深入理解Qt中各種消息框?qū)υ捒虻氖褂?/h1>

來源：本站原創(chuàng)|時(shí)間：2020-01-10|欄目：C語言|點(diǎn)擊： 次

最近在學(xué)習(xí)Qt框架，今天學(xué)習(xí)了一下消息框的使用， 現(xiàn)整理出來以作記錄。

在程序運(yùn)行時(shí)，經(jīng)常需要提示用戶一些信息，比如警告啊，提示啊，建議啊之類的東西。這些東西基本上是通過消息框與用戶進(jìn)行交互的，Qt中主要是用QMessageBox類來加以實(shí)現(xiàn)的。

消息框一般分為七種：

1. Question詢問消息框：為正常的操作提供一個(gè)簡單的詢問
2. Information信息消息框：為正常操作提供一個(gè)提示
3. Warning提示消息框：提醒用戶發(fā)生了一個(gè)錯(cuò)誤
4. Critical警告消息框：警告用戶發(fā)生了一個(gè)嚴(yán)重錯(cuò)誤
5. About關(guān)于消息框：自定義的關(guān)于信息
6. AboutQt關(guān)于Qt消息框：Qt自身的關(guān)于信息
7. Custom自定義消息框：自己定制消息框

具體用法見源碼以及分析：

Dialog.pro

#-------------------------------------------------
#
# Project created by QtCreator 2015-10-24T17:32:35
#
#-------------------------------------------------

QT    += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = Dialog
TEMPLATE = app

SOURCES += main.cpp
    dialog.cpp

HEADERS += dialog.h

dialog.h

#ifndefDIALOG_H
#defineDIALOG_H

#include<QDialog>
#include<QGridLayout>
#include<QPushButton>
#include<QLabel>
#include<QMessageBox>
class Dialog: public QDialog
{
  Q_OBJECT

public:
  Dialog(QWidget *parent = 0);
  ~Dialog();
public://配置部件和布局
  QLabel *label;
  QPushButton *QuestionBtn,*InformationBtn,*WarningBtn,*CriticalBtn,*AboutBtn,*AboutQtBtn,*CustomBtn;
  QGridLayout *layout,*layoutLabel,*layoutBtn;
protected slots://各種按鈕的槽
  void slotQuestion();
  void slotInformation();
  void slotWarning();
  void slotCritical();
  void slotAbout();
  void slotAboutQt();
  void slotCustom();
};

#endif// DIALOG_H

dialog.cpp

#include"dialog.h"

Dialog::Dialog(QWidget *parent)
  : QDialog(parent)
{
  setWindowTitle("QMessageBox");

  QuestionBtn=new QPushButton("Question");
  InformationBtn=new QPushButton("Information");
  WarningBtn=new QPushButton("Warning");
  CriticalBtn=new QPushButton("Critical");
  AboutBtn=new QPushButton("About");
  AboutQtBtn=new QPushButton("AboutQt");
  CustomBtn=new QPushButton("Custom");

  label=new QLabel("About Qt MessageBox:");
  layout=new QGridLayout(this);
  layoutLabel=new QGridLayout;
  layoutBtn=new QGridLayout;
  layoutLabel->addWidget(label,0,0);
  layoutBtn->addWidget(QuestionBtn,1,0);
  layoutBtn->addWidget(InformationBtn,1,1);
  layoutBtn->addWidget(WarningBtn,2,0);
  layoutBtn->addWidget(CriticalBtn,2,1);
  layoutBtn->addWidget(AboutBtn,3,0);
  layoutBtn->addWidget(AboutQtBtn,3,1);
  layoutBtn->addWidget(CustomBtn,4,0);
  layoutBtn->setSpacing(15);

  //嵌套布局
  layout->addLayout(layoutLabel,0,0);
  layout->addLayout(layoutBtn,1,0);
  setFixedSize(300,220);//固定大小

  connect(QuestionBtn,SIGNAL(clicked()),this,SLOT(slotQuestion()));
  connect(InformationBtn,SIGNAL(clicked()),this,SLOT(slotInformation()));
  connect(WarningBtn,SIGNAL(clicked()),this,SLOT(slotWarning()));
  connect(CriticalBtn,SIGNAL(clicked()),this,SLOT(slotCritical()));
  connect(AboutBtn,SIGNAL(clicked()),this,SLOT(slotAbout()));
  connect(AboutQtBtn,SIGNAL(clicked()),this,SLOT(slotAboutQt()));
  connect(CustomBtn,SIGNAL(clicked()),this,SLOT(slotCustom()));
}

Dialog::~Dialog()
{

}

//直接調(diào)用AboutQt，設(shè)置句柄和標(biāo)題即可
void Dialog::slotAboutQt(){
 QMessageBox::aboutQt(this,"This is the title");
}

//以下三個(gè)函數(shù)均是設(shè)置句柄標(biāo)題和信息即可，也可以在最后設(shè)置默認(rèn)按鈕，一般默認(rèn)的是QMessageBox::Ok。
void Dialog::slotAbout(){
   QMessageBox::about(this,"About","This is the label.");
}
void Dialog::slotCritical(){
  QMessageBox::critical(this,"Critical","This is the label.");
}
void Dialog::slotInformation(){
 QMessageBox::information(this,"Information","This is the label.");
}

//自定義消息框
void Dialog::slotCustom(){

  QMessageBox customMsgBox;
  customMsgBox.setWindowTitle("Custom message box");

  //添加按鍵
  QPushButton *lockBtn=customMsgBox.addButton("Lock",QMessageBox::ActionRole);
  QPushButton *unlockBtn=customMsgBox.addButton("Unlock",QMessageBox::ActionRole);
  QPushButton *cancelBtn=customMsgBox.addButton(QMessageBox::Cancel);//注意cancel不能指定Text

  //customMsgBox.setIconPixmap(QPixmap("a.png"));//設(shè)置圖片
  customMsgBox.setText("This is the label");
  customMsgBox.exec();//執(zhí)行消息框

  QPushButton *msg=(QPushButton*)customMsgBox.clickedButton();//接受按鍵信息

  //判斷按鍵
  if(msg==lockBtn)
    label->setText("Custom button /lock");

  if(msg==unlockBtn)
    label->setText("Custom button /unlock");

  if(msg==cancelBtn)
    label->setText("Custom button /cancel");

}

void Dialog::slotQuestion(){
  //QMessageBox::**question()**函數(shù)，傳入句柄，標(biāo)題，文本，按鈕值，返回按鍵對應(yīng)的值，最后也可以加默認(rèn)按鍵的位置
  int msg=QMessageBox::question(this,"Question","This is the label.",QMessageBox::Ok|QMessageBox::Cancel);

  //判斷選擇信息
  switch(msg){
  case QMessageBox::Ok:
    label->setText("Question button /OK");
    break;
  case QMessageBox::Cancel:
    label->setText("Question button /Cancel");
    break;
  default:
    break;
  }
}

void Dialog::slotWarning(){

  //QmessageBox::warning()函數(shù)同Question函數(shù)
  int msg=QMessageBox::warning(this,"Question","This is the label.",QMessageBox::Save|QMessageBox::Discard|QMessageBox::Cancel,QMessageBox::Save);

  switch(msg){//判斷選擇信息
  case QMessageBox::Save:
    label->setText("Warning button /Save");
    break;
  case QMessageBox::Cancel:
    label->setText("Warning button /Cancel");
    break;
  case QMessageBox::Discard:
    label->setText("Warning button /Discard");
    break;
  default:
    break;
  }

}

##main.cpp

#include"dialog.h"
#include<QApplication>

int main(intargc,char*argv[])
{
  QApplicationa(argc, argv);
  Dialog w;
  w.show();

  return a.exec();
}

運(yùn)行截圖

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