Qt 5.3 QWidget::paintEngine : Should no longer be called

问题

I'm moving my code from a Qt 4.x to Qt 5.3 and I am running into a weird Qt warning shown in the command prompt. There are no errors or anything but the command prompt will show the following:

QWidget::paintEngine: Should no longer be called
QPainter::begin: Paint device returned engine == 0, type: 1
QPainter::setClipRegion: Painter not active
QPainter::setClipRect: Painter not active

I believe I narrowed it down to one class: Header:

#pragma once

#include <QtCore\qmetaobject.h>
#include <QtWidgets\Qwidget.h>
#include <QtWidgets\Qslider.h>
#include <Qtwidgets\Qpushbutton.h>
#include <Qtwidgets\Qcheckbox.h>
#include "MyGLWindow.h"
#include <QtWidgets\QHboxLayout>
#include <QtWidgets\QVboxLayout>
#include <QtWidgets\qmenubar.h>
#include <QtWidgets\qlabel.h>

class MeWidg : public QGLWidget
{
public:
    QTimer myTimer;
    bool testToggle;
    float testRow;
    bool noToggle;

    MyGLWindow *gameGLWindow;
    MeWidg();
private:
    void myUpdate();
    void loadModel();
};

and Source:

#include "MeWidg.h"
#include "DebugMenu.h"

MeWidg::MeWidg()
{
QVBoxLayout* mainLayout=new QVBoxLayout();
setLayout(mainLayout);

QHBoxLayout* setUpLayout=new QHBoxLayout();

setWindowTitle("Game Creator");

QHBoxLayout *game =new QHBoxLayout();
gameGLWindow=new MyGLWindow();

debugMenu.initialize(setUpLayout);
debugMenu.addLayout("World");

QMenuBar* mb=new QMenuBar();
mb->setMaximumHeight(20);

QMenu* fileMenu = mb->addMenu("File");

QAction* action;
fileMenu->addAction(action = new QAction("Load Project", this));
//action->setShortcut(QKeySequence::Open);
//connect(action, SIGNAL(triggered()), this, SLOT(loadObj()));

fileMenu->addAction(action = new QAction("Save Project", this));
//action->setShortcuts(QKeySequence::Save);
//connect(action, SIGNAL(triggered()), this, SLOT(saveNative()));

fileMenu->addSeparator();

fileMenu->addAction(action = new QAction("Load level", this));
//action->setShortcuts(QKeySequence::Save);
//connect(action, SIGNAL(triggered()), this, SLOT(loadLVL()));

fileMenu->addAction(action = new QAction("Save Level", this));
//action->setShortcuts(QKeySequence::Save);
//connect(action, SIGNAL(triggered()), this, SLOT(saveNative()));

fileMenu->addSeparator();

fileMenu->addAction(action = new QAction("Close", this));
//action->setShortcuts(QKeySequence::Save);
//connect(action, SIGNAL(triggered()), this, SLOT(saveNative()));

QMenu* objectMenu=mb->addMenu("Objects");
objectMenu->addAction(action=new QAction("Load Model", this));
//action->setShortcut(QKeySequence::Open);
connect(action, &QAction::triggered, [=]() { this->loadModel();});

objectMenu->addAction(action=new QAction("Add Light", this));
//action->setShortcut(QKeySequence::Open);
//connect(action, SIGNAL(triggered()), this, SLOT(loadObj()));

objectMenu->addAction(action=new QAction("Add Sound", this));
//action->setShortcut(QKeySequence::Open);
//connect(action, SIGNAL(triggered()), this, SLOT(loadObj()));

objectMenu->addAction(action=new QAction("Add Game Object", this));
//action->setShortcut(QKeySequence::Open);
//connect(action, SIGNAL(triggered()), this, SLOT(loadObj()));

mainLayout->addWidget(mb);

game -> addWidget(gameGLWindow,1, 0);
setUpLayout -> addLayout(game);
gameGLWindow->setMinimumHeight(600);
gameGLWindow->setMinimumWidth(500);

mainLayout->addLayout(setUpLayout, 1);

connect(&myTimer, &QTimer::timeout, [=]() { this->myUpdate(); });
myTimer.start(16);
}

void MeWidg::myUpdate()
{
debugMenu.update();

if(GetAsyncKeyState(VK_ESCAPE) && !noToggle)
{
    noToggle=true;
    debugMenu.toggleVisibility();
}
else if(!GetAsyncKeyState(VK_ESCAPE) && noToggle)
{
    noToggle=false;
}
}

void MeWidg::loadModel()
{
gameGLWindow->loadModel();
}

Would anyone know why I am getting these warnings? Also none of the widgets I have been using are showing up, the only thing that shows up is a blank box where the layouts used to be. If I can't figure this out I will prolly just go back to qt 4.x.

回答1:

You are not showing the relevant part of your code. There seems to be some custom widget that calls the paintEngine() method on it's base class (which is not allowed). Find that widget by finding the paintEngine() call and fix it.

来源：https://stackoverflow.com/questions/26306391/qt-5-3-qwidgetpaintengine-should-no-longer-be-called

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