六、标准对话框、多应用窗体

一、标准对话框

Qt提供了一些常用的标准对话框，如打开文件对话框、选择颜色对话框、信息提示和确认选择对话框、标准输入对话框等。

1、预定义标准对话框

（1）QFileDialog 文件对话框

QString getOpenFileName() 打开一个文件
QstringList getOpenFileNames() 打开多个文件
QString getSaveFileName() 选择保存一个文件
QString getExistingDirectory() 选择一个已有目录
QUrl getOpenFileUrl() 打开一个网络文件

（2）QColorDialog 颜色对话框

QColor getColor() 选择颜色

（3）QFontDialog 选择字体

QFont getFont() 选择字体

（4）QInputDialog 输入对话框

QString getText() 的呼入单行文字
int getInt() 输入整数
double getDouble() 输入浮点数
QString getItem() 从一个下拉列表中选择输入
QString getMultiLineText() 输入多行字符串

（5）QMessageBox 消息对话框

StandardButton information() 信息提示对话框
StandardButton question() 询问并获取是否确定对话框
StandardButton warning() 警告信息提示对话框
StandardButton critical() 错误信息提示对话框
void about() 设置自定义信息的关于对话框
void aboutQt() 关于Qt的对话框

2、实现工具

（1）创建项目，基于QDialog

（2）添加组件

在这里插入图片描述

（3）实现信号与槽

#include "dialog.h"
#include "ui_dialog.h"#include <QFileDialog>
#include <QColorDialog>
#include <QFontDialog>
#include <QInputDialog>
#include <QMessageBox>Dialog::Dialog(QWidget *parent) :QDialog(parent),ui(new Ui::Dialog)
{ui->setupUi(this);
}Dialog::~Dialog()
{delete ui;
}void Dialog::on_btnClearText_clicked()
{ui->plainTextEdit->clear();
}void Dialog::on_btnOpenFile_clicked()
{QString strCurPath = QDir::currentPath();QString strTitle = "选择文件对话框";QString strFilter = "文本文件(*.txt);;图片文件(*.ipg *.png);;所有格式(*.*)";  // 文件选择过滤器QString strFileName = QFileDialog::getOpenFileName(this, strTitle, strCurPath,strFilter);if(strFileName.isEmpty()){return;}ui->plainTextEdit->appendPlainText(strFileName);
}void Dialog::on_btnOpenFiles_clicked()
{QString strCurPath = QDir::currentPath();QString strTitle = "选择文件对话框";QString strFilter = "文本文件(*.txt);;图片文件(*.ipg *.png);;所有格式(*.*)";  // 文件选择过滤器QStringList FileNames = QFileDialog::getOpenFileNames(this, strTitle, strCurPath,strFilter);if(FileNames.count() == 0){return;}foreach (QString strFileName, FileNames){ui->plainTextEdit->appendPlainText(strFileName);}
}void Dialog::on_btnSelectDir_clicked()
{QString strCurPath = QDir::currentPath();QString strTitle = "选择文件对话框";QString strSelectDir = QFileDialog::getExistingDirectory(this, strTitle, strCurPath,QFileDialog::ShowDirsOnly);if(strSelectDir.isEmpty()){return;}ui->plainTextEdit->appendPlainText(strSelectDir);
}void Dialog::on_btnSaveFile_clicked()
{QString strCurPath = QCoreApplication::applicationDirPath();QString strTitle = "选择文件对话框";QString strFilter = "文本文件(*.txt);;图片文件(*.ipg *.png);;所有格式(*.*)";  // 文件选择过滤器QString strFileName = QFileDialog::getSaveFileName(this, strTitle, strCurPath,strFilter);if(strFileName.isEmpty()){return;}ui->plainTextEdit->appendPlainText(strFileName);
}void Dialog::on_btnSelectColor_clicked()
{QPalette pal = ui->plainTextEdit->palette();QColor initColor = pal.color(QPalette::Text);QColor color = QColorDialog::getColor(initColor, this, "选择颜色");if(!color.isValid()){return;}pal.setColor(QPalette::Text, color);ui->plainTextEdit->setPalette(pal);
}void Dialog::on_btnSelectFont_clicked()
{bool ok = false;QFont initFont = ui->plainTextEdit->font();QFont font = QFontDialog::getFont(&ok, initFont, this, "选择字体");if(!ok){return;}ui->plainTextEdit->setFont(font);
}void Dialog::on_btnInputString_clicked()
{QString strTitle = "输入文字对话框";QString strLabel = "请输入文字";QString strDefault = "默认文字";QLineEdit::EchoMode echoMode = QLineEdit::Normal;bool ok = false;QString str = QInputDialog::getText(this, strTitle, strLabel,echoMode, strDefault, &ok);if(!ok){return;}ui->plainTextEdit->appendPlainText(str);
}void Dialog::on_btnInputInt_clicked()
{QString strTitle = "输入整数对话框";QString strLabel = "请输入数字";int nDefault = ui->plainTextEdit->font().pointSize();int nMinValue = 0, nMaxValue = 100;bool ok = false;int nValue = QInputDialog::getInt(this, strTitle, strLabel, nDefault,nMinValue, nMaxValue, 1, &ok);if(!ok){return;}QFont font = ui->plainTextEdit->font();font.setPointSize(nValue);ui->plainTextEdit->setFont(font);ui->plainTextEdit->appendPlainText(QString::asprintf("输入整数：%d", nValue));
}void Dialog::on_btnInputFloat_clicked()
{QString strTitle = "输入整数对话框";QString strLabel = "请输入数字";double dDefault = 10.123;double dMinValue = 0.0, dMaxValue = 100.0;bool ok = false;double dValue = QInputDialog::getDouble(this, strTitle, strLabel, dDefault,dMinValue, dMaxValue, 3, &ok);if(!ok){return;}ui->plainTextEdit->appendPlainText(QString::asprintf("输入整数：%.3lf", dValue));
}void Dialog::on_btnInputSelect_clicked()
{QStringList items;items << "条目1" << "条目2" << "条目3" << "条目4";QString strTitle = "输入条目对话框";QString strLabel = "请选择一个条目";bool ok = false;QString str = QInputDialog::getItem(this, strTitle, strLabel, items, 0,true, &ok);if(!ok || str.isEmpty()){return;}ui->plainTextEdit->appendPlainText(str);
}void Dialog::on_btnQuestion_clicked()
{QString strTitle = "Question消息框";QString strLabel = "选择是与否";QMessageBox::StandardButton result = QMessageBox::question(this, strTitle, strLabel,QMessageBox::Yes | QMessageBox::No | QMessageBox::Cancel,QMessageBox::Cancel);if(result == QMessageBox::Yes){ui->plainTextEdit->appendPlainText("Yes");}else if (result == QMessageBox::No){ui->plainTextEdit->appendPlainText("No");}else if (result == QMessageBox::Cancel){ui->plainTextEdit->appendPlainText("Cancel");}
}void Dialog::on_btnInformation_clicked()
{QMessageBox::information(this, "Information对话框", "信息", QMessageBox::Ok);
}void Dialog::on_btnWarning_clicked()
{QMessageBox::warning(this, "Warning对话框", "警告", QMessageBox::Ok);
}void Dialog::on_btnCritical_clicked()
{QMessageBox::critical(this, "Critical对话框", "错误", QMessageBox::Ok);
}void Dialog::on_btnAbout_clicked()
{QMessageBox::about(this, "About对话框", "关于");
}void Dialog::on_btnAboutQt_clicked()
{QMessageBox::aboutQt(this, "About对话框");
}

二、自定义标准对话框

1、实现工具

QWDialogSize 设置表格行列数对话框
QWDialogHeaders 设置表头对话框
QWDialogLocate 单元格定位于文字设置对话框

（1）创建项目，基于QMainWindow

（2）添加组件

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#include "qdialogsetsize.h"
#include "ui_qdialogsetsize.h"#include <QMessageBox>int QDialogSetSize::rowCount()
{return ui->spinBoxRow->value();
}int QDialogSetSize::columnCount()
{return ui->spinBoxColumn->value();
}void QDialogSetSize::setRowColumns(int nRow, int nColumn)
{ui->spinBoxRow->setValue(nRow);ui->spinBoxColumn->setValue(nColumn);
}QDialogSetSize::QDialogSetSize(QWidget *parent) :QDialog(parent),ui(new Ui::QDialogSetSize)
{ui->setupUi(this);
}QDialogSetSize::~QDialogSetSize()
{QMessageBox::information(this, "", "设置大小对话框已经退出");delete ui;
}

（3）添加设置表格行列数UI于类

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（4）添加设置表头的UI与类

在这里插入图片描述

#include "qdialogsetheaders.h"
#include "ui_qdialogsetheaders.h"QDialogSetHeaders::QDialogSetHeaders(QWidget *parent) :QDialog(parent),ui(new Ui::QDialogSetHeaders)
{ui->setupUi(this);theModel = new QStringListModel(this);ui->listView->setModel(theModel);
}QDialogSetHeaders::~QDialogSetHeaders()
{QMessageBox::information(this, "", "设置表头对话框退出");delete ui;
}void QDialogSetHeaders::setStringList(QStringList strList)
{theModel->setStringList(strList);
}QStringList QDialogSetHeaders::getStringList()
{return theModel->stringList();
}

（5）添加定位单元格UI与类

在这里插入图片描述

#include "qdialoglocate.h"
#include "ui_qdialoglocate.h"
#include <QMessageBox>QDialogLocate::QDialogLocate(QWidget *parent) :QDialog(parent),ui(new Ui::QDialogLocate)
{ui->setupUi(this);
}QDialogLocate::~QDialogLocate()
{QMessageBox::information(this, "", "单元格定位对话框退出");delete ui;
}void QDialogLocate::setRange(int nRow, int nColumn)
{ui->spinBoxRow->setRange(0, nRow - 1);ui->spinBoxCol->setRange(0, nColumn - 1);
}void QDialogLocate::setValue(int nRow, int nColumn)
{ui->spinBoxRow->setValue(nRow);ui->spinBoxCol->setValue(nColumn);
}#include <mainwindow.h>
void QDialogLocate::closeEvent(QCloseEvent *event)
{Q_UNUSED(event)MainWindow *parent = (MainWindow*)parentWidget();parent->setActLocateEnable(true);parent->resetDlgLocate();
}void QDialogLocate::on_btnSetText_clicked()
{int row = ui->spinBoxRow->value();int col = ui->spinBoxCol->value();MainWindow *parent = (MainWindow*)parentWidget();parent->setCelltext(row, col, ui->lineEdit->text());if(ui->checkBoxAddRow->isChecked()){ui->spinBoxRow->setValue(ui->spinBoxRow->value() + 1);}if(ui->checkBoxAddCol->isChecked()){ui->spinBoxCol->setValue(ui->spinBoxCol->value() + 1);}}

（6）设置主程序功能

#include "mainwindow.h"
#include "ui_mainwindow.h"#include <QMessageBox>MainWindow::MainWindow(QWidget *parent) :QMainWindow(parent),ui(new Ui::MainWindow)
{ui->setupUi(this);theModel = new QStandardItemModel(this);theSelect = new QItemSelectionModel(theModel);ui->tableView->setModel(theModel);ui->tableView->setSelectionModel(theSelect);
}MainWindow::~MainWindow()
{delete ui;
}void MainWindow::setActLocateEnable(bool enable)
{ui->actLocate->setEnabled(enable);
}void MainWindow::resetDlgLocate()
{dialogLocate = nullptr;
}void MainWindow::setCelltext(int row, int col, QString strText)
{QModelIndex index = theModel->index(row, col);theModel->setData(index, strText, Qt::DisplayRole);theSelect->clearSelection();theSelect->setCurrentIndex(index, QItemSelectionModel::Select);
}#include "qdialogsetsize.h"
void MainWindow::on_actSetSize_triggered()
{QDialogSetSize *dlg = new QDialogSetSize(this);dlg->setRowColumns(theModel->rowCount(), theModel->columnCount());int ret = dlg->exec();if(ret == QDialog::Accepted){int row = dlg->rowCount();int col = dlg->columnCount();theModel->setRowCount(row);theModel->setColumnCount(col);}delete dlg;
}void MainWindow::on_actSetHeader_triggered()
{if(nullptr == dialogHeader){dialogHeader = new QDialogSetHeaders(this);}if(dialogHeader->getStringList().count() != theModel->columnCount()){QStringList strList;for (int i = 0; i < theModel->columnCount(); ++i){strList << theModel->headerData(i, Qt::Horizontal).toString();}dialogHeader->setStringList(strList);}int ret = dialogHeader->exec();if(ret == QDialog::Accepted){QStringList strList = dialogHeader->getStringList();theModel->setHorizontalHeaderLabels(strList);}
}void MainWindow::on_actLocate_triggered()
{ui->actLocate->setEnabled(false);if(nullptr == dialogLocate){dialogLocate = new QDialogLocate(this);}dialogLocate->setAttribute(Qt::WA_DeleteOnClose); //关闭自动删除Qt::WindowFlags flags = dialogLocate->windowFlags();dialogLocate->setWindowFlags(flags | Qt::WindowCloseButtonHint); //置于主界面上层dialogLocate->setRange(theModel->rowCount(), theModel->columnCount());QModelIndex curIndex = theSelect->currentIndex();if(curIndex.isValid()){dialogLocate->setValue(curIndex.row(), curIndex.column());}dialogLocate->show();
}void MainWindow::on_tableView_clicked(const QModelIndex &index)
{if(dialogLocate != nullptr){dialogLocate->setValue(index.row(), index.column());}
}

三、多窗体应用程序设计

1、视图类

QWidget：在没有指定父容器时，可以作为独立的窗口，指定父容器后可以作为容器的内部组件
QDialog：设计对话框，以独立窗口显示
QMainWindow：用于设计带有菜单栏、工具栏、状态栏的主窗口，一般独立窗口显示。
QSplashScreen：用作应用程序启动时的splash窗口，没有边框。
QMdiSubWindow：用于为QMdiArea提供一个子窗体，用于MDI（多文档）的设计。
QDesktopWidget：具有多个显卡和多个显示器的系统具有多个左面，这个类提供用户桌面信息，如屏幕个数，每个屏幕的大小等。
QWindow：通过底层的窗口系统表示一个窗口类，一般作为一个父容器的嵌入式窗体，不作为独立窗体。

QObjectQWidgetQDialogQMainWindowQSplashScreenQMdiSubWindowQDesktopWidgetQWindow

2、窗体特性

（1）设置运行特性和显示特性

void QWidget::setWindowState(Qt::WindowStates windowstate)Qt::NonModal 无模态，不会阻止其他窗体的输入Qt::WindowModal 窗口对于其父窗口、所有的商机父窗口都是模态的Qt::ApplicationModal 窗口对整个应用程序时模态的，阻止所有窗口的输入

void QWidget::setWindowOpacity(qreal level)参数level是1.0（完全不透明）至0.0（完全透明）之间的数。窗口透明度缺省值为1.0，即完全不透明。

void QWidgwt::setAttribute(Qt::WidgwtAttribute attribute, bool on = true)Qt::WA_AcceptDrops	允许窗体接受拖拽来的组件Qt::WA_DeleteOnClose	窗体关闭时删除自己，释放内存Qt::WA_Hover	鼠标进入或移除窗体时产生paint事件Qt::WA_AcceptTouchEvents	窗体是否接受触屏事件

表示窗体类型
void QWidget::setWindowFlags(Qt::WindowFlags type)Qt::Widget	这是QWidget类的缺省类型，如果有父窗体，就作为父窗体的子窗体，否则就作为一个独立的窗口Qt::Window	表明这个窗体是一个窗口，通常具有窗口的边框、标题栏，而不管它是都有父窗体Qt::Dialog	表明窗体是一个窗口，并且要显示为对话框（如：没有标题栏、没笑最小化、最大化），这是QDialog类的缺省类型Qt::Popup	表明扯个窗体是用作弹出式菜单的窗体Qt::Tool	表明这个窗体是工具窗体，具有更小的标题栏和关闭按钮，通常作为工具栏的窗体Qt::ToolTip	表明这是用于ToolTip消息提示的窗体Qt::SplashScreen	表明窗体是Splash屏幕，是QSplashScreen类的缺省类型Qt::DeskTop	表明窗体时桌面，这是QDesktopWidget类的类型Qt::SubWindow	表明窗体是子窗体，例如QMdiSubWindow就是这种类型
控制窗体显示效果Qt::MSWindowsFisedSizeDialogHint	在WIndows平台上，是的窗口具有更窄的边框Qt::FramelessWindowHint		创建无边框窗口
QindowHint要行医窗体外观定制窗体外观的常量，需要先设置Qt::CustomizeQt::CustmizeWindowHint	关闭缺省的窗口标题栏Qt::WindowTitleHint		窗口有标题栏Qt::WindowSystemMenuHint	有窗口系统菜单Qt::WindowMinimizeButtonHint	有最小化按钮Qt::WindowMaximizeButtonHint	有最大化按钮Qt::WindowMinMaxButtonHint	有最小化、最大化按钮Qt::WindowCloseButtonHint	有关闭按钮Qt::wContextHelpButtonHint	有上下文帮助按钮Qt::WindowStaysOnTopHint	窗口总是处于最上层Qt::WindowStaysOnBottomHint	窗口总是处于最下层Qt::WindowtransparentForInput	窗口只作为输出，不接受输入

3、实现工具

（1）创建项目，基于QMainWindow

（2）添加源文件图标

（3）添加工具栏

在这里插入图片描述

（4）添加UI界面

在这里插入图片描述

（5）实现功能

#include "mainwindow.h"
#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent) :QMainWindow(parent),ui(new Ui::MainWindow)
{ui->setupUi(this);setCentralWidget(ui->tabWidget);ui->tabWidget->setVisible(false);   //不显示}MainWindow::~MainWindow()
{delete ui;
}#include <QPainter>
void MainWindow::paintEvent(QPaintEvent *event)
{// 使用图片绘制底板Q_UNUSED(event)QPainter painter(this);painter.drawPixmap(0, ui->mainToolBar->height(), width(),height() - ui->mainToolBar->height() - ui->statusBar->height(),QPixmap(":/images/images/back.jpg"));
}#include "formdoc.h"
void MainWindow::on_actWidgetInsite_triggered()
{FormDoc *formDoc = new FormDoc(this);formDoc->setAttribute(Qt::WA_DeleteOnClose);int cur = ui->tabWidget->addTab(formDoc, QString::asprintf("Doc %d", ui->tabWidget->count()));ui->tabWidget->setCurrentIndex(cur);ui->tabWidget->setVisible(true);
}void MainWindow::on_tabWidget_tabCloseRequested(int index)
{if(index < 0){return;}QWidget* tab = ui->tabWidget->widget(index);tab->close();
}void MainWindow::on_tabWidget_currentChanged(int index)
{Q_UNUSED(index)if(ui->tabWidget->count() == 0){ui->tabWidget->setVisible(false);}
}void MainWindow::on_actWidget_triggered()
{FormDoc *formDoc = new FormDoc();formDoc->setAttribute(Qt::WA_DeleteOnClose);formDoc->setWindowTitle("Widget独立窗口");formDoc->setWindowOpacity(0.7); //半透明formDoc->show();
}#include "formtable.h"
void MainWindow::on_actMainWindowInsite_triggered()
{FormTable *formtable = new FormTable(this);formtable->setAttribute(Qt::WA_DeleteOnClose);int cur = ui->tabWidget->addTab(formtable, QString::asprintf("Table %d", ui->tabWidget->count()));ui->tabWidget->setCurrentIndex(cur);ui->tabWidget->setVisible(true);
}void MainWindow::on_actMainWindow_triggered()
{FormTable *formtable = new FormTable(this);formtable->setAttribute(Qt::WA_DeleteOnClose);formtable->setWindowTitle("MainWindow独立窗口");formtable->setWindowOpacity(0.7); //半透明formtable->show();
}

四、MDI应用程序设计

QMdiArea（Multiple Document Interface Area）提供一个可以同时显示多个文档窗口的区域。区域本身是一个框架，每个窗口是都一个QMdiSubWindow对象。
设置MDI视图窗口模式用setViewMode()函数，有两种选择：

setViewMode()QMdiArea::SubWindowView	传统的子窗口模式WMdiArea::TabbedView	多页显示模式，类似tabView

1、实现工具

在这里插入图片描述

（1）创建项目，基于QMainWindow

（2）添加资源文件，设置界面

在这里插入图片描述

（3）添加UI与类

在这里插入图片描述

（4）实现功能

#include "mainwindow.h"
#include "ui_mainwindow.h"#include "formdoc.h"MainWindow::MainWindow(QWidget *parent) :QMainWindow(parent),ui(new Ui::MainWindow)
{ui->setupUi(this);setCentralWidget(ui->mdiArea);
}MainWindow::~MainWindow()
{delete ui;
}void MainWindow::on_actDocNew_triggered()
{FormDoc *formDoc = new FormDoc(this);// formDoc->setAttribute(Qt::WA_DeleteOnClose); 不需要，框架会自动回收ui->mdiArea->addSubWindow(formDoc);formDoc->show();ui->actCopy->setEnabled(true);ui->actCut->setEnabled(true);ui->actPaste->setEnabled(true);ui->actFont->setEnabled(true);
}#include <QMdiSubWindow>
#include <QFileDialog>
void MainWindow::on_actDocOpen_triggered()
{bool needNew = false;FormDoc *formDoc = nullptr;if(ui->mdiArea->subWindowList().count() > 0){formDoc = (FormDoc*)ui->mdiArea->activeSubWindow()->widget();needNew = formDoc->isFileOpenedDoc();}else{needNew = true;}if(needNew){formDoc = new FormDoc(this);ui->mdiArea->addSubWindow(formDoc);}QString strFileName = QFileDialog::getOpenFileName(this, "打开文档", "","文本文件(*.txt);;所有文件(*.*)");formDoc->loadFromFile(strFileName);formDoc->show();ui->actCopy->setEnabled(true);ui->actCut->setEnabled(true);ui->actPaste->setEnabled(true);ui->actFont->setEnabled(true);}void MainWindow::on_actCloseAll_triggered()
{ui->mdiArea->closeAllSubWindows();ui->actCopy->setEnabled(false);ui->actCut->setEnabled(false);ui->actPaste->setEnabled(false);ui->actFont->setEnabled(false);
}void MainWindow::on_actFont_triggered()
{FormDoc *formDoc = (FormDoc*)ui->mdiArea->activeSubWindow()->widget();formDoc->setTextFont();
}void MainWindow::on_actCut_triggered()
{FormDoc *formDoc = (FormDoc*)ui->mdiArea->activeSubWindow()->widget();formDoc->textCut();
}void MainWindow::on_actCopy_triggered()
{FormDoc *formDoc = (FormDoc*)ui->mdiArea->activeSubWindow()->widget();formDoc->textCopy();
}void MainWindow::on_actPaste_triggered()
{FormDoc *formDoc = (FormDoc*)ui->mdiArea->activeSubWindow()->widget();formDoc->textPaste();
}void MainWindow::on_actMdiMode_triggered(bool checked)
{if(checked){ui->mdiArea->setViewMode(QMdiArea::TabbedView);ui->mdiArea->setTabsClosable(true); //可关闭ui->actCascade->setEnabled(false);ui->actTile->setEnabled(false);}else{ui->mdiArea->setViewMode(QMdiArea::SubWindowView);ui->actCascade->setEnabled(true);ui->actTile->setEnabled(true);}
}void MainWindow::on_actCascade_triggered()
{ui->mdiArea->cascadeSubWindows();
}void MainWindow::on_actTile_triggered()
{ui->mdiArea->tileSubWindows();
}void MainWindow::on_mdiArea_subWindowActivated(QMdiSubWindow *arg1)
{Q_UNUSED(arg1)// 将选项变化，显示在状态栏if(ui->mdiArea->subWindowList().count() == 0){ui->actCopy->setEnabled(false);ui->actCut->setEnabled(false);ui->actPaste->setEnabled(false);ui->actFont->setEnabled(false);ui->statusBar->clearMessage();}else{FormDoc *formDoc = (FormDoc*)ui->mdiArea->activeSubWindow()->widget();ui->statusBar->showMessage(formDoc->getCurFileName());}
}

五、Splash与登录窗口

Qt有一个QSplashScreen类可以实现Splash窗口的功能，它提供了载入图片，自动设置窗口无边框效果功能。可以在加载界面使用。

	(QMouseEvent *)event->globalPos()	获取鼠标的位置，即鼠偏离屏幕左上角的位置pos()	获取主窗口（Widget窗口）左上角（边框的左上角，外左上角）相对于屏幕左上角的偏移位置。

1、实现工具

（1）拷贝上一个项目

（2）添加UI，选择Dialog

在这里插入图片描述

（3）添加登录验证

#include "mainwindow.h"
#include <QApplication>
#include "dialoglogin.h"int main(int argc, char *argv[])
{QApplication a(argc, argv);DialogLogin *dlg = new DialogLogin();if(dlg->exec() == QDialog::Accepted){MainWindow w;w.show();return a.exec();}return 0;
}

（4）鼠标和窗口位置计算方法

在这里插入图片描述
使用向量原理，可以得到：使用鼠标的向量减去相对向量（鼠标相对窗口的向量），可以得出目标窗口的向量。

void DialogLogin::mousePressEvent(QMouseEvent *event)
{//左击if(event->button()  == Qt::LeftButton){m_moveing = true;m_lastPos = event->globalPos() - pos();}return QDialog::mousePressEvent(event);
}void DialogLogin::mouseMoveEvent(QMouseEvent *event)
{//移动if(m_moveing && (event->buttons() && Qt::LeftButton)){move(event->globalPos() - m_lastPos);m_lastPos = event->globalPos() - pos();}return QDialog::mouseMoveEvent(event);
}void DialogLogin::mouseReleaseEvent(QMouseEvent *event)
{//松开Q_UNUSED(event)m_moveing = false;//    return QDialog::mouseReleaseEvent(event);
}

（5）实现功能

#include "dialoglogin.h"
#include "ui_dialoglogin.h"DialogLogin::DialogLogin(QWidget *parent) :QDialog(parent),ui(new Ui::DialogLogin)
{ui->setupUi(this);setAttribute(Qt::WA_DeleteOnClose);setWindowFlag(Qt::SplashScreen); //关闭边框setFixedSize(this->width(), this->height());    // 禁止拖动窗口大小readSettings();
}DialogLogin::~DialogLogin()
{delete ui;
}void DialogLogin::mousePressEvent(QMouseEvent *event)
{//左击if(event->button()  == Qt::LeftButton){m_moveing = true;m_lastPos = event->globalPos() - pos();}return QDialog::mousePressEvent(event);
}void DialogLogin::mouseMoveEvent(QMouseEvent *event)
{//移动if(m_moveing && (event->buttons() && Qt::LeftButton)){move(event->globalPos() - m_lastPos);m_lastPos = event->globalPos() - pos();}return QDialog::mouseMoveEvent(event);
}void DialogLogin::mouseReleaseEvent(QMouseEvent *event)
{//松开Q_UNUSED(event)m_moveing = false;//    return QDialog::mouseReleaseEvent(event);
}#include <QSettings>
void DialogLogin::writeSettings()
{// 写入注册表QSettings settings("公司-liutt", "应用名称-text");settings.setValue("UserName", m_user);settings.setValue("Passwd", m_passwd);settings.setValue("saved", ui->checkBoxSave->isChecked());
}void DialogLogin::readSettings()
{// 读取注册表QSettings settings("公司-liutt", "应用名称-text");bool saved = settings.value("saved", false).toBool(); //默认值m_user = settings.value("UserName", "user").toString(); //默认值QString defaultPasswd = encrypt("123456"); //加密m_passwd = settings.value("Passwd", defaultPasswd).toString(); //默认值if(saved){ui->checkBoxSave->setChecked(true);ui->lineEditUser->setText(m_user);}
}#include <QCryptographicHash>
QString DialogLogin::encrypt(const QString &str)
{QByteArray btArray;btArray.append(str);QCryptographicHash hash(QCryptographicHash::Md5);hash.addData(btArray);QByteArray btResult = hash.result();QString md5 = btResult.toHex();return md5;
}#include <QMessageBox>
void DialogLogin::on_btnOk_clicked()
{QString strUser = ui->lineEditUser->text().trimmed();QString strPasswd = ui->lineEditPasswd->text().trimmed();if(strUser == m_user && encrypt(strPasswd) == m_passwd){writeSettings();accept();}else{m_tryCount++;if(m_tryCount > 3){QMessageBox::critical(this, "error", "错误次数太多,强制退出");reject();}QMessageBox::warning(this, "error", "账号不存在或密码错误");}
}