Qt的进度条实现

// progressbar.h

#ifndef PROGRESSBAR_H
#define PROGRESSBAR_H
#include <QDialog>
class QLabel;
class QLineEdit;
class QComboBox;
class QPushButton;
class QProgressBar;
class Progress : public QDialog
{
     Q_OBJECT
public:
     Progress(QWidget *parent=0,Qt::WindowFlags f=0);
     ~Progress();
private:
     QLabel *numLabel;
     QLineEdit *numLineEdit;
     QLabel *typeLabel;
     QComboBox *typeComboBox;
     QProgressBar *progressBar;
     QPushButton *startPushButton;
private slots:
     void slotStart();
};
#endif // PROGRESSBAR_H

#include "progressbar.h"
#include <QLabel>
#include <QLineEdit>
#include <QComboBox>
#include <QProgressBar>
#include <QPushButton>
#include <QGridLayout>
#include <QProgressDialog>
#include <QApplication>
#include <QTest>                                           //以便调用QTest::qSleep(); 实现延时功能

Progress::Progress(QWidget *parent,Qt::WindowFlags f):QDialog(parent,f)
{
     QFont font("Times", 10, QFont::Bold);
     setFont(font);
     setWindowTitle("ProgressBar");
     numLabel=new QLabel("File Num:");
     numLineEdit=new QLineEdit;
     numLineEdit->setText("10");
     typeLabel=new QLabel("Progress Type:");
     typeComboBox=new QComboBox;
     typeComboBox->addItem("ProgressBar");
     typeComboBox->addItem("ProgressDialog");

     progressBar=new QProgressBar;
     startPushButton=new QPushButton("Start");

     QGridLayout *layout=new QGridLayout;
     layout->addWidget(numLabel,0,0);
     layout->addWidget(numLineEdit,0,1);
     layout->addWidget(typeLabel,1,0);
     layout->addWidget(typeComboBox,1,1);
     layout->addWidget(progressBar,2,0,1,2);
     layout->addWidget(startPushButton,3,1);
     layout->setMargin(15);                                                           // 布局外边框的宽度
     layout->setSpacing(10);                                                         //部件间的间距

     setLayout(layout);

     connect(startPushButton,SIGNAL(clicked()),this,SLOT(slotStart()));
}

Progress::~Progress(){}

void Progress::slotStart()
{
     int num=numLineEdit->text().toInt();
     if (typeComboBox->currentIndex()==0)
     {
         progressBar->setRange(0,num);
         for (int i=0;i<num;i++)
         {
             progressBar->setValue(i+1);                     // 注意，这里是i+1，不是i，这样才能显示100%
             QTest::qSleep(100);
         }
     }
     else if (typeComboBox->currentIndex()==1)
     {
         QProgressDialog *progressDialog=new QProgressDialog(this);
         QFont font("Times", 10, QFont::Bold);
         progressDialog->setFont(font);
         progressDialog->setWindowModality(Qt::WindowModal);       //设置窗口模式，这里复制对话框弹出后，无法操作父窗口
         progressDialog->setMinimumDuration(5);                            //设置任务执行的预期时间，若小于此值，就不弹出复制对话框
         progressDialog->setWindowTitle("Please Wait...");
         progressDialog->setLabelText("Copying...");
         progressDialog->setCancelButtonText("Cancel");
         progressDialog->setRange(0,num);

         for (int i=0;i<num;i++)
         {
             progressDialog->setValue(i+1);                 // 注意，这里是i+1，不是i，这样才能显示100%
             qApp->processEvents();                         //来正常相应时间循环，以确保应用程序不会出现阻塞。
             QTest::qSleep(100);
             if (progressDialog->wasCanceled()) return;
         }
     }
}




这个程序只是个实例，模拟文件的复制过程，这里用到了延时函数qSleep(),它包含于QTest类中，在使用它之前，首先要在pro文件中加入：CONFIG +=qtestlib注意，在加入上述声明后，运行程序以后会弹出cmd窗口，这个是正常的，QTest用来测试，默认就带cmd黑色窗口，我一开不了解，四处找去掉的原因，在实际运用过程中，我们不需要QTest类，只需要将实际的文件复制代码覆盖程序中的QTest::qSleep(100);即可...