002：CWnd类中采用D2D绘制，并测试帧率

1、简介

 

        在001中，D2D绘制的代码直接放在了对话框类中，实际使用过程中，通常是继承CWnd来实现显示窗口，因此本例子实现在CWnd子类中采用D2D进行绘制，并测试FPS，后续会与GDI和GDI+的绘制帧率进行对比。

2、实现

        背景绘制渐变色，每隔10个像素绘制水平和垂直直线，中间绘制矩形和填充矩形，然后随机绘制 1000个圆，最后绘制字符串“你好，Direct 2D!”。

 继承CWnd类生成子类 CWndDirect2D，在类向导中，添加类=》MFC类，在弹出框中添加类名称，本例子为CWndDirect2D

在头文件中添加成员变量

private:
	CD2DTextFormat* m_pTextFormat;
	CD2DSolidColorBrush* m_pBlackBrush;
	CD2DSolidColorBrush* m_pLightSlateGrayBrush;
	CD2DSolidColorBrush* m_pCornflowerBlueBrush;
	CD2DLinearGradientBrush* m_pLinearGradientBrush;

然后给CWndDirect2D类添加三个消息函数，分别为Create、Size、和自定义的Draw2D，如下打开类向导，选择CWndDirect2D类，然后分别添加上述三个消息，具体如下：

    ON_WM_CREATE()
	ON_WM_SIZE()
	ON_REGISTERED_MESSAGE(AFX_WM_DRAW2D, &CWndDirect2D::OnDrawD2D)

具体添加过程为：

其中在CREATE中开启D2D，并初始化相关变量：如下代码所示：

int CWndDirect2D::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
	if (CWnd::OnCreate(lpCreateStruct) == -1)
		return -1;

	// TODO:  在此添加您专用的创建代码
	// Enable D2D support for this window:  
	this->EnableD2DSupport();

	if (!IsD2DSupportEnabled())
		return -1;

	// Initialize D2D resources: 
	m_pBlackBrush = new CD2DSolidColorBrush(GetRenderTarget(), D2D1::ColorF(D2D1::ColorF::Black));
	m_pLightSlateGrayBrush = new CD2DSolidColorBrush(GetRenderTarget(), D2D1::ColorF(D2D1::ColorF::LightSlateGray));
	m_pCornflowerBlueBrush = new CD2DSolidColorBrush(GetRenderTarget(), D2D1::ColorF(D2D1::ColorF::CornflowerBlue));

	m_pTextFormat = new CD2DTextFormat(GetRenderTarget(), _T("Verdana"), 50);
	m_pTextFormat->Get()->SetTextAlignment(DWRITE_TEXT_ALIGNMENT_CENTER);
	m_pTextFormat->Get()->SetParagraphAlignment(DWRITE_PARAGRAPH_ALIGNMENT_CENTER);
	D2D1_GRADIENT_STOP gradientStops[2];
	gradientStops[0].color = D2D1::ColorF(D2D1::ColorF::White);
	gradientStops[0].position = 0.f;
	gradientStops[1].color = D2D1::ColorF(D2D1::ColorF::Indigo);
	gradientStops[1].position = 1.f;
	m_pLinearGradientBrush = new CD2DLinearGradientBrush(GetRenderTarget(), gradientStops, ARRAYSIZE(gradientStops), D2D1::LinearGradientBrushProperties(D2D1::Point2F(0, 0), D2D1::Point2F(0, 0)));

	return 0;
}

在OnSize中添加渐变背景的范围，如下：

void CWndDirect2D::OnSize(UINT nType, int cx, int cy)
{
	CWnd::OnSize(nType, cx, cy);

	// TODO: 在此处添加消息处理程序代码
	m_pLinearGradientBrush->SetEndPoint(CPoint(cx, cy));
}

在Draw2D中添加绘制代码：

afx_msg LRESULT CWndDirect2D::OnDrawD2D(WPARAM wParam, LPARAM lParam)
{
	LARGE_INTEGER start_counter, end_counter, counters, nFreq;

	CHwndRenderTarget* pRenderTarget = (CHwndRenderTarget*)lParam;
	//CHwndRenderTarget* pRenderTarget = (CHwndRenderTarget*)m_pRenderTarget;

	QueryPerformanceFrequency(&nFreq);
	QueryPerformanceCounter(&start_counter);


	ASSERT_VALID(pRenderTarget);

	CRect rect1;
	GetClientRect(rect1);


	pRenderTarget->FillRectangle(rect1, m_pLinearGradientBrush);

	D2D1_SIZE_F rtSize = pRenderTarget->GetSize();
	// Draw a grid background.
	int width = static_cast(rtSize.width);
	int height = static_cast(rtSize.height);

	for (int x = 0; x < width; x += 10)
	{
		pRenderTarget->DrawLine(
			D2D1::Point2F(static_cast(x), 0.0f),
			D2D1::Point2F(static_cast(x), rtSize.height),
			m_pLightSlateGrayBrush,
			0.5f
		);
	}
	for (int y = 0; y < height; y += 10)
	{
		pRenderTarget->DrawLine(
			D2D1::Point2F(0.0f, static_cast(y)),
			D2D1::Point2F(rtSize.width, static_cast(y)),
			m_pLightSlateGrayBrush,
			0.5f
		);
	}

	// Draw two rectangles.
	D2D1_RECT_F rectangle1 = D2D1::RectF(
		rtSize.width / 2 - 50.0f,
		rtSize.height / 2 - 50.0f,
		rtSize.width / 2 + 50.0f,
		rtSize.height / 2 + 50.0f
	);

	D2D1_RECT_F rectangle2 = D2D1::RectF(
		rtSize.width / 2 - 100.0f,
		rtSize.height / 2 - 100.0f,
		rtSize.width / 2 + 100.0f,
		rtSize.height / 2 + 100.0f
	);

	// Draw a filled rectangle.
	pRenderTarget->FillRectangle(&rectangle1, m_pLightSlateGrayBrush);

	// Draw the outline of a rectangle.
	pRenderTarget->DrawRectangle(&rectangle2, m_pCornflowerBlueBrush);

	for (int i = 0; i < 1000; ++i)
	{
		FLOAT left = rand() % width;
		FLOAT top = rand() % height;
		FLOAT radius = rand() % 200;
		CD2DEllipse ellipse(CD2DRectF(left, top, left + radius, top + radius));
		CD2DSolidColorBrush brush(pRenderTarget, D2D1::ColorF(rand() % 100 / 100.f, rand() % 100 / 100.f, rand() % 100 / 100.f, 100));
		pRenderTarget->DrawEllipse(ellipse, &brush);
		//pRenderTarget->FillEllipse(ellipse, &brush);
	}

	pRenderTarget->DrawText(_T("你好 Direct 2D!"), rect1, m_pBlackBrush, m_pTextFormat);
	//pRenderTarget->DrawBitmap();

	QueryPerformanceCounter(&end_counter);

	counters.QuadPart = end_counter.QuadPart - start_counter.QuadPart;

	start_counter = end_counter;

	LONGLONG fps = nFreq.QuadPart / counters.QuadPart;
	//wchar_t buf[100];

	//swprintf_s(buf,sizeof(buf),_T("counts:%lld\n"), counters.QuadPart);
	CString str;
	str.Format(_T("%i"), fps);
	str += "\n";
	OutputDebugString(_T("FPS:") + str);

	return TRUE;
}

完成

3、效果与帧率

Debug模式下的FPS 

4、总结

 动态拖拽测试FPS，结果显示FPS能够稳定在80以上，偶尔为70多帧(Debug模式下)。下一步准备与GDI和GDI+的绘制速度进行对比。