//第一步，定义回调函数。注意回调函数的签名，不能更改。
void CallbackFunc(vtkObject*, unsigned long eid, void* clientdata, void *calldata)
{std::cout<<" ZYH "<<std::endl;
}
//第二步，将回调函数和 vtkCallbackCommand 联系起来
vtkSmartPointer<vtkCallbackCommand> mouseCallback = vtkSmartPointer<vtkCallbackCommand>::New();
mouseCallback->SetCallback ( CallbackFunc );//第三步，将vtkCallbackCommand对象添加到观察者列表。
interactor->AddObserver(vtkCommand::LeftButtonPressEvent, mouseCallback);

步骤就是上面所示的三步，需要注意的是：

class vtkSeedCallback : public vtkCommand
{
public:static vtkSeedCallback *New(){ return new vtkSeedCallback; }vtkSeedCallback() {}//继承函数，实现回调时的响应操作，第一个参数是调用该事件的对象，第二个参数树消息类型，第三个参数为可以传递给 command 的参数  virtual void Execute(vtkObject*, unsigned long event, void *calldata){if (event == vtkCommand::PlacePointEvent){std::cout << "Placing point..." << std::endl;std::cout << "There are now " << this->SeedRepresentation->GetNumberOfSeeds() << " seeds." << std::endl;for(unsigned int seedId = 0; seedId < this->SeedRepresentation->GetNumberOfSeeds(); seedId++){double pos[3];this->SeedRepresentation->GetSeedDisplayPosition(seedId, pos);std::cout << "Seed " << seedId << " : (" << pos[0] << " " << pos[1] << " " << pos[2] << ")" << std::endl;}return;}if (event == vtkCommand::InteractionEvent){std::cout << "Interaction..." << std::endl;if (calldata){double pos[3];this->SeedRepresentation->GetSeedDisplayPosition(0, pos);std::cout << "Moved to (" << pos[0] << " " << pos[1] << " " << pos[2] << ")" << std::endl;}return;}}void SetRepresentation(vtkSmartPointer<vtkSeedRepresentation> rep){this->SeedRepresentation = rep;}void SetWidget(vtkSmartPointer<vtkSeedWidget> widget) {this->SeedWidget = widget;}private:vtkSeedRepresentation* SeedRepresentation;vtkSeedWidget* SeedWidget;
};

实现种子点的交互【个人觉得这个InteractorEvent这个有点麻烦，只要focus到这个窗口也响应，移动种子点也响应】

    // Create the representation  设置点的颜色vtkSmartPointer<vtkPointHandleRepresentation2D> handle = vtkSmartPointer<vtkPointHandleRepresentation2D>::New();handle->GetProperty()->SetColor(1,0,0);vtkSmartPointer<vtkSeedRepresentation> rep = vtkSmartPointer<vtkSeedRepresentation>::New();rep->SetHandleRepresentation(handle);// Seed widgetvtkSmartPointer<vtkSeedWidget> seedWidget = vtkSmartPointer<vtkSeedWidget>::New();seedWidget->SetInteractor(renderWindowInteractor);seedWidget->SetRepresentation(rep);<strong>vtkSmartPointer<vtkSeedCallback> seedCallback = vtkSmartPointer<vtkSeedCallback>::New();</strong>seedCallback->SetRepresentation(rep);seedCallback->SetWidget(seedWidget);seedWidget->AddObserver(vtkCommand::PlacePointEvent,seedCallback);seedWidget->AddObserver(vtkCommand::InteractionEvent,seedCallback);renderWindow->Render();renderWindowInteractor->Initialize();renderWindow->Render();seedWidget->On();

AddObserver 监听感兴趣的事件