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Joerg Desch
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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
2 comments
 
+Miroslav Baranko​ thank you. I'll try that on Monday. For now, if added an entry to fstab.
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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 / Questions  - 
 
Hi. I've done all my GUI programming with FLTK for 10+ years. Now I want to switch to Qt and may be QML. My first plan was to start slowly, because my spare time is limited. But now I must start a development (inhouse application at my office) of an application which is a good candidate for QML. The problem is, the time frame is really short. For both, starting with Qt/QML/QtCreator and the application code itself.

The application should resemble the membrane keypad of one of our devices. This device is connected to the PC over a serial port (UART). So what I want to do is implementing a serial protocol with Qt in C++ and the keypad with QML.

Are there any samples on the internet which can show the the implementation of the look and feel of a membrane keypad?

I already have the final button design made with Inkscape. So I can either export PNG or SVG buttons or icons.

Are there any short examples / tutorials showing the integration of the serial port in C++ and the GUI in QML?

Thanks for some helpful comments or links. ;-)
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Isaac Salazar (Iktwo)'s profile photoFrancis Mortanian's profile photorumbler soppa's profile photoJoerg Desch's profile photo
4 comments
 
Much stuff to read and watch... ;-) Thanks.
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Joerg Desch

Discussion  - 
 
I've written my very first QT5 (5.3 on Debian Jessie) mini test to get a feeling for composite widgets within scrollable lists. To implement this, I've created my own widget (MyWidget) derived from QWidget. This contains a Q*Layout as containment for the widgets I want to have in this composite widget (only QLabel and QPushButton).
Within main, I've added a QVBoxLayout to the main windows and attached a QListWidget to it. After this, strings can be added directly, all other QWidget based widgets must be added indirectly by adding a QListWidgetItem with the composite widget assigned by addItem() / setItemWidget(). After setting setSizeHint() all is displayed fine.
Now I have some questions:
* QListWidget is one way of implementing a scrollable list of composite widgets. The other way seems to be QScrollArea based. Which is the preferred way?
* are own classes with composite widgets (like MyWidget here) compatible to the QML way of doing UI's?
* the Qt examples always allocate elements dynamically using new. I've done this too by creating the entries for QListWidgetItem and MyWidget with new. Is this safe? Who frees the memory? addItem() and setItemWidget() are all getting pointers to the allocated objects.

Update:
Is it better to put the whole list into a QWidget derived class to hide the handling with QListWidgetItem's? So MyWidget would become a local class not seen from the outside... The wrapping MyWidgetList could hide all the internal handling. Would this be "common practice" for Qt?
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Joerg Desch's profile photoBeldì Luca's profile photo
7 comments
 
Selection and context menu behaviour are controlled directly by the view
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Joerg Desch

Discussion  - 
 
Are there any Debian users here? I'm running Debian Jessie.

I've decided to spent some time trying Qt5 and QtCreator. Sadly the QtCreator come without the sample which are referenced in the IDEs overview.

I have installed qtbase5-examples (and qtsensors5-examples qttools5-examples) to see if this adds the missing code.

QtCreator still doesn't see the example!

How do I fix this situation? It would be nice to have these sample projects reachable from within the IDE.

By the way...
Is there a reason why the sample are installed below /usr/lib/x86_64-linux-gnu/qt5/examples? I would expect them below /usr/share/doc.
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Marco Battistella's profile photoJoerg Desch's profile photo
2 comments
 
+Marco Battistella thanks for the tipp. I prefer the more save and easy way of installing the packages of the distribution. I don't need the "bleeding edge" releases. ;-)
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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
6 comments
 
You could derive your own listview from QListWidget (not QListView) and implement the view specific methods yourself +Joerg Desch .
Your widget is then derived from QListWidgetItem and your view fills the list with those.
Alternatively, but more complex, is to use a QAbstractItemDelegate which renders your widget in the QLIstView. A bit tricky and you lose the abilty to interact with the widget itself as it is only an image.
Just to get you started here.
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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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Joerg Desch

Diskussion  - 
 
Ich möchte mit der Umgebung titlepage einen Satz verschiedener Titelseiten entwerfen. Dabei will ich auf die definierten Felder \title, \author etc. zugreifen. Wie komme ich an diese Einstellungen ran?
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Joachim Schlosser's profile photoJoerg Desch's profile photo
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Super. Danke!
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Joerg Desch

Discussion  - 
 
I would like to have different sized QLabel within a composite widget. Since I don't know (I really don't want to care about) the default font size of the system, I would like to change the font size with a relative factor! I've tried different style sheets, but the relative units em or ex doesn't work.
So I only want to set the font of the label to bold and large. I don't want to get some platform specific dependencies!
Here is what I've already tried:

// does NOT work
titleLabel->setStyleSheet("QLabel{ font-weight: bold; font-size: large; }");

// does NOT work
titleLabel->setStyleSheet("QLabel{ font: bold large \"Serif\"; }");

// work -- but: size absolute, font specified
titleLabel->setStyleSheet("QLabel{ font: bold 20px \"Serif\"; }");

// work -- but: size missing
titleLabel->setStyleSheet("QLabel{ font: bold }");

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Beldì Luca's profile photoJoerg Desch's profile photo
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+Beldì Luca sorry, doesn't work here. The label is bold but not larger.
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Joerg Desch

Allgemeine Diskussion  - 
 
Ich weiß, ich bin hier eigentlich falsch, aber an anderer Stelle bekommt man nur schwachsinnige Empfehlungen. Also...
Ich habe ein LG G3 mit Cyanogen Mod 13 versehen und habe eine SD-Karte reingepackt. Da ich sonst nur Nexus-Geräte hatte, war das ein vollkommen neues Erlebnis. ;-)
Dumm nur ist das Handling der SD-Karten unter Andoid... Ich habe die Karte (Sandisk Ultra 64GB) als "portablen Speicher" formatieren und einbinden lassen. Ich wusste nicht, ob die Performance der Karte ausreichend hoch ist.
Jetzt wollte ich bei verschiedenen Apps (wie Komoot) den Speicherpfad auf ein Verzeichniss auf der Karte umbiegen (storage/XXXX-XXXX/irgendwas), aber die Apps melden mir immer, dass sie keine Berechtigung dazu haben.
Warum ist das so? Und wie kann man das abstellen?
So wie es jetzt aussieht, ist das ja eine fürchterliche Verschlimmbesserung.
Ach ja, mit Total Commander kann ich Daten kopieren!
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Joerg Desch's profile photoRoland Schumacher's profile photo
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So in etwa. Intern, dann verhält sich das System anders.
Einfach auf eigene Gefahr hin. Keine Ahnung ob das blöde Auswirkungen haben kann.
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