General and Desktop

@jsulm https://forum.qt.io/post/775285

Created bug report: https://bugreports.qt.io/browse/QTBUG-118406

I used QString::number(doubleNumber, 'g' , 3) to get String representing the significant decimals up to 3. The g format doesn't give 3 "significant decimals", it gives 3 "significant digits" - this includes digits both before (excluding leading 0's) and after the decimal. Have a read of https://en.wikipedia.org/wiki/Significant_figures for more info. It works well in 99.9999% cases but for 14.25 instead of giving 14.25 it returns 14.3 14.3 is correct. The three significant digits there are 1, 4, and .3. I know I could use QString::number(doubleNumber'f',3) ... Why is that The reason the f format gives more decimals in your example, is that the f format interprets the precision parameter as a number of decimals, whereas g interprets it as a number of significant digits (which, as I mentioned above, includes digits before the decimal too). This is documented in the table under QLocale::toString(), which QString::number() links to (and @JonB referenced above). See the "Meaining of precision column: [image: 2f1ad327-50d1-40ae-a2f0-d5cf4ca0c35c.png] and what to use instead? If you specifically want "up to 3 decimals", as opposed to "exactly 3 decimals" (f) or "up to 3 significant digits" (g), then I suppose using f then trimming trailing 0 chars is one way to go. Just one of many ways to do it: const double doubleNumber = 14.25; qDebug() << QString::number(doubleNumber,'f',3); qDebug() << QString::number(doubleNumber,'g',3); qDebug() << QString::number(doubleNumber,'f',3).remove(QRegularExpression(QStringLiteral("0+$"))); Outputs: "14.250" "14.3" "14.25" Cheers.

@1XU7 Different in what way? You are setting the layout's alignment within its parent. The widgets you put in the layout have their own alignment value.

Hi, To add to @KH-219Design, since 6.5, the default backend has been set to ffmpeg.

@Christian-Ehrlicher So i got this working pretty great, but somehow when i move 2 items at ones out of it's parent only the data of one item gets copied over to both new inserted items: This i the start situation (1 parent with 2 child items): [image: 7af7df79-973a-4e1d-ae2a-a21aebd2be91.png] Than i select both items and drop than onto their parent item: [image: 0b7bbbd0-3700-4b67-9d56-b3ea8d06d023.png] After dropping i get two items named identically, but instead they should keep their data: [image: 8fe0b267-976b-43d6-81e0-7d0c679fa1ad.png] Here is my code: void ViewLayerList::dragEnterEvent(QDragEnterEvent *event) { // Ermitteln Sie den Index des Items unter der Maus QModelIndex index = indexAt(event->position().toPoint()); if (!index.isValid()) { // Wenn kein gültiges Item unter der Maus ist, rufen Sie die Basisklasse-Methode auf und kehren Sie zurück QTreeView::dragEnterEvent(event); return; } // Zugriff auf das Modell QStandardItemModel *modelObj = dynamic_cast<QStandardItemModel*>(model); // Überprüfen Sie, ob das Modell korrekt gecastet wurde if (modelObj) { // Vor jedem Drag-Event leeren Sie die Parent-Index-Liste parentChildMap.clear(); selectedIndexList.clear(); // Sammeln Sie die Parent-Indizes für ausgewählte Items QModelIndexList selectedIndexes = selectionModel()->selectedIndexes(); for (const QModelIndex& selectedIndex : selectedIndexes) { QModelIndex parentIndex = selectedIndex.parent(); // Fügen Sie das Paar zur Map hinzu parentChildMap.insert(selectedIndex, parentIndex); // Fügen Sie den ausgewählten Index zur Liste hinzu selectedIndexList.append(selectedIndex); // Zugriff auf das ausgewählte Element und fügen Sie es zur Liste hinzu QStandardItem* selectedItem = modelObj->itemFromIndex(selectedIndex); } int selectedItemCount = selectedIndexes.count(); qDebug() << "Anzahl der ausgewählten Items: " << selectedItemCount; // Nachdem Sie die Map gefüllt haben... for(auto it = parentChildMap.constBegin(); it != parentChildMap.constEnd(); ++it) { qDebug() << "Child: " << it.key().data() << ", Parent: " << it.value().data(); } } QTreeView::dragEnterEvent(event); } void ViewLayerList::dropEvent(QDropEvent *event) { // Ermitteln Sie den Index des Items unter der Maus QModelIndex index = indexAt(event->position().toPoint()); if (!index.isValid()) { QTreeView::dropEvent(event); return; } QModelIndex destinationIndex = indexAt(event->position().toPoint()); // Rufen Sie die Basisklasse-Methode auf, um die Standard-Verarbeitung fortzusetzen QTreeView::dropEvent(event); // Zugriff auf das Modell QStandardItemModel *modelObj = dynamic_cast<QStandardItemModel*>(this->model); // Überprüfen Sie, ob das Modell korrekt gecastet wurde if(modelObj) { qDebug() << "destinationIndex data: " << destinationIndex.data(); // Überprüfen Sie, ob der Zielindex das Wurzelelement als Elternteil hat bool isDestinationRoot = (destinationIndex.parent() == QModelIndex()); qDebug() << "DestinationHasROOT as parent: " << isDestinationRoot; // Nachdem Sie das Ereignis verarbeitet haben... for (const QModelIndex& selectedIndex : selectedIndexList) { // Holen Sie sich den Elternindex für das ausgewählte Element QModelIndex parentIndex = parentChildMap.value(selectedIndex); // Zugriff auf das Elternelement QStandardItem* parentItem = modelObj->itemFromIndex(parentIndex); // Vergleichen Sie die Daten des Elternindex mit den Daten des Zielindex if(parentIndex.data() == destinationIndex.data() && isDestinationRoot) { // Entfernen Sie das Kind-Element aus seinem Elternelement int row = 0; QList<QStandardItem*> items = parentItem->takeRow(row); //THIS COMMET BEHAVES REALLY STRANGE WHEN I REMOVE IT //SEE THE PICTURE BELOW qDebug() << "ItemList:" << parentItem->takeRow(row); // Bestimmen Sie die Position, an die das Element verschoben werden soll int newPosition = parentIndex.row() + 1; // Fügen Sie das Kind-Element an der neuen Position zum invisibleRootItem hinzu modelObj->invisibleRootItem()->insertRow(newPosition, items); } } } } There also is this one comment, everytime i try to remove it,my items get only copied in the dragging process but not removed anymore, so i end up with copies like this: (if the comment is there everything works fine, i found that strange) [image: bb1f24a2-433c-49f4-974b-9a6a90c802a1.png] I only commented out the comment: //qDebug() << "ItemList:" << parentItem->takeRow(row);

@chandrakant2023 https://lists.qt-project.org/listinfo/development

@sierdzio I changed the if statement to read: if (!underMouse() || !displayRect.contains(mouseLocation)) return; and added an update() call to the leaveEvent() handler. Problem solved.

@Ahimson2 First thing to do if your app is crashing: run through debugger and see where exactly it crashes. You can also post stack trace after crash here. Else we cannot do more than guessing.

@jgxy1123 See https://forum.qt.io/topic/74306/how-to-manage-zip-file

@KenAppleby-0 In the documentations of Qt https://doc.qt.io/qt-5/sql-driver.html#qsqlite SQLite has some restrictions regarding multiple users and multiple transactions. If you try to read/write on a resource from different transactions, your application might freeze until one transaction commits or rolls back. The Qt SQLite driver will retry to write to a locked resource until it runs into a timeout (see QSQLITE_BUSY_TIMEOUT at QSqlDatabase::setConnectOptions()). In the Sqlite documentation https://www.sqlite.org/c3ref/c_config_covering_index_scan.html#sqliteconfigserialized SQLITE_CONFIG_SERIALIZED There are no arguments to this option. This option sets the threading mode to Serialized. In other words, this option enables all mutexes including the recursive mutexes on database connection and prepared statement objects. In this mode (which is the default when SQLite is compiled with SQLITE_THREADSAFE=1) Final considerations Sqlite is builded with flag THREADSAFE=1 we can check with the query "PRAGMA compile_options;", all mutex are enabled and for default configuration thread mode is SQLITE_CONFIG_SERIALIZED. Until the timeout Sqlite retry to write. For my case I changed to timeout to 5 minute i haved limited the transaction to strictly necessary, because the transaction locks all. In addition PRAGMA journal_mode=WAL; is useful for multithreading. The global QMutex is not necessary.

I think you have a use case that shows the limit of the current implementation. You should open a bug report to explain your situation and issue.

@Perdrix Sorry to come later on this. But there is an interesting note about this in documentation of QPalette: Note that we do not use the Link and LinkVisited roles when rendering rich text in Qt, and that we recommend that you use CSS and the QTextDocument::setDefaultStyleSheet() function to alter the appearance of links. For example: QTextBrowser browser; QColor linkColor(Qt::red); QString sheet = QString::fromLatin1("a { text-decoration: underline; color: %1 }").arg(linkColor.name()); browser.document()->setDefaultStyleSheet(sheet);

Thank you for all your support guys! Everything is much more clear now!

@jsulm , thank you, thats what I'm looking at implementing now.

@JoeCFD said in QTextStream question: std::cout << qPrintable( QString( "%1." ).arg( a, 2, 10, QChar( '0' ) ) ) << qPrintable( QString( "%1" ).arg( b, 2, 10, QChar( '0' ) ) ) << std::endl; Compare your statement with mine if I define a simple macro: #define co(width, what) qSetPadChar('0') << qSetFieldWidth(width) << what << qSetFieldWidth(0) Then: "01.02" output is much simpler: cout << co(2,a) << co(0,'.') <<co(2, b) << Qt::endl;