angle_test.cpp

#include <Windows.h>
#include <string>
#include <sstream>

float g_angle = 0;

LRESULT CALLBACK WndProc ( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam )
{
	switch ( uMsg )
	{
		case WM_PAINT:
			{
				PAINTSTRUCT ps;
				HDC hDC = BeginPaint ( hWnd, &ps );

				RECT rect;
				GetClientRect ( hWnd, &rect );

				HBITMAP compBitmap = CreateCompatibleBitmap ( hDC, rect.right - rect.left, rect.bottom - rect.top );
				HDC compDC = CreateCompatibleDC ( hDC );

				HBITMAP oldBitmap = ( HBITMAP ) SelectObject ( compDC, compBitmap );

				FillRect ( compDC, &rect, ( HBRUSH ) GetStockObject ( WHITE_BRUSH ) );

				const int XOffset = 50, YOffset = 50;

				Ellipse ( compDC, XOffset, YOffset, 100 + XOffset, 100 + YOffset );

				float rad = g_angle / 180 * 3.141592f;
				float xr = cos ( rad ), yr = sin ( rad );

				MoveToEx ( compDC, 50 + XOffset, 50 + YOffset, nullptr );
				LineTo ( compDC, XOffset + ( 1 + xr ) * 50, YOffset + ( 1 + yr ) * 50 );

				std::wstringstream wss;
				wss << g_angle << L"˚(" << rad << "RAD), xr: " << xr << ", yr: " << yr;
				std::wstring wsss = wss.str ();
				TextOut ( compDC, 0, 0, wsss.c_str (), wsss.size () );

				BitBlt ( hDC, 0, 0, rect.right - rect.left, rect.bottom - rect.top, compDC, 0, 0, SRCCOPY );

				SelectObject ( compDC, oldBitmap );
				DeleteObject ( compDC );
				DeleteObject ( compBitmap );

				EndPaint ( hWnd, &ps );
			}
			break;

		case WM_CLOSE:
			PostQuitMessage ( 0 );
			break;

		default: return DefWindowProc ( hWnd, uMsg, wParam, lParam );
	}
	return 0;
}

int WINAPI WinMain ( HINSTANCE hInstance, HINSTANCE, LPSTR, int )
{
	WNDCLASS wndClass = {
		CS_VREDRAW | CS_HREDRAW, WndProc,
		0, 0,
		hInstance,
		0, 0,
		( HBRUSH ) GetStockObject ( WHITE_BRUSH ),
		NULL,
		L"AngleTest"
	};
	if ( INVALID_ATOM == RegisterClass ( &wndClass ) )
		return -1;

	HWND hWnd = CreateWindow ( L"AngleTest", L"Angle Test", WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
		NULL, NULL, hInstance, nullptr );
	if ( 0 == hWnd )
		return -2;

	ShowWindow ( hWnd, SW_SHOW );
	UpdateWindow ( hWnd );

	DWORD lastTickCount = GetTickCount (), currentTickCount;

	MSG msg;
	while ( true )
	{
		if ( PeekMessage ( &msg, 0, 0, 0, PM_NOREMOVE ) )
		{
			if ( !GetMessage ( &msg, 0, 0, 0 ) )
				break;
			TranslateMessage ( &msg );
			DispatchMessage ( &msg );
		}
		else
		{
			currentTickCount = GetTickCount ();
			if ( currentTickCount - lastTickCount > 1 / 60.0f * 1000 )
			{
				g_angle += 5.f * ( ( currentTickCount - lastTickCount ) / 1000.0f );
				InvalidateRect ( hWnd, nullptr, false );

				lastTickCount = currentTickCount;
			}
			Sleep ( 1 );
		}
	}
		
	return msg.wParam;
}