STR #1639

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STR #1639

Application:FLTK Library
Status:1 - Closed w/Resolution
Priority:4 - High, e.g. key functionality not working
Scope:3 - Applies to all machines and operating systems
Subsystem:Documentation
Summary:Fl::event_button[1,2,3]() always returns 0
Version:1.1.7
Created By:scorpion007
Assigned To:matt
Fix Version:1.1-current (SVN: v5786)
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Name/Time/Date Text top right image
 
#1 scorpion007
17:20 Mar 24, 2007
Calling either of these functions inside an event callback for a button, while pressing either of the 3 mouse buttons returns false (0).

Yet, when I call Fl::event_button() it returns the correct button
number (1,2,3).

static void button_cb(Fl_Widget *w, void *v)
{
    MyApp *app = (MyApp *)v;
    if (Fl::event_button() == FL_LEFT_MOUSE)
    {
        app->addNum();
    }
    else
    {
        printf("button %d was pressed (%d, %d, %d)\n", Fl::event_button(),
            Fl::event_button1(), Fl::event_button2(), Fl::event_button3());
    }
}

If I right- or middle-click, I get the following output:
button 3 was pressed (0, 0, 0) // <- all zero's inside the brackets
button 2 was pressed (0, 0, 0)
button 3 was pressed (0, 0, 0)
 
 
#2 scorpion007
17:21 Mar 24, 2007
Forgot to mention, I'm using Win32.  
 
#3 greg.ercolano
18:23 Mar 24, 2007
Just some notes from the sidelines, as I thought this was interesting.

I think the problem here is the functions in question [event_button123()] all work with the event_state(), which returns the buttons being held down at the time of the event.

Since the button callback is called when buttons are /released/, the event_state() has already been cleared.

The functions in question work OK in the context of handle() in response to an FL_PUSH, but return all 0's when FL_RELEASE occurs because the button is no longer down.

Or so it seems, looking at how the event_button123() and event_buttons() [plural] methods work.

The event_button() [singluar] and event_key() methods have a different implementation that doesn't look at the event_state(), but rather, the event e_keysym.

Not sure if this is a bug in the code, or an undocumented or misdocumented feature.. as the docs for the 'Fl::event_*() methods' section say these methods are valid in handle() and callback() contexts.. just apparently not in the context of a button callback() though.
 
 
#4 matt
07:12 May 01, 2007
STR #1639: improved documentation to explain the difference between evnt_button() and event_buttons()  
bottom left image   bottom right image

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