[Solved] Image overlay issue during run-time

bc913

Hi all,

In my app, I try to connect each Combobox item to an image file. But, when I would choose one of the item during run-time, the new selected image is overlapped to the previous one. I think it is a result of memory leak but which kind of approach (or func or class) help to fix this issue?

Also, any help/comment about my design approach for this application would highly be appreciated.

Thanks in advance,

@//main.cpp
#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();

return a.exec&#40;&#41;;

}@

@//mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QGraphicsScene>
#include <QGraphicsView>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();

private slots:
void on_comboBox_currentIndexChanged(int index);

private:
Ui::MainWindow *ui;
QGraphicsScene *scene;
QGraphicsView *view;
};

#endif // MAINWINDOW_H
@

@//mainwindow.cpp
#include <QGridLayout>
#include <QGraphicsItem>
#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
scene = new QGraphicsScene(ui->centralWidget);
view = new QGraphicsView(scene);
QGridLayout *gLayout = new QGridLayout(ui->centralWidget);
QVBoxLayout *vLayout = new QVBoxLayout();
gLayout -> addWidget(ui->comboBox,0,0,1,2);
gLayout -> addLayout(vLayout, 1,0,3,2);
gLayout ->addWidget(view,0,2,3,3);

ui->lineEdit->setEnabled(false);
ui->lineEdit_2->setEnabled(false);
ui->lineEdit_3->setEnabled(false);

}

MainWindow::~MainWindow()
{
delete ui;
}

void MainWindow::on_comboBox_currentIndexChanged(int index)
{
QGraphicsPixmapItem *item;

if(index == 0){

    ui->lineEdit->hide();
    ui->lineEdit_2->hide();
    ui->lineEdit_3->hide();
    item = new QGraphicsPixmapItem(QPixmap("C:\\... jpg"));
    scene->addItem(item);
    view->show();}

else if(index == 1) {
    ui->lineEdit->show();
    ui->lineEdit_2->show();
    ui->lineEdit_3->hide();
    ui->lineEdit->setEnabled(true);
    ui->lineEdit_2->setEnabled(true);
    item= new QGraphicsPixmapItem(QPixmap("C:\\... jpg"));
    scene->addItem(item);
    view->show();}

else if(index == 2){
    ui->lineEdit->show();
    ui->lineEdit_2->hide();
    ui->lineEdit_3->hide();
    ui->lineEdit->setEnabled(true);
    item = new QGraphicsPixmapItem(QPixmap("C:\\... jpg"));
    scene->addItem(item);
    view->show();}

}
@

dbzhang800

Every time the currentIndex Changed, you create a new Item but never delete it.

Seems one Item is enough for you.

bc913

Thanks,

But for each combobox index, It would show a different image file. If I use, one item it always shows the same image file per each index.

Also, how can I delete the item? To delete them, first I should check them if they are active(alive) or not? Which function and/or class I should use to check?

dbzhang800

You can change the contents of the your item through QGraphicsPixmapItem::setPixmap()

bc913

Thanks a lot,

It is solved...

@void MainWindow::on_comboBox_currentIndexChanged(int index)
{
//QGraphicsPixmapItem *item;
//scene->addItem(item);
qDebug() << scene->items().isEmpty();
qDebug() << item ->scene();

if(!(scene->items().isEmpty())){scene->removeItem(item);}
//if(item!=0x0) {delete item;}

if(index == 0){
ui->lineEdit->hide();
ui->lineEdit_2->hide();
ui->lineEdit_3->hide();
item ->setPixmap(QPixmap("D:\bc913\capture\Capture115.JPG"));
}
else if(index == 1) {
ui->lineEdit->show();
ui->lineEdit_2->show();
ui->lineEdit_3->hide();
ui->lineEdit->setEnabled(true);
ui->lineEdit_2->setEnabled(true);
item ->setPixmap(QPixmap("D:\bc913\capture\Capture116.JPG"));
}
else if(index == 2){
ui->lineEdit->show();
ui->lineEdit_2->hide();
ui->lineEdit_3->hide();
ui->lineEdit->setEnabled(true);
item ->setPixmap(QPixmap("D:\bc913\capture\Capture117.JPG"));

}
scene->addItem(item);
qDebug() << item ->scene();
qDebug() << item;
view->show();

}@