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Joerg Desch
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Joerg Desch

Discussion  - 
 
I'm using Qt to remote control a device over a serial communication channel. While testing the communication, I've recognized a unknown behavior.

If the user changes a QSpinBox, a valueChanged event is emitted. If I use setValue, this event is emitted too.

Is there a way to disable this behavior?
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Colin Duquesnoy's profile photoJoerg Desch's profile photo
6 comments
 
By the way... Yesterday evening, I've found QSignalBlocker! ;-)
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Joerg Desch

Discussion  - 
 
Just one more question...
I've read somewhere in the documentation, that objects on the heap must not be free'd, if the parent is a QOBJECT based object.
So, I do not need to free a QAction because I pass the this pointer of the main windows as parent. What about a dialog? I allocate my dialogs with new in the constructor of the main windows. They don't get a parent reference.
Do I have to free these objects?
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Sebastian Kügler's profile photoOliver Fels's profile photoJoerg Desch's profile photo
5 comments
 
+Oliver Fels done! ;-) Thanks for the tipps.
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Joerg Desch

Diskussion  - 
 
Das Paket siunitx verhält sich ein wenig seltsam. Wenn ich Toleranzen mit \num verwende, dann bekomme ich den erwarteten Ausdruck. Nutze ich hingegen \SI, dann wird der gesamte Ausdruck in Klammern gesetzt. Ich habe die Paketoption separate-uncertainty global auf true eingestellt.
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Joachim Schlosser's profile photoJoerg Desch's profile photo
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Noch ein Hinweis dazu... Ich bin mir nicht ganz sicher, ob es aus wissenschaftlicher Sicht in Ordnung ist, wenn man die Einheit nur hinter Toleranz packt. Wenn man multi-part-units=repeat nutzt, dann wird die Einheit hinter beide Zahlenwerte gesetzt. Das sieht für mich ein bisschen gewöhnungsbedürftiger aus, ist aber auf jeden Fall mathematisch korrekter. ;-)
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Joerg Desch

project  - 
 
I need some help! I want to make Bananian 16.04 booting with a read-only root. Therefore I've changed the boot arguments in boot.cmd by adding "ro" directly after the entry "root=".

A fresh boot shows no changes! dmesg shows excatly the same output as before!

What is the right was to make mounting / read-only?

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Miroslav Baranko's profile photoJoerg Desch's profile photo
6 comments
 
Thanks.
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Joerg Desch

Discussion  - 
 
Just a simple question. I have used QVector to get a FIFO (queue) for strings (QString). To avoid reallocation (and limit the size), I've used the contructor QVector(int) to preallocate a defined number of strings.
After some first tests, capacity() returns the expected number of items. I don't understand, why size() returns this number too! To ge rid of the unused items, I've tried clear(). Doing this, the whole vector is freed.
As a work-a-round, I now call removeFirst() 'num' times go remove all the empty strings.
* is there a better solution to get a FIFO for Strings?
* how to I get a empty vector without the need for a loop to remove every single item?
Udpate: I'm using QT 5.3 from Debian 8 "Jessie".
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Joerg Desch's profile photoAdam Thompson's profile photoJoaquim Duran Comas's profile photo
15 comments
 
IMO, boost::circular_buffer could be a better option.
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Joerg Desch

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Bitte um eure Mithilfe!

Es geht um eine Online-Petition zu Dr.-Titeln, die in Frankfurt an der Goethe Uni im FB 13/14 gemacht werden. Dort wird zur Zeit "nur" der Dr. phil. nat. vergeben. Ein reiner deutscher Titel, der zwar den gleichen Rang wie Dr. rer. nat. hat, aber nicht international bekannt ist. In anderen Fachbereichen wird aber der Dr. rer. nat. vergeben. In der Petition wird nun dafür geworben, dass man die Wahlfreiheit bekommt.

Hinweis: Die Petition kann "nicht öffentlich" abgegeben werden. Man bekommt zur Bestätigung eine Email auf ein gültiges Mailkonto.

https://www.openpetition.de/petition/online/dr-phil-nat-dr-rer-nat-wir-wollen-die-wahl

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Wir möchten das Dekanat der Fachbereiche 13 (Physik) und 14 (Chemie, Biochemie und Pharmazie) bitten, uns mit sofortiger Wirkung die Wahl zwischen den Titeln Dr. phil. nat. und Dr. rer. nat. zu überlassen (in den Fachbereichen 5, 11, 12 und 15 können Promovierende bereits zwischen den beiden Titeln wählen).
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Joerg Desch

Help Needed  - 
 
I must declare a collection of titltepages (using the titlepage environment and KOMA script). Therefore I want to use the previously made declarations of \title, \author...
How do I access these settings?
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Joerg Desch

Discussion  - 
 
Once again, a silly questions of a Qt beginner... ;-)
I've designed a Qt dialog with QtCreator. To get a "key/value" form, I've used a QGridLayout with two columns. To use radio buttons as selection, I've placed a QHBoxLayout inside a grid cell and added some QRadioButtons. I have two of these groups in my dialog.
After a first try, I've realized, that the two radio button groups are not independent!
After looking into the documentation, I've found QButtonGroup. A thread inside the Qt forum explained how to add radio buttons into these groups.
So far so good. I've placed the radio buttons into two groupd. A "show members" selects the expected buttons. But running the program still shows me the previous behaviour. All the buttons are still in one group.
I've played with the "autoExclusive" attribute of the QRadioButton elements, but without success.
Any hints?
Update: the generated moc output adds the radio buttons into the QButtonGroup es expected.
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Dimitar Hubenov's profile photoJoerg Desch's profile photo
3 comments
 
I thought that Qt Creator runs qmake after cleaning the project and deleting all build directories.
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Joerg Desch

Discussion  - 
 
I'm looking for a simple way to change the color of a QSlider. I want to use 2 QSlider to define the RGB values of a color. Each slider should have the color it changes.
I've played with stylesheets, but this changes the look completly. I just need the knop or the body of the slider colored. What is the easiest solution for that? Thanks.
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David Johnson's profile photoJoerg Desch's profile photo
2 comments
 
Thanks for the reply, but that seems to be ways to complex. I had to add numerical outputs to the sliders and colored their backgrounds instead. ;-)
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Joerg Desch

Help Needed  - 
 
I've tried to use tolerances together with the \SI command of the package siunitx with separate-uncertainty set to true. While \num shows the expected result, \SI put the term into parentheses. Why are the result different? How can I configure siunitx to remove the parentheses?
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Kristoffer Ryhl-Johansen's profile photoJoerg Desch's profile photo
2 comments
 
That's correct, but it looks uncommon. I've found a package option (I can't remember the exact name, something that ends with multi-part) that can place the unit behind each number (repeat) or at the end (single). So I have to think about which one I will use. Thanks for your comment.
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Joerg Desch

Discussion  - 
 
After finishing my first Qt(Widget) application using QSerialPort together with a static keypad emulation (of an existing device) as GUI, I plan to start a more complex test application. I want to implement a (main) window with a list view of TODO cards. Each card should contain a title, a optional description, the author, a creation date and an optional list of tags.

The windows should be resizable and so the TODO cards. Optional fields should only be visible if not empty.

What I'm looking for is a "best practice" recipe using Qt5, not the solution. ;-)

So , what is the best way to implement the TODO cards? How are the optional fields handled?

By the way: I want to compile the application for Linux and Windows.
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Joerg Desch's profile photoOliver Fels's profile photo
8 comments
 
It can handle composite widgets, +Joerg Desch. It just isn´t straight forward.
If your widget is derived from QList ItemWidget you can put it in a QListWidget.
You might have to create your own View derived from QAbstracItemView in which the list widget renders your widget.
Selection can be accomplished by using the selection changed slot from the QListWidget and then change the stylesheet of the selected widget to render a different background color. I did it in a similar way and it works.
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Joerg Desch

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Nett. Aber erst, wenn man das Display hochkant vor dem Gesicht hat! 😉
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Am 8. April landete die ‪#‎Falcon9 ‬von #SpaceX erfolgreich auf einem Drohnenschiff. Die Landung gibts jetzt auch als 360° Video.
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Have him in circles
51 people
Martin Breitenberger (aMBedue)'s profile photo
Sukh MANI's profile photo
Dusan Rasic's profile photo
Elias Dächert's profile photo
Sabrina Meyer-Dommert's profile photo
Norbert Desch's profile photo
Daniela Edel's profile photo
Georg Sauer (Schorsch)'s profile photo
Full Circle Magazine's profile photo
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