这篇文章主要介绍了借助HTML5 Canvas API制作一个简单的猜字单机游戏的实例分享,游戏中每局会自动生成一个字母,玩家按键盘来猜测该字母是哪一个,需要的朋友可以参考下
HTML代码
- <!doctype html>
- <html lang="en">
- <head>
- <meta charset="utf-8" />
- <script type="text/javascript" src="chp1_guess_the_letter.js"></script>
- <script type="text/javascript" src="modernizr.custom.99886.js"></script>
- </head>
- <body>
- <canvas id="canvas_guess_the_letter" width="500" height="300">
- 你的浏览器不支持HTML5 Canvas
- </canvas>
- <form>
- <input type="button" id="createImageData" value="Export Canvas Image" />;
- </form>
- </body>
- </html>
JavaScript Code
- /**
- * @author Rafael
- */
- window.addEventListener("load", eventWindowLoaded, false);
- var Debugger = function() {
- };
- Debugger.log = function(message) {
- try {
- console.log(message);
- } catch(exception) {
- return;
- }
- }
- function eventWindowLoaded() {
- canvasApp();
- }
- function canvasSupport() {
- return Modernizr.canvas;
- }
- function canvasApp() {
- var guesses = 0;
- var message = "Guess The Letter From a(lower) to z(higher)";
- var letters = ["a","b","c","d","e","f","g","h","i","j","k","l",
- "m","n","o","p","q","r","s","t","u","v","w","x","y","z"];
- var today = new Date();
- var letterToGuess = "";
- var higherOrLower = "";
- var letterGuessed = [];
- var gameOver = false;
- if(!canvasSupport()) {
- return;
- }
- var theCanvas = document.getElementById("canvas_guess_the_letter");
- var context = theCanvas.getContext("2d");
- initGame();
- function initGame() {
- var letterIndex = Math.floor(Math.random() * letters.length);
- letterToGuess = letters[letterIndex];
- guesses = 0;
- lettersGuessed = [];
- gameOver = false;
- window.addEventListener("keyup", eventKeyPressed, true);
- var formElement = document.getElementById("createImageData");
- formElement.addEventListener('click', createImageDataPressed, false);
- drawScreen();
- }
- function eventKeyPressed(e) {
- if(!gameOver) {
- var letterPressed = String.fromCharCode(e.keyCode);
- letterPressed = letterPressed.toLowerCase();
- guesses++;
- letterGuessed.push(letterPressed);
- if(letterPressed == letterToGuess) {
- gameOver = true;
- } else {
- letterIndex = letters.indexOf(letterToGuess);
- guessIndex = letters.indexOf(letterPressed);
- if(guessIndex < 0) {
- higherOrLower = "请输入正确的字符";
- } else if(guessIndex < letterIndex) {
- higherOrLower = "小了";
- } else {
- higherOrLower = "大了";
- }
- }
- drawScreen();
- }
- }
- function drawScreen() {
- //背景
- context.fillStyle = "#ffffaa";
- context.fillRect(0, 0, 500, 300);
- //箱子
- context.strokeStyle = "#000000";
- context.strokeRect(5, 5, 490, 290);
- context.textBaseLine = "top";
- //日期
- context.fillStyle = "#000000";
- context.font = "10px _sans";
- context.fillText(today, 150, 20);
- //消息
- context.fillStyle = "#FF0000";
- context.font = "14px _sans";
- context.fillText(message, 125, 40);
- //猜测次数
- context.fillStyle = "#109900";
- context.font = "16px _sans";
- context.fillText("猜测次数： "+guesses, 215, 60);
- //大还是小
- context.fillStyle = "#000000";
- context.font = "16px _sans";
- context.fillText("大还是小： "+higherOrLower, 150, 135);
- //已经猜测的字符
- context.fillStyle = "#FF0000";
- context.font = "16px _sans";
- context.fillText("已经猜测的字符： "+letterGuessed.toString(), 10, 260);
- if(gameOver) {
- context.fillStyle = "#FF0000";
- context.font = "40px _sans";
- context.fillText("你猜中了", 150, 180);
- }
- }
- function createImageDataPressed(e) {
- window.open(theCanvas.toDataURL(), "canvasImage","left=0, top=0, width="+theCanvas.width+", height="+theCanvas.height+", toolbar=0, resizable=0");
- }
- }
-
从游戏名称可以看出，该游戏是猜字游戏。每局系统都会自动生成一个字母，玩家会按键盘来猜测该字母是哪一个。
例如生成的是s，玩家按了h，则游戏就会提示《小了》，因为英文字母当中h的索引比s的索引更靠前。
案例当中涉及的变量。
guesses：猜测次数
message：文字提示，指导用户如何玩该游戏
letters：文字数组，存放我们要猜测的文字的集合。这个例子用的是a到z
today：今天的日期
letterToGuess：要猜测的文字
higherOrLower：是《大了》还是《小了》
letterGuessed：已经猜测过得文字
gameOver：游戏是否结束，是布尔变量，开始的时候是false，猜对后设为true
