用HTML5和原生js实现放大局部图片

时间：2023-01-07 09:07:20

drawImage方法

context.drawImage(image,sx,sy,sh,dx,dy,dw,dh)

sx\sy起始图像的横纵坐标，sh\sd起始图像的大小，dx\dy复制图像的横纵坐标，dw\dy复制图像的大小

下面我们用这个属性来做一个点击局部放大效果

<!DOCTYPE html>

<html>

<head>

	<title></title>

	<script type="text/javascript" src="js/jquery.js"></script>

	<script type="text/javascript">

	    var context;

	    var canvas;

	    var iMouseX, iMouseY = 1;

	    var image;

	   //绘制区域

	    window.onload = function() {

	    	function draw(id){

	    	    canvas = document.getElementById(id);

	    	    if(canvas == null)

	    		    return false;

	    	    context = canvas.getContext('2d');

	    	    context.fillStyle = "#eeeeff";

	    	    context.fillRect(0,0,400,300);

	    	    //一边装载，一边绘制

	    	    image = new Image();

	    	    image.src = "img/2.png";

	    	    image.onload = function() {

	    		    drawImg(context,image);

	    	    };

	        }

	        //将原始图片添加到网页上

	        function drawImg(context,image) {

	    	            context.drawImage(image,0,0,100,100);

	        }

	        draw('canvas');

         //点击原始图片放大事件

        canvas.onclick = function(e) {//监听鼠标动作

           iMouseX = Math.floor(e.pageX);

           iMouseY = Math.floor(e.pageY)-82;

           context.drawImage(image,iMouseX,iMouseY,57,80,110,0,200,200);

        }

        }

	</script>

</head>

<body>

    <h1>canvas元素示例</h1>

    <canvas id="canvas" width="400" height="300" ></canvas>

</body>

</html>

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