Direct2D 第2篇 绘制椭圆

#include 
#include 
#include 
#include 
#pragma comment(lib, "dwrite.lib")
#pragma comment(lib, "d2d1.lib")

HINSTANCE g_hinst;
HWND g_hwnd;

ID2D1Factory * g_factory;
ID2D1HwndRenderTarget * g_render_target;
ID2D1SolidColorBrush  * g_brush;

void OnSize(LPARAM lparam)
{
	if(g_render_target)
		g_render_target->Resize(D2D1::SizeU(LOWORD(lparam),HIWORD(lparam)));
}

bool AppInit()
{
	D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &g_factory);

	RECT rc;
	GetClientRect(g_hwnd, &rc);
 
	g_factory->CreateHwndRenderTarget(
		D2D1::RenderTargetProperties(),
		D2D1::HwndRenderTargetProperties(g_hwnd, D2D1::SizeU(rc.right - rc.left, rc.bottom - rc.top)	),
		&g_render_target);

	g_render_target->CreateSolidColorBrush(D2D1::ColorF(D2D1::ColorF::ForestGreen), &g_brush);

	return true;
}

void OnPaint()
{
	if(!g_render_target)
		return;

	g_render_target->BeginDraw();

	// Clear Background
	g_render_target->Clear(D2D1::ColorF(0.63, 0.84, 0.00)); 

	// Draw Ellipse
	D2D1_SIZE_F size = g_render_target->GetSize();
	D2D1_ELLIPSE ellipse;
 
	ellipse.point = D2D1::Point2F(size.width/2.0, size.height/2.0);
	ellipse.radiusX = 200;
	ellipse.radiusY =100;
	g_render_target->FillEllipse(&ellipse, g_brush);//绘制图形

	g_render_target->EndDraw();
}

void OnDestroy()
{
	g_brush->Release();
	g_render_target->Release();
	g_factory->Release();
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) 
{
	switch(msg) 
	{  
	case WM_PAINT:
		OnPaint();
		break;

	case WM_SIZE:
		OnSize(lparam);
		break;

	case WM_DESTROY: 
		OnDestroy();
		PostQuitMessage(0);
		break;

	default:
		return DefWindowProc(hwnd, msg, wparam, lparam);
	}
	return 0;
}
 
int WINAPI WinMain(HINSTANCE hinst, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) 
{
	WNDCLASSEX wc;  
	MSG msg;  
	 
	memset(&wc,0,sizeof(wc));
	wc.cbSize = sizeof(WNDCLASSEX);
	wc.lpfnWndProc = WndProc; 
	wc.hInstance = hinst;
	wc.hCursor = LoadCursor(NULL, IDC_ARROW);
	wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
	wc.lpszClassName = "WindowClass";
	wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);  
	wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION); 

	if(!RegisterClassEx(&wc)) 
	{
		MessageBox(NULL, "Window Registration Failed!","Error!",MB_ICONEXCLAMATION|MB_OK);
		return 0;
	}

	g_hinst = hinst;

	g_hwnd = CreateWindowEx(WS_EX_CLIENTEDGE,"WindowClass","Direct2D Demo",WS_VISIBLE|WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT, 
		CW_USEDEFAULT, 
		640, 
		480, 
		NULL, NULL, hinst, NULL);

	if(g_hwnd == NULL) 
	{
		MessageBox(NULL, "Window Creation Failed!","Error!",MB_ICONEXCLAMATION|MB_OK);
		return 0;
	}

	if(!AppInit()) 
	{
		MessageBox(NULL, "Application Initialisation Failed !","Error",MB_ICONEXCLAMATION|MB_OK);
		return 0;
	}
 
	while(GetMessage(&msg, NULL, 0, 0) > 0) 
	{  
		TranslateMessage(&msg);  
		DispatchMessage(&msg); 
	}

	return msg.wParam;
}