Review Request 126308: KPushButton: respect SH_DialogButtonBox_ButtonsHaveIcons, also when drawing

Thomas Lübking thomas.luebking at gmail.com
Sun Dec 13 16:35:22 GMT 2015 


> On Dec. 11, 2015, 1:55 p.m., Thomas Lübking wrote:
> > src/kdeui/kdialogbuttonbox.cpp, line 39
> > <https://git.reviewboard.kde.org/r/126308/diff/5/?file=421661#file421661line39>
> >
> >     QDialogButtonBox::addButton should do correctly anyway, so please don't workaround things that are not broken.
> 
> René J.V. Bertin wrote:
>     No, I've looked at Qt 5.5.1 . The only QDialogButtonBox::addButton that "does correctly" is the one that takes a StandardButton. I haven't had time to test this (will need to rebuild QtBase first) but I'm pretty sure that that method creates a button with an icon with its sequence
>     
>     ```
>         QPushButton *button = new QPushButton(text, this);
>         d->addButton(button, role);
>     ```
>     
>     My approach here is to avoid adding an icon if ButtonsHaveIcons is false, or remove the icon if one was already added. That's what QDB does with its ::addButton(StandardButton btn) method (calling a private createButton() method). Any other approach is useless without a style supporting and enforcing ButtonsHaveIcons, but which such a style KDialogButtonBox doesn't need to be fixed in the first place...

::addButton(text, role) creates "new QPushButton(text, this)" - those should seriously not have any icons.

> whith such a style KDialogButtonBox doesn't need to be fixed in the first place

If it's broken, it needs to be fixed - you cannot bail out with "the style is correcting that for us" (I've been fixing far too many kdelibs/qtgui bugs in the style ;-)


> On Dec. 11, 2015, 1:55 p.m., Thomas Lübking wrote:
> > src/kdeui/kdialogbuttonbox.cpp, line 57
> > <https://git.reviewboard.kde.org/r/126308/diff/5/?file=421661#file421661line57>
> >
> >     you can completely spare this, there's no reason to manipulate a copy of the GuiItem, just burns CPU
> 
> René J.V. Bertin wrote:
>     In that case I'll have to remove the `const` from guiitem, meaning a change to the API.

No, you do not touch the KGuiItem that comes (it's not yours!) and it's pointless to create a copy, strip the icon from that, assign it to the button (and maybe even strip the icon from the button) - you just apply the GuiItem that enters and strip the icon from the button. The interim (deep) GuiItem copy is just detour in the path to remove the icon from the button.


> On Dec. 11, 2015, 1:55 p.m., Thomas Lübking wrote:
> > src/kdeui/kdialogbuttonbox.cpp, line 61
> > <https://git.reviewboard.kde.org/r/126308/diff/5/?file=421661#file421661line61>
> >
> >     unrelated and it won't leak, since the cleanup is done by the parent/child relation ("this" passed to KPushButton)
> 
> René J.V. Bertin wrote:
>     Maybe it won't leak, but the question remains why what buttons with an invalid role are good for.

Did you see such role being used? It would be a client code bug (the symbol is juts for completeness sake, so that you can eg. assign it to a role, pipe that to some transformation functions, check whether it's still invalid and then react to that)


> On Dec. 11, 2015, 1:55 p.m., Thomas Lübking wrote:
> > src/kdeui/kdialogbuttonbox.cpp, line 70
> > <https://git.reviewboard.kde.org/r/126308/diff/5/?file=421661#file421661line70>
> >
> >     Setting the icon is sufficient, please do not mess around with other attributes.
> 
> René J.V. Bertin wrote:
>     Are you sure? setIcon() doesn't call setIconSize() nor does it reset any size information already present. Is it a good idea to replace an icon and leaving the size information from the previous icon)? NB: should the icon from the KGuiItem override the role's standard icon or should it be the other way round (provided icon as a default when the role doesn't provide an icon, for instance)?

setIcon *shall* not setIconSize, the two values are completely orhtogonal. Dropping the size information will just get you into trouble when you should require it again.
If eg. a style would reserve icon space of iconSize despite there actually is no icon to paint, the style is simply broken.

The icon size refers to the wanted size in the widget, not what the icon provides. Resolving that is job of the icon loader (or painting routine, eg. the style)

About GuiItem ./. StdRole: FIFO, ie. the last setter should usually win (if you've a button with a dedicated icon and role "ok" and switch the role to "delete", the "ok" icon is most certainly no longer correct ;-)


> On Dec. 11, 2015, 1:55 p.m., Thomas Lübking wrote:
> > src/kdeui/kdialogbuttonbox.cpp, line 75
> > <https://git.reviewboard.kde.org/r/126308/diff/5/?file=421661#file421661line75>
> >
> >     this is really the only thing you should need to do here.
> 
> René J.V. Bertin wrote:
>     Cf. the previous comment about icon priority: this method can provide 2 icons that the button will have to chose from.
>     
>     And I think that it's probably a good idea to set the icon size to 0 when the intent is to remove the icon completely.

> this method can provide 2 icons that the button will have to chose from.

Humm? You're unsetting the icon by pb->setIcon(QIcon());
QPushButton (actually QAbstractButton) provides *one* icon member, not a list.


> And I think that it's probably a good idea to set the icon size to 0 when the intent is to remove the icon completely.

No. Really not. Please don't do that.


> On Dec. 11, 2015, 1:55 p.m., Thomas Lübking wrote:
> > src/kdeui/kpushbutton.cpp, line 257
> > <https://git.reviewboard.kde.org/r/126308/diff/5/?file=421662#file421662line257>
> >
> >     still wrong and again, please don't mess with the icon size - you're just tempting DIV zero segfaults.
> 
> René J.V. Bertin wrote:
>     what?? Code that doesn't check integer div 0 should be encouraged to crash. A different bug than the one we're addressing here, but not one I have any patience with/for.
>     
>     I could use QSize() instead of QSize(0,0); the former would mean iconSize.isValid() will return false while with the latter it'll return true. But note that functions like QPushButton::sizeHint() do not check isValid. A bit of a conundrum.
>     Am I right that a button that never had an icon will have `iconSize() == QSize()` ?

> Code that doesn't check integer div 0 should be encouraged to crash

Sure, but provoking such crashes is, next to pointless information loss, really the only thing you'll achieve here.
Stay away from the size hint, please, I urge you.


> Am I right that a button that never had an icon will have iconSize() == QSize() ?

"The default size is defined by the GUI style"


- Thomas


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On Dec. 11, 2015, 4:26 p.m., René J.V. Bertin wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/126308/
> -----------------------------------------------------------
> 
> (Updated Dec. 11, 2015, 4:26 p.m.)
> 
> 
> Review request for KDE Software on Mac OS X, KDE Frameworks, Qt KDE, Hugo Pereira Da Costa, and Yichao Yu.
> 
> 
> Repository: kdelibs4support
> 
> 
> Description
> -------
> 
> KF5 applications have long had a habit of drawing icons on buttons even when this feature was turned off in the user's setting. This was mostly noticeable in applications built on kdelibs4support.
> 
> It seems that the actual culprit is in Qt's QPushButton implementation (https://bugreports.qt.io/browse/QTBUG-49887), but it is possible to work around it in `KPushButton::paintEvent`, by removing the icon (forcing it to the null icon) in the option instance, before handing off control to the painter.
> 
> 
> Diffs
> -----
> 
>   src/kdeui/kdialogbuttonbox.cpp 0f6649b 
>   src/kdeui/kpushbutton.cpp 98534fa 
> 
> Diff: https://git.reviewboard.kde.org/r/126308/diff/
> 
> 
> Testing
> -------
> 
> On Kubuntu 14.04 and OS X 10.9.5 with Qt 5.5.1 and KF5 frameworks 5.16.0 .
> 
> I have not yet verified if there are other classes where this modification would be relevant too.
> 
> 
> Thanks,
> 
> René J.V. Bertin
> 
>

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