java-gnome-hackers

[java-gnome-hackers] org.gnome.gdk.EventButton.getX()/getY(): double vs int

[Stefan P. <st...@pr...>]

Hi all,

I just stumbled upon the not yet exposed methods getX() and getY()
in org.gnome.gdk.EventButton and Andrew's comment:

* I'm not exposing these yet; why on earth are they double? If there's
* no good reason or it's legacy crap, we're going to change the return
* signature to int.

I agree that I don't see a point in not having integers here. So, if
noone is coming with a good example why to use doubles here, I suggest
that we expose them as ints.

Any comments?

Stefan

Re: [java-gnome-hackers] org.gnome.gdk.EventButton.getX()/getY(): double vs int

[Stefan P. <st...@pr...>]

Hi,

Am Montag, den 06.10.2008, 15:33 -0400 schrieb Gerald Butler:
> Is it possible to have fractional mouse locations reported under
> various coordinate transformation matrixes? Perhaps when things like
> "Multi-Touch" become wide-spread? What does the underlying GTK API
> have to say about this?

Nearly nothing.

gdouble x; the x coordinate of the pointer relative to the window.

is all I can find in the API docs for that type. 

Regarding transformation: The only way that I can imagine coordinate
transformation leading to non-integer values is for example when a kind
of magnifying glass follows the mouse cursor so that the screen pixels
may not match application pixels. (Just a quick thought - might prove
false when you think closer about it.) But even dropping the fractional
part or rounding it seems ok.

Plus: We avoid confusion for application developers.

Cheers,
  Stefan

Re: [java-gnome-hackers] org.gnome.gdk.EventButton.getX()/getY(): double vs int

[Andrew C. <an...@op...>]

On Mon, 2008-10-06 at 20:14 +0200, Stefan Prelle wrote:
> I just stumbled upon the not yet exposed methods getX() and getY()
...
> I agree that I don't see a point in not having integers here.

Great.

As it happens, I actually ran into needing these a few weeks ago and so
went ahead and did this. See revision
an...@op...-20080924020725-15qyh3lc7y8rwavh which was
merged to 'mainline' at revno 565.

AfC
Sydney

-- 
Andrew Frederick Cowie

Operational Dynamics is an operations and engineering consultancy
focusing on IT strategy, organizational architecture, systems
review, and effective procedures for change management. We actively
carry out research and development in these areas on behalf of our
clients, and enable successful use of open source in their mission
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Re: [java-gnome-hackers] org.gnome.gdk.EventButton.getX()/getY(): double vs int

[Owen T. <ot...@re...>]

On Mon, 2008-10-06 at 20:14 +0200, Stefan Prelle wrote:
> Hi all,
> 
> I just stumbled upon the not yet exposed methods getX() and getY()
> in org.gnome.gdk.EventButton and Andrew's comment:
> 
> * I'm not exposing these yet; why on earth are they double? If there's
> * no good reason or it's legacy crap, we're going to change the return
> * signature to int.
> 
> I agree that I don't see a point in not having integers here. So, if
> noone is coming with a good example why to use doubles here, I suggest
> that we expose them as ints.
> 
> Any comments?

They are double because in some cases sub-pixel positioning is
available... for example, when tablet support is enabled. This is
important for, among things, painting programs.

Any questions?

- Owen

Re: [java-gnome-hackers] org.gnome.gdk.EventButton.getX()/getY(): double vs int

[Srichand P. <sri...@gm...>]

On Mon, Oct 6, 2008 at 2:14 PM, Stefan Prelle <st...@pr...> wrote:

> Hi all,
>

Hi Stefan,

I just stumbled upon the not yet exposed methods getX() and getY()
> in org.gnome.gdk.EventButton and Andrew's comment:
>
> * I'm not exposing these yet; why on earth are they double? If there's
> * no good reason or it's legacy crap, we're going to change the return
> * signature to int.
>
> I agree that I don't see a point in not having integers here. So, if
> noone is coming with a good example why to use doubles here, I suggest
> that we expose them as ints.
>
> Any comments?
>
> Stefan
>
>
There certainly are useful applications where doubles rather than ints would
be useful. I've been working on some research on pen strokes on touchscreen
surfaces, such as tablet PCs, external USB tablets (Wacom style stuff) and
handheld devices. For a lot of the algorithms, subpixel accuracy is
certainly useful. By constraining values to ints, you're losing (possibly)
valuable bits of information. Instead of deciding which pixel to select (by
truncating the numbers after the decimal), sometimes its useful to let the
application/algorithm decide what it wants to do.

Just my 2c.

Srichand
-- 
Srichand Pendyala
http://srichand.net.in/

Re: [java-gnome-hackers] org.gnome.gdk.EventButton.getX()/getY(): double vs int

[Andrew C. <an...@op...>]

Informed participation, great!

On Wed, 2008-10-08 at 01:13 -0400, Srichand Pendyala wrote:

> There certainly are useful applications where doubles rather than ints
> would be useful...

The consensus is clearly to leave it as double. [Now that I think about
it, doubles line up with Cairo space, so hey.]

In any event, the bar to diverge from underlying API is high and clearly
not being met (anymore) in this case. So I don't object.

So which one of you who wants it double is going to fix it? :) Make sure
you add some casts to the example at TreeView's getPathAtPos() as well.
http://java-gnome.sourceforge.net/4.0/doc/api/org/gnome/gtk/TreeView.html#getPathAtPos(int,%20int)

AfC
Sydney