VTK 鼠标交互实时显示窗口内图像的像素坐标（二维图像）

 这是VTK的例子：

https://vtk.org/Wiki/VTK/Examples/Cxx/Images/PickPixel

 

#include 
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// The mouse motion callback, to pick the image and recover pixel values
class vtkImageInteractionCallback1 : public vtkCommand
{
public:
    
    static vtkImageInteractionCallback1 *New()
    {
        return new vtkImageInteractionCallback1;
    }
    
    vtkImageInteractionCallback1()
    {
        this->Viewer = 0;
        this->Picker = 0;
        this->Annotation = 0;
        this->PointData = vtkPointData::New();
    }
    
    ~vtkImageInteractionCallback1()
    {
        this->Viewer = 0;
        this->Picker = 0;
        this->Annotation = 0;
        this->PointData->Delete();
    }
    
    void SetPicker(vtkPropPicker *picker)
    {
        this->Picker = picker;
    }
    
    void SetAnnotation(vtkCornerAnnotation *annotation)
    {
        this->Annotation = annotation;
    }
    
    void SetViewer(vtkImageViewer2 *viewer)
    {
        this->Viewer = viewer;
    }
    
    virtual void Execute(vtkObject *, unsigned long vtkNotUsed(event), void *)
    {
        //this->Viewer;
        vtkRenderWindowInteractor *interactor =
        this->Viewer->GetRenderWindow()->GetInteractor();
        vtkRenderer* renderer = this->Viewer->GetRenderer();
        vtkImageActor* actor = this->Viewer->GetImageActor();
        vtkImageData* image = this->Viewer->GetInput();
        vtkInteractorStyle *style = vtkInteractorStyle::SafeDownCast(
                                                                     interactor->GetInteractorStyle());
        
#if VTK_MAJOR_VERSION <= 5
        image->Update();
#endif
        
        // Pick at the mouse location provided by the interactor
        this->Picker->Pick( interactor->GetEventPosition()[0],
                           interactor->GetEventPosition()[1],
                           0.0, renderer );
        
        // There could be other props assigned to this picker, so
        // make sure we picked the image actor
        vtkAssemblyPath* path = this->Picker->GetPath();
        bool validPick = false;
        
        if( path )
        {
            vtkCollectionSimpleIterator sit;
            path->InitTraversal( sit );
            vtkAssemblyNode *node;
            for( int i = 0; i < path->GetNumberOfItems() && !validPick; ++i )
            {
                node = path->GetNextNode( sit );
                if( actor == vtkImageActor::SafeDownCast( node->GetViewProp() ) )
                {
                    validPick = true;
                }
            }
        }
        
        if( !validPick )
        {
            this->Annotation->SetText( 0, "Off Image" );
            interactor->Render();
            // Pass the event further on
            style->OnMouseMove();
            return;
        }
        
        // Get the world coordinates of the pick
        double pos[3];
        this->Picker->GetPickPosition( pos );
        // Fixes some numerical problems with the picking
        double *bounds = actor->GetDisplayBounds();
        int axis = this->Viewer->GetSliceOrientation();
        pos[axis] = bounds[2*axis];
        cout<GetPointData();
        if( !pd )
        {
            return;
        }
        
        this->PointData->InterpolateAllocate( pd, 1, 1 );
        
        // Use tolerance as a function of size of source data
        double tol2 = image->GetLength();
        tol2 = tol2 ? tol2*tol2 / 1000.0 : 0.001;
        
        // Find the cell that contains pos
        int subId;
        double pcoords[3], weights[8];
        vtkCell* cell = image->FindAndGetCell(
                                              pos, NULL, -1, tol2, subId, pcoords, weights );
        if( cell )
        {
            // Interpolate the point data
            this->PointData->InterpolatePoint( pd, 0, cell->PointIds, weights );
            int components =
            this->PointData->GetScalars()->GetNumberOfComponents();
            double* tuple = this->PointData->GetScalars()->GetTuple( 0 );
            
            std::string message = "Location: ( ";
            message += vtkVariant( pos[0] ).ToString();
            message += ", ";
            message += vtkVariant( pos[1] ).ToString();
            message += ", ";
            message += vtkVariant( pos[2] ).ToString();
            message += " )\nValue: ( ";
            
            for( int c = 0; c < components; ++c )
            {
                message += vtkVariant( tuple[ c ] ).ToString();
                if( c != components - 1 )
                {
                    message += ", ";
                }
            }
            message += " )";
            this->Annotation->SetText( 0, message.c_str() );
            interactor->Render();
            style->OnMouseMove();
        }
    }
    
private:
    
    // Pointer to the viewer
    vtkImageViewer2 *Viewer;
    
    // Pointer to the picker
    vtkPropPicker *Picker;
    
    // Pointer to the annotation
    vtkCornerAnnotation *Annotation;
    
    // Interpolator
    vtkPointData* PointData;
};


int main ( int argc, char* argv[] )
{
   
  
    vtkSmartPointer reader =vtkSmartPointer::New();
    reader->SetFileName( "/Users/mac/Desktop/CT数据/肺2/YeGuangKun_04_0060_0061.dcm" );
    reader->Update();
    
    
    
    // Picker to pick pixels
    vtkSmartPointer propPicker =
    vtkSmartPointer::New();
    propPicker->PickFromListOn();
    
    // Give the picker a prop to pick
    vtkSmartPointer imageViewer =
    vtkSmartPointer::New();
    propPicker->AddPickList( imageViewer->GetImageActor() );
    
    // Visualize
    vtkSmartPointer renderWindowInteractor =
    vtkSmartPointer::New();
    imageViewer->SetInputConnection(reader->GetOutputPort());
    imageViewer->SetupInteractor( renderWindowInteractor );
    imageViewer->SetSize( 600, 600 );
    
    vtkRenderer* renderer = imageViewer->GetRenderer();
    renderer->ResetCamera();
    renderer->GradientBackgroundOn();
    renderer->SetBackground(0,0,0);
    renderer->SetBackground2(1,1,1);
    
    // Annotate the image with window/level and mouse over pixel information
    vtkSmartPointer cornerAnnotation =
    vtkSmartPointer::New();
    cornerAnnotation->SetLinearFontScaleFactor( 2 );
    cornerAnnotation->SetNonlinearFontScaleFactor( 1 );
    cornerAnnotation->SetMaximumFontSize( 20 );
    cornerAnnotation->SetText( 0, "Off Image" );
    cornerAnnotation->SetText( 3, "\n" );
    cornerAnnotation->GetTextProperty()->SetColor( 1,0,0);
    
    imageViewer->GetRenderer()->AddViewProp( cornerAnnotation );
    
    // Callback listens to MouseMoveEvents invoked by the interactor's style
    vtkSmartPointer callback =
    vtkSmartPointer::New();
    callback->SetViewer( imageViewer );
    callback->SetAnnotation( cornerAnnotation );
    callback->SetPicker( propPicker );
    
    // InteractorStyleImage allows for the following controls:
    // 1) middle mouse + move = camera pan
    // 2) left mouse + move = window/level
    // 3) right mouse + move = camera zoom
    // 4) middle mouse wheel scroll = zoom
    // 5) 'r' = reset window/level
    // 6) shift + 'r' = reset camera
    vtkInteractorStyleImage* imageStyle = imageViewer->GetInteractorStyle();
    imageStyle->AddObserver( vtkCommand::MouseMoveEvent, callback );
    
    renderWindowInteractor->Initialize();
    renderWindowInteractor->Start();
    
    return EXIT_SUCCESS;
}

 显示结果：左下角是当前鼠标指向的像素点的坐标 （如果鼠标指向窗口的地方不是像素点，左下角显示OFF）

 

 

 

还有可参考的例子：https://vtk.org/Wiki/VTK/Examples/Cxx/Images/PickPixel2