Qt 编程点滴 10

qss 收集：Setting QObject properties

From 4.3 and above, any designable Q_PROPERTY can be set using the qproperty- syntax.

For example,

MyLabel { qproperty-pixmap: url(pixmap.png); }
MyGroupBox { qproperty-titleColor: rgb(100, 200, 100); }
QPushButton { qproperty-iconSize: 20px 20px; }
If the property references an enum declared with Q_ENUMS, you should reference its constants by name, i.e., not their numeric value.

类成员函数里定义的临时指针不能做为参数传递;函数里取得的指针无法返回到外面；

groupmanage.h:
class GroupManage
{
private:
/// 组在线数据
/** . */
class OnLineData
{
public:
IGPSNav* iGpsNav; /**< GPS聊天接口 */
int groupId;  /**< 组ID */
};
QList onLineList; /**< 组在线列表 */
private:
///查找GPS聊天接口
/**
@param groupId 组id
@param gpsNav(返回值) 只有在查到时才返回指针
@return true:查找到 false: 未查找到
*/
bool findGpsNav(int groupId,unsigned int & gpsNav);  //正确的写法：返回对象指针地址

bool findGpsNav(int groupId,IGPSNav* iGpsNav);//如果是这样写法请注意调用方法
void test();
};
groupmanage.cpp:
//查找GPS聊天接口
bool GroupManage::findGpsNav(int groupId,unsigned int & gpsNav)
{
bool ok = false;
for (int i=0; i < onLineList.count() ; i++)
{
OnLineData* onLineData = onLineList.at(i);
if ( onLineData->groupId == groupId )
{
ok = true;
gpsNav = (unsigned int)(onLineData->iGpsNav);

break;
}
}
_EDEBUG("findGpsNav gpsNav="<     return ok;
}
bool GroupManage::findGpsNav(int groupId,IGPSNav* iGpsNav)
{
bool ok = false;
for (int i=0; i < onLineList.count() ; i++)
{
OnLineData* onLineData = onLineList.at(i);
if ( onLineData->groupId == groupId )
{
ok = true;
iGpsNav = onLineData->iGpsNav;

break;
}
}
_EDEBUG("findGpsNav gpsNav="<     return ok;
}
void GroupManage::test()
{
IGPSNav* iGpsNav;
unsigned int iGpsNavInt;
bool ok;
ok = findGpsNav(groupId,iGpsNavInt);
iGpsNav = (IGPSNav*)iGpsNavInt;
_EDEBUG("iGpsNav:"<
/*--下面的写法指针返回不了
IGPSNav* iGpsNav; //把此句申明放在类的private:下就可以解决问题
bool ok;
ok = findGpsNav(groupId,iGpsNav);
_EDEBUG("iGpsNav:"<     */
}
QPushButton{
background-color: rgba( 255, 255, 255, 50% );
}

透明度50%

1.问题1: connect函数不存在，对象没有从QObject继承.

2.问題2

采用Event方法连接,在对象方法里启动定时器,在运行时发生:

QT timers cannot be started from another thread

解决：采用Signal/Slot并且连接方式采用 Qt::QueuedConnection

3.利用Signal/Slot删除对象本身:

解决：采用Signal/Slot并且连接方式采用 Qt::QueuedConnection,这时在另一个对象中就可以删除对象本身了。用qss增加每个菜单项的高度，在用StyleSheet美化QMenu时，如何指定菜单项与快捷键的间距？

QMenu::item {
border: 1px solid transparent;
margin: 0px 2px 0px 2px;
padding: 2px 9px 2px 30px; // Top Right Bottom Left(用这种方式能增加menu中每一行的高度,这就使得在小的触摸屏上进行菜单项的选择的时候,不会那么困难了)

}
QGraphicsView无法接收到一些widget传过来的消息的处理方法:
bool event ( QEvent * event )
{
if(event->type()==QEvent::MouseButtonPress)
{
QMouseEvent *ke = static_cast(event);
qDebug()<<"Base Mouse Pressed...."             QWidget::event(event);  //关键语句
return true;
}
return QGraphicsView::event(event);
};

基于Signal/Slot机制的接口写法:

MyInterface: public QObject{  //QObject子类都可以
Q_OBJECT
public:
explicit MyInterface(QObject* parent = 0);  //防止出现异常 显式
virtual ~MyInterface(){}
virtual void myFunc(int i) = 0; //纯虚函数
//....
signals:
void mySignal(int i);
//....
public slots:
virtual void mySlot(){//do nothing};
private:
//...
}
MyImpl:public MyInterface{
Q_OBJECT
public:
MyImpl(parent = 0);
virtual MyImpl(){};
virtual void myFunc(int i){emit mySignal();};
public slots:
void mySlot(){//my code};
}
MyImpl2:public MyInterface{
Q_OBJECT
public:
MyImpl(parent = 0);
virtual MyImpl(){};
virtual void myFunc(int i){emit mySignal();};
public slots:
void mySlot(){//my code};
}
IMyInterface& createMyImpl1(parent = 0)
{
return * new MyImpl1(parent);
}
IMyInterface& createMyImpl2(parent = 0)
{
return * new MyImpl2(parent);
}

析构函数 前一定要加 virtual。