将参数传递给插槽

Question

我想用一堆QActions和QMenus覆盖mouseReleaseEvent ...

connect(action1, SIGNAL(triggered()), this, SLOT(onStepIncreased()));

connect(action5, SIGNAL(triggered()), this, SLOT(onStepIncreased()));

connect(action10, SIGNAL(triggered()), this, SLOT(onStepIncreased()));

connect(action25, SIGNAL(triggered()), this, SLOT(onStepIncreased()));

connect(action50, SIGNAL(triggered()), this, SLOT(onStepIncreased()));

所以我想把一个参数传递给插槽onStepIncreased(你可以想象它们是1,5,10,25,50).你知道我怎么做吗？

Answer 1

使用QSignalMapper.像这样:

QSignalMapper* signalMapper = new QSignalMapper (this) ;
connect (action1, SIGNAL(triggered()), signalMapper, SLOT(map())) ;
connect (action5, SIGNAL(triggered()), signalMapper, SLOT(map())) ;
connect (action10, SIGNAL(triggered()), signalMapper, SLOT(map())) ;
connect (action25, SIGNAL(triggered()), signalMapper, SLOT(map())) ;
connect (action50, SIGNAL(triggered()), signalMapper, SLOT(map())) ;

signalMapper -> setMapping (action1, 1) ;
signalMapper -> setMapping (action5, 5) ;
signalMapper -> setMapping (action10, 10) ;
signalMapper -> setMapping (action25, 25) ;
signalMapper -> setMapping (action50, 50) ;

connect (signalMapper, SIGNAL(mapped(int)), this, SLOT(onStepIncreased(int))) ;

Answer 2

使用Qt 5和C++ 11编译器,执行此类操作的惯用方法是使用以下函数connect:

connect(action1,  &QAction::triggered, this, [this]{ onStepIncreased(1); });
connect(action5,  &QAction::triggered, this, [this]{ onStepIncreased(5); });
connect(action10, &QAction::triggered, this, [this]{ onStepIncreased(10); });
connect(action25, &QAction::triggered, this, [this]{ onStepIncreased(25); });
connect(action50, &QAction::triggered, this, [this]{ onStepIncreased(50); });

第三个参数connect名义上是可选的.它用于设置仿函数将在其中执行的线程上下文.当函子使用QObject实例时总是需要的.如果函子使用多个QObject实例,那么它们应该有一些共同的父级来管理它们的生命周期,而仿函数应该引用那个父级,或者应该确保这些对象比这个对象更长.

在Windows上,这适用于MSVC2012及更高版本.

Answer 3

该QObject::sender()函数返回指向已通知槽的对象的指针.您可以使用它来找出触发了哪个操作