QT如何實現後臺運行（即最小化到右下角托盤）

第一期:

用hello world簡單的代碼更容易看懂托盤的具體實現，一些細節問題，比如爲什麼提示消息沒有顯示在托盤上，如何在tip消息上增加圖標等。

#include <QtGui>

class myclass: public QWidget

{

public:

myclass();

private:

QPushButton *b1;

QSystemTrayIcon *trayIcon;

};

myclass::myclass()

{

QTextCodec::setCodecForTr(QTextCodec::codecForName("GB2312"));

setMinimumSize(200,100);

setMaximumSize(200,100);

b1=new QPushButton("hello world",this);

b1->setGeometry(20,20,160,40);

QIcon icon = QIcon("./images/bad.svg");

setWindowIcon(icon);

trayIcon = new QSystemTrayIcon(this);

trayIcon->setIcon(icon);

trayIcon->setToolTip("a trayicon example");

QString titlec=tr("Hello");

QString textc=QString::fromLocal8Bit("Hello QT?");

trayIcon->show();

trayIcon->showMessage(titlec,textc,QSystemTrayIcon::Information,5000);

setWindowTitle(tr("Systray"));

}

int main(int argc,char **argv)

{

QApplication testc(argc,argv);

myclass newc;

newc.show();

return testc.exec();

}

第二期:

進一步研究，加入點擊托盤的響應，使提示信息顯示在托盤上,托盤的右鍵菜單。

經驗一：編譯信號和槽需要有.h .cpp這樣的格式，否則不會生成相應的信號和槽；

經驗二：信號和槽之間可以遞參數，但是不允許函數直接給槽提供參數。
hello.h

hello.cpp

#include <QtGui>
#include "hello.h"
myclass::myclass()
{
QTextCodec::setCodecForTr(QTextCodec::codecForName("GB2312"));
setMinimumSize(200,100);
setMaximumSize(200,100);
b1=new QPushButton("hello world",this);
b1->setGeometry(20,20,160,40);
QIcon icon = QIcon("./images/bad.svg");
setWindowIcon(icon);
trayIcon = new QSystemTrayIcon(this);
trayIcon->setIcon(icon);
trayIcon->setToolTip("a trayicon example");
trayIcon->show();
setWindowTitle(tr("Systray"));

connect(trayIcon,SIGNAL(activated(QSystemTrayIcon::ActivationReason)),
this,SLOT(iconActivated(QSystemTrayIcon::ActivationReason)));
connect(b1,SIGNAL(clicked()),this,SLOT(showM()));
}

void myclass::showM()
{
QString titlec=tr("slot需要signal相同的參數進行傳遞");
QString textc=QString::fromLocal8Bit("測試內容單擊、雙擊、中鍵、按鈕");
trayIcon->showMessage(titlec,textc,QSystemTrayIcon::Information,5000);
}

void myclass::showMessage(char *msg)
{
QString titlec=tr(msg);
QString textc=QString::fromLocal8Bit("測試內容單擊、雙擊、中鍵、按鈕");
trayIcon->showMessage(titlec,textc,QSystemTrayIcon::Information,5000);
}

void myclass::iconActivated(QSystemTrayIcon::ActivationReason reason)
{
switch (reason) {
case QSystemTrayIcon::Trigger:
showMessage("單擊");
break;
case QSystemTrayIcon::DoubleClick:
showMessage("雙擊啦");
break;
case QSystemTrayIcon::MiddleClick:
showMessage("你用的是三輪鼠標還是滾輪鼠標啊");
break;
default:
;
}
}

int main(int argc,char **argv)
{
QApplication testc(argc,argv);
myclass newc;
newc.show();
return testc.exec();
}

第三期:

那麼最後我們把所有元素都結合在一起來實現這麼一個托盤程序，比較上個例子我們增加了右鍵菜單並使它管理窗口的大小。
hello.h

#include <QtGui>
class myclass: public QWidget
{
        Q_OBJECT
public:
        myclass();
private:
        QPushButton *b1;
        QSystemTrayIcon *trayIcon;
        char *msg;
        void showMessage(char *msg);
        void createActions();
        void createTrayIcon();
        QAction *minimizeAction;
        QAction *maximizeAction;
        QAction *restoreAction;
        QAction *quitAction;
        QMenu *trayIconMenu;
private slots:
        void showM();
        void iconActivated(QSystemTrayIcon::ActivationReason reason);
};

hello.cpp

#include <QtGui>
#include "hello.h"
myclass::myclass()
{
        QTextCodec::setCodecForTr(QTextCodec::codecForName("GB2312"));
        setMinimumSize(200,100);
        b1=new QPushButton("hello world",this);
        b1->setGeometry(20,20,160,40);
        QIcon icon = QIcon("./images/bad.svg");
        setWindowIcon(icon);
        trayIcon = new QSystemTrayIcon(this);
        trayIcon->setIcon(icon);
        trayIcon->setToolTip("a trayicon example");
createActions();
createTrayIcon();
        trayIcon->show();
        setWindowTitle(tr("Systray"));
connect(trayIcon,SIGNAL(activated(QSystemTrayIcon::ActivationReason)),this,SLOT(iconActivated(QSystemTrayIcon::ActivationReason)));
connect(b1,SIGNAL(clicked()),this,SLOT(showM()));
}

void myclass::showM()
{
        QString titlec=tr("slot需要signal相同的參數進行傳遞");
        QString textc=QString::fromLocal8Bit("測試內容單擊、雙擊、中鍵、按鈕");
        trayIcon->showMessage(titlec,textc,QSystemTrayIcon::Information,5000);
      }

void myclass::showMessage(char *msg)
{
        QString titlec=tr(msg);
        QString textc=QString::fromLocal8Bit("測試內容單擊、雙擊、中鍵、按鈕");
        trayIcon->showMessage(titlec,textc,QSystemTrayIcon::Information,5000);
      }

void myclass::iconActivated(QSystemTrayIcon::ActivationReason reason)
{
     switch (reason) {
     case QSystemTrayIcon::Trigger:
showMessage("單擊");
        break;
     case QSystemTrayIcon::DoubleClick:
showMessage("雙擊啦");
         break;
     case QSystemTrayIcon::MiddleClick:
showMessage("你用的是三輪鼠標還是滾輪鼠標啊");
         break;
     default:
         ;
     }
}

void myclass::createActions()
{
     minimizeAction = new QAction(tr("最小化 (&I)"), this);
     connect(minimizeAction, SIGNAL(triggered()), this, SLOT(hide()));

     maximizeAction = new QAction(tr("最大化 (&X)"), this);
     connect(maximizeAction, SIGNAL(triggered()), this, SLOT(showMaximized()));

     restoreAction = new QAction(tr("還原 (&R)"), this);
     connect(restoreAction, SIGNAL(triggered()), this, SLOT(showNormal()));

     quitAction = new QAction(tr("退出 (&Q)"), this);
     connect(quitAction, SIGNAL(triggered()), qApp, SLOT(quit()));
}

void myclass::createTrayIcon()
{
     trayIconMenu = new QMenu(this);
     trayIconMenu->addAction(minimizeAction);
     trayIconMenu->addAction(maximizeAction);
     trayIconMenu->addAction(restoreAction);
     trayIconMenu->addSeparator();
     trayIconMenu->addAction(quitAction);
     trayIcon->setContextMenu(trayIconMenu);
}

int main(int argc,char **argv)
{
        QApplication testc(argc,argv);
        myclass newc;
        newc.show();
        return testc.exec();
}