1、主窗口中的状态栏

• 状态栏的概念和意义
  — 状态栏是应用程序中输出简要信息的区域
  — 状态栏一般位于主窗口的最底部
  — 状态栏的消息类型
  　实时消息：如（当前程序状态）
  　永久消息：如（程序版本号，机构名称）
  　进度消息：如（进度条提示，百分比提示）
• 在 Qt 中提供与状态栏相关的类组件
  
• 在 Qt 主窗口中创建状态栏
  
• Qt 状态栏的设计原则
  — 左边的区域用于输出实时消息
  — 右边的区域用于设置永久消息
  — addWidget 在状态栏的左半部分添加组件
  — addPermanentWidget 在状态栏的右半部分添加组件

状态栏初体验：

MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include class MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();
};
#endif // MAINWINDOW_H

MainWindow.cpp

#include "MainWindow.h"#include 
#include 
#include 
#include MainWindow::MainWindow(QWidget *parent): QMainWindow(parent)
{QStatusBar* sb = statusBar();QLabel* label = new QLabel("label");QLineEdit* edit = new QLineEdit("edit");QPushButton* btn = new QPushButton("btn");sb->addPermanentWidget(label);sb->addPermanentWidget(edit);sb->addPermanentWidget(btn);sb->showMessage("xiebs");}MainWindow::~MainWindow()
{
}

main.cpp

#include "MainWindow.h"#include int main(int argc, char *argv[])
{QApplication a(argc, argv);MainWindow w;w.show();return a.exec();
}

记事本程序：

MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include class MainWindow : public QMainWindow
{Q_OBJECT
private:MainWindow();MainWindow(const MainWindow& obj);MainWindow& operator= (const MainWindow& obj);bool construct();bool initMenuBar();bool initToolBar();bool initStatusBar();bool initFileMenu(QMenuBar* mb);bool initEditMenu(QMenuBar* mb);bool initFormatMenu(QMenuBar* mb);bool initViewMenu(QMenuBar* mb);bool initHelpMenu(QMenuBar* mb);bool initFileToolItem(QToolBar* tb);bool initEditToolItem(QToolBar* tb);bool initFormatToolItem(QToolBar* tb);bool initViewToolItem(QToolBar* tb);bool makeAction(QAction*& action, QString str, int key);bool makeAction(QAction*& action, QString tip, QString res);public:static MainWindow* NewInstance();~MainWindow();
};
#endif // MAINWINDOW_H

MainWindow.cpp

#include "MainWindow.h"
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include MainWindow::MainWindow(): QMainWindow()
{}bool MainWindow::construct()
{bool ret = true;ret = ret && initMenuBar();ret = ret && initToolBar();ret = ret && initStatusBar();return ret;
}MainWindow* MainWindow::NewInstance()
{MainWindow* ret = new MainWindow();if(!(ret && ret->construct())){delete ret;ret = nullptr;}return ret;
}bool MainWindow::initMenuBar()
{bool ret = true;QMenuBar* mb = menuBar();if(mb != nullptr){ret = ret && initFileMenu(mb);ret = ret && initEditMenu(mb);ret = ret && initFormatMenu(mb);ret = ret && initViewMenu(mb);ret = ret && initHelpMenu(mb);}else{ret = false;}return ret;
}bool MainWindow::initToolBar()
{bool ret = true;QToolBar* tb = addToolBar("ToolBar");tb->setFloatable(false);tb->setMovable(false);tb->setIconSize(QSize(16, 16));ret = ret && initFileToolItem(tb);tb->addSeparator();ret = ret && initEditToolItem(tb);tb->addSeparator();ret = ret && initFormatToolItem(tb);tb->addSeparator();ret = ret && initViewToolItem(tb);return ret;
}bool MainWindow::initStatusBar()
{bool ret = true;QStatusBar* sb = statusBar();QLabel* label = new QLabel("D.T.software");if(label != nullptr){sb->addPermanentWidget(label);label->setMinimumWidth(40);label->setAlignment(Qt::AlignCenter);}else{ret = false;}return ret;
}bool MainWindow::initFileMenu(QMenuBar* mb)
{QMenu* menu = new QMenu("File(&F)", nullptr);bool ret = (menu != nullptr);if(ret){QAction* action = nullptr;ret = ret && makeAction(action, "New(&N)", Qt::CTRL + Qt::Key_N);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Open(&O)", Qt::CTRL + Qt::Key_O);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Save(&N)", Qt::CTRL + Qt::Key_S);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Save As(&A)", Qt::CTRL + Qt::SHIFT + Qt::Key_S);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Print(&P)", Qt::CTRL + Qt::Key_P);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Exit(&X)", 0);if(ret){menu->addAction(action);}menu->addSeparator();}if(ret){mb->addMenu(menu);}else{delete menu;}return ret;
}bool MainWindow::initEditMenu(QMenuBar* mb)
{QMenu* menu = new QMenu("Edit(&E)", nullptr);bool ret = (menu != nullptr);if(ret){QAction* action = nullptr;ret = ret && makeAction(action, "Undo(&U)", Qt::CTRL + Qt::Key_Z);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Redo(&R)", Qt::CTRL + Qt::Key_Y);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Cut(&T)", Qt::CTRL + Qt::Key_X);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Copy(&C)", Qt::CTRL + Qt::Key_C);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Paste(&P)", Qt::CTRL + Qt::Key_V);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Delete(&L)", Qt::Key_Delete);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Find(&F)", Qt::CTRL + Qt::Key_F);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Replace(&R)", Qt::CTRL + Qt::Key_H);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Goto(&G)", Qt::CTRL + Qt::Key_G);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Select All(&A)", Qt::CTRL + Qt::Key_A);if(ret){menu->addAction(action);}menu->addSeparator();}if(ret){mb->addMenu(menu);}else{delete menu;}return ret;
}bool MainWindow::initFormatMenu(QMenuBar* mb)
{QMenu* menu = new QMenu("Format(&O)", nullptr);bool ret = (menu != nullptr);if(ret){QAction* action = nullptr;ret = ret && makeAction(action, "AutoWrap(&W)", 0);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "Font(&F)", 0);if(ret){menu->addAction(action);}menu->addSeparator();}if(ret){mb->addMenu(menu);}else{delete menu;}return ret;
}bool MainWindow::initViewMenu(QMenuBar* mb)
{QMenu* menu = new QMenu("View(&V)", nullptr);bool ret = (menu != nullptr);if(ret){QAction* action = nullptr;ret = ret && makeAction(action, "ToolBar(&T)", 0);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "StatusBar(&S)", 0);if(ret){menu->addAction(action);}menu->addSeparator();}if(ret){mb->addMenu(menu);}else{delete menu;}return ret;
}bool MainWindow::initHelpMenu(QMenuBar* mb)
{QMenu* menu = new QMenu("Help(&H)", nullptr);bool ret = (menu != nullptr);if(ret){QAction* action = nullptr;ret = ret && makeAction(action, "User Manual", 0);if(ret){menu->addAction(action);}menu->addSeparator();ret = ret && makeAction(action, "About NotePad...", 0);if(ret){menu->addAction(action);}menu->addSeparator();}if(ret){mb->addMenu(menu);}else{delete menu;}return ret;
}bool MainWindow::initFileToolItem(QToolBar* tb)
{bool ret = true;QAction* action = nullptr;ret = ret && makeAction(action, "New", ":/res/pic/new.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Open", ":/res/pic/open.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Save", ":/res/pic/save.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Save as", ":/res/pic/saveas.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Print", ":/res/pic/print.png");if(ret){tb->addAction(action);}return ret;
}bool MainWindow::initEditToolItem(QToolBar* tb)
{bool ret = true;QAction* action = nullptr;ret = ret && makeAction(action, "Undo", ":/res/pic/undo.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Redo", ":/res/pic/redo.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Cut", ":/res/pic/cut.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Copy", ":/res/pic/copy.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Paste", ":/res/pic/paste.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Find", ":/res/pic/find.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Replace", ":/res/pic/replace.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Goto", ":/res/pic/goto.png");if(ret){tb->addAction(action);}return ret;
}bool MainWindow::initFormatToolItem(QToolBar* tb)
{bool ret = true;QAction* action = nullptr;ret = ret && makeAction(action, "Wrap", ":/res/pic/wrap.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Font", ":/res/pic/font.png");if(ret){tb->addAction(action);}return ret;
}bool MainWindow::initViewToolItem(QToolBar* tb)
{bool ret = true;QAction* action = nullptr;ret = ret && makeAction(action, "Tool", ":/res/pic/tool.png");if(ret){tb->addAction(action);}ret = ret && makeAction(action, "Status", ":/res/pic/status.png");if(ret){tb->addAction(action);}return ret;
}bool MainWindow::makeAction(QAction*& action, QString str, int key)
{bool ret = true;action = new QAction(str, nullptr);if(action != nullptr){action->setShortcut(QKeySequence(key));}else{ret = false;}return ret;
}bool MainWindow::makeAction(QAction*& action, QString tip, QString res)
{bool ret = true;action = new QAction("", nullptr);if(action != nullptr){action->setToolTip(tip);action->setIcon(QIcon(res));}else{ret = false;}return ret;
}MainWindow::~MainWindow()
{}

main.cpp

#include "MainWindow.h"#include int main(int argc, char *argv[])
{QApplication a(argc, argv);int ret = 0;MainWindow* w = MainWindow::NewInstance();if(w != nullptr){w->show();ret = a.exec();}delete w;return ret;
}

• 小结：
  — 状态栏是程序中输出简要信息的区域
  — QStatusBar 是 Qt 中创建状态栏组件的类
  — QStatusBar 中可以添加任意的QWidget
  — QStatusBar 有自己内置的设计原则
  — QStatusBar 可以定制出各种形式的状态栏