vtk读取显示dicom 并能通过滑轮改变切片层数

使用VTK读取并显示DICOM文件，可以按照以下步骤进行：

1. 加载DICOM文件：使用vtkDICOMImageReader类加载DICOM文件

vtkNew<vtkDICOMImageReader> reader;
reader->SetFileName("DICOM文件路径");
reader->Update();

2. 创建vtkImageActor对象并设置显示属性

vtkNew<vtkImageActor> actor;
actor->GetMapper()->SetInputConnection(reader->GetOutputPort());
actor->GetProperty()->SetColorWindow(256);
actor->GetProperty()->SetColorLevel(128);

3. 创建vtkRenderer和vtkRenderWindow对象，将vtkImageActor添加到vtkRenderer中

vtkNew<vtkRenderer> renderer;
renderer->AddActor(actor);

vtkNew<vtkRenderWindow> renderWindow;
renderWindow->AddRenderer(renderer);

4. 创建vtkRenderWindowInteractor对象，将vtkRenderWindow添加到vtkRenderWindowInteractor中

vtkNew<vtkRenderWindowInteractor> interactor;
interactor->SetRenderWindow(renderWindow);

5. 启动交互式模式

interactor->Initialize();
interactor->Start();

这样就可以加载DICOM文件并显示出来了。接下来是通过滑轮改变切片层数的实现，具体步骤如下：

1. 创建vtkImageSliceMapper对象，并将vtkImageActor的Mapper设置为vtkImageSliceMapper

vtkNew<vtkImageSliceMapper> mapper;
actor->SetMapper(mapper);

2. 在vtkRenderWindowInteractor的回调函数中添加对滑轮事件的处理代码

vtkSmartPointer<vtkCallbackCommand> callback = vtkSmartPointer<vtkCallbackCommand>::New();
callback->SetCallback(ScrollCallback);

interactor->AddObserver(vtkCommand::MouseWheelForwardEvent, callback);
interactor->AddObserver(vtkCommand::MouseWheelBackwardEvent, callback);

3. 编写处理滑轮事件的回调函数ScrollCallback，该函数会根据滑轮事件的方向更新切片层数，并重新渲染图像

void ScrollCallback(vtkObject* caller, long unsigned int eventId, void* clientData, void* callData)
{
    vtkRenderWindowInteractor* interactor = static_cast<vtkRenderWindowInteractor*>(caller);
    int direction = interactor->GetMouseWheelForwardEvent() == eventId ? 1 : -1;

    vtkImageSliceMapper* mapper = static_cast<vtkImageSliceMapper*>(actor->GetMapper());
    int slice = mapper->GetSliceNumber();
    slice += direction;

    int maxSlice = mapper->GetInput()->GetDimensions()[2] - 1;
    if (slice < 0 || slice > maxSlice) {
        return;
    }

    mapper->SetSliceNumber(slice);
    interactor->Render();
}

这样就可以通过滑轮改变切片层数了。完整代码示例如下：

#include <vtkSmartPointer.h>
#include <vtkDICOMImageReader.h>
#include <vtkImageActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkImageSliceMapper.h>
#include <vtkCallbackCommand.h>
#include <vtkCommand.h>

vtkNew<vtkDICOMImageReader> reader;
vtkNew<vtkImageActor> actor;
vtkNew<vtkRenderer> renderer;
vtkNew<vtkRenderWindow> renderWindow;
vtkNew<vtkRenderWindowInteractor> interactor;
vtkNew<vtkImageSliceMapper> mapper;

void ScrollCallback(vtkObject* caller, long unsigned int eventId, void* clientData, void* callData)
{
    vtkRenderWindowInteractor* interactor = static_cast<vtkRenderWindowInteractor*>(caller);
    int direction = interactor->GetMouseWheelForwardEvent() == eventId ? 1 : -1;

    int slice = mapper->GetSliceNumber();
    slice += direction;

    int maxSlice = mapper->GetInput()->GetDimensions()[2] - 1;
    if (slice < 0 || slice > maxSlice) {
        return;
    }

    mapper->SetSliceNumber(slice);
    interactor->Render();
}

int main(int argc, char** argv)
{
    reader->SetFileName("DICOM文件路径");
    reader->Update();

    actor->SetMapper(mapper);
    actor->GetProperty()->SetColorWindow(256);
    actor->GetProperty()->SetColorLevel(128);

    renderer->AddActor(actor);

    renderWindow->AddRenderer(renderer);

    interactor->SetRenderWindow(renderWindow);

    vtkSmartPointer<vtkCallbackCommand> callback = vtkSmartPointer<vtkCallbackCommand>::New();
    callback->SetCallback(ScrollCallback);
    interactor->AddObserver(vtkCommand::MouseWheelForwardEvent, callback);
    interactor->AddObserver(vtkCommand::MouseWheelBackwardEvent, callback);

    interactor->Initialize();
    interactor->Start();

    return 0;
}