qlabel can't use setPixmap() function

[emailhy]

I build a widget has a qlabel, below is its constructor

#ifndef VIEWER_H
#define VIEWER_H
 
#include <iostream>
 
#include <QWidget>
#include <QPixmap>
#include <QLabel>
#include <QImage>
#include <QVBoxLayout>
 
 
using namespace std;
 
class Viewer : public QWidget
{
	Q_OBJECT
 
	public:
		Viewer(QWidget *parent=0);
    public slots:
		void setIplImage();
 
 
	private:
 
		QVBoxLayout *mainLayout;
		QLabel *movieLabel;
 
 
};
 
#endif
 
Viewer::Viewer(QWidget* parent)
    : QWidget(parent)
{
 movieLabel = new QLabel(tr("No movie loaded"));
    movieLabel->setAlignment(Qt::AlignCenter);
    movieLabel->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
    movieLabel->setBackgroundRole(QPalette::Dark);
    movieLabel->setAutoFillBackground(true);
    movieLabel->setScaledContents(true);
 
 
 
	mainLayout = new QVBoxLayout;
    mainLayout->addWidget(movieLabel);
	setLayout(mainLayout);
 
}
 
 
void
Viewer::setIplImage()
{
 
    QImage image("test.jpg");
    //image.save("test2.jpg"); //it works
 
   movieLabel->setPixmap(QPixmap::fromImage(image)); //compile success but runtime error with access violation.
 
 }

#ifndef VIEWER_H
#define VIEWER_H

#include <iostream>

#include <QWidget>
#include <QPixmap>
#include <QLabel>
#include <QImage>
#include <QVBoxLayout>


using namespace std;

class Viewer : public QWidget
{
	Q_OBJECT
    
	public:
		Viewer(QWidget *parent=0);
    public slots:
		void setIplImage();
		
	
	private:
		
		QVBoxLayout *mainLayout;
		QLabel *movieLabel;
		
		
};

#endif

Viewer::Viewer(QWidget* parent)
    : QWidget(parent)
{
 movieLabel = new QLabel(tr("No movie loaded"));
    movieLabel->setAlignment(Qt::AlignCenter);
    movieLabel->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
    movieLabel->setBackgroundRole(QPalette::Dark);
    movieLabel->setAutoFillBackground(true);
    movieLabel->setScaledContents(true);
	
    
   
	mainLayout = new QVBoxLayout;
    mainLayout->addWidget(movieLabel);
	setLayout(mainLayout);
	
}


void
Viewer::setIplImage()
{
	
    QImage image("test.jpg");
    //image.save("test2.jpg"); //it works
    
   movieLabel->setPixmap(QPixmap::fromImage(image)); //compile success but runtime error with access violation.
    
 }

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and if i use it in constructor, the setPixmap() can run.
Thanks for any comments

[Coises]

Are you by any chance calling setIplImage(), or connecting to it using Qt::DirectConnection, from a thread other than the GUI thread?