本文主要用到了Canvas API中的drawImage方法，下面对此方法略做介绍。
在Canvas API中绘制图像用drawImage方法，这是一个重载方法，定义如下：
context.drawImage(image,x,y); context.drawImage(image,x,y,w,h); context.drawImage(image,sx,sy,sw,sh,dx,dy,dw,dh);
第一个方法有三个参数，第一个参数为要绘制的图像(还可以是video元素)，x和y为该图像在画布中的起始坐标。
第二个方法有五个参数，前三个跟第一个方法意义一样，w和h指绘制时的图像宽度和高度，可以用来进行图像缩放。
第三个方法有九个参数，第一个参数跟前二个方法意义相同，后八个参数中前四个在源图像上一取一个矩形，后四个参数用于在画布上定义一个矩形，整个方法的作用就是把源图像上部分区域(第二到五个参数定义的部分)复制到画布上(后四个参数定义的部分)。
本文主要利用了第三个方法完成绘制。
<!DOCTYPE html><html><head>
<meta charset="UTF-8">
<title>用动画的形式切换图片</title>
<script type="text/javascript">
var width, height;
var context, image, functionId;
var drawLeft, drawWidth;
var drawTop, drawHeight;
var spaceWidth, spaceHeight;
var speed=5000;
var images = ["http://i.6.cn/cvbnm/4e/7e/bb/75f251a8e2ae935d598f17b4f8275060.jpg",
"http://i.6.cn/cvbnm/4a/6e/fb/805175016e502c483b75276f29801df3.jpg",
"http://i.6.cn/cvbnm/6a/72/18/1787a3b2754ef48e374bbd14635f5c36.jpg",
"http://i.6.cn/cvbnm/94/55/6c/b1ba743ba617be2891fa06b67d795511.jpg",
"http://i.6.cn/cvbnm/02/1b/04/8018ee9e5756ac6b30f27d7ad6396b03.jpg",
"http://i.6.cn/cvbnm/85/ea/d1/65f15857b971afb3b6e38b5fcdadc9c0.jpg"];
function selectFrom(iFirstValue, iLastValue) {
var iChoices = iLastValue - iFirstValue + 1;
return Math.floor(Math.random() * iChoices + iFirstValue);
} function showPicture(effects) {
var count = 0;
for (var o in effects) {
count++;
}
var canvas = document.getElementById('canvas');
context = canvas.getContext('2d');
width = canvas.width;
height = canvas.height;
var currImage = 0;
image = new Image();
image.src = images[currImage];
context.drawImage(image, 0, 0, width, height);
currImage++;
if (count > 0) {
setInterval(function () {
var rand = selectFrom(0, count - 1);
image.src = images[currImage];
currImage++;
if (currImage == images.length) {
currImage = 0;
}
var index = 0;
for (var effect in effects) {
if (index++ == rand) {
effects[effect]();
break;
}
}
}, speed);
}
}
window.onload=function(){
showPicture({
leftToRight: function () {
context.fillStyle = "#EEEEFF";
context.fillRect(0, 0, width, height);
drawWidth = 0;
functionId = self.setInterval("drawleftToRight()", 10);
},
topToBottom: function () {
context.fillStyle = "#EEEEFF";
context.fillRect(0, 0, width, height);
drawHeight = 0;
functionId = self.setInterval("drawtopToBottom()", 10);
},
hcenter: function () {
context.fillStyle = "#EEEEFF";
context.fillRect(0, 0, width, height);
drawLeft = width / 2;
drawWidth = 0;
functionId = self.setInterval("drawhcenter()", 10);
},
vcenter: function () {
context.fillStyle = "#EEEEFF";
context.fillRect(0, 0, width, height);
drawTop = height / 2;
drawHeight = 0;
functionId = self.setInterval("drawvcenter()", 10);
},
hwindow: function () {
context.fillStyle = "#EEEEFF";
context.fillRect(0, 0, width, height);
spaceWidth = width / 10;
drawWidth = 0;
functionId = self.setInterval("drawhwindow()", 50);
},
vwindow: function () {
context.fillStyle = "#EEEEFF";
context.fillRect(0, 0, width, height);
spaceHeight = height / 10;
drawHeight = 0;
functionId = self.setInterval("drawvwindow()", 50);
},
hvwindow: function () {
context.fillStyle = "#EEEEFF";
context.fillRect(0, 0, width, height);
spaceHeight = height / 10;
spaceWidth = width / 10;
drawWidth = 0;
drawHeight = 0;
functionId = self.setInterval("drawhvwindow()", 50);
}
});
} function drawleftToRight() {
context.drawImage(image, 0, 0, drawWidth, image.height, 0, 0, drawWidth, image.height);
drawWidth = drawWidth + 2;
if (drawWidth > width) {
window.clearInterval(functionId);
}
} function drawtopToBottom() {
context.save();
context.drawImage(image, 0, 0, image.width, drawHeight, 0, 0, image.width, drawHeight);
drawHeight = drawHeight + 2;
if (drawHeight > height) {
window.clearInterval(functionId);
}
context.restore();
}
function drawhcenter() {
context.save();
context.drawImage(image, drawLeft, 0, drawWidth, image.height, drawLeft, 0, drawWidth, image.height);
drawLeft = drawLeft - 1;
drawWidth = drawWidth + 2;
if (drawLeft <= 0) {
window.clearInterval(functionId);
}
context.restore();
}
function drawvcenter() {
context.save();
context.drawImage(image, 0, drawTop, image.width, drawHeight, 0, drawTop, image.width, drawHeight);
drawTop = drawTop - 1;
drawHeight = drawHeight + 2;
if (drawTop <= 0) {
window.clearInterval(functionId);
}
context.restore();
} function drawhwindow() {
for (i = 0; i < 10; i++) {
context.drawImage(image, 0 + i * spaceWidth, 0, drawWidth,
image.height, 0 + i * spaceWidth, 0, drawWidth, image.height);
}
drawWidth += 1;
if (drawWidth - 1 > spaceWidth) {
window.clearInterval(functionId);
}
} function drawvwindow() {
context.save();
context.clearRect(0, 0, width, height);
for (i = 0; i < 10; i++) {
context.drawImage(image, 0, 0 + i * spaceHeight, image.width,
drawHeight, 0, 0 + i * spaceHeight, image.width, drawHeight);
}
drawHeight += 1;
if (drawHeight - 1 > spaceHeight) {
window.clearInterval(functionId);
}
context.restore();
} function drawhvwindow() {
context.save();
context.clearRect(0, 0, width, height);
for (i = 0; i < 10; i++) {
for (j = 0; j < 10; j++) {
context.drawImage(image, 0 + j * spaceWidth, 0 + i *
spaceHeight, drawWidth, drawHeight, 0 + j * spaceWidth, 0 + i *
spaceHeight, drawWidth, drawHeight);
}
}
drawHeight += height / width;
drawWidth += 1;
if (drawHeight > spaceHeight) {
context.drawImage(image, 0, 0, width, height);
window.clearInterval(functionId);
}
context.restore();
} </script></head><body>
<h1>用动画的形式切换图片</h1>
<canvas id="canvas" width="192px" height="255px"></canvas></body></html>drawleftToRight()：效果为从左向右显示，主要把第四个参数和第八个参数从0逐渐增加到图片的宽度
drawtopToBottom()：效果为从上向下显示，主要把第五个参数和第九个参数从0逐渐增加到图片的高度
drawhcenter()：效果为从中间水平向两边显示，主要把第二、六个参数从图像宽度的一半减小到0，第四、八个参数从0增加到图像宽度
drawvcenter()：效果为从中间向上下两边显示，跟上一个类似
drawhwindow()：效果为水平方向百叶窗，跟drawhcenter方法原理类似，只是这里是从多个地方进行的
drawvwindow()：效果为垂直方面百叶窗，跟drawvcenter方法原理类似，只是这里是从多个地方进行的
drawhvwindow()：效果为百叶窗，是drawhwindow()跟drawvwindow()的组合
欢迎大家补充和完善。
由于图片是放在其他网站上，所以加载比较慢，显的不是那么流畅，大家使用时可以换为本地图片，效果更佳。
Atas ialah kandungan terperinci HTML5编程实战之二-使用动画的形式切换图片代码案例. Untuk maklumat lanjut, sila ikut artikel berkaitan lain di laman web China PHP!
Apakah kaedah penghasilan penghasilan animasi html5?
Perbezaan antara HTML dan HTML5
Bagaimana untuk menyimpan program yang ditulis dalam pycharm
Perbezaan antara halaman web statik dan halaman web dinamik
Bagaimana untuk membuka kunci sekatan kebenaran android
Kaedah perwakilan pemalar rentetan
Bagaimana untuk mengekalkan bilangan tempat perpuluhan dalam C++
Penggunaan fungsi get dalam bahasa c
![[Web front-end] Permulaan pantas Node.js](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
