nmWTAI-Platform/Src/nmNum/nmRender/nmVTKInteractionManager.cpp

#include "nmVTKInteractionManager.h"

#include <QCoreApplication>
#include <QThread>

#include <vtkInteractorStyle.h>
#include <vtkInteractorStyleTrackballCamera.h>
#include <vtkRenderWindowInteractor.h>

namespace {

// InteractorStyle 会注册 VTK 观察关系，绑定与解除都限定在 GUI 线程。
bool isInteractionGuiThread()
{
    QCoreApplication* pApplication = QCoreApplication::instance();
    return pApplication == NULL ||
            pApplication->thread() == QThread::currentThread();
}

}

nmVTKInteractionManager::nmVTKInteractionManager()
    : m_pInteractor(NULL),
      m_pDefaultStyle(
          vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New()),
      m_pActiveStyle(NULL)
{
    Q_ASSERT(isInteractionGuiThread());
}

nmVTKInteractionManager::~nmVTKInteractionManager()
{
    Q_ASSERT(isInteractionGuiThread());
    // Interactor 持有 Style 引用，必须先清除绑定再释放智能指针。
    unbindInteractor();
    m_pActiveStyle = NULL;
    m_pDefaultStyle = NULL;
}

bool nmVTKInteractionManager::bindInteractor(
        vtkRenderWindowInteractor* pInteractor)
{
    Q_ASSERT(isInteractionGuiThread());
    if(!isInteractionGuiThread() || pInteractor == NULL ||
       m_pDefaultStyle == NULL) {
        return false;
    }

    if(m_pInteractor != pInteractor) {
        // 切换对象前先清除旧 Interactor 持有的 Style 引用。
        unbindInteractor();
        m_pInteractor = pInteractor;
    }
    return restoreDefaultInteraction();
}

bool nmVTKInteractionManager::installInteractionStyle(
        vtkInteractorStyle* pStyle)
{
    Q_ASSERT(isInteractionGuiThread());
    if(!isInteractionGuiThread() || m_pInteractor == NULL || pStyle == NULL) {
        return false;
    }

    // 管理器和 Interactor 各持有一个 VTK 引用，直到恢复或清除当前模式。
    m_pActiveStyle = pStyle;
    m_pInteractor->SetInteractorStyle(m_pActiveStyle);
    return true;
}

bool nmVTKInteractionManager::restoreDefaultInteraction()
{
    Q_ASSERT(isInteractionGuiThread());
    if(!isInteractionGuiThread() || m_pInteractor == NULL ||
       m_pDefaultStyle == NULL) {
        return false;
    }
    // 后续工具临时替换样式后，可通过本入口回到唯一默认交互模式。
    return installInteractionStyle(m_pDefaultStyle);
}

void nmVTKInteractionManager::clearInteractionStyle()
{
    Q_ASSERT(isInteractionGuiThread());
    if(!isInteractionGuiThread()) {
        return;
    }

    if(m_pInteractor != NULL) {
        m_pInteractor->SetInteractorStyle(NULL);
    }
    m_pActiveStyle = NULL;
}

void nmVTKInteractionManager::unbindInteractor()
{
    Q_ASSERT(isInteractionGuiThread());
    if(!isInteractionGuiThread()) {
        return;
    }

    // 本管理器定义单一活动模式边界，解绑时不保留任何旧 Style。
    clearInteractionStyle();
    m_pInteractor = NULL;
}

vtkRenderWindowInteractor* nmVTKInteractionManager::getInteractor() const
{
    return m_pInteractor;
}

vtkInteractorStyleTrackballCamera*
nmVTKInteractionManager::getDefaultStyle() const
{
    return m_pDefaultStyle;
}

vtkInteractorStyle* nmVTKInteractionManager::getActiveStyle() const
{
    return m_pActiveStyle;
}