From 497afccb07164373e0de6639e754d7d691f1926f Mon Sep 17 00:00:00 2001 From: Fabien Costantini Date: Tue, 14 Oct 2008 22:12:25 +0000 Subject: Doxygen pdf man: First version added in documentation/fltk.pdf, old doc removed, images, dox files moved to a new src directory. git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@6431 ea41ed52-d2ee-0310-a9c1-e6b18d33e121 --- documentation/events.html | 394 ---------------------------------------------- 1 file changed, 394 deletions(-) delete mode 100644 documentation/events.html (limited to 'documentation/events.html') diff --git a/documentation/events.html b/documentation/events.html deleted file mode 100644 index d6717de89..000000000 --- a/documentation/events.html +++ /dev/null @@ -1,394 +0,0 @@ - - - 6 - Handling Events - - - -

6 - Handling Events

- -

This chapter discusses the FLTK event model and how to handle -events in your program or widget. - -

The FLTK Event Model

- -

Every time a user moves the mouse pointer, clicks a button, -or presses a key, an event is generated and sent to your -application. Events can also come from other programs like the -window manager. - -

Events are identified by the integer argument passed to the -Fl_Widget::handle() virtual -method. Other information about the most recent event is stored in -static locations and acquired by calling the Fl::event_*() methods. This static -information remains valid until the next event is read from the window -system, so it is ok to look at it outside of the handle() -method. - -

Mouse Events

- -

FL_PUSH

- -

A mouse button has gone down with the mouse pointing at this -widget. You can find out what button by calling -Fl::event_button(). You find out the mouse position by -calling Fl::event_x() and Fl::event_y(). - -

A widget indicates that it "wants" the mouse click -by returning non-zero from its handle() method. It -will then become the -Fl::pushed() widget and will get FL_DRAG and -the matching FL_RELEASE events. If handle() -returns zero then FLTK will try sending the FL_PUSH to -another widget.

- -

FL_DRAG

- -

The mouse has moved with a button held down. The current -button state is in Fl::event_state(). -The mouse position is in Fl::event_x() and Fl::event_y(). - -

In order to receive FL_DRAG events, the widget must -return non-zero when handling FL_PUSH.

- -

FL_RELEASE

- -

A mouse button has been released. You can find out what -button by calling Fl::event_button(). - -

In order to receive the FL_RELEASE event, the widget must -return non-zero when handling FL_PUSH.

- -

FL_MOVE

- -

The mouse has moved without any mouse buttons held down. -This event is sent to the Fl::belowmouse() -widget.

- -

In order to receive FL_MOVE events, the widget must -return non-zero when handling FL_ENTER.

- -

FL_MOUSEWHEEL

- -

The user has moved the mouse wheel. The Fl::event_dx() and Fl::event_dy() methods -can be used to find the amount to scroll horizontally and -vertically. - -

Focus Events

- -

FL_ENTER

- -

The mouse has been moved to point at this widget. This can -be used for highlighting feedback. If a widget wants to -highlight or otherwise track the mouse, it indicates this by -returning non-zero from its handle() method. It then -becomes the Fl::belowmouse() -widget and will receive FL_MOVE and FL_LEAVE -events. - -

FL_LEAVE

- -

The mouse has moved out of the widget. - -

In order to receive the FL_LEAVE event, the widget must -return non-zero when handling FL_ENTER.

- -

FL_FOCUS

- -

This indicates an attempt to give a widget the -keyboard focus. - -

If a widget wants the focus, it should change itself to -display the fact that it has the focus, and return non-zero from -its handle() -method. It then becomes the Fl::focus() widget and gets -FL_KEYDOWN, FL_KEYUP, and FL_UNFOCUS -events. - -

The focus will change either because the window manager -changed which window gets the focus, or because the user tried -to navigate using tab, arrows, or other keys. You can check Fl::event_key() to -figure out why it moved. For navigation it will be the key -pressed and interaction with the window manager it will be -zero. - -

FL_UNFOCUS

- -

This event is sent to the previous Fl::focus() widget when -another widget gets the focus or the window loses focus. - -

Keyboard Events

- -

FL_KEYDOWN, FL_KEYUP

- -

A key was pressed or released. The key can be found in Fl::event_key(). The -text that the key should insert can be found with Fl::event_text() and -its length is in Fl::event_length(). -If you use the key handle() should return 1. If you -return zero then FLTK assumes you ignored the key and will -then attempt to send it to a parent widget. If none of them want -it, it will change the event into a FL_SHORTCUT event. - -

To receive FL_KEYBOARD events you must also -respond to the FL_FOCUS and FL_UNFOCUS -events. - -

If you are writing a text-editing widget you may also want to -call the Fl::compose() -function to translate individual keystrokes into foreign -characters. - -

FL_KEYUP events are sent to the widget that -currently has focus. This is not necessarily the same widget -that received the corresponding FL_KEYDOWN event -because focus may have changed between events. - -

FL_SHORTCUT

- -

If the Fl::focus() -widget is zero or ignores an FL_KEYBOARD event then -FLTK tries sending this event to every widget it can, until one -of them returns non-zero. FL_SHORTCUT is first sent to -the Fl::belowmouse() widget, then its parents and -siblings, and eventually to every widget in the window, trying -to find an object that returns non-zero. FLTK tries really hard -to not to ignore any keystrokes! - -

You can also make "global" shortcuts by using Fl::add_handler(). A -global shortcut will work no matter what windows are displayed -or which one has the focus.

- -

Widget Events

- -

FL_DEACTIVATE

- -

This widget is no longer active, due to deactivate() -being called on it or one of its parents. active() may -still be true after this, the widget is only active if -active() is true on it and all its parents (use active_r() to check this). - -

FL_ACTIVATE

- -

This widget is now active, due to activate() -being called on it or one of its parents. - -

FL_HIDE

- -

This widget is no longer visible, due to hide() being -called on it or one of its parents, or due to a parent window -being minimized. visible() may still be true after -this, but the widget is visible only if visible() is -true for it and all its parents (use visible_r() to -check this). - -

FL_SHOW

- -

This widget is visible again, due to show() being -called on it or one of its parents, or due to a parent window -being restored. Child Fl_Windows respond to this by -actually creating the window if not done already, so if you -subclass a window, be sure to pass FL_SHOW to the base -class handle() method! - -

Clipboard Events

- -

FL_PASTE

- -

You should get this event some time after you call Fl::paste(). The contents -of Fl::event_text() -is the text to insert and the number of characters is in Fl::event_length(). - -

FL_SELECTIONCLEAR

- -

The Fl::selection_owner() -will get this event before the selection is moved to another -widget. This indicates that some other widget or program has -claimed the selection. Motif programs used this to clear the -selection indication. Most modern programs ignore this. - -

Drag And Drop Events

- -

FLTK supports drag and drop of text and files from any -application on the desktop. Text is transfered using -the current code page. Files are received as a list of full path -and file names, seperated by newline. On some platforms, path -names are prepended with file://. - -

The drag and drop data is available in Fl::event_text() -at the concluding FL_PASTE. On some platforms, the -event text is also available for the FL_DND_* events, -however application must not depend on that behavior because it -depends on the protocol used on each platform. - -

FL_DND_* events cannot be used in widgets derived -from Fl_Group or Fl_Window. - -

FL_DND_ENTER

- -

The mouse has been moved to point at this widget. A widget -that is interested in receiving drag'n'drop data must return 1 -to receive FL_DND_DRAG, FL_DND_LEAVE and FL_DND_RELEASE events. - -

FL_DND_DRAG

- -

The mouse has been moved inside a widget while dragging data. -A widget that is interested in receiving drag'n'drop data should -indicate the possible drop position. - -

FL_DND_LEAVE

- -

The mouse has moved out of the widget. - -

FL_DND_RELEASE

- -

The user has released the mouse button dropping data into -the widget. If the widget returns 1, it will receive the data in -the immediatly following FL_PASTE event. - - - -

Fl::event_*() methods

- -

FLTK keeps the information about the most recent event in -static storage. This information is good until the next event is -processed. Thus it is valid inside handle() and -callback() methods. - -

These are all trivial inline functions and thus very fast and small:

- - - -

Event Propagation

- -

FLTK follows very simple and unchangeable rules for sending -events. The major innovation is that widgets can indicate (by -returning 0 from the handle() method) that they are not -interested in an event, and FLTK can then send that event -elsewhere. This eliminates the need for "interests" -(event masks or tables), and this is probably the main reason -FLTK is much smaller than other toolkits. - -

Most events are sent directly to the handle() method -of the Fl_Window that the window system says they -belong to. The window (actually the Fl_Group that -Fl_Window is a subclass of) is responsible for sending -the events on to any child widgets. To make the -Fl_Group code somewhat easier, FLTK sends some events -(FL_DRAG, FL_RELEASE, FL_KEYBOARD, -FL_SHORTCUT, FL_UNFOCUS, and -FL_LEAVE) directly to leaf widgets. These procedures -control those leaf widgets: - -

- -

FLTK Compose-Character Sequences

- -

The foreign-letter compose processing done by the Fl_Input widget is provided in -a function that you can call if you are writing your own text editor -widget. - -

FLTK uses its own compose processing to allow "preview" of -the partially composed sequence, which is impossible with the -usual "dead key" processing. - -

Although currently only characters in the ISO-8859-1 -character set are handled, you should call this in case any -enhancements to the processing are done in the future. The -interface has been designed to handle arbitrary UTF-8 encoded -text. - -

The following methods are provided for character composition: - -

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