HTML5 canvas做的一个图片局部放大的效果
HTML5 canvas做的一个图片局部放大的效果
看到老外做HTML5的越来越多了,今天看到一个其中用HTML5做的效果不错, 是在canvas上画的圈,做放大器,并且监视了鼠标的相关事件,代码如下:
HTML部分
- <!DOCTYPE html>
- <html lang="en" >
CSS部分:
- *{
- margin:0;
- padding:0;
- }
- body {
- background-color:#bababa;
- color:#fff;
- font:14px/1.3 Arial,sans-serif;
- }
- footer {
- background-color:#212121;
- bottom:0;
- box-shadow: 0 -1px 2px #111111;
- display:block;
- height:70px;
- left:0;
- position:fixed;
- width:100%;
- z-index:100;
- }
- footer h2{
- font-size:22px;
- font-weight:normal;
- left:50%;
- margin-left:-400px;
- padding:22px 0;
- position:absolute;
- width:540px;
- }
- footer a.stuts,a.stuts:visited{
- border:none;
- text-decoration:none;
- color:#fcfcfc;
- font-size:14px;
- left:50%;
- line-height:31px;
- margin:23px 0 0 110px;
- position:absolute;
- top:0;
- }
- footer .stuts span {
- font-size:22px;
- font-weight:bold;
- margin-left:5px;
- }
- .container {
- color:#000;
- margin:20px auto;
- position:relative;
- width:800px;
- }
- #panel {
- border:1px #000 solid;
- box-shadow:4px 6px 6px #444444;
- cursor:crosshair;
- }
script.js
- // variables
- var canvas, ctx;
- var image;
- var iMouseX, iMouseY = 1;
- var bMouseDown = false;
- var iZoomRadius = 100;
- var iZoomPower = 2;
- // drawing functions
- function clear() { // clear canvas function
- ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
- }
- function drawScene() { // main drawScene function
- clear(); // clear canvas
- if (bMouseDown) { // drawing zoom area
- ctx.drawImage(image, 0 - iMouseX * (iZoomPower - 1), 0 - iMouseY * (iZoomPower - 1), ctx.canvas.width * iZoomPower, ctx.canvas.height * iZoomPower);
- ctx.globalCompositeOperation = 'destination-atop';
- var oGrd = ctx.createRadialGradient(iMouseX, iMouseY, 0, iMouseX, iMouseY, iZoomRadius);
- oGrd.addColorStop(0.8, "rgba(0, 0, 0, 1.0)");
- oGrd.addColorStop(1.0, "rgba(0, 0, 0, 0.1)");
- ctx.fillStyle = oGrd;
- ctx.beginPath();
- ctx.arc(iMouseX, iMouseY, iZoomRadius, 0, Math.PI*2, true);
- ctx.closePath();
- ctx.fill();
- }
- // draw source image
- ctx.drawImage(image, 0, 0, ctx.canvas.width, ctx.canvas.height);
- }
- $(function(){
- // loading source image
- image = new Image();
- image.onload = function () {
- }
- image.src = 'images/image.jpg';
- // creating canvas object
- canvas = document.getElementById('panel');
- ctx = canvas.getContext('2d');
- $('#panel').mousemove(function(e) { // mouse move handler
- var canvasOffset = $(canvas).offset();
- iMouseX = Math.floor(e.pageX - canvasOffset.left);
- iMouseY = Math.floor(e.pageY - canvasOffset.top);
- });
- $('#panel').mousedown(function(e) { // binding mousedown event
- bMouseDown = true;
- });
- $('#panel').mouseup(function(e) { // binding mouseup event
- bMouseDown = false;
- });
- setInterval(drawScene, 30); // loop drawScene
- });
一个在线效果在:
http://www.muu.cc/html5/Imagezoomer/index.html
要用chrome,firefox,safri等浏览器看
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