Qt 让窗口（或控件）居中

 1 XXX::XXX(QWidget *parent /* = 0 */)  
 2 {  
 3     ..................  
 4     //注意，resize一定要放在这段代码的前面  
 5     resize(300, 300);  
 6     int cx, cy;  
 7     //当parent为空时，窗口就显示在桌面中央  
 8     if( NULL == parent )  
 9     {  
10         cx = (QApplication::desktop()->width() - width()) / 2;  
11         cy = (QApplication::desktop()->height() - height()) / 2;  
12     }  
13     //否则，控件就显示在父部件中央  
14     else  
15     {  
16         cx = ( parent->width() - width() ) / 2;  
17         cy = ( parent->height() - height() ) / 2;  
18     }  
19     move(cx, cy);  
20     ....................  
21 }