I've decided no to use OpenCV. I will use the QCamera class. Everything is working perfect to this moment. I can capture and save images wherever I want, but the problem is how I can set the camera to a label or graphics view?
I mean, to see what is happening at the moment. When I make infinite loop everything crashes. Write any information you know, cause there are no examples how to do that, or I just can't see. If you can please write some source code.
Use QCameraVievFinder or QVideoWidget widgets ( docs - here) for that purpose, here is example for you:
#include <QCameraViewfinder>
// .......
QCamera *camera=new QCamera(this);
QCameraViewfinder *viewfinder = new QCameraViewfinder(this);
viewfinder->setSizePolicy(QSizePolicy::Maximum,QSizePolicy::Maximum);
camera->setViewfinder(viewfinder);
setCentralWidget(viewfinder);
//viewfinder->show();
camera->start(); // to start the viewfinder
Note: you need to add to your *,pro file this config to use them: QT += multimedia multimediawidgets
If you want a bit more low level widget (to process every frame the way you like (face detection etc), subclass QAbstractVideoSurface, docs - here
or try to connect to QVideoProbe class (docs - here), though i could not do it myself, this class is a bit experimental i guess, didn't worked
Related
I did some survey, if it might be possible to use QtTest to test some of my custom Qt Widgets.
I was able to build and run tests and I was also able to simulate events and check them with QSignalSpy.
The widgets I'm going to tests are not revealing their internal subwidgets, so that I have to simulate the positions of my mouse clicks relative to their parent widget.
For some reason I'm failing with this approach. The following snippet shows what I'm trying to achieve.
auto button=new QPushButton("Hello");
auto grpBox = new QGroupBox("Group Box");
grpBox->setLayout(new QVBoxLayout);
grpBox->layout()->addWidget(button);
QSignalSpy spy(button, &QPushButton::clicked);
grpBox->show();
QTest::mouseClick(button, Qt::MouseButton::LeftButton);
QTest::mouseClick(grpBox, Qt::MouseButton::LeftButton, Qt::KeyboardModifier::NoModifier, QPoint(250,70));
QCOMPARE(spy.count(), 2); // 1!=2
The first click is considered correctly, whereas the second one vanishes somehow. Why is that?
I'm wondering, if I really understood how to use the framework correctly, as dealing with mouse positions, seems to be too tedious and fragile for a practical test framework.
Revision:
It's obvious that using coordinates in a GUI test are very fragile. Hence, I found a solution utilizing findChild that actually does the same thing.
auto button=new QPushButton("Hello");
button->setObjectName("PushButton");
auto grpBox = new QGroupBox("Group Box");
grpBox->setLayout(new QVBoxLayout);
grpBox->layout()->addWidget(button);
QSignalSpy spy(button, &QPushButton::clicked);
grpBox->show();
QTest::mouseClick(button, Qt::MouseButton::LeftButton);
if (auto btn = grpBox->findChild<QPushButton*>("PushButton")) {
QTest::mouseClick(btn, Qt::MouseButton::LeftButton, Qt::KeyboardModifier::NoModifier);
} else {
QVERIFY(false);
}
QCOMPARE(spy.count(), 2);
This combines two advantages. Firstly, it is no longer necessary to deal with coordinates and secondly you still doesn't need to touch the code of the widgets you are going to test.
For this approach it seems to be advantageous, if every gui element has a unique objectName() supporting an easy search mechanism.
What is an optimal and an appropriate way to save the state of a Qt GUI so I get the same state I had back when I closed the application ?
By state I mean : current indexes (for combo box ...), color palette, widgets positions... right before closing the application
You can use the QSettings class.
Simple use of QSettings class (code inspired from Qt's documentation):
In the main-window of your application code member functions that saves and restore the settings:
void MainWindow::writeSettings()
{
QSettings settings("reaffer Soft", "reafferApp");
settings.beginGroup("MainWindow");
settings.setValue("size", size());
settings.setValue("pos", pos());
settings.endGroup();
}
void MainWindow::readSettings()
{
QSettings settings("reaffer Soft", "reafferApp");
settings.beginGroup("MainWindow");
resize(settings.value("size", QSize(400, 400)).toSize());
move(settings.value("pos", QPoint(200, 200)).toPoint());
settings.endGroup();
}
Call those 2 functions from the MainWindow constructor and from the closeEvent override, like this:
MainWindow::MainWindow()
{
// code from constructor
//...
readSettings();
}
void MainWindow::closeEvent(QCloseEvent *event)
{
//optional check if the user really want to quit
// and/or if the user want to save settings
writeSettings();
event->accept();
}
The direct answer requires specific elaborated design for your code and not really a short Qt question or even the question specific to Qt. That is about C++ which is not the VM-based language that assists with serializing the state of program code to data. Having all objects serializable we can then attempt to apply certain C++/Qt classes/techniques.
This task is much easier to accomplish with languages like Java, though. And with C++/Qt you have to routinely make serialize-able / serialize / restore everything that is running in your code and still no guarantee that works as long as the context is not fully captured. This task is not easy for sure and makes sense only in specific application.
The most you can get directly from Qt is to save/restore QMainWindow and other independent widgets geometry (position/size):
saveGeometry
restoreGeometry
... and that solution is still somewhat incomplete or you may/not use QSettings for the storage.
I use QSettings for this. With routines similar to Zlatomir's.
For each window I have in the project I use a different section in QSettings and have readSettings() and writeSettings() in the source for each window.
Anything on the form that I want to persist I have to explicitly save and recall. In the case of a QComboBox it would be something like:
QSettings settings("Organisation", "MySoftware");
settings.beginGroup("WindowNumberTwo");
settings.setValue("ComboIndex", combobox->currentIndex());
// save more values here
// ...
settings.endGroup();
I don't know of a built in way to persist your window states - it has to be don't value by value.
I am trying to play a sound with QSound module.
It try with this code and works:
QSound::play(":/sounds/sources/BeepSound.wav");
But I want this and doesn't work:
I create a dynamic instance of QSound and played:
sounds = new QSound(":/sounds/sources/BeepSound.wav");
sounds->setLoops(3);
sounds->play();
Any tips?
Update
I don't want to use others modules like QMediaPlayer, QAudioOutput because I want something really simple, just play a sound.
I've just started with Qt. I saw some articles, but don't understand one thing.
Here it is.
At this link filesTable comes from nowhere. I don't understand where it was inited?
Another example.
void MainWindow::on_pushButton_clicked()
{
ui->tableWidget->setColumnCount('');
ui->tableWidget->setRowCount('');
}
What is
tableWidget
? I mean, how I can create it?
Sorry for such question. I have to.
filesTable could be a member variable declared in the header file. If you're new to C++, you should probably start by learning C++ first, and then start using Qt.
tableWidget is a variable that points to a QTableWidget type object, which was created in the Qt Designer. It was declared somewhere in the ui header file, for example ui_mainwindow.h. This is a file that is usually auto generated by Qt Creator.
this generates a segmentation fault becuase of "QColor colorMap[9]";. If I remove colorMap the segmentation fault goes away. If I put it back. It comes back. If I do a clean all then build all, it goes away. If I increase its arraysize it comes back. On the other hand if I reduce it it doesnt come back. I tired adding this array to another project and
What could be happening. I am really curious to know. I have removed everything else in that class. This widget subclassed is used to promote a widget in a QMainWindow.
class LevelIndicator : public QWidget
{
public:
LevelIndicator(QWidget * parent);
void paintEvent(QPaintEvent * event );
float percent;
QColor colorMap[9];
int NUM_GRADS;
};
the error happens inside ui_mainwindow.h at one of these lines:
hpaFwdPwrLvl->setObjectName(QString::fromUtf8("hpaFwdPwrLvl"));
verticalLayout->addWidget(hpaFwdPwrLvl);
I know i am not providing much but I will give alink to the app. Im trying to see if anyone has a quick answer for this.
If I do a clean all then build all, it goes away.
This makes it sound as though your build system isn't recognizing a dependency and that a change to that class definition isn't triggering a rebuild of something that should be recompiled when the definition changes.
Make sure class LevelIndicator is defined in exactly one place (generally that would be a header file that gets included by whatever modules need to use a LevelIndicator object). Also make sure that any global/static instances of LevelIndicator objects are following the one definition rule.
Firstly it might not be QColor, that may simply be changing the memory layout enough that a buffer overrun somewhere else triggers a segfault - try a different size QColor ..[1] for example.
Can QColor be used as an array like this, does it have the correct default ctor?