/**
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returns 1, if the watched widget has been deleted.
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This is a convenience method. You can also use something like
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if (watch.widget() == 0) // ...
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where watch is an Fl_Watch object.
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*/
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int deleted() {return wp_ == 0;}
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/**
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returns 1, if the watched widget exists (has not been deleted).
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This is a convenience method. You can also use something like
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if (watch.widget() != 0) // ...
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where watch is an Fl_Watch object.
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*/
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int exists() {return wp_ != 0;}
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};
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#endif // !Fl_H
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//
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+5
-14
@@ -793,29 +793,20 @@ public:
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static void default_callback(Fl_Widget *cb, void *d);
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/** Calls the widget callback.
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Causes a widget to invoke its callback function, optionally
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with arbitrary arguments.
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Causes a widget to invoke its callback function with default arguments.
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\see callback()
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*/
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void do_callback() {callback_(this,user_data_); if (callback_ != default_callback) clear_changed();}
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void do_callback() {do_callback(this,user_data_);}
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/** Calls the widget callback.
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Causes a widget to invoke its callback function, optionally
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with arbitrary arguments.
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Causes a widget to invoke its callback function with arbitrary arguments.
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\param[in] o call the callback with \em o as the widget argument
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\param[in] arg call the callback with \em arg as the user data argument
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\see callback()
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*/
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void do_callback(Fl_Widget* o,void* arg=0) {callback_(o,arg); if (callback_ != default_callback) clear_changed();}
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void do_callback(Fl_Widget* o,long arg) {do_callback(o,(void*)arg);}
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/** Calls the widget callback.
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Causes a widget to invoke its callback function, optionally
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with arbitrary arguments.
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\param[in] o call the callback with \em o as the widget argument
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\param[in] arg call the callback with \em arg as the user data argument
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\see callback()
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*/
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void do_callback(Fl_Widget* o,long arg) {callback_(o,(void*)arg); if (callback_ != default_callback) clear_changed();}
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void do_callback(Fl_Widget* o,void* arg=0); // impl. in Fl_Widget.cxx
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/** Internal use only. */
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int test_shortcut();
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+77
-37
@@ -1518,40 +1518,47 @@ static int max_widget_watch = 0;
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/**
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Adds a widget pointer to the widget watch list.
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\note Internal use only, please use class Fl_Watch instead.
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This should be used, if it is possible that a widget might be deleted during
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a callback or similar function. The widget pointer must be added to the
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watch list before calling the callback. After the callback the widget
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pointer can be queried, if it is NULL. \e If it is NULL, then the widget has been
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deleted during the callback and must not be accessed anymore. If the widget
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pointer is \e not NULL, then the widget has not been deleted and can be accessed
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safely.
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This can be used, if it is possible that a widget might be deleted during
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a callback or similar function. The widget pointer must be added to the
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watch list before calling the callback. After the callback the widget
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pointer can be queried, if it is NULL. \e If it is NULL, then the widget has been
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deleted during the callback and must not be accessed anymore. If the widget
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pointer is \e not NULL, then the widget has not been deleted and can be accessed
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safely.
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After accessing the widget, the widget pointer should be released from the
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watch list by calling Fl::release_widget_pointer().
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After accessing the widget, the widget pointer must be released from the
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watch list by calling Fl::release_widget_pointer().
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Example for a button that is clicked (from its handle() method):
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\code
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Fl_Widget *wp = this; // save 'this' in a pointer variable
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Fl::watch_widget_pointer(wp); // add the pointer to the watch list
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set_changed(); // set the changed flag
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do_callback(); // call the callback
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if (!wp) { // the widget has been deleted
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Example for a button that is clicked (from its handle() method):
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\code
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Fl_Widget *wp = this; // save 'this' in a pointer variable
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Fl::watch_widget_pointer(wp); // add the pointer to the watch list
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set_changed(); // set the changed flag
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do_callback(); // call the callback
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if (!wp) { // the widget has been deleted
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// DO NOT ACCESS THE DELETED WIDGET !
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// DO NOT ACCESS THE DELETED WIDGET !
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} else { // the widget still exists
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clear_changed(); // reset the changed flag
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}
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} else { // the widget still exists
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clear_changed(); // reset the changed flag
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}
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Fl::release_widget_pointer(wp); // remove the pointer from the watch list
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\endcode
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Fl::release_widget_pointer(wp); // remove the pointer from the watch list
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\endcode
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This works, because all widgets call Fl::clear_widget_pointer() in their
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destructors.
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\see Fl::release_widget_pointer()
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\see Fl::clear_widget_pointer()
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This works, because all widgets call Fl::clear_widget_pointer() in their
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destructors.
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\see Fl::release_widget_pointer()
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\see Fl::clear_widget_pointer()
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An easier and more convenient method to control widget deletion during
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callbacks is to use the class Fl_Watch with a local (automatic) variable.
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\see class Fl_Watch
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*/
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void Fl::watch_widget_pointer(Fl_Widget *&w)
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{
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@@ -1560,17 +1567,16 @@ void Fl::watch_widget_pointer(Fl_Widget *&w)
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for (i=0; i<num_widget_watch; ++i) {
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if (widget_watch[i]==wp) return;
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}
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for (i=0; i<num_widget_watch; ++i) {
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if (widget_watch[i]==0L) {
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widget_watch[i] = wp;
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return;
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}
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}
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if (num_widget_watch==max_widget_watch) {
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max_widget_watch += 8;
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widget_watch = (Fl_Widget***)realloc(widget_watch, sizeof(Fl_Widget**)*max_widget_watch);
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}
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widget_watch[num_widget_watch++] = wp;
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#ifdef DEBUG
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printf ("\nwatch_widget_pointer: (%d/%d) %8p => %8p\n",
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num_widget_watch,num_widget_watch,wp,*wp);
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fflush(stdout);
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#endif // DEBUG
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}
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/**
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@@ -1578,19 +1584,33 @@ void Fl::watch_widget_pointer(Fl_Widget *&w)
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This is used to remove a widget pointer that has been added to the watch list
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with Fl::watch_widget_pointer(), when it is not needed anymore.
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\note Internal use only, please use class Fl_Watch instead.
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\see Fl::watch_widget_pointer()
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*/
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void Fl::release_widget_pointer(Fl_Widget *&w)
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{
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Fl_Widget **wp = &w;
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int i;
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int i,j=0;
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for (i=0; i<num_widget_watch; ++i) {
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if (widget_watch[i]==wp) {
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widget_watch[i] = 0L;
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return;
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if (widget_watch[i]!=wp) {
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if (j<i) widget_watch[j] = widget_watch[i]; // fill gap
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j++;
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}
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#ifdef DEBUG
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else { // found widget pointer
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printf ("release_widget_pointer: (%d/%d) %8p => %8p\n",
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i+1,num_widget_watch,wp,*wp);
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}
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#endif //DEBUG
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}
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num_widget_watch = j;
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#ifdef DEBUG
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printf (" num_widget_watch = %d\n\n",num_widget_watch);
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fflush(stdout);
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#endif // DEBUG
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return;
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}
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/**
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Clears a widget pointer \e in the watch list.
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@@ -1598,6 +1618,8 @@ void Fl::release_widget_pointer(Fl_Widget *&w)
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This is called when a widget is destroyed (by its destructor). You should never
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call this directly.
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\note Internal use only, please use class Fl_Watch instead.
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This method searches the widget watch list for pointers to the widget and clears
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all pointers that point to it. Widget pointers can be added to the widget
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watch list by calling Fl::watch_widget_pointer().
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@@ -1615,6 +1637,24 @@ void Fl::clear_widget_pointer(Fl_Widget const *w)
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}
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}
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// Helper class Fl_Watch
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/**
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The constructor adds a widget to the watch list.
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*/
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Fl_Watch::Fl_Watch(Fl_Widget *wi) {
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wp_ = wi;
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Fl::watch_widget_pointer(wp_); // add pointer to watch list
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}
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/**
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The destructor removes a widget from the watch list.
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*/
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Fl_Watch::~Fl_Watch() {
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Fl::release_widget_pointer(wp_); // remove pointer from watch list
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}
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//
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// End of "$Id$".
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@@ -58,8 +58,7 @@ const Fl_Menu_Item* Fl_Menu_Button::popup() {
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const Fl_Menu_Item* m;
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pressed_menu_button_ = this;
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redraw();
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Fl_Widget *mb = this;
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Fl::watch_widget_pointer(mb);
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Fl_Watch mb(this);
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if (!box() || type()) {
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m = menu()->popup(Fl::event_x(), Fl::event_y(), label(), mvalue(), this);
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} else {
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@@ -67,8 +66,7 @@ const Fl_Menu_Item* Fl_Menu_Button::popup() {
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}
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picked(m);
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pressed_menu_button_ = 0;
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if (mb) mb->redraw();
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Fl::release_widget_pointer(mb);
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if (mb.exists()) redraw();
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return m;
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}
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@@ -293,6 +293,21 @@ Fl_Widget::copy_label(const char *a) {
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redraw_label();
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}
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/** Calls the widget callback.
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Causes a widget to invoke its callback function with arbitrary arguments.
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\param[in] o call the callback with \a o as the widget argument
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\param[in] arg call the callback with \a arg as the user data argument
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\see callback()
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*/
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void
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Fl_Widget::do_callback(Fl_Widget* o,void* arg) {
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Fl_Watch wp(o);
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callback_(o,arg);
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if (wp.deleted()) return;
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if (callback_ != default_callback)
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clear_changed();
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}
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//
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// End of "$Id$".
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Reference in New Issue
Block a user