主è¦ææ³ï¼
é¦å
è¦åå¤ä¸å¼ æè¿ç»å¸§çå¾çï¼ç¶åå©ç¨HTML5 Canvasçdrawæ¹æ³å¨ä¸åçæ¶é´é´éç»å¶ä¸åç帧ï¼è¿æ ·çèµ·æ¥å°±åå¨ç»å¨ææ¾ã
å
³é®ææ¯ç¹ï¼
JavaScript å½æ°setTimeout()æ两个åæ°ï¼ç¬¬ä¸ä¸ªæ¯åæ°å¯ä»¥ä¼ éä¸ä¸ªJavaScriptæ¹æ³ï¼
å¦å¤ä¸ä¸ªåæ°ä»£è¡¨é´éæ¶é´ï¼åä½ä¸ºæ¯«ç§æ°ã代ç 示ä¾ï¼
setTimeout( update, 1000/30);
CanvasçAPI-drawImage()æ¹æ³ï¼éè¦æå®å
¨é¨9个åæ°ï¼
ctx.drawImage(myImage, offw, offh, width,height, x2, y2, width, height);
å
¶ä¸offw, offhæ¯ææºå¾åçèµ·å§åæ ç¹ï¼width, height表示æºå¾åç宽ä¸é«ï¼x2,y2表
示æºå¾åå¨ç®æ Canvasä¸çèµ·å§åæ ç¹ã
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="X-UA-Compatible" content="chrome=IE8">
<meta http-equiv="Content-type" content="text/html;charset=UTF-8">
<title>Canvas Mouse Event Demo</title>
<link href="default.css" rel="stylesheet" />
<script>
var ctx = null; // global variable 2d context
var started = false;
var mText_canvas = null;
var x = 0, y =0;
var frame = 0; // 22 5*5 + 2
var imageReady = false;
var myImage = null;
var px = 300;
var py = 300;
var x2 = 300;
var y2 = 0;
window.onload = function() {
var canvas = document.getElementById("animation_canvas");
console.log(canvas.parentNode.clientWidth);
canvas.width = canvas.parentNode.clientWidth;
canvas.height = canvas.parentNode.clientHeight;
if (!canvas.getContext) {
console.log("Canvas not supported. Please install a HTML5 compatible browser.");
return;
}
// get 2D context of canvas and draw rectangel
ctx = canvas.getContext("2d");
ctx.fillStyle="black";
ctx.fillRect(0, 0, canvas.width, canvas.height);
myImage = document.createElement('img');
myImage.src = "../robin.png";
myImage.onload = loaded();
}
function loaded() {
imageReady = true;
setTimeout( update, 1000/30);
}
function redraw() {
ctx.clearRect(0, 0, 460, 460)
ctx.fillStyle="black";
ctx.fillRect(0, 0, 460, 460);
// find the index of frames in image
var height = myImage.naturalHeight/5;
var width = myImage.naturalWidth/5;
var row = Math.floor(frame / 5);
var col = frame - row * 5;
var offw = col * width;
var offh = row * height;
// first robin
px = px - 5;
py = py - 5;
if(px < -50) {
px = 300;
}
if(py < -50) {
py = 300;
}
//var rate = (frame+1) /22;
//var rw = Math.floor(rate * width);
//var rh = Math.floor(rate * height);
ctx.drawImage(myImage, offw, offh, width, height, px, py, width, height);
// second robin
x2 = x2 - 5;
y2 = y2 + 5;
if(x2 < -50) {
x2 = 300;
y2 = 0;
}
ctx.drawImage(myImage, offw, offh, width, height, x2, y2, width, height);
}
function update() {
redraw();
frame++;
if (frame >= 22) frame = 0;
setTimeout( update, 1000/30);
}
</script>
</head>
<body>
<h1>HTML Canvas Animations Demo - By Gloomy Fish</h1>
<pre>Play Animations</pre>
<div id="my_painter">
<canvas id="animation_canvas"></canvas>
</div>
</body>
</html>