为什么在单独线程(Qt)中复制文件时，带有QFileSystemModel的GUI中的树形视图有时会冻结?

问题描述

这是我的模型，它继承了QFileSystemModel

Here is my Model, that inherits QFileSystemModel

class MyFileSysModel : public QFileSystemModel
{
    Q_OBJECT
public:
    MyFileSysModel( QObject *parent = 0);
    Qt::ItemFlags  flags(const QModelIndex &index) const;
    bool dropMimeData(const QMimeData *data,
    Qt::DropActions supportedDropActions() const;
};

在MainWindow中，我创建了模型并初始化了树视图

in MainWindow I created model and initializied treeview

 MainWindow::MainWindow(QWidget *parent) :
        QMainWindow(parent),
        ui(new Ui::MainWindow)
    {
        ui->setupUi(this);
        model = new MyFileSysModel(this);
        model->setRootPath("/");
       ui->treeView->setModel(model);

         ui->treeView->setSelectionMode(QAbstractItemView::ExtendedSelection);
         ui->treeView->setDragEnabled(true);
         ui->treeView->viewport()->setAcceptDrops(true);
         ui->treeView->setDropIndicatorShown(true);
         ui->treeView->setDragDropMode(QAbstractItemView::DragDrop);
         ui->treeView->setAcceptDrops(true);
         ui->treeView->setDefaultDropAction(Qt::MoveAction);
    }

当用户拖放文件时，它将复制到单独线程中的其他目录

When user drag and drop file it is copying to other directory in separate thread

 class MoveFilesTask : public QObject, QRunnable
    {
        Q_OBJECT
        void run()
        {
            QFile source("source_file_name");
            source.open(QIODevice::ReadOnly);
            QFile destination("some_destination");
            destination.open(QIODevice::WriteOnly);
            QByteArray buffer;
            int chunksize = 200;

            while(!(buffer = source.read(chunksize)).isEmpty())
            {
                destination.write(buffer);
            }
            destination.close();
            source.close();
        }
       void MoveFilesTask::runFilesTransfer(QString source, QString destination)
        {
           QThreadPool::globalInstance()->start(this);
        }
};

文件正在复制，但是MainWindow中带有我的Treeview的GUI不能正常工作，有时会冻结和阻塞.我认为这是因为我的模型经常更新.我该如何解决这个问题并防止经常更新?

File is copying but the GUI in MainWindow with my treeview doesn't work well, it is freezing and blocking sometimes. I think this is because my model updating very often. How can I solve this and prevent updating very often ?

推荐答案

QFileSystemModel在后台线程上列出目录，以避免阻塞UI.但是，一旦它在QFileSystemModelPrivate::_q_fileSystemChanged中获取更新列表，便会使用QFileInfoGatherer::getInfo()提取主线程中文件的图标，该文件又调用QFileIconProvider::icon(QFileInfo).

QFileSystemModel lists directories on a background thread to avoid blocking the UI. However, once it gets a list of updates in QFileSystemModelPrivate::_q_fileSystemChanged it then fetches the icons for the file in the main thread using QFileInfoGatherer::getInfo() which in turn calls QFileIconProvider::icon(QFileInfo).

您应该知道模型没有使用其他线程.他们正在使用主线程.

You should know Models are not using a different thread. they're using main thread.

如果要使用模型，请在用户界面中使用加载动画(加载gif)以显示进度.

If you want to use Model, use a loading animation (loading gif) in your UI to show progressing time.

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