File browser? QT can also be achieved!

introduction

Are familiar with Windows File browser under , You can open a disk or a folder with the mouse , Or a file in a subfolder , You can also return to the previous menu , You can also go to the specified directory according to the input .

Borrow here Qt To realize such a file browser , Implement the following functions ：

1. You can display the list of files in the specified directory ;
2. Double click the folder in the file list , You can enter its subfolder , You can also return to the previous level .

Environmental Science ：vs2008+Qt4.8.6+Qt The designer ,win7 System

01

preparation

Make a simple one UI Well , Here's the picture ：

• QLineEdit： Used to input and display the current path ;
• QListWidget： Used to display the files and folders under the current path .

preservation ,OK！

02

Header work

My whole project is named FileBrowser, Class names are also called FileBrowser. The header file code is as follows ：

#ifndef FILEBROWER_H
#define FILEBROWER_H

#include <QtGui/QWidget>
#include "ui_FileBrower.h"
/// Icon 
#include <QIcon>
/// Catalog 
#include <QDir>

class FileBrower : public QWidget
{
  Q_OBJECT

public:
  FileBrower(QWidget *parent = 0, Qt::WFlags flags = 0);
  ~FileBrower();

  /// stay QListWidget The details under the current directory are displayed in 
  void showFileInfoList(QFileInfoList pInfoList);

  /// Get the icon according to the nature of the file 
  ///iType=1: Folder 
  ///iType=2: file 
  QIcon *getItemPropertyIcon(int iType);

public slots:
  /// Display the folders and files in the current directory 
  void showCurrentDirFiles();
  /// Display the files under the folder in the list double clicked by the mouse 
  void showNextDirFiles(QListWidgetItem *item);

private:
  Ui::FileBrowerClass ui;
};

#endif // FILEBROWER_H

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It should be noted that ：

1. Icon acquisition function ：getItemPropertyIcon(int iType);

This is not necessary , Just to be able to distinguish folders and files more intuitively . I made two icons myself , Put it in the project directory , Later in CPP You can see how to use .

2.QListWidgetItem

This class can look at the official documents by itself , When to use , How to use it? . Quote the original ：

The QListWidgetItem class provides an item for use with the QListWidget item view class.

03

Method realization

First of all, the signal slot connection must be carried out in the constructor ：

  connect(ui.lineEdit,SIGNAL(returnPressed()),this,SLOT(showCurrentDirFiles()));
  connect(ui.listWidget,SIGNAL(itemDoubleClicked(QListWidgetItem*)),this,SLOT(showNextDirFiles(QListWidgetItem*)));

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the second connect There's nothing to say , It is the display function after double clicking the mouse . The key lies in the first , When QLineEdit Of returnPressed() The signal can be transmitted ？ Here I searched the official documents ：

This signal is emitted when the Return or Enter key is pressed. Note that if there is a validator() or inputMask() set on the line edit, the returnPressed() signal will only be emitted if the input follows the inputMask() and the validator() returns QValidator::Acceptable.

The document says that when the return key or enter key is pressed , This signal can be transmitted . There are a lot of complicated , I didn't go to study . in other words , When lineEdit Input in completed , After pressing enter , The signal will be transmitted , Then execute the slot function . In this case, the first connect There is no problem .

But in many blogs and many people are asking questions , The general question is as follows ：

1. The connect The connection fails , The connected slot function cannot be triggered at all

Whether the connection is successful or not , You can verify that connect The return value of , Return on success true, Otherwise return to false;

2. tangle returnPressed() How to use it ？

For example, some blogs will connect like this

connect(ui.lineEdit, SIGNAL(returnPressed()),  this, SLOT(showCurrentDirFiles(QDir)));

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I have also tried this connection , The return value is false, That is, the connection failed . Many foreign technical Q & A websites are also right returnPressed() There was a lot of discussion about . Avoid this in this method , Adopt the above connect, Verification is feasible . All roads lead to Rome , You don't have to pass parameters , Besides, , It is originally a member variable of a class , Accessible at any time .

04

Each method implements

void FileBrower::showNextDirFiles(QListWidgetItem *item)
{
  /// Get the name of the file double clicked by the mouse 
  QString strName = item->text();
  QDir dir;
  // Set the path to the current directory path 
  dir.setPath(ui.lineEdit->text());
  // Reset path 
  dir.cd(strName);
  // Update current display path , And display all the files in the current directory 
  ui.lineEdit->setText(dir.absolutePath());
  showCurrentDirFiles();
}

void FileBrower::showCurrentDirFiles()
{
  // Get the currently entered directory 
  QDir currentDir(ui.lineEdit->text());
  QStringList fileList;
  fileList<<"*";
  QFileInfoList infoList = currentDir.entryInfoList(fileList,QDir::AllEntries,QDir::DirsFirst);
  // stay QListWidget A list of documents is displayed in 
  this->showFileInfoList(infoList);
}

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Here's a description QDir Methods entryInfoList(), This method returns a list containing all the files and folders in this directory . Check official documents , The method has three arguments ：

QFileInfoList QDir::entryInfoList ( const QStringList & nameFilters, Filters filters = NoFilter, SortFlags sort = NoSort ) const

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The second is filter , The official documents contain the following categories and their meanings ：

Here we choose to show all . The third parameter is the sort order , By time 、 size 、 Names and so on , Instructions are also given in official documents ：

void FileBrower::showFileInfoList(QFileInfoList pInfoList)
{
  ui.listWidget->clear();
  for(int i=0;i<pInfoList.size();i++)
  {
    QFileInfo tmpInfo = pInfoList.at(i);
    QString pFileName = tmpInfo.fileName();
    QListWidgetItem *tmpItem = new QListWidgetItem(pFileName);
    if(tmpInfo.isDir())
      tmpItem->setIcon(*getItemPropertyIcon(1));
    else
      tmpItem->setIcon(*getItemPropertyIcon(2));
    ui.listWidget->addItem(tmpItem);
  }
}

QIcon * FileBrower::getItemPropertyIcon(int iType)
{
  QDir dir;
  QString path = dir.currentPath();
  switch(iType)
  {
  case 1:
    return new QIcon(path+"/Folder.png");
    break;
  case 2:
    return new QIcon(path+"/File.png");
    break;
  }
  return NULL;
}

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05

test result

stay lineEdit Internal input D:/, Enter key , Pictured

double-click AutoCAD2015, Pictured ：

Double click the second （ Two points ）, You can return to the previous menu . stay lineEdit Internal input “/”, Is the root directory of the disk where the project is currently located , For example, I put it on the desktop , That will show C Folder under disk .

Source code address ：https://github.com/FengJungle/Qt_Project I hope that's helpful ！