can I force my Qt application to use different look and feel just like it is done in KDE ?
You can always change styles of widgets using QApplication::setStyle.
There are a few predefined options available in Qt4.
In main.cpp do something like this
#include <QPlastiqueStyle>
int main(int argc, char *argv[])
{
[...]
QApplication::setStyle(new QPlastiqueStyle());
}
This way your application will alwyas look the same on different OS.
In my opinion Plastique looks better under windowsXP/2000 then default QWindowsXPStyle.
Cleanlooks is quite nice too.
There are other options:
#include <QPlastiqueStyle>
#include <QCleanlooksStyle>
#include <QWindowsXPStyle>
#include <QWindowsVistaStyle>
#include <QMotifStyle>
#include <QCDEStyle>
I hope this helps.
You can use CSS to style widgets https://doc.qt.io/qt-5/stylesheet.html
Related
Having trouble adding background image on the widget, even though I referenced the recent codes online.
This is my current code for main.cpp:
#include <QApplication>
#include <QWidget>
int main (int argc, char **argv){
QApplication app (argc,argv);
QWidget *w=new QWidget();
w->setStyleSheet("background-image: url(:/cover.jpg);");
w->setWindowTitle("Test");
w->show();
return app.exec();
}
After executing the code, how come the widget remains blank? Thanks in advance!
QtCreator is an IDE designed by Qt. It's just an interface.
I checked your implementation and I don't see anything wrong. It also work well on my pc. Can you check your image url or try with another image ?
Btw, if you're on linux, try removing : character after url ;
w->setStyleSheet("background-image: url(/cover.jpg);");
EDİT:
If jpg is in the same directory with your application, it should be ;
w->setStyleSheet("background-image: url(./cover.jpg);");
You can give a full path to avoid this kind of errors.
"Is it possible to add background image on QWidget without using QtCreator?"
Yes, of course it is.
QtCreator is just an IDE. You don't need to use it at all to write code using the Qt library.
Just as you can use it to write code that does not use Qt at all.
I'm simply looking for a quick and easy solution on how to change the default source code (if at all possible) for when you open a qtCreator C++ project.
As soon as you open up a new project you see something like below in your main.cpp file.
#include <QCoreApplication>
int main(int argc, char *argv[]) {
QCoreApplication a(argc, argv);
return a.exec(); }
I'm wondering if there's a way to change this code snippet to user defined code. I personally just think its a hassle to wipe all this code out every time I create a project and would rather it look something like below, when I make a new project.
#include <QCoreApplication>
#include <iostream>
using namespace std;
int main() {
}
Anyways, open to all different types of solutions just let me know...
I'm trying hardly to convert the Modbusmaster example (qt example) which is a widget application to a console application. I wanted to build a connection between a local slave and my master. The problem I'm facing is that my code is changing its state to “Connecting state” ,gets stuck and doesn't want to build a connection. That's why, I recon that the Modbus library is limited and it's only compatible with the widget form.
Could someone tell me if my guesses are right.
down below you will find my code:
#include <QCoreApplication>
#include <QDebug>
#include <QModbusDataUnit>
#include<iostream>
#include <QTimer>// this bib was add to the 50ms Loop check
#include <string>
#include <QString>
#include <QThread>
#include <QModbusTcpClient>
#include <QModbusDataUnit>
#include <QUrl>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
Mainmodbus T ;
T.modbusDevice = new QModbusTcpClient();
if (!T.modbusDevice) qDebug()<<"error 1";
if (T.modbusDevice->state() != QModbusDevice::ConnectedState) {
T.modbusDevice->setConnectionParameter(QModbusDevice::NetworkAddressParameter, "127.0.0.1");
T.modbusDevice->setConnectionParameter(QModbusDevice::NetworkPortParameter, 502);
T.modbusDevice->connectDevice();
while(true){
qDebug()<<T.modbusDevice->state();}
}
return a.exec();
}
I can be wrong but I think the QModbusDevice::ConnectingState you see actually means your server is up and running and waiting for a connection.
I guess what you are missing is opening a connection from a Modbus client. You can do that with different tools, I guess running the client example
would be a good idea. Otherwise, you can use QModMaster or any other tool you like.
Once you open the connection from the client the state on your server should change to QModbusDevice::ConnectedState.
Be aware that the server you built is just an empty shell, there is no register map defined so if you query the contents of any register from the client you will get an error.
At the very minimum, you should at least define a map with some default values or get them from command-line options. To do that you need to look at the server example a bit more carefully.
First you need to define the register map with something like this:
QModbusDataUnitMap reg;
reg.insert(QModbusDataUnit::Coils, { QModbusDataUnit::Coils, 0, 10 });
reg.insert(QModbusDataUnit::DiscreteInputs, { QModbusDataUnit::DiscreteInputs, 0, 10 });
reg.insert(QModbusDataUnit::InputRegisters, { QModbusDataUnit::InputRegisters, 0, 10 });
reg.insert(QModbusDataUnit::HoldingRegisters, { QModbusDataUnit::HoldingRegisters, 0, 10 });
modbusDevice->setMap(reg);
setupDeviceData();
And then for the setupDeviceData(); you can copy the function in the example but instead of taking the data from the widget, you will have to load default values or something from the command line.
In answer to your question: no, there should be no limitation and you should be able to run the server from the command line. I wonder why somebody on his/her right mind would want to do that when you have excellent alternatives like libmodbus. But honestly, I won't miss much sleep wondering.
Goal
For documentation purposes I would like to export a C++ code snippet from QtCreator as an HTML file and then use CSS to highlight its syntax, for example like that:
Since QtCreator does not have an export option, I am using QDoc to achieve that.
As per documentation, I use \quotefile in a qdoc-file in my project to turn the source code from main.cpp into an HTML:
/*!
\page index
\quotefile main.cpp
*/
Running qdoc produces an index.html and when I open it, there is indeed the marked-up content of main.cpp.
Note: To demonstrate the issue I am using the code from the documentation:
#include <QApplication>
#include <QPushButton>
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QPushButton hello("Hello world!");
hello.resize(100, 30);
hello.show();
return app.exec();
}
Problem
When I inspect the produced html code in the browser, for the hello( part for example, I get:
hello(
When I inspect the html code of the documentation however, which I believe is generated with the help of QDoc as well, for the same part I see:
<span class="pln"> hello</span>
I do not know why in my case the additional markup is missing.
Question
How to setup QDoc so, that I can specify the rules of how each part of the code snippet should be marked up?
We have an application (QCoreApplication) that takes some images as input, does something to them, and exports them again. We now need to add some text to the images, and tried to do this with the QPainter class. It all worked well when using it in one of our other apps (using QApplication), but not in our main QCoreApplication app.
Here is the code:
void drawTextOnImage(QImage* image, const QString& text, const QFont& font)
{
QPainter p;
if (!p.begin(image)) return;
p.setFont(font);
p.drawText(image->rect(), Qt::AlignLeft | Qt::AlignTop | Qt::TextWordWrap, text);
p.end();
}
The application crashes on the drawText line.
Any ideas?
It is a very simple text, so suggestions without using Qt will also be appreaciated.
When using classes from "Qt Gui" like QPainter, you are supposed to use a QGuiApplication, not a QCoreApplication.
You might get lucky and be able to make some GUI stuff works while using only a QCoreApplication. But as you have discovered, it makes your application very brittle. Some classes like QPixmap will print an error message, but others will just crash.
The same is applicable with "Qt Widget": if you use a widget related class, you must use a QApplication.
Note that since QApplication inherits QGuiApplication, if you have a QApplication you can use "Qt Gui".
In case you need to run a non-GUI application on something without a windowing system, you need, aside from creating an instance of QGuiApplication, to also choose an appropriate Qt platform.
For me, offscreen platform worked fine. I was generating images with textual elements and saving them to files on a headless Raspberry Pi. My code then was like the example below. Note that setenv is a POSIX function and may need a replacement on Windows, though I'm not sure whether windowless Windows is a thing at all.
#include <stdlib.h>
#include <QImage>
#include <QPainter>
#include <QGuiApplication>
int main(int argc, char** argv)
{
setenv("QT_QPA_PLATFORM","offscreen",1);
QGuiApplication app(argc,argv);
QImage img(128,128, QImage::Format_RGB888);
img.fill(Qt::white);
QPainter p(&img);
p.drawText(QPoint(0,64), "Works!");
img.save("/tmp/test.png");
}