一步步学Qt,第四天-Qt 建立MainWindow的小小bug处理

一步步学Qt,第四天-Qt 建立MainWindow的小小bug处理

刚写好的小小的记事本,差不多可以使用了,不过在测试中发现了很多的bug,这才一个个的修改了,修改后的实现文件code是:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMessageBox>
#include <QFileDialog>
#include <QTextStream>
#include <QTextEdit>
#include <QDebug>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
   setCentralWidget(ui->textEdit);
    //action setting
    ui->mainToolBar->addAction(ui->action_New);
    ui->mainToolBar->addAction(ui->action_Open);
    ui->mainToolBar->addAction(ui->action_Cut);
    ui->mainToolBar->addAction(ui->action_About);
    //slot setting
    connect(ui->action_About,SIGNAL(triggered()),this,SLOT(about()));
    connect(ui->action_New,SIGNAL(triggered()),this,SLOT(newFile()));
    connect(ui->action_Open,SIGNAL(triggered()),this,SLOT(openFile()));
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::about()
{
    QMessageBox::about(this,tr("About this app"),tr("copyrigth by PowerLinux"));
    return;
}

void MainWindow::newFile()
{
    int i = fileChanged();
    if(i == 1){
        int s = QMessageBox::question(this,tr("Asking"),tr("File is changed ,Save it?"),QMessageBox::Ok | QMessageBox::Cancel);
        if(s == QMessageBox::Ok){
            saveFile();
             ui->textEdit->setText("");
        }
        else{
            ui->textEdit->setText("");
        }
    }
    else{
            MainWindow *newWin = new MainWindow;
                newWin->show();
    }


}

void MainWindow::openFile()
{
    int i = fileChanged();
    if(i == 1){
        fileName = QFileDialog::getOpenFileName(this);
       QString openfilename = fileName;
        if(!fileName.isEmpty())
        {
            int s = QMessageBox::question(this,tr("Asking"),tr("the old File is changed ,are you sure?"),QMessageBox::Ok | QMessageBox::Cancel);
            if(s == QMessageBox::Ok){
                saveFile();                
                ui->textEdit->setText("");
                loadFile(openfilename);
            }
            if(s == QMessageBox::Cancel){
                ui->textEdit->setText("");
                loadFile(openfilename);
            }
        }
    }
    else{
        fileName = QFileDialog::getOpenFileName(this);
        if (!fileName.isEmpty())
        {
            loadFile(fileName);
        }
    }
}

void MainWindow::loadFile(QString filename){
    QFile file(filename);
    if(file.open(QIODevice::ReadOnly | QIODevice::Text)){
        QTextStream textStream(&file);
        while(!textStream.atEnd()){
            ui->textEdit->append(textStream.readLine());
        }
    }
}

int MainWindow::fileChanged(){
    if(ui->textEdit->document()->isModified()){
       return 1;
    }
    else{
        return 0;
    }
}
void MainWindow::saveFile()
//! [44] //! [45]
{
    fileName = QFileDialog::getSaveFileName(this);
    if (!fileName.isEmpty()){
        QFile file(fileName);
        if (!file.open(QFile::WriteOnly | QFile::Text)) {
            QMessageBox::warning(this, tr("Application"),
                                 tr("Cannot write file %1:\n%2.")
                                 .arg(fileName)
                                 .arg(file.errorString()));
        }
        else{
            QTextStream out(&file);
            out << ui->textEdit->toPlainText();
        }
    }
}

注意code中

   QString openfilename = fileName;

openfilename是一个临时使用的数据,为了是在getOpenFileName的时候不会与在使用saveFile时与对应的fileName不会重复,这样在loadfile就不会出错了.