四种语言画国旗

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国庆假期，闲来无事，用HTML、C、Java、Python四种语言画国旗

  • HTML

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<html>
<head>
	<script>
	var col=new Array("red","brown");
	var ticker=0;
	var step=0;
	function drawBackground(){
		var g=document.getElementById("background").getContext("2d");
		var grd=g.createLinearGradient(-560+ticker, 0, 1400+ticker,0);
		for (var i=0; i<10; i++)
			grd.addColorStop(i/10,col[(i + step)%col.length]);
		ticker=ticker+10;
		if (ticker>=196){
			ticker=0;
			step++;
		}
		g.fillStyle=grd;
		g.fillRect(0,0,1600,700);
	}
	function preperation(){
		setInterval('drawBackground()',100);
	}
	</script>

	<style type="text/css">
	#myCanvas{
	 z-index:2;	
	 position:absolute; left:0px; top:-5px;
	}
	#background{
		z-index:1;
		position:absolute;
		left:0px;
		top:0px;
	}
	</style>
</head>

<body onLoad="preperation()">
	<canvas id="myCanvas" width="900" height="600" >
		Your browser does not support the HTML5 canvas tag.
	</canvas>
	<canvas id="background" width="1600" height="700" ></canvas>
	<script>
	var x=new Array(0,12,54,18,28,0,-28,-18,-54,-12,0);    //五角星样品坐标xx数组
	var y=new Array(-53,-17,-17,1,45,19,45,1,-17,-17,-53); //五角星样品坐标y数组

	var c=document.getElementById("myCanvas");
	var ctx=c.getContext("2d"); //获得画笔
	//样品数组x轴坐标 a , 和y轴坐标 b
	//指定位置[locationX,locationY]
	//真实五角星的大小，与样品五角星尺寸之比 f
	//五角星画完后，旋转的角度 rotation
	function star(a,b,locationX,locationY,f,rotation){
		ctx.save();//记录画图（画笔）的初始环境
		ctx.translate(locationX,locationY);
		ctx.rotate(rotation*Math.PI/180.0);
		ctx.beginPath();
		ctx.moveTo(Math.round(a[0]*f),Math.round(b[0]*f));
		for (var i=1;i<a.length;i++)
		ctx.lineTo(Math.round(a[i]*f),Math.round(b[i]*f));
		ctx.closePath();
		ctx.fillStyle="yellow";
		ctx.fill();
		ctx.restore();//还原画图（画笔）的初始环境
	}
	star(x,y,165,165,1.4,0);//画大五角星
	star(x,y,301,65,0.5,30);//画小五角星
	star(x,y,362,126,0.5,-30);//画小五角星
	star(x,y,359,216,0.5,0);//画小五角星
	star(x,y,301,273,0.5,30);//画小五角星
	</script>
</body>
</html>

  • C

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#include <windows.h>
#include <math.h>

/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);
void DrawFiveStarFlag(HDC hdc, int x, int y, int w);
void DrawFivePointedStar(HDC hdc, int x, int y, int r, float d);

/* Current app instance */
HINSTANCE hInst;
/*  Make the class name into a global variable  */
TCHAR szClassName[] = TEXT("WindowsApp");

int WINAPI
WinMain (HINSTANCE hThisInstance, HINSTANCE hPrevInstance, LPSTR lpszArgument, int nFunsterStil)
{
	HWND hwnd;			   /* This is the handle for our window */
	MSG messages;			/* Here messages to the application are saved */
	WNDCLASSEX wincl;		/* Data structure for the windowclass */

				/* Save this instance */
				hInst = hThisInstance;
		
	/* The Window structure */
	wincl.hInstance = hThisInstance;
	wincl.lpszClassName = szClassName;
	wincl.lpfnWndProc = WindowProcedure;	  /* This function is called by windows */
	wincl.style = CS_DBLCLKS;				 /* Catch double-clicks */
	wincl.cbSize = sizeof (WNDCLASSEX);

	/* Use default icon and mouse-pointer */
	wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
	wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
	wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
	wincl.lpszMenuName = NULL;
	wincl.cbClsExtra = 0;					  /* No extra bytes after the window class */
	wincl.cbWndExtra = 0;					  /* structure or the window instance */
	/* Use Windows's default color as the background of the window */
	wincl.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);

	/* Register the window class, and if it fails quit the program */
	if (!RegisterClassEx (&wincl))
		return 0;

	/* The class is registered, let's create the program*/
	hwnd = CreateWindowEx (
		   0,				   /* Extended possibilites for variation */
		   szClassName,		 /* Classname */
		   TEXT("TestPie"),				 /* Title Text */
		   WS_OVERLAPPEDWINDOW, /* default window */
		   CW_USEDEFAULT,	   /* Windows decides the position */
		   0,													   /* where the window ends up on the screen */
		   CW_USEDEFAULT,	   /* The programs width */
		   0,						 /* and height in pixels */
		   HWND_DESKTOP,		/* The window is a child-window to desktop */
		   NULL,				/* No menu */
		   hThisInstance,	   /* Program Instance handler */
		   NULL				 /* No Window Creation data */
		   );

	/* Make the window visible on the screen */
	ShowWindow (hwnd, nFunsterStil);

	/* Run the message loop. It will run until GetMessage() returns 0 */
	while (GetMessage (&messages, NULL, 0, 0))
	{
		/* Translate virtual-key messages into character messages */
		TranslateMessage(&messages);
		/* Send message to WindowProcedure */
		DispatchMessage(&messages);
	}

	/* The program return-value is 0 - The value that PostQuitMessage() gave */
	return messages.wParam;
}


/*  This function is called by the Windows function DispatchMessage()  */

LRESULT CALLBACK
WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
		PAINTSTRUCT ps;
		HDC hdc;

	switch (message)				  /* handle the messages */
	{
			case WM_PAINT:
						hdc = BeginPaint(hwnd, &ps);
						/* TODO: Add any drawing code here... */
						DrawFiveStarFlag(hdc, 50, 50, 300);
						EndPaint(hwnd, &ps);
						break;
		case WM_DESTROY:
			PostQuitMessage (0);	   /* send a WM_QUIT to the message queue */
			break;
		default:					  /* for messages that we don't deal with */
			return DefWindowProc (hwnd, message, wParam, lParam);
	}

	return 0;
}

/* 画五角星
 * 参数：hdc画图句柄，xy中心点坐标，r外圆半径，d偏斜角度（逆时针）
 */
void DrawFivePointedStar(HDC hdc, int x, int y, int r, float d)
{
	float r0 = 0.381966*r;				//内圆半径：r*sin(0.1*M_PI)/sin(0.7*M_PI)
	int i;
	POINT p[10];

	//计算10个顶点的坐标（72度为实心五角星，144为空心五角星） 
	for(i=0; i<5; i++)
	{
		p[2*i].x = x + r*cos((i*72-18+d)*M_PI/180);
		p[2*i].y = y + r*sin((i*72-18+d)*M_PI/180);

		p[2*i+1].x = x + r0*cos((i*72+18+d)*M_PI/180);
		p[2*i+1].y = y + r0*sin((i*72+18+d)*M_PI/180);
	}

	//画五角星
	Polygon(hdc, p, 10);
}

/* 画五星红旗
 * 参数：hdc画图句柄，xy旗左上角坐标，w旗宽
 */
void DrawFiveStarFlag(HDC hdc, int x, int y, int w)
{
	COLORREF RED = RGB(255, 0, 0), YELLOW = RGB(255, 255, 0);
	HPEN hPen1 = CreatePen(PS_SOLID, 1, RED), hPen2 = CreatePen(PS_SOLID, 1, YELLOW);
	HBRUSH hBrush1 = CreateSolidBrush(RED), hBrush2 = CreateSolidBrush(YELLOW);

		//画旗面
	SelectObject(hdc, hPen1);
	SelectObject(hdc, hBrush1);
	Rectangle(hdc, x, y, x+w, y+2*w/3);

		//画5星 
	SelectObject(hdc, hPen2);
	SelectObject(hdc, hBrush2);
	DrawFivePointedStar(hdc, x+w/6,   y+w/6,	w/10, 0);				//大星
	DrawFivePointedStar(hdc, x+w/3,   y+w/15,   w/30, 18);				//4个小星，倾斜角度都是估的
	DrawFivePointedStar(hdc, x+2*w/5, y+2*w/15, w/30, 45);
	DrawFivePointedStar(hdc, x+2*w/5, y+7*w/30, w/30, 9);
	DrawFivePointedStar(hdc, x+w/3,   y+3*w/10, w/30, 27);

	DeleteObject(hPen1);
	DeleteObject(hPen2);
	DeleteObject(hBrush1);
	DeleteObject(hBrush2);
}

  • Java

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import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.geom.GeneralPath;
 
import javax.swing.JFrame;
 
public class NationalFlag extends JFrame {
	private int width = 288,height = width/3*2;  
	private double maxR = 0.15, minR = 0.05;  
	private double maxX = 0.50, maxY = 0.50;  
	private double[] minX = {0.75, 0.85, 0.85, 0.75};  
	private double[] minY = {0.35, 0.45, 0.60, 0.70};  
	
	public NationalFlag() {
		setTitle("国旗  - by PotatoChipsNinja");
		setDefaultCloseOperation(EXIT_ON_CLOSE);
	}

	@Override
	public void paint(java.awt.Graphics graphics) {
		super.paint(graphics);
		java.awt.Graphics2D g = (java.awt.Graphics2D)graphics;
		g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
		 
		//棋面
		g.setColor(java.awt.Color.red);
		g.fillRect(50, 50, width, height);
 
		g.setColor(java.awt.Color.yellow);
		//画大星星
		double ox = height*maxX, oy = height*maxY;
		g.fill(createPentacle(ox,oy,height*maxR,-Math.PI/2));  
		 
		//画小星星
		for(int idx =0;idx < 4;idx ++){  
			double sx = minX[idx]*height, sy = minY[idx]*height;  
			double theta = Math.atan2(oy-sy,ox-sx);  
			g.fill(createPentacle(sx,sy,height*minR,theta));  
		}  
	}
 
	/**
	 * 创建一个五角星形状. 该五角星的中心坐标为(sx,sy),中心到顶点的距离为radius,其中某个顶点与中心的连线的偏移角度为theta(弧度)
	 * 
	 * @return pentacle 一个☆
	 */
	public static java.awt.Shape createPentacle(double sx, double sy, double radius,double theta) {
		final double arc = Math.PI / 5;
		final double rad = Math.sin(Math.PI / 10) / Math.sin(3 * Math.PI / 10);
		GeneralPath path = new GeneralPath();
		path.moveTo(1, 0);
		for (int idx = 0; idx < 5; idx++) {
			path.lineTo(rad * Math.cos((1 + 2 * idx) * arc),rad * Math.sin((1 + 2 * idx) * arc));
			path.lineTo(Math.cos(2 * (idx + 1) * arc),Math.sin(2 * (idx + 1) * arc));
		}
		path.closePath();
		AffineTransform atf = AffineTransform.getScaleInstance(radius, radius);
		atf.translate(sx / radius, sy / radius);
		atf.rotate(theta);
		return atf.createTransformedShape(path);
	}
 
	public static void main(String[] args) {
		NationalFlag flag = new NationalFlag();
		flag.setBounds(100, 100, 400, 400);
		flag.setVisible(true);
	}
}

  • Python

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#coding=utf-8
import turtle
import math
 
def draw_polygon(aTurtle, size=50, n=3):
	''' 绘制正多边形
 
	args:
		aTurtle: turtle对象实例
		size: int类型，正多边形的边长
		n: int类型，是几边形		
	'''
	for i in xrange(n):
		aTurtle.forward(size)
		aTurtle.left(360.0/n)
 
def draw_n_angle(aTurtle, size=50, num=5, color=None):
	''' 绘制正n角形，默认为黄色
 
	args:
		aTurtle: turtle对象实例
		size: int类型，正多角形的边长
		n: int类型，是几角形	
		color: str， 图形颜色，默认不填色
	'''
	if color:
		aTurtle.begin_fill()
		aTurtle.fillcolor(color)
	for i in xrange(num):
		aTurtle.forward(size)
		aTurtle.left(360.0/num)
		aTurtle.forward(size)
		aTurtle.right(2*360.0/num)
	if color:
		aTurtle.end_fill()
 
def draw_5_angle(aTurtle=None, start_pos=(0,0), end_pos=(0,10), radius=100, color=None):
	''' 根据起始位置、结束位置和外接圆半径画五角星
 
	args:
		aTurtle: turtle对象实例
		start_pos: int的二元tuple，要画的五角星的外接圆圆心
		end_pos: int的二元tuple，圆心指向的位置坐标点
		radius: 五角星外接圆半径
		color: str， 图形颜色，默认不填色	
	'''
	aTurtle = aTurtle or turtle.Turtle()
	size = radius * math.sin(math.pi/5)/math.sin(math.pi*2/5)
	aTurtle.left(math.degrees(math.atan2(end_pos[1]-start_pos[1], end_pos[0]-start_pos[0])))
	aTurtle.penup()
	aTurtle.goto(start_pos)
	aTurtle.fd(radius)
	aTurtle.pendown()
	aTurtle.right(math.degrees(math.pi*9/10))
	draw_n_angle(aTurtle, size, 5, color)
 
def draw_5_star_flag(times=20.0):
	''' 绘制五星红旗
 
	args:
		times: 五星红旗的规格为30*20， times为倍数，默认大小为10倍， 即300*200
	'''
	width, height = 30*times, 20*times
	# 初始化屏幕和海龟
	window = turtle.Screen()
	aTurtle = turtle.Turtle()
	aTurtle.hideturtle()
	aTurtle.speed(10)
	# 画红旗
	aTurtle.penup()
	aTurtle.goto(-width/2, height/2)
	aTurtle.pendown()
	aTurtle.begin_fill()
	aTurtle.fillcolor('red')
	aTurtle.fd(width)
	aTurtle.right(90)
	aTurtle.fd(height)
	aTurtle.right(90)
	aTurtle.fd(width)
	aTurtle.right(90)
	aTurtle.fd(height)
	aTurtle.right(90)	
	aTurtle.end_fill()
	# 画大星星
	draw_5_angle(aTurtle, start_pos=(-10*times, 5*times), end_pos=(-10*times, 8*times), radius=3*times, color='yellow')  
	# 画四个小星星
	stars_start_pos = [(-5, 8), (-3, 6), (-3, 3), (-5, 1)]
	for pos in stars_start_pos:
		draw_5_angle(aTurtle, start_pos=(pos[0]*times, pos[1]*times), end_pos=(-10*times, 5*times), radius=1*times, color='yellow')  
	# 点击关闭窗口
	window.exitonclick()
 
if __name__ == '__main__':
	draw_5_star_flag()