<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>canvas</title> <script type="text/javascript" src="../js/jQuery.js"></script> <style type="text/css"> #canvas{ width: 7rem; margin: .25rem 0 0 1.5rem; border: 1px solid black; display: block; } </style> </head> <body> <canvas id="canvas" width="1000" height="600"></canvas> </body> </html> <script type="text/javascript"> /** * rem 布局初始化 */ $('html').css('font-size', $(window).width()/10); /** * 獲取 canvas 畫布 * 獲取 canvas 繪圖上下文環境 */ var canvas = $('#canvas')[0]; var cxt = canvas.getContext('2d'); var balls = []; /** * 事件交互, 點擊事件為例 * isPointInPath(橫坐標, 縱坐標) */ for(var i = 0; i < 10; i++){ var ball = { X: Math.random()*canvas.width, Y: Math.random()*canvas.height, R: Math.random()*50 + 20 } balls[i] = ball; } draw(); $("#canvas").click(function(){ //標准的獲取鼠標點擊相對於canvas畫布的坐標公式 var x = event.pageX - canvas.getBoundingClientRect().left; var y = event.pageY - canvas.getBoundingClientRect().top; for(var i = 0; i < balls.length; i++){ cxt.beginPath(); cxt.arc(balls[i].X, balls[i].Y, balls[i].R, 0, Math.PI*2); if(cxt.isPointInPath(x, y)){ cxt.fillStyle = "red"; cxt.fill(); } } }); function draw(){ cxt.fillStyle = "blue"; for(var i = 0; i < balls.length; i++){ cxt.beginPath(); cxt.arc(balls[i].X, balls[i].Y, balls[i].R, 0, Math.PI*2); cxt.fill(); } } </script>