Qt学习笔记第71到80讲

    bool eventFilter(QObject *watched,QEvent *event);

③在Widget.cpp文件内做出实现，引入了新的类型QGuiApplication

bool Widget::eventFilter(QObject *watched, QEvent *event)
{//滚轮滑动时用keyboardModifiers方法捕获Ctrl按键是否按下if(event->type()==QEvent::Wheel){if(QGuiApplication::keyboardModifiers()==Qt::ControlModifier){QWheelEvent *wheelEvent=dynamic_cast<QWheelEvent *>(event);if(wheelEvent->angleDelta().y()>0){textEditEnlarge();}else if(wheelEvent->angleDelta().y()<0){textEditReduce();}return true;}}return false;
}

第72讲 记事本项目总结

#include "widget.h"
#include "ui_widget.h"#include <QFileDialog>
#include <QDebug>
#include <QList>
#include <QColor>
#include <QMessageBox>
#include <QShortcut>Widget::Widget(QWidget *parent) : QWidget(parent) , ui(new Ui::Widget)
{ui->setupUi(this);QShortcut *shortcutOpen = new QShortcut(QKeySequence(tr("Ctrl+O", "File|Open")),this);QShortcut *shortcutSave = new QShortcut(QKeySequence(tr("Ctrl+S", "File|Save")),this);QShortcut *shortcutEnlarge = new QShortcut(QKeySequence(tr("Ctrl+Shift+=", "File|Enlarge")),this);QShortcut *shortcutReduce = new QShortcut(QKeySequence(tr("Ctrl+Shift+-", "File|Reduce")),this);connect(shortcutOpen,&QShortcut::activated,[=](){on_btnOpen_clicked();});connect(shortcutSave,&QShortcut::activated,[=](){on_btnSave_clicked();});connect(shortcutEnlarge,&QShortcut::activated,[=](){textEditEnlarge();});connect(shortcutReduce, &QShortcut::activated,[=](){textEditReduce();});this->setLayout(ui->verticalLayout);ui->widgetBottom->setLayout(ui->horizontalLayout);connect(ui->comboBox,SIGNAL(currentIndexChanged(int)),this,SLOT(onCurrentIndexChanged(void)));connect(ui->textEdit,SIGNAL(cursorPositionChanged()),this,SLOT(onCursorPositionChanged()));
}Widget::~Widget()
{delete ui;
}void Widget::textEditEnlarge()
{//获取当前TextEdit内的字体信息QFont font=ui->textEdit->font();//获取当前字体的大小int fontSize=font.pointSize();if(fontSize==-1) return;//改变大小，并设置字体大小int newFontSize=fontSize+1;font.setPointSize(newFontSize);ui->textEdit->setFont(font);
}void Widget::textEditReduce()
{//获取当前TextEdit内的字体信息QFont font=ui->textEdit->font();//获取当前字体的大小int fontSize=font.pointSize();if(fontSize==-1) return;//改变大小，并设置字体大小int newFontSize=fontSize-1;font.setPointSize(newFontSize);ui->textEdit->setFont(font);
}void Widget::on_btnOpen_clicked()
{QString fileName=QFileDialog::getOpenFileName(this,tr("Open File"),"E:\\6_Qt Projects\\31_NotepadCodec\\files",tr("Text(*.txt *.doc)"));//QFileDialog限制程序可打开的文件形式为txt文件或者doc文本ui->textEdit->clear();//每次打开文件时清除控件区域“textEdit”file.setFileName(fileName);if(!file.open(QIODevice::ReadWrite|QIODevice::Text)){qDebug()<<"file open error";}this->setWindowTitle(fileName+"-NotesBook");QTextStream in(&file);QString str=ui->comboBox->currentText();const char* c_str=str.toStdString().c_str();in.setCodec(c_str);while(!in.atEnd()){QString context=in.readLine();//qDebug()<<qPrintable(context);ui->textEdit->append(context);//将读取到的每行内容通过 append 方法添加到界面的文本编辑框（ui->textEdit）中}// 将此时ui->textEdit中的文本内容保存到initialText变量中，作为初始文本initialText = ui->textEdit->toPlainText();//主动设置焦点（重要，解决了点击textEdit控件区域之后才能使用滚轮缩放的Bug）ui->textEdit->setFocus(Qt::OtherFocusReason);
}void Widget::on_btnSave_clicked()
{//如果当前没有文件打开，就弹窗让用户选择新文件，创建新文件;//而不是原来那样，都弹出新的文件保存窗口if(!file.isOpen()){QString fileName = QFileDialog::getSaveFileName(this, tr("SaveFile"),"E:\\6_Qt Projects\\31_NotepadCodec\\files\\untitled file.txt",tr("Text (*.txt*.doc)"));file.setFileName(fileName);if(!file.open(QIODevice::WriteOnly | QIODevice::Text)){qDebug() << "file open error";}this->setWindowTitle(fileName + "- MyNoteBook");}else{// 如果文件已打开，先将文件指针移动到文件开头，准备覆盖原有内容file.seek(0);// 截断文件内容，清除原有内容file.resize(0);}//当保存被按下，不管是已有打开的文件还是上面if满足后用户选择新文件，//都要读取TextEdit内容并写入文件中QTextStream out(&file);out.setCodec(ui->comboBox->currentText().toStdString().c_str());QString context = ui->textEdit->toPlainText();out << context;initialText=ui->textEdit->toPlainText();
}void Widget::on_btnClose_clicked()
{QString currentText = ui->textEdit->toPlainText();if(currentText!= initialText){int ret = QMessageBox::warning(this, tr("NotesBook Notice"),tr("The document has been modified.\n""Do you want to save your changes?"),QMessageBox::Save | QMessageBox::Discard| QMessageBox::Cancel, QMessageBox::Save);switch (ret) {case QMessageBox::Save:// Save was clickedon_btnSave_clicked();ui->textEdit->clear();break;case QMessageBox::Discard:// Don't Save was clickedui->textEdit->clear();if (file.isOpen()) {file.close();this->setWindowTitle("NotesBook");}break;case QMessageBox::Cancel:// Cancel was clickedbreak;default:// should never be reachedbreak;}} else {ui->textEdit->clear();if (file.isOpen()) {file.close();this->setWindowTitle("NotesBook");}}
}void Widget::onCurrentIndexChanged(void)
{ui->textEdit->clear();if(file.isOpen()){QTextStream in(&file);in.setCodec(ui->comboBox->currentText().toStdString().c_str());//链式调用访问成员变量file.seek(0);//将光标移动回起始点while(!in.atEnd()){QString context=in.readLine();ui->textEdit->append(context);}}
}void Widget::onCursorPositionChanged(void)
{QTextCursor cursor=ui->textEdit->textCursor();//qDebug()<<cursor.blockNumber()+1 <<cursor.columnNumber()+1;QString blockNum=QString::number(cursor.blockNumber()+1);QString columnNum=QString::number(cursor.columnNumber()+1);const QString labelMes="L:"+blockNum+" "+"C:"+columnNum;ui->labelPositon->setText(labelMes);/*设置当前行高亮*///0.声明了一个 QList 容器 extraSelectionsQList <QTextEdit::ExtraSelection> extraSelections;//同时声明了ext这个结构体变量QTextEdit::ExtraSelection ext;//1.获取当前行的数值ext.cursor=ui->textEdit->textCursor();//2.配置颜色QBrush qBrush(Qt::lightGray);ext.format.setBackground(qBrush);//3.配置段属性，整行显示ext.format.setProperty(QTextFormat::FullWidthSelection,true);//4.整体配置extraSelections.append(ext);ui->textEdit->setExtraSelections(extraSelections);}

widget.h

#ifndef WIDGET_H
#define WIDGET_H#include <QFile>
#include <QWidget>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();/*personel public components begin*/QFile file;QString initialText;  // 新增成员变量，用于保存初始的文件文本内容void textEditEnlarge(void);void textEditReduce(void);/*personel public components end*/private:Ui::Widget *ui;   /*personel private components begin*/private slots:void on_btnOpen_clicked();void on_btnSave_clicked();void on_btnClose_clicked();void onCurrentIndexChanged(void);void onCursorPositionChanged(void);/*personel private components end*/
};
#endif // WIDGET_H

mytextedit.cpp

​
#include "mytextedit.h"
#include <QWheelEvent>
#include <QDebug>
#include "widget.h"MyTextEdit::MyTextEdit(QWidget *parent) :QTextEdit(parent)
{}void MyTextEdit::wheelEvent(QWheelEvent *e)
{//qDebug() << "wheelEvent entered";if(ctrlKeyPressed==1){//qDebug()<<e->angleDelta().y();if(e->angleDelta().y()>0){zoomIn();}else if(e->angleDelta().y()<0){zoomOut();}e->accept();}else{QTextEdit::wheelEvent(e);}
}void MyTextEdit::keyPressEvent(QKeyEvent *e)
{if(e->key()==Qt::Key_Control){qDebug()<<"Ctrl was pressed";ctrlKeyPressed=1;}QTextEdit::keyPressEvent(e);
}void MyTextEdit::keyReleaseEvent(QKeyEvent *e)
{if(e->key()==Qt::Key_Control){qDebug()<<"Ctrl was released";ctrlKeyPressed=0;}QTextEdit::keyReleaseEvent(e);
}​

mytextedit.h

#ifndef MYTEXTEDIT_H
#define MYTEXTEDIT_H#include <QTextEdit>class MyTextEdit : public QTextEdit
{
public:MyTextEdit(QWidget *parent);/*personel compenents begin*/
protected:void wheelEvent(QWheelEvent *e) override;void keyPressEvent(QKeyEvent *e) override;void keyReleaseEvent(QKeyEvent *e) override;private:bool ctrlKeyPressed=0;/*personel compenents end*/};#endif // MYTEXTEDIT_H

运行测试一下，先放大字体：

#include "widget.h"
#include "ui_widget.h"#include <QFileDialog>
#include <QDebug>
#include <QList>
#include <QColor>
#include <QMessageBox>
#include <QShortcut>Widget::Widget(QWidget *parent) : QWidget(parent) , ui(new Ui::Widget)
{ui->setupUi(this);ui->textEdit->installEventFilter(this);QShortcut *shortcutOpen = new QShortcut(QKeySequence(tr("Ctrl+O", "File|Open")),this);QShortcut *shortcutSave = new QShortcut(QKeySequence(tr("Ctrl+S", "File|Save")),this);QShortcut *shortcutEnlarge = new QShortcut(QKeySequence(tr("Ctrl+Shift+=", "File|Enlarge")),this);QShortcut *shortcutReduce = new QShortcut(QKeySequence(tr("Ctrl+Shift+-", "File|Reduce")),this);connect(shortcutOpen,&QShortcut::activated,[=](){on_btnOpen_clicked();});connect(shortcutSave,&QShortcut::activated,[=](){on_btnSave_clicked();});connect(shortcutEnlarge,&QShortcut::activated,[=](){textEditEnlarge();});connect(shortcutReduce, &QShortcut::activated,[=](){textEditReduce();});this->setLayout(ui->verticalLayout);ui->widgetBottom->setLayout(ui->horizontalLayout);connect(ui->comboBox,SIGNAL(currentIndexChanged(int)),this,SLOT(onCurrentIndexChanged(void)));connect(ui->textEdit,SIGNAL(cursorPositionChanged()),this,SLOT(onCursorPositionChanged()));
}Widget::~Widget()
{delete ui;
}void Widget::textEditEnlarge()
{//获取当前TextEdit内的字体信息QFont font=ui->textEdit->font();//获取当前字体的大小int fontSize=font.pointSize();if(fontSize==-1) return;//改变大小，并设置字体大小int newFontSize=fontSize+1;font.setPointSize(newFontSize);ui->textEdit->setFont(font);
}void Widget::textEditReduce()
{//获取当前TextEdit内的字体信息QFont font=ui->textEdit->font();//获取当前字体的大小int fontSize=font.pointSize();if(fontSize==-1) return;//改变大小，并设置字体大小int newFontSize=fontSize-1;font.setPointSize(newFontSize);ui->textEdit->setFont(font);
}bool Widget::eventFilter(QObject *watched, QEvent *event)
{//滚轮滑动时用keyboardModifiers方法捕获Ctrl按键是否按下if(event->type()==QEvent::Wheel){if(QGuiApplication::keyboardModifiers()==Qt::ControlModifier){QWheelEvent *wheelEvent=dynamic_cast<QWheelEvent *>(event);if(wheelEvent->angleDelta().y()>0){textEditEnlarge();}else if(wheelEvent->angleDelta().y()<0){textEditReduce();}return true;}}return false;
}void Widget::on_btnOpen_clicked()
{QString fileName=QFileDialog::getOpenFileName(this,tr("Open File"),"E:\\6_Qt Projects\\31_NotepadCodec\\files",tr("Text(*.txt *.doc)"));//QFileDialog限制程序可打开的文件形式为txt文件或者doc文本ui->textEdit->clear();//每次打开文件时清除控件区域“textEdit”file.setFileName(fileName);if(!file.open(QIODevice::ReadWrite|QIODevice::Text)){qDebug()<<"file open error";}this->setWindowTitle(fileName+"-NotesBook");QTextStream in(&file);QString str=ui->comboBox->currentText();const char* c_str=str.toStdString().c_str();in.setCodec(c_str);while(!in.atEnd()){QString context=in.readLine();//qDebug()<<qPrintable(context);ui->textEdit->append(context);//将读取到的每行内容通过 append 方法添加到界面的文本编辑框（ui->textEdit）中}// 将此时ui->textEdit中的文本内容保存到initialText变量中，作为初始文本initialText = ui->textEdit->toPlainText();ui->textEdit->setFocus(Qt::OtherFocusReason);
}void Widget::on_btnSave_clicked()
{//如果当前没有文件打开，就弹窗让用户选择新文件，创建新文件;//而不是原来那样，都弹出新的文件保存窗口if(!file.isOpen()){QString fileName = QFileDialog::getSaveFileName(this, tr("SaveFile"),"E:\\6_Qt Projects\\31_NotepadCodec\\files\\untitled file.txt",tr("Text (*.txt*.doc)"));file.setFileName(fileName);if(!file.open(QIODevice::WriteOnly | QIODevice::Text)){qDebug() << "file open error";}this->setWindowTitle(fileName + "- MyNoteBook");}else{// 如果文件已打开，先将文件指针移动到文件开头，准备覆盖原有内容file.seek(0);// 截断文件内容，清除原有内容file.resize(0);}//当保存被按下，不管是已有打开的文件还是上面if满足后用户选择新文件，//都要读取TextEdit内容并写入文件中QTextStream out(&file);out.setCodec(ui->comboBox->currentText().toStdString().c_str());QString context = ui->textEdit->toPlainText();out << context;initialText=ui->textEdit->toPlainText();
}void Widget::on_btnClose_clicked()
{QString currentText = ui->textEdit->toPlainText();if(currentText!= initialText){int ret = QMessageBox::warning(this, tr("NotesBook Notice"),tr("The document has been modified.\n""Do you want to save your changes?"),QMessageBox::Save | QMessageBox::Discard| QMessageBox::Cancel, QMessageBox::Save);switch (ret) {case QMessageBox::Save:// Save was clickedon_btnSave_clicked();ui->textEdit->clear();break;case QMessageBox::Discard:// Don't Save was clickedui->textEdit->clear();if (file.isOpen()) {file.close();this->setWindowTitle("NotesBook");}break;case QMessageBox::Cancel:// Cancel was clickedbreak;default:// should never be reachedbreak;}} else {ui->textEdit->clear();if (file.isOpen()) {file.close();this->setWindowTitle("NotesBook");}}
}void Widget::onCurrentIndexChanged(void)
{ui->textEdit->clear();if(file.isOpen()){QTextStream in(&file);in.setCodec(ui->comboBox->currentText().toStdString().c_str());//链式调用访问成员变量file.seek(0);//将光标移动回起始点while(!in.atEnd()){QString context=in.readLine();ui->textEdit->append(context);}}
}void Widget::onCursorPositionChanged(void)
{QTextCursor cursor=ui->textEdit->textCursor();//qDebug()<<cursor.blockNumber()+1 <<cursor.columnNumber()+1;QString blockNum=QString::number(cursor.blockNumber()+1);QString columnNum=QString::number(cursor.columnNumber()+1);const QString labelMes="L:"+blockNum+" "+"C:"+columnNum;ui->labelPositon->setText(labelMes);/*设置当前行高亮*///0.声明了一个 QList 容器 extraSelectionsQList <QTextEdit::ExtraSelection> extraSelections;//同时声明了ext这个结构体变量QTextEdit::ExtraSelection ext;//1.获取当前行的数值ext.cursor=ui->textEdit->textCursor();//2.配置颜色QBrush qBrush(Qt::lightGray);ext.format.setBackground(qBrush);//3.配置段属性，整行显示ext.format.setProperty(QTextFormat::FullWidthSelection,true);//4.整体配置extraSelections.append(ext);ui->textEdit->setExtraSelections(extraSelections);}

widget.h

#ifndef WIDGET_H
#define WIDGET_H#include <QFile>
#include <QWidget>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();/*personel public components begin*/QFile file;QString initialText;  // 新增成员变量，用于保存初始的文件文本内容void textEditEnlarge(void);void textEditReduce(void);bool eventFilter(QObject *watched,QEvent *event);/*personel public components end*/private:Ui::Widget *ui;   /*personel private components begin*/private slots:void on_btnOpen_clicked();void on_btnSave_clicked();void on_btnClose_clicked();void onCurrentIndexChanged(void);void onCursorPositionChanged(void);/*personel private components end*/
};
#endif // WIDGET_H

第73讲 串口调试助手界面01