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操作和惯性示例

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操作和惯性示例演示如何将 Windows 触控支持添加到使用 Windows 触控 API 的基于 Windows 的本机应用程序。 此示例实现 API 的基本功能，以便为对象启用平移、旋转和缩放，并对其应用惯性属性。 此示例还演示如何为 Windows Touch 应用程序提供基本的鼠标支持。 下图显示了示例在运行时的外观。

显示操作和惯性示例中具有渐变的两个框的屏幕截图

当用户从支持 Windows Touch 的计算机运行应用程序时，具有渐变的框可以独立操作。

注册触摸窗口

在接收触摸输入之前，必须先通过调用以下函数来通知系统应用程序是 Windows Touch 应用程序：

   RegisterTouchWindow(g_hWnd, 0);

实现 _IManipulationEventSink 接口

_IManipulationEvents 事件接收器包含三个函数：ManipulationStarted、ManipulationDelta 和 ManipulationCompleted。 IManipulationProcessor 接口和 IInertiaProcessor 接口使用这些回调函数返回处理器在调用 ProcessTime、ProcessUpWithTime、ProcessDownWithTime 和 ProcessMoveWithTime 函数后计算的值。 下面的代码示例演示 _IManipulationEvents 接口的示例实现。

#include "cmanipulationeventsink.h"
#include <math.h>

CManipulationEventSink::CManipulationEventSink(HWND hWnd, CDrawingObject *dObj, int iTimerId, BOOL inertia) {
    // Manipulation & Inertia Processors
    m_manip = NULL;
    m_inert = NULL;

    // Connection points for COM.
    m_pConPointContainer = NULL;
    m_pConnPoint = NULL;

    // Reference to an object associated with this event sink.
    m_dObj = dObj;

    // Handle to the window used for computing boundaries.
    m_hWnd = hWnd;

    // The unique timer id for this manipulation event sink.
    m_iTimerId = iTimerId;

    m_bInertia = inertia;

    m_cRefCount = 1;
}


CManipulationEventSink::~CManipulationEventSink()
{

}


HRESULT STDMETHODCALLTYPE CManipulationEventSink::ManipulationStarted(
    FLOAT x,
    FLOAT y)
{
    KillTimer(m_hWnd, m_iTimerId);

    return S_OK;
}

HRESULT STDMETHODCALLTYPE CManipulationEventSink::ManipulationDelta(
    FLOAT x,
    FLOAT y,
    FLOAT translationDeltaX,
    FLOAT translationDeltaY,
    FLOAT scaleDelta,
    FLOAT expansionDelta,
    FLOAT rotationDelta,
    FLOAT cumulativeTranslationX,
    FLOAT cumulativeTranslationY,
    FLOAT cumulativeScale,
    FLOAT cumulativeExpansion,
    FLOAT cumulativeRotation)
{
    FLOAT pivot = 0.0f;

    // Apply transformation based on rotationDelta (in radians).
    FLOAT rads = 180.0f / 3.14159f;
    m_dObj->Rotate(rotationDelta*rads, x, y);

    // Apply translation based on scaleDelta.
    m_dObj->Scale(scaleDelta);

    // Apply translation based on translationDelta.
    m_dObj->Translate(translationDeltaX, translationDeltaY);

    if(!m_bInertia)
    {
        // Set values for one-finger rotations.
        FLOAT fPivotRadius = (FLOAT)(sqrt(pow(m_dObj->GetWidth()/2, 2)
                           + pow(m_dObj->GetHeight()/2, 2)))*0.4f;
        FLOAT fPivotPtX    = m_dObj->GetCenterX();
        FLOAT fPivotPtY    = m_dObj->GetCenterY();

        m_manip->put_PivotPointX(fPivotPtX);
        m_manip->put_PivotPointY(fPivotPtY);
        m_manip->put_PivotRadius(fPivotRadius);
    }
    return S_OK;
}

HRESULT STDMETHODCALLTYPE CManipulationEventSink::ManipulationCompleted(
    FLOAT x,
    FLOAT y,
    FLOAT cumulativeTranslationX,
    FLOAT cumulativeTranslationY,
    FLOAT cumulativeScale,
    FLOAT cumulativeExpansion,
    FLOAT cumulativeRotation)
{
    if(!m_bInertia)
    {
        SetupInertia();

        // Kick off timer that handles inertia.
        SetTimer(m_hWnd, m_iTimerId, DESIRED_MILLISECONDS, NULL);
    }
    else
    {
        // Stop timer that handles inertia.
        KillTimer(m_hWnd, m_iTimerId);
    }

    return S_OK;
}

创建 COM 对象并设置 IManipulationProcessor 和 IInertiaProcessor 接口

API 提供 IManipulationProcessor 和 IInertiaProcessor 接口的实现。 应创建 的实例，并从之前实现的 IManipulationEvents 事件接收器引用 COM 对象。

处理WM_TOUCH消息

必须从 WM_TOUCH 消息中提取输入数据，然后必须稍后进行处理以馈送正确的操作处理器。

switch (msg)
{
    case WM_TOUCH:

      iNumContacts = LOWORD(wParam);
      hInput       = (HTOUCHINPUT)lParam;
      pInputs      = new TOUCHINPUT[iNumContacts];

      // Get each touch input info and feed each
      // tagTOUCHINPUT into the process input handler.

      if(pInputs != NULL)
      {
          if(GetTouchInputInfo(hInput, iNumContacts,
               pInputs, sizeof(TOUCHINPUT)))
          {
              for(int i = 0; i < iNumContacts; i++)
              {
                  // Bring touch input info into client coordinates.
                  ptInputs.x = pInputs[i].x/100;
                  ptInputs.y = pInputs[i].y/100;
                  ScreenToClient(g_hWnd, &ptInputs);

                  pInputs[i].x = ptInputs.x;
                  pInputs[i].y = ptInputs.y;

                  g_ctDriver->ProcessInputEvent(pInputs[i]);
              }
          }
      }

      delete [] pInputs;
      break;
}

注意

若要使用 ScreenToClient 函数，必须在应用程序中具有高 DPI 支持。 有关支持高 DPI 的详细信息，请访问 MSDN 的高 DPI 部分。

将 TOUCHINPUT 结构传递给相应的处理器

使用 GetTouchInputInfo 函数从WM_TOUCH消息中提取数据后，根据 TOUCHINPUT 结构中设置的 dwFlag，通过调用 ProcessUpWithTime、ProcessDownWithTime 或 ProcessMoveWithTime 函数将数据馈送到操作处理器中。

注意

支持多个操作时，如果必须使用 TOUCHINPUT 结构中定义的 dwID 将数据发送到正确的 IManipulationProcessor 对象，则必须创建新的操作处理器。

CoreObject* coCurrent = m_coHead;

while(coCurrent!=NULL && !bFoundObj)
{
    if(dwEvent & TOUCHEVENTF_DOWN)
    {
        DownEvent(coCurrent, inData, &bFoundObj);
    }
    else if(dwEvent & TOUCHEVENTF_MOVE)
    {
        MoveEvent(coCurrent, inData);
    }
    else if(dwEvent & TOUCHEVENTF_UP)
    {
        UpEvent(coCurrent, inData);
    }
    coCurrent = coCurrent->coNext;
}

VOID CComTouchDriver::DownEvent(CoreObject* coRef, tagTOUCHINPUT inData, BOOL* bFound) {
    DWORD dwPCursor = inData.dwID;
    DWORD dwPTime   = inData.dwTime;
    int x           = inData.x;
    int y           = inData.y;

    // Check that the user has touched within an object's region and fed to the object's manipulation processor.

    if(coRef->doDrawing->InRegion(x, y) &&
        !HasCursor(coRef, dwPCursor))
    {
        ...

        // Feed values to the Manipulation Processor.
        coRef->manipulationProc->ProcessDownWithTime(dwPCursor, (FLOAT)x, (FLOAT)y, dwPTime);

        ...
    }
}

在 ManipulationCompleted 中设置惯性

调用 ManipulationCompleted 方法后，IManipulationProcessor 对象必须设置链接到 IManipulationProcessor 的 IInertiaProcessor 对象的值，以调用惯性。 下面的代码示例演示如何从 IManipulationProcessor 方法 ManipulationCompleted 设置 IInertiaProcessor 对象。

    int iVWidth       = GetSystemMetrics(SM_CXVIRTUALSCREEN);
    int iVHeight      = GetSystemMetrics(SM_CYVIRTUALSCREEN);

    RECT rc;
    GetClientRect(m_hWnd, &rc);
    FLOAT lCWidth     = (FLOAT)rc.right;
    FLOAT lCHeight    = (FLOAT)rc.bottom;

    // Set properties for inertia events.

    // Deceleration for tranlations in pixel / msec^2.
    m_inert->put_DesiredDeceleration(0.001f);

    // Deceleration for rotations in radians / msec^2.
    m_inert->put_DesiredAngularDeceleration(0.00001f);

    // Calculate borders and elastic margin to be set.
    // They are relative to the width and height of the object.

    FLOAT fHOffset = m_dObj->GetWidth()  * 0.5f;
    FLOAT fVOffset = m_dObj->GetHeight() * 0.5f;

    // Elastic margin is in pixels - note that it offsets the boundary.

    FLOAT fHElasticMargin = 25.0f;
    FLOAT fVElasticMargin = 25.0f;

    FLOAT fBoundaryLeft   = fHOffset + fHElasticMargin;
    FLOAT fBoundaryTop    = fVOffset + fVElasticMargin;
    FLOAT fBoundaryRight  = lCWidth - fHOffset - fHElasticMargin;
    FLOAT fBoundaryBottom = lCHeight - fVOffset - fVElasticMargin;

    // Set borders and elastic margin.

    m_inert->put_BoundaryLeft(fBoundaryLeft);
    m_inert->put_BoundaryTop(fBoundaryTop);
    m_inert->put_BoundaryRight(fBoundaryRight);
    m_inert->put_BoundaryBottom(fBoundaryBottom);

    m_inert->put_ElasticMarginLeft(fHElasticMargin);
    m_inert->put_ElasticMarginTop(fVElasticMargin);
    m_inert->put_ElasticMarginRight(fHElasticMargin);
    m_inert->put_ElasticMarginBottom(fVElasticMargin);

    // Set initial origins.

    m_inert->put_InitialOriginX(m_dObj->GetCenterX());
    m_inert->put_InitialOriginY(m_dObj->GetCenterY());

    FLOAT fVX;
    FLOAT fVY;
    FLOAT fVR;

    m_manip->GetVelocityX(&fVX);
    m_manip->GetVelocityY(&fVY);
    m_manip->GetAngularVelocity(&fVR);

    // Set initial velocities for inertia processor.

    m_inert->put_InitialVelocityX(fVX);
    m_inert->put_InitialVelocityY(fVY);
    m_inert->put_InitialAngularVelocity(fVR);

清理 COM 对象

应用程序关闭时，必须清理 COM 对象。 以下代码演示如何释放示例中分配的资源。

CComTouchDriver::~CComTouchDriver(VOID) {
    CoreObject* coCurrent = m_coHead;

    // Clean up COM objects.

    while(coCurrent!=NULL)
    {
        coCurrent->inertiaEventSink->Release();
        coCurrent->manipulationEventSink->Release();
        coCurrent->inertiaProc->Release();
        coCurrent->manipulationProc->Release();
        coCurrent = coCurrent->coNext;
    }
}

多点触控操作应用程序、 操作和惯性示例、 Windows 触控示例