日期:2014-05-16 浏览次数:20954 次


<!DOCTYPE html>
<html>
<head>
<meta charset="gbk">
<title>精灵表动画实例</title>
<style type="text/css">
#draw-target {
width:480px;
height:320px;
background-color:#ccf;
position:relative;
border:1px solid;
}
</style>
<script type="text/javascript">
function CanvasSprite(params) {
this.x=params.x;//精灵在画布中的x坐标
this.y=params.y;
this.index=params.index;//精灵图片的索引,从左到右,从0开始
this.ctx = params.ctx;//画布的上下文,绘图的地方
this.width = params.width;//精灵图片的宽
this.height = params.height;
this.imagesWidth = params.imagesWidth;//精灵表的宽
//精灵在精灵表中的位置
this.vOffset = Math.floor(this.index*this.width / this.imagesWidth) * this.height;
this.hOffset = (this.index*this.width) % this.imagesWidth;
this.hide = false;
this.img = new Image();
this.img.src = params.images;//精灵表图片
this.act=params.act;//精灵的动作行为
}
//在画布中绘制精灵
CanvasSprite.prototype.draw=function() {
if (this.hide) {
return;
}
this.ctx.drawImage(this.img, this.hOffset, this.vOffset, this.width, this.height,this.x , this.y, this.width, this.height);
}
//改变精灵的索引
CanvasSprite.prototype.changeImage=function(index) {
this.index =index;
this.vOffset = Math.floor(this.index*this.width / this.imagesWidth) * this.height;
this.hOffset = (this.index*this.width) % this.imagesWidth;
}
CanvasSprite.prototype.show=function() {
this.hide = false;
}
CanvasSprite.prototype.hide=function() {
this.hide = true;
}
CanvasSprite.prototype.destroy=function () {
return;
}
//精灵的行为,交给实现了ac()方法的对象
CanvasSprite.prototype.move= function(drawTarget) {
this.act.ac(this,drawTarget);
}
//精灵1的动作
function action(){
this.ac=function(canvasSprite,drawTarget){
var maxX=drawTarget.width - 64;
var maxY= drawTarget.height - 64;
canvasSprite.x += 2;
canvasSprite.y += 2;
canvasSprite.index++;
if(canvasSprite.index>=5) canvasSprite.index=0;
if(canvasSprite.x>maxX) canvasSprite.x-=2;
if(canvasSprite.y>maxY) canvasSprite.y-=2;
canvasSprite.changeImage(canvasSprite.index);
}
}
//精灵2的动作
function action1(){
this.ac=function(canvasSprite,drawTarget){
canvasSprite.index++;
if(canvasSprite.index>=4) canvasSprite.index=0;
canvasSprite.changeImage(canvasSprite.index);
}
}
window.onload=function() {
var canvas = document.getElementById('draw-target');
var ctx=canvas.getContext("2d");
var drawTarget=document.getElementById("draw-target");
//精灵1的参数
var para={
x:0,
y:0,
index:0,
images: 'cogs.png',
imagesWidth: 256,
width: 64,
height: 64,
ctx:ctx,
act:new action()
}
//精灵2的参数
var para1={
x:200,
y:0,
index:0,
images: 'ren.png',
imagesWidth: 240,
width: 60,
height: 60,
ctx:ctx,
act:new action1()
}
var sprite1=new CanvasSprite(para);
var sprite2=new CanvasSprite(para1);
function moveAll() {
ctx.clearRect(0,0,ctx.canvas.width,ctx.canvas.height);
sprite2.move(drawTarget);
sprite1.move(drawTarget