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List:       pykde
Subject:    Re: [PyQt] QLabel with scaled contents pixmap not updated after painting
From:       Maurizio Berti <maurizio.berti () gmail ! com>
Date:       2019-11-26 13:51:45
Message-ID: CAPn+-XSNS8Q==dxH+OzfD-0AdyxKV__VzhCAzsf6PyEQpc80ig () mail ! gmail ! com
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Il giorno mar 26 nov 2019 alle ore 14:00 Florian Bruhin <me@the-compiler.org>
ha scritto:
> I can reproduce with Qt 5.14, but I don't think it necessarily is a Qt
bug.
>
> Looking at the code, turning on scaledContents resizes the underlying
pixmap
> once and then caches it:
>
>
https://github.com/qt/qtbase/blob/v5.14.0-beta3/src/widgets/widgets/qlabel.cpp#L1092-L1104

Oh, I see.

> What's your actual usecase? You could probably either modify/redisplay the
> pixmap, or perhaps have a widget with a transparent background over the
QLabel
> instead.

I don't really need it right now, I just stumbled upon it from this
question:
https://stackoverflow.com/q/59047167/2001654

I can understand the behavior (and the necessity for caching), and the fact
that
technically it's not a bug, but still looks a bit consistent and might be
useful
to notify the team (possibly by adding a note in the docs).

Thank you,
Maurizio
-- 
È difficile avere una convinzione precisa quando si parla delle ragioni del
cuore. - "Sostiene Pereira", Antonio Tabucchi
http://www.jidesk.net

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<div dir="ltr"><div dir="ltr"><div dir="ltr">Il giorno mar 26 nov 2019 alle ore 14:00 \
Florian Bruhin &lt;<a href="mailto:me@the-compiler.org">me@the-compiler.org</a>&gt; \
ha scritto:<br>&gt; I can reproduce with Qt 5.14, but I don&#39;t think it \
necessarily is a Qt bug.<br>&gt;<br>&gt; Looking at the code, turning on \
scaledContents resizes the underlying pixmap<br>&gt; once and then caches \
it:<br>&gt;<br>&gt; <a \
href="https://github.com/qt/qtbase/blob/v5.14.0-beta3/src/widgets/widgets/qlabel.cpp#L \
1092-L1104">https://github.com/qt/qtbase/blob/v5.14.0-beta3/src/widgets/widgets/qlabel.cpp#L1092-L1104</a></div><div><br></div><div>Oh, \
I see.</div><div dir="ltr"><br>&gt; What&#39;s your actual usecase? You could \
probably either modify/redisplay the<br>&gt; pixmap, or perhaps have a widget with a \
transparent background over the QLabel<br>&gt; instead.</div><div \
dir="ltr"><br></div><div>I don&#39;t really need it right now, I just stumbled upon \
it from this question:</div><div><a \
href="https://stackoverflow.com/q/59047167/2001654">https://stackoverflow.com/q/59047167/2001654</a></div><div \
dir="ltr"><br></div><div>I can understand the behavior (and the necessity for \
caching), and the fact that</div><div>technically it&#39;s not a bug, but still looks \
a bit consistent and might be useful</div><div>to notify the team (possibly by adding \
a note in the docs).</div><div></div><div dir="ltr"><br></div><div>Thank \
you,</div><div>Maurizio  <br></div>-- <br><div dir="ltr" class="gmail_signature">È \
difficile avere una convinzione precisa quando si parla delle ragioni del cuore. - \
&quot;Sostiene Pereira&quot;, Antonio Tabucchi<br><a href="http://www.jidesk.net" \
target="_blank">http://www.jidesk.net</a></div></div></div>


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