QT显示从网络访问管理器获取的图像

发布于 2024-11-16 15:51:53 字数 608 浏览 3 评论 0原文

我正在尝试显示从使用网络访问管理器发出的获取请求中获得的图像。我能够编译甚至能够运行它。但我无法在 Qlabel 中显示图像。

QNetworkAccessManager* nam;

void MainWindow::on_pushButton_clicked()
{
    nam = new QNetworkAccessManager(this);
    QUrl url("http://i.imgur.com/Uw7Fk.jpg");
    QNetworkReply* reply = nam->get(QNetworkRequest(url));
    if (reply->error() == QNetworkReply::NoError)
    {
        QImageReader imageReader(reply);
        imageReader.setAutoDetectImageFormat (false);
        QImage pic = imageReader.read();
        ui->label_2->setPixmap(QPixmap::fromImage(pic));

     }


}

请告诉我哪里出错了。

原文

I am trying to display the image obtained from the get request made using networkaccess manager. I am able to compile and even able to run it. but I am unable to show the image in a Qlabel.

QNetworkAccessManager* nam;

void MainWindow::on_pushButton_clicked()
{
    nam = new QNetworkAccessManager(this);
    QUrl url("http://i.imgur.com/Uw7Fk.jpg");
    QNetworkReply* reply = nam->get(QNetworkRequest(url));
    if (reply->error() == QNetworkReply::NoError)
    {
        QImageReader imageReader(reply);
        imageReader.setAutoDetectImageFormat (false);
        QImage pic = imageReader.read();
        ui->label_2->setPixmap(QPixmap::fromImage(pic));

     }


}

Please tell me where I am going wrong.

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往昔成烟 2024-11-23 15:51:53

调用 QNetworkAccessManager::get() 后，QNetworkReply 中的数据尚未准备好。该调用是异步的，在尝试检索任何数据之前，您需要连接到 QNetworkAccessManager 的 finished() 信号或 QNetworkReply 的 readyRead() 信号。

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鱼窥荷 2024-11-23 15:51:53

要同步获取图像，您可以使用 QEventLoop，如下所示：

QNetworkAccessManager* nam;

void MainWindow::on_pushButton_clicked()
{
    nam = new QNetworkAccessManager(this);
    QUrl url("http://i.imgur.com/Uw7Fk.jpg");
    QNetworkReply* reply = nam->get(QNetworkRequest(url));

    QEventLoop eventloop;
    connect(reply,SIGNAL(finished()),&eventloop,SLOT(quit()));
    eventLoop.exec();

    if (reply->error() == QNetworkReply::NoError)
    {
        QImageReader imageReader(reply);
        imageReader.setAutoDetectImageFormat (false);
        QImage pic = imageReader.read();
        ui->label_2->setPixmap(QPixmap::fromImage(pic));

     }


}

To get image synchronously, you can use QEventLoop like below:

QNetworkAccessManager* nam;

void MainWindow::on_pushButton_clicked()
{
    nam = new QNetworkAccessManager(this);
    QUrl url("http://i.imgur.com/Uw7Fk.jpg");
    QNetworkReply* reply = nam->get(QNetworkRequest(url));

    QEventLoop eventloop;
    connect(reply,SIGNAL(finished()),&eventloop,SLOT(quit()));
    eventLoop.exec();

    if (reply->error() == QNetworkReply::NoError)
    {
        QImageReader imageReader(reply);
        imageReader.setAutoDetectImageFormat (false);
        QImage pic = imageReader.read();
        ui->label_2->setPixmap(QPixmap::fromImage(pic));

     }


}

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