WTL学习笔记(5)双缓冲技术和动画(BufferedPaint)

 

Vista+添加了相关函数对GDI双缓冲进行了支持,下面是wtl进行的封装

1.CBufferedPaint

对相关的BufferedPaint函数进行封装

class CBufferedPaint
{
public:
HPAINTBUFFER m_hPaintBuffer;

CBufferedPaint() : m_hPaintBuffer(NULL)
{ }

~CBufferedPaint()
{
ATLVERIFY(SUCCEEDED(End()));
}

bool IsNull() const
{
return (m_hPaintBuffer == NULL);
}

HPAINTBUFFER Begin(HDC hdcTarget, const RECT* prcTarget, BP_BUFFERFORMAT dwFormat, BP_PAINTPARAMS* pPaintParams, HDC* phdcPaint)
{
ATLASSERT(m_hPaintBuffer == NULL);
m_hPaintBuffer = ::BeginBufferedPaint(hdcTarget, prcTarget, dwFormat, pPaintParams, phdcPaint);
return m_hPaintBuffer;
}

HRESULT End(BOOL bUpdate = TRUE)
{
HRESULT hRet = S_FALSE;
if(m_hPaintBuffer != NULL)
{
hRet = ::EndBufferedPaint(m_hPaintBuffer, bUpdate);
m_hPaintBuffer = NULL;
}
return hRet;
}
…
};

好像构造函数和析构函数中没有添加BufferedPaintInit和BufferedPaintUnInit函数,使用相关函数必须先调用BufferedPaintInit,结束时调用BufferedPaintUnInit

2.CBufferedPaintBase

CBufferedPaintBase封装了BufferedPaintInit和BufferedPaintUnInit函数,IsBufferedPaintSupported判断必须是vista+

class CBufferedPaintBase
{
public:
static int m_nIsBufferedPaintSupported;

CBufferedPaintBase()
{
if(IsBufferedPaintSupported())
ATLVERIFY(SUCCEEDED(::BufferedPaintInit()));
}

~CBufferedPaintBase()
{
if(IsBufferedPaintSupported())
ATLVERIFY(SUCCEEDED(::BufferedPaintUnInit()));
}

static bool IsBufferedPaintSupported()
{
if(m_nIsBufferedPaintSupported == -1)
{
CStaticDataInitCriticalSectionLock lock;
if(FAILED(lock.Lock()))
{
ATLTRACE2(atlTraceUI, 0, _T("ERROR : Unable to lock critical section in CBufferedPaintBase::IsBufferedPaintSupported.\n"));
ATLASSERT(FALSE);
return false;
}

if(m_nIsBufferedPaintSupported == -1)
m_nIsBufferedPaintSupported = RunTimeHelper::IsVista() ? 1 : 0;

lock.Unlock();
}

ATLASSERT(m_nIsBufferedPaintSupported != -1);
return (m_nIsBufferedPaintSupported == 1);
}
};

3.CBufferedPaintImpl

CBufferedPaintImpl继承了CBufferedPaintBase,并在内部调用了CBufferedPaint的相关方法

4.CBufferedPaintWindowImpl

继承自CBufferedPaintImpl,默认实现BufferedPaint功能

参考:

/article/4589322.html

http://www.codeguru.com/cpp/w-p/vista/print.php/c15709/(源码示例参考)

动画支持

5.CBufferedAnimation

BeginBufferedAnimation,EndBufferedAnimation,BufferedPaintRenderAnimation是新增了三个函数，可以在画图时提供动画支持.

CBufferedAnimation封装了这3个函数

6.CBufferedAnimationImpl

除了了解上面三个函数之外，动画肯定需要提供默认的动画效果,BP_ANIMATIONPARAMS用来设置动画效果和动画间隔时间

// BP_ANIMATIONSTYLE
typedef enum _BP_ANIMATIONSTYLE
{
BPAS_NONE,                // No animation
BPAS_LINEAR,              // Linear fade animation
BPAS_CUBIC,               // Cubic fade animation
BPAS_SINE                 // Sinusoid fade animation
} BP_ANIMATIONSTYLE;

// BP_ANIMATIONPARAMS
typedef struct _BP_ANIMATIONPARAMS
{
DWORD               cbSize;
DWORD               dwFlags; // BPAF_ flags
BP_ANIMATIONSTYLE   style;
DWORD               dwDuration;
} BP_ANIMATIONPARAMS, *PBP_ANIMATIONPARAMS;

CBufferedAnimationImpl继承自CBufferedPaintBase,并在内部设置了默认的动画效果,同时添加了DoPaint方法，供子类重写

7.CBufferedAnimationWindowImpl

继承自CBufferedAnimationImpl,重写DoPaint方法,默认支持GDI动画程序效果

参考:http://www.codeguru.com/cpp/w-p/vista/print.php/c15841/

感谢这位作者提供的2个通俗易懂的例子