HTML5 Canvas 绘图入门
jopen
10年前
HTML5 Canvas 绘图入门，仅供学习参考
<!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>HTML5 移动Web开发指南</title> <style type="text/css"> h1, h5 { text-align: center; } canvas { float: left; margin: 10px; overflow: hidden; } </style> <script type="text/javascript" language="javascript"> window.onload = function () { drawCanvas(0, 0, "canvase_01", "red", 200, 200); drawCanvas(0, 0, "canvase_02", "green", 200, 100); drawCanvas(0, 0, "canvase_05", "blank", 300, 60); drawCanvas(75, 60, "canvase_05", "gray", 150, 90); drawCanvas(0, 0, "canvase_06", "blank", 300, 50); drawCanvas(0, 50, "canvase_06", "red", 300, 50); drawCanvas(0, 100, "canvase_06", "#F8CB1C", 300, 50); drawCanvas(0, 0, "canvase_07", "green", 100, 150); drawCanvas(100, 0, "canvase_07", "white", 100, 150); drawCanvas(200, 0, "canvase_07", "red", 100, 150); drawRound("canvase_03", "blue", 75, true); drawRound("canvase_04", "yellow", 75, false); drawRound("canvase_08", "red", 75, true); drawRound("canvase_08", "yellow", 75, false); }; /* * Canvas 画非圆图形测试 * x: 图形的X轴开始坐标 * y: 图形的Y轴开始坐标 * id： 元素id * bgColor: 填充的背景颜色 * width: 宽 * height: 高 */ function drawCanvas(x, y, id, bgColor, width, height) { var canvas = document.getElementById(id); if (canvas != null && canvas != undefined) { var ctx = canvas.getContext("2d"); ctx.fillStyle = bgColor; //第一个和第二个参数，代表开始坐标 //第三个参数是图形的宽 //第四个参数是图形的高 ctx.fillRect(Number(x), Number(y), Number(width), Number(height)); } } /* * Canvas 画圆测试 * id： 元素id * bgColor: 填充的背景颜色 * R： 圆半径 * IsRound: 是否为正圆(true正圆、false 半圆) */ function drawRound(id, bgColor, R, IsRound) { var canvas = document.getElementById(id); if (canvas != null && canvas != undefined) { var ctx = canvas.getContext("2d"); ctx.fillStyle = bgColor; ctx.beginPath(); var round = Math.PI; if (Boolean(IsRound)) round = Math.PI * 2; //第一个和第二个参数，代表圆心坐标 //第三个参数是圆的半径 //第四个参数代表圆周起始位置(0 起始位置。沿顺时针路线，分别是0.5 (正下方)，1 PI和1.5 PI(正上方)，为画饼图提供了扇形范围的依据) //第五个参数是弧长(Math.PI*1 半圆、Math.PI*2就是整个圆) ctx.arc(150, 75, Number(R), 0, round, true); ctx.closePath(); ctx.fill(); } } </script> </head> <body> <header> <section> <h1> HTML5 移动Web开发指南</h1> </section> </header> <fieldset> <legend>HTML5 新元素--Canvas绘图元素</legend> <article> <section> <canvas id="canvase_01"> 您的浏览器不支持Canvas元素！ </canvas> <canvas id="canvase_02"> 您的浏览器不支持Canvas元素！ </canvas> <canvas id="canvase_03"> 您的浏览器不支持Canvas元素！ </canvas> <canvas id="canvase_04"> 您的浏览器不支持Canvas元素！ </canvas> <canvas id="canvase_05"> 您的浏览器不支持Canvas元素！ </canvas> <canvas id="canvase_06"> 您的浏览器不支持Canvas元素！ </canvas> <canvas id="canvase_07"> 您的浏览器不支持Canvas元素！ </canvas> <canvas id="canvase_08"> 您的浏览器不支持Canvas元素！ </canvas> </section> </article> </fieldset> <footer> <section> <h5> <span style="font-family: Arial, Helvetica, sans-serif;">HTML5 新元素--Canvas绘图元素</span> </h5> </section> </footer> </body> </html> 