打开 QDialog 并同时运行 QProcess

Question

这是我的 btconnect.h 文件

#ifndef BTCONNECT_H
#define BTCONNECT_H

#include "scandialog.h"

namespace Ui {
class BTConnect;
}

class BTConnect : public QWidget
{
    Q_OBJECT

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

private slots:
    void on_ScanButton_clicked();

    void ScanBTDevices();

    //some slots here

    void ScanDialogShow();

    void ScanDialogClose();

public slots:
//some slots here

private:
    Ui::BTConnect *ui;

    QProcess BTscan_Process;

    scanDialog *scan;
};

#endif // BTCONNECT_H

btconnect.cpp

BTConnect::BTConnect(QWidget *parent) :
QWidget(parent),
ui(new Ui::BTConnect)
{
    //set the userinterface as BTConnect.ui
    ui->setupUi(this);

    scan = new scanDialog(this);
}


void BTConnect::ScanDialogShow()
{
    scan->show();
}

void BTConnect::ScanDialogClose()
{
    scan->close();
}

void BTConnect::ScanBTDevices()
{
    ScanDialogShow();

    //Command to scan nearby bluetooth devices
    //"hcitool scan"
    QString cmd("hcitool scan");

    //start the process
    BTscan_Process.start(cmd);

    //Wait for the processs to finish with a timeout of 20 seconds
    if(BTscan_Process.waitForFinished(20000))
    {
        //Clear the list widget
        this->ui->listWidget->clear();

        //Read the command line output and store it in QString out
        QString out(BTscan_Process.readAllStandardOutput());

        //Split the QString every new line and save theve in a QStringList
        QStringList OutSplit = out.split("\n");

        //Parse the QStringList in btCellsParser
        btCellsParser cp(OutSplit);

        for(unsigned int i = 0; i<cp.count(); i++)
        {
           //writing in listwidget
        }

    }

    ScanDialogClose();
}

void BTConnect::on_ScanButton_clicked()
{
    //Scan for available nearby bluetooth devices
    ScanBTDevices();
}

如果我使用上面的代码，qdialog scandialog 确实会在进程开始时打开并在 qlistwidget 中加载数据时关闭，但不会显示 qdialog scandialog 的内容。如果我将 show() 更改为 exec()，将显示内容，但 QProcess 在对话框关闭之前不会运行。

我希望对话框在 Qprocess 启动时打开，并在 qlistwidget 加载扫描数据时关闭。我希望显示 scandialog 的内容。它有两个标签。一个是 .GIF 文件，另一个是扫描文字。

感谢任何帮助。

Answer 1

当你做show时你永远不会返回到事件循环（因为waitForFinished）当你做exec时你永远不会继续处理代码

您应该连接到finished 信号而不是waitForFinished 并在那里处理它，并使用将取消它的单次计时器：

void BTConnect::on_BTscanFinished()//new slot
{
   //Clear the list widget
    this->ui->listWidget->clear();

    //Read the command line output and store it in QString out
    QString out(BTscan_Process.readAllStandardOutput());

    //Split the QString every new line and save theve in a QStringList
    QStringList OutSplit = out.split("\n");

    //Parse the QStringList in btCellsParser
    btCellsParser cp(OutSplit);

    for(unsigned int i = 0; i<cp.count(); i++)
    {
       //writing in listwidget
    }
    ScanDialogClose();
}

void BTConnect::ScanBTDevices()
{
    ScanDialogShow();

    //Command to scan nearby bluetooth devices
    //"hcitool scan"
    QString cmd("hcitool scan");

    //start the process
    connect(BTscan_Process, SIGNAL(finished()), this, SLOT(on_BTscanFinished()));
    BTscan_Process.start(cmd);
    QTimer::singleShot(20000, scan, SLOT(close()));
}

Answer 2

问题在于QDialog::exec 和QProcess::waitForFinished 函数阻塞了事件循环。 永远不要阻塞事件循环。所以你只需要更异步地做事情。

QProcess 类可以使用readReadStandardOutput 等信号异步处理。并且QDialog 可以使用open 插槽异步显示。

例子：

void ScanBTDevices() {
    // Open dialog when process is started
    connect(process, SIGNAL(started()), dialog, SLOT(open()));

    // Read standard output asynchronously
    connect(process, SIGNAL(readyReadStandardOutput()), SLOT(onReadyRead()));

    // Start process asynchronously (for example I use recursive ls)
    process->start("ls -R /");
}

void onReadyRead() {
    // Write to list widget
    dialog->appendText(QString(process->readAllStandardOutput()));
}

数据将在进程生成期间附加到对话框中。 也可以使用QProcess::finished 信号关闭对话框。