Problem with QWidget->mapToGlobal()

[Michael Jansen]

Hi

If i open the window menu (alt+f3) with the mouse the window shows up in the 
top left corner of my screen. The reason is that the following code from 
workspace/kwin/libkdecorations/kcommondecoration.cpp line 706

  QRect menuRect = m_button[MenuButton]->rect();
  QPoint menutop = m_button[MenuButton]->mapToGlobal(menuRect.topLeft());

  QPoint menubottom = m_button[MenuButton]->
mapToGlobal(menuRect.bottomRight()) + QPoint(0, 2);

  KDecorationFactory* f = factory();
  showWindowMenu(QRect(menutop, menubottom));


The mapToGlobal() call is supposed to map the coordinates to screen 
coordinates as far i can see. But it does not do that. It always returns some 
small values like 

(gdb) p menubottom
$2 = {xp = 23, yp = 24}

I could even say always those values because it looks like the menu is always 
on the same spot.

I have a two screen setup here. That could be related.

Any ideas what is wrong here?

Mike

Re: Problem with QWidget->mapToGlobal()

[Till Adam]

On Tuesday 26 July 2011 09:34:57 Michael Jansen wrote:

> The mapToGlobal() call is supposed to map the coordinates to screen
> coordinates as far i can see. But it does not do that. It always returns
> some small values like

We've seen this fail in Kontact mobile in situations where the widget was 
embedded in a graphicsview, directly or indirectly. Could be totally 
unrelated, of course, just thought I'd mention it. Fixed in Qt, I believe, 
back then.

Till

Re: Problem with QWidget->mapToGlobal()

[Shaun Reich]

I have the same problem with master and Qt 4.7.

Clicking the windeco icon on a window which is on either screen
results in the menu displaying as far left on the left screen, and the
top of the screen + (heightOfTitlebar) it seems.
Simply right-clicking the titlebar itself results in an incorrect
offset (resulting in it being on the left-most screen at the top. The
difference is that the first one is statically always at left-top. The
second case (sort of) follows the x axis of the titlebar, but at the
top.

Anyways, ran it through gdb just for curiousity's sake and yeah
mapToGlobal isn't giving what one might expect. Does the widget need a
parent or something? Because other uses of it seem pretty similar to
this one, yet they work fine. or is this some qt/x bug?


-- 
Shaun Reich,
KDE Software Developer (kde.org)

Re: Problem with QWidget->mapToGlobal()

[Sean Harmer]

On 26/07/2011 22:55, Shaun Reich wrote:

I have the same problem with master and Qt 4.7.

Clicking the windeco icon on a window which is on either screen
results in the menu displaying as far left on the left screen, and the
top of the screen + (heightOfTitlebar) it seems.
Simply right-clicking the titlebar itself results in an incorrect
offset (resulting in it being on the left-most screen at the top. The
difference is that the first one is statically always at left-top. The
second case (sort of) follows the x axis of the titlebar, but at the
top.

Anyways, ran it through gdb just for curiousity's sake and yeah
mapToGlobal isn't giving what one might expect. Does the widget need a
parent or something? Because other uses of it seem pretty similar to
this one, yet they work fine. or is this some qt/x bug?


It has also been noticed here:

http://developer.qt.nokia.com/forums/viewthread/7980/

where the reporter seems to think that (on embedded at least) there was 
a byte->pixel conversion missing in some cases.


Sean


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