Qt 5.3 QWidget::paintEngine:不应再调用

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

本文关键字：调用 paintEngine QWidget Qt      更新时间：2023-10-16

我正在将我的代码从Qt4.x移动到Qt5.3，我遇到了一个奇怪的Qt警告，显示在命令提示符中。没有错误或任何东西，但命令提示符将显示以下内容：

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

我想我把它缩小到了一个类别：标题：

#pragma once
#include <QtCoreqmetaobject.h>
#include <QtWidgetsQwidget.h>
#include <QtWidgetsQslider.h>
#include <QtwidgetsQpushbutton.h>
#include <QtwidgetsQcheckbox.h>
#include "MyGLWindow.h"
#include <QtWidgetsQHboxLayout>
#include <QtWidgetsQVboxLayout>
#include <QtWidgetsqmenubar.h>
#include <QtWidgetsqlabel.h>
class MeWidg : public QGLWidget
{
public:
    QTimer myTimer;
    bool testToggle;
    float testRow;
    bool noToggle;
    MyGLWindow *gameGLWindow;
    MeWidg();
private:
    void myUpdate();
    void loadModel();
};

和来源：

#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();
}

有人知道我为什么收到这些警告吗？此外，我一直在使用的小部件都没有显示，唯一显示的是一个空白框，其中的布局曾经是。如果我不能弄清楚这一点，我将很长时间回到qt4.x.

您没有显示代码的相关部分。似乎有一些自定义小部件在其基类上调用paintEngine()方法（这是不允许的）。通过查找paintEngine()调用找到该小部件并修复它。

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