i'm following a tutorial to write a small piece of code of opengl in qt.here's the link
http://www.youtube.com/watch?v=1nzHSkY4K18
but in the 6:13 when I bluid the code it show a couple of error that
..\testopgl\glwidget.cpp: In member function 'virtual void GLWidget::paintGL()':
..\testopgl\glwidget.cpp:17:20: error: 'glColor3f' was not declared in this scope
..\testopgl\glwidget.cpp:19:25: error: 'glBegin' was not declared in this scope
..\testopgl\glwidget.cpp:20:31: error: 'glVertex3f' was not declared in this scope
..\testopgl\glwidget.cpp:23:11: error: 'glEnd' was not declared in this scope
..\testopgl\glwidget.cpp: At global scope:
what I really don't understand is when I only put the glClear(GL_COLOR_BUFFER_BIT) it builds alright,but occurs error even i just put the glColor3f().Does the GLWidget not support the glColor*() or glBegin() command?
here's my code.
testopgl.pro
#-------------------------------------------------
#
# Project created by QtCreator 2013-03-28T09:48:44
#
#-------------------------------------------------
QT += core gui opengl
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = testopgl
TEMPLATE = app
SOURCES += main.cpp\
mainwindow.cpp \
glwidget.cpp
HEADERS += mainwindow.h \
glwidget.h
FORMS += mainwindow.ui
glwidget.h
#ifndef GLWIDGET_H
#define GLWIDGET_H
#include <QGLWidget>
class GLWidget : public QGLWidget
{
Q_OBJECT
public:
explicit GLWidget(QWidget *parent = 0);
void initializeGL();
void paintGL();
void resizeGL(int w,int h);
};
#endif // GLWIDGET_H
glwidget.cpp
#include "glwidget.h"
GLWidget::GLWidget(QWidget *parent) :
QGLWidget(parent)
{
}
void GLWidget::initializeGL(){
glClearColor(1,1,0,1);
}
void GLWidget::paintGL(){
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1,0,0);
glBegin(GL_TRIANGLES);
glVertex3f(-0.5,-0.5,0);
glVertex3f(0.5,-0.5,0);
glVertex3f(0.0,0.5,0);
glEnd();
}
void GLWidget::resizeGL(int w,int h){
}
The functions you mention are simply not present in any modern version of GL, so the tutorial you are following sounds like it is quite out of date.
So probably the version of GL exposed through your build of QT does not have these functions. It may be possible to reconfigure/rebuild QT to use an older version of GL, but I would instead recommend getting to know and use the modern programmable interface.
Related
Anyone got QT 5.6 working with OpenCV ?
Tried OpenCV latest 2.4.13 (at time of writing) and went back to OpenCV 2.4.9.
None worked - program will compile, link but crash on "During Startup program exited with code 0xc0000139". I never had any problems with QT 5.5.1 and OpenCV.
Here is stripped down code:
**mainwindow.cpp:**
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <opencv/cv.h>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
cv::Mat image = cv::imread("C:/Users/foo/pics/cheetah.jpg");
cv::namedWindow("My Image");
cv::imshow("My Image", image);
cvWaitKey(0);
}
MainWindow::~MainWindow()
{
delete ui;
}
**main.cpp (used default):**
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
**mainwindow.h: (used default)**
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
**test_opencv.pro:**
INCLUDEPATH += "C:\Users\foo\Downloads\opencv\build\include"
LIBS += -LC:\Users\foo\Downloads\opencv\build\lib \
-lopencv_core249.dll \
-lopencv_highgui249.dll \
-lopencv_imgproc249.dll \
-lopencv_features2d249.dll \
-lopencv_video249.dll \
-lopencv_calib3d249.dll
QT += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = test_opencv
TEMPLATE = app
SOURCES += main.cpp\
mainwindow.cpp
HEADERS += mainwindow.h
FORMS += mainwindow.ui
Path set:
C:\Qt\Tools\mingw492_32\bin
C:\Qt\5.6\mingw49_32\bin
C:\Users\foo\Downloads\opencv\build\bin
QT works fine with no OpenCV calls. With above code, running with QT Debug will see this:
"During Startup program exited with code 0xc0000139".
QT Error message
I have double checked my path. The OpenCV DLLs are defined in the Path. problem is not about not finding the runtime dynamically link dlls. I also checked my System32 and other directories for any old OpenCV dlls that might interfere as the path is traversed. No issues.
OpenCV was built with CMake and successfully build and installed. No issues there.
Thanks
Sean
I am brand new to programming with Qt. I'm trying to do a simple subtraction of some values fed from an epicsQt widget called QELabel, which simply reads the value of an EPICS channel. I want to subtract values from two QELabels and print it to another QELabel. But, I'm getting 'undefined reference to' errors for these ->
MainWindow::on_qeLabel_dbValueChanged(QString const&) MainWindow::on_ShutterOpen_dbValueChanged(QString const&)
Here is the bit of mainwindow.cpp (I followed the example from this youtube video, especially after about the 15 minute mark)
void MainWindow::on_TopShutter_dbValueChanged(const QString &out)
{
double top,bottom,open;
top=ui->TopShutter->text().toDouble();
bottom=ui->BottomShutter->text().toDouble();
open=top-bottom
ui->ShutterOpen->setText(Qstring::number(open));
}
I'm using QTCreator, so I don't have the usual errors that I've been seeing in other forums. I have the slot declared in the header file, and MainWindow set as a Q_Object (this is the whole mainwindow.h file):
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void on_qelabel_dbValueChanged(const QString &out);
void on_ShutterOpen_dbValueChanged(const QString &out);
void on_TopShutter_dbValueChanged(const QString &out);
private:
Ui::MainWindow *ui;
};
#endif //MAINWINDOW_H
Because they are short, and for completeness, here is the main.cpp, and then the .pro
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
And the FirstWeatherAlarm.pro:
#-------------------------------------------------
QT += core gui xml
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = FirstWeatherAlarm
TEMPLATE = app
SOURCES += main.cpp\
mainwindow.cpp
LIBS += -L/usr/lib64/qt5/plugins/designer -lQEPlugin
INCLUDEPATH += /home/jchavez/epicsqt/3.1.0/framework/include
HEADERS += mainwindow.h
FORMS += mainwindow.ui
Have I got everything declared right at the start of all the files? What is missing so that my slots are not right? I created the slot in the gui, using the "right-click" on my QELabel, and selecting "Go to Slot", so I should think all the formatting would be correct. As I've been editing, I've also run qmake and make clean which are other answers I've seen on forums. But nothing is working.
The problem is with two slots:
MainWindow::on_qeLabel_dbValueChanged(QString const&)
MainWindow::on_ShutterOpen_dbValueChanged(QString const&)
They are declared in MainWindow.h file and used somewhere in your project (otherwise you won't get an error).
But they are not implemented in mainwindow.cpp. You should add implementation to this file and the error will go away.
You have implementation for
void MainWindow::on_TopShutter_dbValueChanged(const QString &out)
in mainwindow.cpp, you can add implementation for two more slots. Think about slot as a function. And read more about signals/slots.
#include <QtCore/QCoreApplication>
#include <QTCore>
#include <QtNetwork>
#include <QDebug>
#define CONNECT(sndr, sig, rcvr, slt) connect(sndr, SIGNAL(sig), rcvr, SLOT(slt))
class mynet : QObject
{
Q_OBJECT
public:
mynet()
{}
void start()
{
CONNECT(tcpServer, newConnection(), this, acceptConnection());
CONNECT(tcpClient, connected(), this, startTransfer());
CONNECT(tcpClient, bytesWritten(qint64), this, updateClientProgress(qint64));
CONNECT(tcpClient, error(QAbstractSocket::SocketError), this, displayError(QAbstractSocket::SocketError));
// start server listening
tcpServer->listen();
while(!tcpServer->isListening());
// make client connection
tcpClient->connectToHost(QHostAddress::LocalHost, tcpServer->serverPort());
}
public slots:
void acceptConnection()
{
tcpServerConnection = tcpServer->nextPendingConnection();
CONNECT(tcpServerConnection, readyRead(), this, updateServerProgress());
CONNECT(tcpServerConnection, error(QAbstractSocket::SocketError), this, displayError(QAbstractSocket));
tcpServer->close();
}
void startTransfer()
{
bytesToWrite = TotalBytes - (int)tcpClient->write(QByteArray(PayloadSize, '#'));
}
void updateServerProgress()
{
bytesReceived += (int)tcpServerConnection->bytesAvailable();
tcpServerConnection->readAll();
if (bytesReceived == TotalBytes)
{
qDebug() << "done";
tcpServerConnection->close();
}
}
void updateClientProgress(qint64 numBytes)
{
// callen when the TCP client has written some bytes
bytesWritten += (int)numBytes;
// only write more if not finished and when the Qt write buffer is below a certain size.
if (bytesToWrite > 0 && tcpClient->bytesToWrite() <= 4*PayloadSize)
bytesToWrite -= (int)tcpClient->write(QByteArray(qMin(bytesToWrite, PayloadSize), '#'));
}
void displayError(QAbstractSocket::SocketError socketError)
{
if (socketError == QTcpSocket::RemoteHostClosedError)
return;
qDebug() << tcpClient->errorString();
tcpClient->close();
tcpServer->close();
}
private:
QTcpServer* tcpServer;
QTcpSocket* tcpClient;
QTcpSocket* tcpServerConnection;
int bytesToWrite;
int bytesWritten;
int bytesReceived;
int TotalBytes;
int PayloadSize;
};
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
mynet m1;
m1.start();
return a.exec();
}
I get an
Undefined symbols for architecture x86_64:
"vtable for mynet", referenced from:
mynet::mynet() in main.o
mynet::~mynet()in main.o.
Please advise what I am doing wrong. Can I not inline the method definitions in the class for some reason in Qt?
You need to add your class to the .pro file
HEADERS += mynet.h
SOURCES += mynet.cpp
so the meta-object compiler can scan them and work out they need moc'ing and generate the relevant stubs.
Assuming that your source file is named foo.cpp, you have to put the following line at the very end:
#include "foo.moc"
This line tells qmake and the VS Qt add-in that the file should be run via moc, and that the generated moc file should be named foo.moc.
You also have problems in the #include lines for Qt headers. I've found that the following work:
#include <QtCore/QCoreApplication>
#include <QtNetwork/QTcpServer>
#include <QtNetwork/QTcpSocket>
Make sure to add network to your .pro file. This will create the correct linking to the network library functions.
QT += core network
Two things:
1) You should publicly derive from QObject.
2) Are you moc'ing this file and then compiling and linking the output? If you include the Q_OBJECT macro and don't moc, you will get an error like that.
I'm trying to use a Singleton Class (its a program-wide debug logger called 'PrisLog') across my Qt Application. The program also has plugins. I want to make my singleton class available to those plugins, but this doesn't work. From what I can tell, trying to use the class in the plugin results in another instance being created.
-The singleton class is just a *.cpp and *.h file, nothing else. I've linked both my main application and the plugin to these files individually... is this the right way to do it?
-I've attached my singleton class's code below, though I think I've created the class correctly. If I use it from within separate classes in my main application, it works as expected (one instance).
EDIT: Linking both the application and plugin to the same static lib (the singleton class) works. Here's how my qmake *.pro files looked:
MySingletonLib.pro
TEMPLATE = lib
CONFIG += staticlib
HEADERS += \
mysingletonlib.h
SOURCES += \
mysingletonlib.cpp
MyPlugin.pro (also incl #include mysingletonlib.h in myplugin.h)
INCLUDEPATH += path/to/MySingletonLib
LIBS += -Lpath/to/MySingletonLib -lMySingletonLib
MyPlugin.pro (also incl #include mysingletonlib.h in myapp.h)
INCLUDEPATH += path/to/MySingletonLib
LIBS += -Lpath/to/MySingletonLib -lMySingletonLib
And the original code:
#ifndef PRISLOG_H
#define PRISLOG_H
#include <QFile>
#include <QDir>
#include <QString>
#include <QMutex>
#include <QDebug>
#include <QMutexLocker>
#include <QTextStream>
#include <QDateTime>
// PrisLog (singleton) class definition
class PrisLog
{
public:
static PrisLog* Instance();
void SetLogsPath(QString);
QString GetLogsPath();
void SetDebugDestination(QString);
void SetElmRxDestination(QString);
void SetElmTxDestination(QString);
void SetDlgDestination(QString);
QTextStream* GetDebugStream();
QTextStream* GetElmRxStream();
QTextStream* GetElmTxStream();
QTextStream* GetDlgStream();
QMutex* GetDebugMutex();
private:
PrisLog(); // private constructor
PrisLog(const PrisLog&); // prevent copy constructor
PrisLog& operator=(const PrisLog&); // prevent assignment
static PrisLog* m_Instance;
static bool m_InitFlag;
QString m_appPath;
QFile m_DebugFile;
QTextStream m_DebugStream;
QMutex m_DebugMutex;
QFile m_ElmRxFile;
QTextStream m_ElmRxStream;
QFile m_ElmTxFile;
QTextStream m_ElmTxStream;
QFile m_DlgFile;
QTextStream m_DlgStream;
};
// thread-UNSAFE writer, but less expensive
// use: single stream <--> single thread!
class PrisLogWriter
{
public:
PrisLogWriter(QTextStream*);
~PrisLogWriter();
QTextStream* m_stream;
};
// thread-UNSAFE writer, but less expensive
// this version does not include any formatting
// use: single stream <--> single thread!
class PrisLogRawWriter
{
public:
PrisLogRawWriter(QTextStream*);
~PrisLogRawWriter();
QTextStream* m_stream;
};
// thread-safe writer
// use: single stream <--> many threads
class PrisLogSafeWriter
{
public:
PrisLogSafeWriter(QTextStream*, QMutex*);
~PrisLogSafeWriter();
QTextStream* m_stream;
private:
QMutex* m_mutex;
};
#define PRISLOGDEBUG (*(PrisLogSafeWriter(PrisLog::Instance()->GetDebugStream(), PrisLog::Instance()->GetDebugMutex()).m_stream))
#define PRISLOGELMRX (*(PrisLogWriter(PrisLog::Instance()->GetElmRxStream()).m_stream))
#define PRISLOGELMTX (*(PrisLogWriter(PrisLog::Instance()->GetElmTxStream()).m_stream))
#define PRISLOGDLG (*(PrisLogRawWriter(PrisLog::Instance()->GetDlgStream()).m_stream))
#endif // PRISLOG_H
I think you should take this class to a statically linked, but separeted shared dll/so.
If your host application does not use this class, the linker simply won't link it into the binary and your plugin could not use it. Additionally: your binary has no library class interface.
You need to make sure, that only one instance exists. The safest is, that the cpp is compiled only once in the overall exe.
To make sure that the other DLLs can call PrisLog::Instance, this class/function (i.e. all public methods if PrisLog) needs to be declared with __declspec(dllexport), even if it is located within the exe.
The DLLs can then dynamically find the object and method.
BTW: Why don't you use the logging from Qt?
I am trying to compile: http://wiki.forum.nokia.com/index.php/Fetching_a_map_tile_in_Qt_using_Google_Maps
I am using Qt-Mobility 1.2 with Qt 4.7 on OpenSuse 11.2
The errors I am receiving are:
MainWindow.h:7: error: ‘QtMobility’ is not a namespace-name
MainWindow.h:7: error: expected namespace-name before ‘;’ token
MainWindow.h:10: error: expected class-name before ‘{’ token
In file included from /opt/qtsdk-2010.05/qt/include/QtCore/qcoreapplication.h:47,
from /opt/qtsdk-2010.05/qt/include/QtGui/qapplication.h:45,
from /opt/qtsdk-2010.05/qt/include/QtGui/QApplication:1,
from main.cpp:2:
/opt/qtsdk-2010.05/qt/include/QtCore/qeventloop.h:51: error: expected initializer before ‘QtCoreModule’
make: *** [main.o] Error 1
My .pro file contains:
TEMPLATE = app
TARGET =
DEPENDPATH += .
INCLUDEPATH += .
HEADERS += MainWindow.h
SOURCES += main.cpp MainWindow.cpp
QT += network
CONFIG += mobility
MOBILITY = location
The error is reported in the header file, which I have shown as follows:
#include <QtNetwork/QNetworkAccessManager>
#include <QtNetwork/QNetworkReply>
#include <QPaintEvent>
#include <QPixmap>
using namespace QtMobility;
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow ();
void paintEvent(QPaintEvent* paintEvent);
public slots:
void handleNetworkData(QNetworkReply* reply);
private:
void fetchMap(const QSize& size, qreal latitude, qreal longitude);
private:
QNetworkAccessManager networkAccessManager;
QPixmap mapPixmap;
}
Please guide.
You'll need to include at least one QtMobility header to be able to use that namespace.
Also that using namespace declaration is not the recommended way anymore. Use:
QTM_USE_NAMESPACE
instead (see QtMobility QuickStart).