使用QPixmap的Qt内存泄漏 [英] Qt memory leak using QPixmap

问题描述

我在这段代码中的某处遇到了一个奇怪的内存泄露。该方法是一个SLOT连接到另一个线程中的方法。它做2件事情：1它更新一个文本框与另一个线程的迭代。 2，它将GUI上显示的图像更新为与该迭代相对应的图像。

I'm getting a strange memory leak somewhere in this code. The method is a SLOT connected to a method in another thread. It does 2 things: 1 it updates a text box with the iteration that that the other thread is on. 2 it updates the image shown on the GUI to the image corresponding to that iteration.

它适用于10-30次迭代，然后爆炸。在任务管理器中看到它的内存使用，我可以看到它的稳定，然后每次迭代增加RAM使用量约10％。

It works great for 10-30 iterations, then blows up. Watching its memory usage in the task manager, I can see that it's steady at first, then each iteration increases the RAM usage by about 10%. What can I do to remove the leak?

Transition::Transition(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::Transition)

    {
    ui->setupUi(this);
    this->files = files;
    imageObject = new QImage();
    scene = new QGraphicsScene(this);
}

Transition::~Transition()
{
    delete ui;
    delete imageObject;
    delete scene;
}

有问题的SLOT：

void Transition::onCounterChanged(QString counter){
    ui->imageCounter->setText(counter);
    foldername = ui ->folderName->toPlainText();
    int m = counter.toInt();
    QString filename = files[m];
    imageObject->load(filename);
    image = QPixmap::fromImage(*imageObject);

    scene->clear();//THIS FIXES THE LEAK

    scene->addPixmap(image);
    ui->picDisplay->setScene(scene);
    ui->picDisplay->fitInView(image.rect(),Qt::IgnoreAspectRatio);
}

推荐答案

更新您的图像，但创建新的像素映射项目到场景：

I think you do not simply update your image, but create new pixmap item to the scene with:

void Transition::onCounterChanged(QString counter)
{
    [..]
    imageObject->load(filename);
    image = QPixmap::fromImage(*imageObject);
    scene->addPixmap(image); // <----- Adds new pixmap item to the scene
    [..]
}

所以，10-30迭代后，你有10-30像素映射项目在你的场景。我想，你必须更新现有 QGraphicsPixmapItem 使用 QGraphicsPixmapItem :: setPixmap（）函数，而不是创建一个新的每次迭代。

So, after 10-30 iterations you have 10-30 pixmap items on your scene. I think, you have to update existing QGraphicsPixmapItem using QGraphicsPixmapItem::setPixmap() function instead of creating a new one on each iteration.

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