使用GDI的一些AIP函数我们可以轻易的绘制出简单的几何图形，上一章提到过HDC是设备环境句柄，通过GetDC函数，我们可以获得在电脑上画画的画布，现在有了画布，我们想要画几何图形，还缺少什么呢？对，你没有听错，我们还缺少画画的工具，在GDI里面我们想要画几何图形一般用两种工具，一个是画笔，一个是画刷，下面分开介绍这两种工具。

//=======================================
//程序名称：GDI几何绘图
//2014年4月30日 Created by 图图
//Copyright (c) 图图
//=======================================

#include<windows.h>
#include<time.h>

//全局变量
HDC g_hDc = NULL; //全局设备环境句柄
HPEN g_hPen[7] = {0}; //定义画笔句柄的数组
HBRUSH g_hBrush[7] = {0}; //定义画刷句柄的.数组
int g_penStyle[7] = {PS_SOLID, PS_DASH, PS_DOT, PS_DASHDOT, PS_DASHDOTDOT, PS_NULL, PS_INSIDEFRAME}; //定义画笔样式数组
int g_brushStyle[6] = {HS_VERTICAL, HS_HORIZONTAL, HS_CROSS, HS_DIAGCROSS, HS_FDIAGONAL, HS_BDIAGONAL}; //定义画刷样式数组

//函数原型
bool InitResource(HWND hWnd);
void Render(HWND hWnd);
void Shutdown(HWND hWnd);

//宏定义
#define WINDOW_WIDTH  800
#define WINDOW_HEIGHT 600
#define WINDOW_CLASS  "GameDevelop"
#define WINDOW_NAME   "GDI几何绘图"

HRESULT CALLBACK WindowProc(
	HWND hwnd, 
	UINT uMsg, 
	WPARAM wParam, 
	LPARAM lParam
)
{
	switch(uMsg)
	{
		case WM_KEYDOWN:
			if(wParam == VK_ESCAPE)
			   PostQuitMessage(0);
			break;

		case WM_DESTROY:
			PostQuitMessage(0);
			break;

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

	return 0;
}

int WINAPI WinMain(
	HINSTANCE hInstance, 
	HINSTANCE hPreInstance, 
	LPSTR lpCmdLine, 
	int nCmdShow
)
{
	//设计窗口类
	WNDCLASSEX wcex;

	wcex.cbClsExtra = 0;
	wcex.cbSize = sizeof(WNDCLASSEX);
	wcex.cbWndExtra = 0;
	wcex.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
	wcex.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	wcex.hIconSm = NULL;
	wcex.hInstance = hInstance;
	wcex.lpfnWndProc = WindowProc;
	wcex.lpszClassName = WINDOW_CLASS;
	wcex.lpszMenuName = NULL;
	wcex.style = CS_HREDRAW | CS_VREDRAW;

	if(!RegisterClassEx(&wcex))
	   MessageBox(NULL, "窗口类注册失败", "图图的消息窗口", MB_OK);

	//创建窗口
	HWND hWnd;

	hWnd = CreateWindow(WINDOW_CLASS, WINDOW_NAME, WS_OVERLAPPEDWINDOW, 
		   0, 0, WINDOW_WIDTH, WINDOW_HEIGHT, NULL, NULL, hInstance, NULL);

	//对窗口位置和大小作调整，然后显示很更新窗口
	MoveWindow(hWnd, 250, 80, WINDOW_WIDTH, WINDOW_HEIGHT, TRUE);
	ShowWindow(hWnd, nCmdShow);
	UpdateWindow(hWnd);

	if(!InitResource(hWnd))
	{
		MessageBox(hWnd, "游戏资源初始化失败", "图图的消息窗口", MB_OK);
		return false;
	}

	MSG msg;
	ZeroMemory(&msg, sizeof(msg));

	while(msg.message != WM_QUIT)
	{
		if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
		{
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
		else
			Render(hWnd);
	}

	Shutdown(hWnd);
	UnregisterClass(WINDOW_CLASS, wcex.hInstance);

	return 0;
}

bool InitResource(HWND hWnd)
{
	g_hDc = GetDC(hWnd); //获得设备环境句柄
	srand((unsigned)time(NULL)); //初始化随机数种子

	//随机初始化画笔和画刷的颜色值
	for(int i = 0; i < 7; i++)
	{
		g_hPen[i] = CreatePen(g_penStyle[i], 1, RGB(rand()%256, rand()%256, rand()%256));

		if(i == 6)
			g_hBrush[i] = CreateSolidBrush(RGB(rand()%256, rand()%256, rand()%256));
		else
			g_hBrush[i] = CreateHatchBrush(g_brushStyle[i], RGB(rand() %256, rand()%256, rand()%256));
	}

	return true;
}

void Render(HWND hWnd)
{
	int y;

	for(int i = 0; i <= 6; i++)
	{
		y = (i+1) * 70;

		SelectObject(g_hDc, g_hPen[i]); //选好对应画笔
		MoveToEx(g_hDc, 30, y, NULL); //将光标移到(30, y)处
		LineTo(g_hDc, 100, y); //从(30, y)到(100, y)处画一条线段
	}

	int x1 = 120;
	int x2 = 190;

	for(i = 0; i <= 6; i++)
	{
		SelectObject(g_hDc, g_hBrush[i]); //选用画刷
		Rectangle(g_hDc, x1, 70, x2, y); //画出一个封闭的矩形，矩形左上角为(x1, 50)，右下角为(x2, y)
		x1 += 90;
		x2 += 90;
	}
}

void Shutdown(HWND hWnd)
{
	for(int i = 0; i < 7; i++)
	{
		DeleteObject(g_hPen[i]);
		DeleteObject(g_hBrush[i]);
	}

	ReleaseDC(hWnd, g_hDc);
}