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canvas学习-1.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>圣诞雪花图</title>
<link rel="stylesheet" href="">
<style>
#snow {
/*width: 100%;
height: 900px;*/
border: 1px solid green;
background: green;
}
</style>
</head>
<body>
<canvas id="snow" width="1500" height="900"></canvas>
<script>
// console.log(document.getElementById('snow'))
let canvas = document.querySelector("#snow");
let ctx = canvas.getContext("2d");
/*
绘制矩形 （x, y, width, height）
设置透明度 ctx.globalAlpha 0-1
*/
ctx.fillStyle = "blue";
ctx.fillRect(10, 10, 100, 100);
ctx.strokeStyle = "yellow";
ctx.strokeRect(120, 10, 50, 50);
ctx.clearRect(20, 20, 20, 20);
ctx.fillStyle = "yellow"
ctx.rect(400, 10, 100, 100);
// ctx.globalAlpha = 0.5;
for (var i=0;i<6;i++){
for (var j=0;j<6;j++){
ctx.fillStyle = 'rgb(' + Math.floor(255-42.5*i) + ',' +
Math.floor(255-42.5*j) + ',0)';
ctx.fillRect(400+j*25,10+i*25,25,25);
}
}
/*
绘制路径
1、lineTo(x, y) lineWidth、lineCap(butt、round、square) lineJoin(miter、round、bevel)
2、arc(x, y, radius, startAngle, endAngle, anticlockwise) 以x,y为圆心，radius为半径，开始角度，结束角度，顺时针默认false
*/
ctx.beginPath();
ctx.fillStyle = "red";
ctx.moveTo(200, 10);
ctx.lineTo(200, 40);
ctx.lineTo(225, 25);
ctx.fill();
ctx.closePath();
ctx.beginPath();
ctx.strokeStyle = "blue"
ctx.arc(300, 300, 100, 0, Math.PI*2, true);
ctx.moveTo(375, 300);
ctx.arc(300, 300, 75, 0, Math.PI, false);
ctx.moveTo(260, 280);
ctx.arc(250, 280, 10, 0, Math.PI*2, true);
ctx.moveTo(350, 280);
ctx.arc(340, 280, 10, 0, Math.PI*2, true);
ctx.stroke();
ctx.closePath();
/*
虚线
setLineDash([])
lineDashOffset = 10
*/
ctx.globalAlpha = 1;
ctx.setLineDash([10, 5]);
ctx.lineDashOffset = 10;
ctx.strokeStyle = "orange"
ctx.strokeRect(600,10, 100, 100);
var offset = 0;
function march() {
offset = offset + 2;
if (offset > 16) {
offset = 0;
}
ctx.clearRect(740, 5, 120, 120);
ctx.setLineDash([10, 6]);
ctx.lineDashOffset = -offset;
ctx.strokeStyle = "blue"
ctx.strokeRect(750, 10, 100, 100);
setTimeout(march, 300);
}
march();
function snow() {
let canvas = document.getElementById('snow');
let w = canvas.clientWidth,
h = canvas.clientHeight,
ctx = canvas.getContext("2d"),
rate = 20,
arc = 200,
time,
count,
size = 2,
speed = 10,
lights = [],
colors = ['#eee'];
// // 设置 canvas 宽高和 banner 图一致
// canvas.setAttribute('width', w);
// canvas.setAttribute('height', h);
function init() {
time = 0;
count = 0;
for (var i = 0; i < arc; i++) {
lights[i] = {
x: Math.ceil(Math.random() * w),
y: Math.ceil(Math.random() * h),
toX: Math.random() * 5 + 1,
toY: Math.random() * 5 + 1,
c: colors[Math.floor(Math.random() * colors.length)],
size: Math.random() * size
}
}
}
function bubble() {
ctx.clearRect(0, 0, w, h);
for (var i = 0; i < arc; i++) {
var li = lights[i];
ctx.beginPath();
ctx.arc(li.x, li.y, li.size, 0, Math.PI * 2, false);
ctx.fillStyle = li.c;
ctx.fill();
li.x = li.x + li.toX * (time * 0.05);
li.y = li.y + li.toY * (time * 0.05);
if (li.x > w) { li.x = 0; }
if (li.y > h) { li.y = 0; }
if (li.x < 0) { li.x = w; }
if (li.y < 0) { li.y = h; }
}
if (time < speed) {
time++;
}
timerID = setTimeout(bubble, 1000 / rate);
}
init();
bubble();
};
window.onload = function () {
// snow();
}
</script>
</body>
</html>