If you’re coming here from Google and not having luck with the accepted answer, that’s because you’re missing the other secret invocation: QScrollArea::setWidget. You must create and explicitly identify a single widget which is to be scrolled. It’s not enough to just add the item as a child! Adding multiple items directly to the ScrollArea … Read more
I think Qt stores the slots a given signal is connected to, so that when you emit it all receivers are called, therefore you can access the list of receivers: For debugging purposes, you have: void QObject::dumpObjectInfo () Dumps information about signal connections, etc. for this object to the debug output. This function is useful … Read more
I’ve had the same problem, the Qt documentation is providing a pretty good answer: http://doc.qt.io/qt-5/qml-qtquick-loader.html#using-a-loader-within-a-view-delegate The easiest solution is an inline Component with a Loader to set a source file: ListView { id: contactsView anchors.left: parent.left anchors.top: parent.top width: parent.width height: parent.height orientation: Qt.Vertical spacing: 10 model: contactsModel delegate: Component { Loader { source: switch(position) … Read more
Thanks for the answers, but I finally revisited this problem and came up with a rather simple solution that gives good performance. It involves deriving from QGLWidget and overriding the paintEvent() function. Inside the paintEvent() function, you can call QPainter::drawImage(…) and it will perform the scaling to a specified rectangle for you using hardware if … Read more
I think you need to subclass QItemDelegate. QItemDelegate can be used to provide custom display features and editor widgets for item views based on QAbstractItemView subclasses. Using a delegate for this purpose allows the display and editing mechanisms to be customized and developed independently from the model and view. This code is taken from Qt’s … Read more
I got same problem, it was from opencv-python version problem for me. My Linux machine’s environment is as following: $ cat /etc/lsb-release … DISTRIB_DESCRIPTION=”Ubuntu 18.04.5 LTS” $ date Tue Aug 11 11:43:16 KST 2020 $ python –version Python 3.7.8 $ pip list|grep Qt PyQt5 5.15.0 PyQt5-sip 12.8.0 $ pip list|grep opencv-python opencv-python 4.3.0.38 I downgraded … Read more
Depending on your build system it’s either in your qmake project file(.pro, standard for new projects) or in one of the CMake files (CMakeLists.txt, used by KDE and several other projects). Using .pro: QMAKE_CXXFLAGS += -O2 Using CMake: set( CMAKE_CXX_FLAGS “-g -Wall”)
High DPI support is enabled from Qt 5.6 onward. Setting QGuiApplication::setAttribute(Qt::AA_EnableHighDpiScaling) in your application source code allows automatic high-DPI scaling. NOTICE: To use the attribute method, you must set the attribute before you create your QApplication object: #include <QApplication> int main(int argc, char *argv[]) { QApplication::setAttribute(Qt::AA_EnableHighDpiScaling); QApplication app(argc, argv); return app.exec(); }
This problem was solved in Qt 5.2. The cute solution is: QSizePolicy sp_retain = widget->sizePolicy(); sp_retain.setRetainSizeWhenHidden(true); widget->setSizePolicy(sp_retain); http://doc.qt.io/qt-5/qsizepolicy.html#setRetainSizeWhenHidden
Simple, but complete example showing how to display QImage might look like this: #include <QtGui/QApplication> #include <QLabel> int main(int argc, char *argv[]) { QApplication a(argc, argv); QImage myImage; myImage.load(“test.png”); QLabel myLabel; myLabel.setPixmap(QPixmap::fromImage(myImage)); myLabel.show(); return a.exec(); }