有时我们需要在 VTK 窗口中增加 按钮，右上角；

 实现，通过回调函数，vtkButtonCallback 获取点击：

#include <vtkVersion.h>
#include <vtkSmartPointer.h>

#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkPolyData.h>
#include <vtkImageData.h>

#include <vtkCoordinate.h>
#include <vtkSphereSource.h>
#include <vtkButtonWidget.h>
#include <vtkTexturedButtonRepresentation2D.h>
#include <QDebug>
#include <vtkPNGReader.h>
#include <vtkProp3DButtonRepresentation.h>
#include <vtkProperty.h>
#include <vtkCommand.h>

class vtkButtonCallback : public vtkCommand
{
public:
	static vtkButtonCallback *New()
	{
		return new vtkButtonCallback;
	}
	virtual void Execute(vtkObject *caller, unsigned long, void*)
	{
		vtkButtonWidget *buttonWidget =
			reinterpret_cast<vtkButtonWidget*>(caller);
		vtkProp3DButtonRepresentation *rep =
			reinterpret_cast<vtkProp3DButtonRepresentation *>
			(buttonWidget->GetRepresentation());
		int state = rep->GetState();
		//        this->Actor->GetProperty()->SetColor(reinterpret_cast<vtkActor *>(rep->GetButtonProp(state))->GetProperty()->GetColor());
		qDebug() << "State: " << state;
	}
	vtkButtonCallback() :Actor(0) {}
	vtkActor *Actor;
};


int main(int, char *[])
{
	// Create two images for texture
	vtkSmartPointer<vtkImageData> image1 =
		vtkSmartPointer<vtkImageData>::New();
	vtkSmartPointer<vtkImageData> image2 =
		vtkSmartPointer<vtkImageData>::New();
	unsigned char banana[3] = { 227, 207, 87 };
	unsigned char tomato[3] = { 255, 99, 71 };

	vtkSmartPointer<vtkPNGReader> pngReader1 = vtkSmartPointer<vtkPNGReader>::New();
	pngReader1->SetFileName("icon-maximize-pressed.png");
	pngReader1->Update();
	vtkSmartPointer<vtkPNGReader> pngReader2 = vtkSmartPointer<vtkPNGReader>::New();
	pngReader2->SetFileName("icon-restore-hover.png");
	pngReader2->Update();
	image1 = pngReader1->GetOutput();
	image2 = pngReader2->GetOutput();
	//    CreateImage(image1, banana, tomato);
	//    CreateImage(image2, tomato, banana);

		// Create some geometry
	vtkSmartPointer<vtkSphereSource> sphereSource =
		vtkSmartPointer<vtkSphereSource>::New();
	sphereSource->Update();

	vtkSmartPointer<vtkPolyDataMapper> mapper =
		vtkSmartPointer<vtkPolyDataMapper>::New();
	mapper->SetInputConnection(sphereSource->GetOutputPort());

	vtkSmartPointer<vtkActor> actor =
		vtkSmartPointer<vtkActor>::New();
	actor->SetMapper(mapper);

	// A renderer and render window
	vtkSmartPointer<vtkRenderer> renderer =
		vtkSmartPointer<vtkRenderer>::New();
	vtkSmartPointer<vtkRenderWindow> renderWindow =
		vtkSmartPointer<vtkRenderWindow>::New();
	renderWindow->AddRenderer(renderer);

	// An interactor
	vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
		vtkSmartPointer<vtkRenderWindowInteractor>::New();
	renderWindowInteractor->SetRenderWindow(renderWindow);

	// Create the widget and its representation
	vtkSmartPointer<vtkTexturedButtonRepresentation2D> buttonRepresentation =
		vtkSmartPointer<vtkTexturedButtonRepresentation2D>::New();
	buttonRepresentation->SetNumberOfStates(2);
	buttonRepresentation->SetButtonTexture(0, image1);
	buttonRepresentation->SetButtonTexture(1, image2);

	vtkSmartPointer<vtkButtonCallback> callback =
		vtkSmartPointer<vtkButtonCallback>::New();
	callback->Actor = actor;

	vtkButtonWidget *buttonWidget = vtkButtonWidget::New();
	buttonWidget->SetInteractor(renderWindowInteractor);
	buttonWidget->SetRepresentation(buttonRepresentation);
	buttonWidget->AddObserver(vtkCommand::StateChangedEvent, callback);
	buttonWidget->SetEnabled(1);

	// Add the actors to the scene
	renderer->AddActor(actor);
	renderer->SetBackground(.1, .2, .5);

	renderWindow->SetSize(640, 480);
	renderWindow->Render();

	// Place the widget. Must be done after a render so that the
	// viewport is defined.
	// Here the widget placement is in normalized display coordinates
	vtkSmartPointer<vtkCoordinate> upperRight =
		vtkSmartPointer<vtkCoordinate>::New();
	upperRight->SetCoordinateSystemToNormalizedDisplay();
	upperRight->SetValue(1.0, 1.0);

	double bds[6];
	double sz = 135;
	bds[0] = upperRight->GetComputedDisplayValue(renderer)[0];
	bds[1] = bds[0] + sz / 2;
	bds[2] = upperRight->GetComputedDisplayValue(renderer)[1];
	bds[3] = bds[2] + sz / 2;
	bds[4] = bds[5] = 0.0;

	// Scale to 1, default is .5
//    buttonRepresentation->SetPlaceFactor(1);
	buttonRepresentation->PlaceWidget(bds);

	buttonWidget->On();

	// Begin mouse interaction
	renderWindowInteractor->Start();

	return EXIT_SUCCESS;
}