Re: units updater for figures is broken when using fltk

[Ben Abbott]

On Feb 7, 2012, at 11:41 AM, Ben Abbott wrote:

> On Feb 7, 2012, at 10:40 AM, Michael Goffioul wrote:
> 
>> On Sun, Feb 5, 2012 at 5:00 PM, Ben Abbott <address@hidden> wrote:
>>>> I think the problem is not in get_boundingbox, but in the incorrect
>>>> interpretation of the position property in the FLTK code. Moreover,
>>>> the code is probably not robust against feedback loops when changing
>>>> properties, like:
>>>> 1) the user change figure position
>>>> 2) the backend is notified and move/resize the figure window
>>>> 3) as in any toolkit, moving/resizing the window triggers corresponding 
>>>> events
>>>> 4) the backend receives events and propagates the changes back to the
>>>> figure position (this is needed as the move/resize could be the result
>>>> of a user action with the mouse)
>>>> 5) if the newly computed position does not match the previous one, goto 1)
>>>> 
>>>> Step 4) above should not happen when the position change is coming
>>>> from octave, but I suspect it does, which can explain the infinite
>>>> loop you're seeing.
>>>> 
>>>> Michael.
>>> 
>>> The loop may have been due to my not understanding what I was doing. I used 
>>> ...
>>> 
>>>       Matrix pos = fp.get_boundingbox (true);
>>> 
>>> But I don't understand what the boolean arg is intended for. In graphics.cc 
>>> (figure::properties::get_boundingbox) the boolean is named "internal" and 
>>> is references in the snippet below.
>>> 
>>>       Matrix pos = (internal ?
>>>                     get_position ().matrix_value () :
>>>                     get_outerposition ().matrix_value ());
>>> 
>>> I choose get_boundingbox (true) because I don't know the purpose of the 
>>> outerposition property for figures (there's none in Matlab). I notice you 
>>> added it  below.
>>> 
>>>       
>>> http://hg.savannah.gnu.org/hgweb/octave/annotate/d99aa455296e/src/graphics.cc
>>> 
>>> What is the figure's outerposition property for ?
>> 
>> http://www.mathworks.co.uk/help/techdoc/ref/figure_props.html#OuterPosition
>> 
>>> Back to the need to obtain the figure position property in pixels, I 
>>> attempted the change below, but ran into scoping problems.
>>> 
>>> void draw (void)
>>> {
>>>   Matrix screen_size = screen_size_pixels ();
>>>   Matrix pos = fp.get_position ().matrix_value ();
>>>   pos = convert_position (pos, get_units (), "pixels", screen_size);
>>>   Fl_Window::resize (pos(0), pos(1), pos(2), pos(3) + status_h + menu_h);
>>> 
>>>   return Fl_Window::draw ();
>>> }
>> 
>> The code above does not flip the Y axis. If you also flip the Y-axis,
>> it will be equivalent to get_boundingbox(true) and you'll probably run
>> into the same endless loop.
> 
> I've been experimented with a few approaches, but always encounter the loop 
> problem. 
> 
> Even the example below starts looping if the windows is moved with the mouse.
> 
> diff --git a/src/DLD-FUNCTIONS/__init_fltk__.cc 
> b/src/DLD-FUNCTIONS/__init_fltk__.cc
> --- a/src/DLD-FUNCTIONS/__init_fltk__.cc
> +++ b/src/DLD-FUNCTIONS/__init_fltk__.cc
> @@ -1173,9 +1173,14 @@
> 
>   void draw (void)
>   {
> +    // Get the figure position in pixels
> +    octave_value funits = fp.get_units ();
> +    fp.set_units (octave_value ("pixels"));
>     Matrix pos = fp.get_position ().matrix_value ();
> +    fp.set_units (funits);
> +    // Adjust for the menu and status bars
>     Fl_Window::resize (pos(0), pos(1), pos(2), pos(3) + status_h + menu_h);
> -
> +    // Draw the figure
>     return Fl_Window::draw ();
>   }
> 
> My impression is another place where a similar change is needed ... either 
> that or I'm just missing something ? 
> 
> Ben

There are two locations in __init_fltk__.cc that fp.get_postion() and one that 
fp.set_postion(). 

I've managed a working changeset that relies upon switching the figure units to 
and from pixels in each instance.

I'll attempt a solution that does have the liability of having listeners 
trigger when the figure's units property is changed.

Ben