CAccelerateDecelerateTransition 这个组件怎么使用，请详细讲解

Question

CAccelerateDecelerateTransition 里面的

CAccelerateDecelerateTransition 方法

Create方法这两个方法怎么使用，请举例说明

Answer 1

您好

查看源代码可以得知 CAccelerateDecelerateTransition是对IUIAnimationTransitionLibrary::CreateAccelerateDecelerateTransition method进行了简单的封装。

pLibrary->CreateAccelerateDecelerateTransition中使用了构造函数和create（）里面填入的参数 (create的第二个参数为不使用)，并将结果保存到[out]参数&m_transition中。m_transition是父类CBaseTransition的成员变量，使用GetTransition得到值。

源代码：

class CAccelerateDecelerateTransition : public CBaseTransition
{
public:
	/// <summary>
	/// Constructs a transition object.
	/// </summary>
	/// <param name="duration">The duration of the transition. </param>
	/// <param name="finalValue">The value of the animation variable at the end of the transition. </param>
	/// <param name="accelerationRatio">The ratio of the time spent accelerating to the duration.</param>
	/// <param name="decelerationRatio">The ratio of the time spent decelerating to the duration. </param>
	CAccelerateDecelerateTransition(UI_ANIMATION_SECONDS duration, DOUBLE finalValue, DOUBLE accelerationRatio = 0.3,
		DOUBLE decelerationRatio = 0.3) : m_duration(duration), m_finalValue(finalValue),
		m_accelerationRatio(accelerationRatio), m_decelerationRatio(decelerationRatio)
	{
		m_type = ACCELERATE_DECELERATE;
	}
public:
	/// <summary>
	/// The duration of the transition.
	/// </summary>
	UI_ANIMATION_SECONDS m_duration;
	/// <summary>
	/// The value of the animation variable at the end of the transition.
	/// </summary>
	DOUBLE m_finalValue;
	/// <summary>
	/// The ratio of the time spent accelerating to the duration.
	/// </summary>
	DOUBLE m_accelerationRatio;
	/// <summary>
	/// The ratio of the time spent decelerating to the duration.
	/// </summary>
	DOUBLE m_decelerationRatio;
	/// <summary>
	/// Calls the transition library to create encapsulated transition COM object.
	/// </summary>
	/// <returns>
	/// TRUE if transition is created successfully; otherwise FALSE.
	/// </returns>
	/// <param name="pLibrary">A pointer to transition library, which is responsible for creation of standard transitions.</param>
	/// <param name="pFactory">A pointer to transition factory, which is responsible for creation of custom transitions.</param>
	BOOL Create(IUIAnimationTransitionLibrary* pLibrary, IUIAnimationTransitionFactory* pFactory) override
	{
		UNREFERENCED_PARAMETER(pFactory);
		Clear();
		if (pLibrary != NULL)
		{
			HRESULT hr = pLibrary->CreateAccelerateDecelerateTransition(m_duration, m_finalValue, m_accelerationRatio,m_decelerationRatio, &m_transition);
			return SUCCEEDED(hr);
		}
		return FALSE;
	}
};

参考 CreateAccelerateDecelerateTransition Example Code

	CoInitialize(NULL);
   //填入两个double值
	CAccelerateDecelerateTransition transition(1/*DURATION*/,1 /*FinalValue*/);
	IUIAnimationTransitionLibrary* m_aniPtr;
	auto hr = CoCreateInstance(
		CLSID_UIAnimationTransitionLibrary,
		NULL,
		CLSCTX_INPROC_SERVER,
		IID_PPV_ARGS(&m_aniPtr)
	);
	bool res = transition.Create(m_aniPtr, NULL);
	//
	CoUninitialize();

res返回true则转换创建成功。

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