QtVirtualKeyboard在QTableView单元格编辑时的焦点与触发问题

Let's tackle these two issues one by one—they're both rooted in focus management and how Qt Virtual Keyboard integrates with QTableView's editor widgets.

Issue 1: Cell loses focus when tapping virtual keyboard keys, with "InputContext::sendKeyClick(): no focus to send key click" error #

This happens because the QQuickWidget hosting your virtual keyboard is stealing focus from the table cell's editor whenever you tap a key. The input context can't find a focused input control to send key events to, hence the error.

Fix Steps: #

1. Prevent QQuickWidget from grabbing focus
   When initializing the QQuickWidget that loads your virtual keyboard QML, set its focus policy to avoid competing with the cell editor:

   QQuickWidget *keyboardWidget = new QQuickWidget(this);
   keyboardWidget->setFocusPolicy(Qt::NoFocus); // Critical line to keep focus on the editor
   keyboardWidget->setSource(QUrl("qrc:/virtualkeyboard.qml"));
   // Add to your layout as usual
   

2. Disable focus on the virtual keyboard QML component
   In your virtualkeyboard.qml, ensure the InputPanel doesn't request focus, so it never takes focus away from the cell editor:

   import QtQuick 2.15
   import QtQuick.VirtualKeyboard 2.15
   
   InputPanel {
       id: inputPanel
       anchors.fill: parent
       visible: inputMethod.visible
       focus: false // Don't let the keyboard claim focus
   }
   

3. Force focus on the cell editor when created
   Override your QTableView's createEditor method to explicitly set focus on the editor, ensuring the input context tracks it correctly:

   QWidget *CustomTableView::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
   {
       QWidget *editor = QTableView::createEditor(parent, option, index);
       if (editor) {
           editor->setFocus(); // Ensure the editor holds focus
       }
       return editor;
   }
   

Issue 2: Virtual keyboard only appears on double-click, not single-click (even with editTriggers = CurrentChanged) #

Setting editTriggers to CurrentChanged enables single-click editing, but the virtual keyboard relies on detecting a focus change in an input widget to show up. Sometimes this focus transition isn't automatically picked up by the input context.

Fix Steps: #

1. Manually trigger the keyboard when editing starts
   Extend the createEditor override from Issue 1 to explicitly show the input method when the editor is created:

   QWidget *CustomTableView::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
   {
       QWidget *editor = QTableView::createEditor(parent, option, index);
       if (editor) {
           editor->setFocus();
           QGuiApplication::inputMethod()->show(); // Force the keyboard to appear
       }
       return editor;
   }
   

2. Verify edit triggers configuration
   Double-check that your QTableView's edit triggers are correctly set (either in Qt Designer or code):

   ui->tableView->setEditTriggers(QAbstractItemView::CurrentChanged | QAbstractItemView::DoubleClicked);
   

3. Ensure the QT_IM_MODULE variable is set early
   Set the environment variable before initializing QApplication in main.cpp—system-level variables might not always propagate correctly to the app:

   int main(int argc, char *argv[])
   {
       qputenv("QT_IM_MODULE", QByteArray("qtvirtualkeyboard")); // Set this first
       QApplication app(argc, argv);
       // Rest of your app initialization
       return app.exec();
   }
   

Additional Checks #

• Make sure your .pro file includes all required modules:

  QT += core gui widgets quickwidgets virtualkeyboard
  

• Test the virtual keyboard with a simple QLineEdit first to confirm it works with basic input widgets—this helps rule out QTableView-specific conflicts.

内容的提问来源于stack exchange，提问作者Simpsons