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639 lines
13 KiB
Markdown
639 lines
13 KiB
Markdown
## 一、canvas
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通过JS完成画图而不是css
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canvas 默认 inline-block，可以认为是一种特殊的图片。
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### 1、canvas 划线
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```html
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<canvas id="can" width="800" height="800"></canvas>
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```
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> （宽高不能放在style里面，否则比例不对）
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>
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> canvas里面的width和height相当于图片的原始尺寸，加了外部style的宽高，就相当于对图片进行压缩和拉伸。
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```js
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// 1、获取原生dom对象
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let dom = document.getElementById('can');
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// 2、获取绘图对象
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let can = dom.getContext('2d'); // 3d是webgl
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// 定义线条起点
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can.moveTo(0,0);
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// 定义线条中点（非终点）
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can.lineTo(400,400);
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can.lineTo(800,0);
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// 对标记范围进行描边
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can.stroke()
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// 对标记范围进行填充
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can.fill();
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```
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### 2、设置线条属性
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线条默认宽度是1.
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> （一定要在绘图之前设置。）
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```js
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can.lineWidth = 2; //设置线条宽度
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can.strokeStyle = '#f00'; // 设置线条颜色
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can.fillStyle = '#f00'; // 设置填充区域颜色
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```
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### 3、折线样式
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- `miter`：尖角（当尖角长度值过长时会自动变成折角，如果强制显示尖角：`can.miterLimit = 100`设置尖角长度阈值）
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- `round`：圆角
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- `bevel`：折角
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```js
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can.lineJoin = 'miter';
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can.moveTo(100, 100);
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can.lineTo(300, 100);
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can.lineTo(100, 200);
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can.stroke()
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can.lineJoin = 'round';
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can.moveTo(400, 100);
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can.lineTo(600, 100);
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can.lineTo(400, 200);
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can.stroke()
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can.lineJoin = 'bevel';
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can.moveTo(700, 100);
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can.lineTo(900, 100);
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can.lineTo(700, 200);
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can.stroke()
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```
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### 4、设置线帽
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- `round`：加圆角线帽
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- `square`：加直角线帽
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- `butt`：不加线帽
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```js
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can.lineCap = 'round';
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can.moveTo(100, 100);
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can.lineTo(300, 100);
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can.stroke()
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// 新建绘图，使得上一次的绘画样式不会影响下面的绘画样式（代码加在上一次绘画和下一次绘画中间。）
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can.beginPath()
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can.lineCap = 'square';
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can.moveTo(100, 200);
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can.lineTo(300, 200);
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can.stroke()
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can.beginPath()
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can.lineCap = 'butt';
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can.moveTo(100, 300);
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can.lineTo(300, 300);
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```
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### 5、画矩形
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```js
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// 参数：x,y,宽，高
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can.rect(100,100,100,100);
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can.stroke();
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```
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```js
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// 画完即填充
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can.fillRect(100,100,100,100);
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```
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### 6、画圆弧
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```js
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// 参数：圆心x，圆心y，半径，圆弧起点与圆心的夹角度数，圆弧终点与圆心的夹角度数，true（逆时针绘画）
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can.arc(500,300,200,0,2*Math.PI/360*90,false);
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can.stroke()
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```
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示例：
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```js
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can.moveTo(500,300);
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can.lineTo(500 + Math.sqrt(100), 300 + Math.sqrt(100))
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can.arc(500, 300, 100, 2 * Math.PI / 360 *startDeg, 2 * Math.PI / 360 *endDeg, false);
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can.closePath()//将图形起点和终点用线连接起来使之成为封闭的图形
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can.fill()
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```
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> 1、`can.beginPath()` // 新建绘图，使得上一次的绘画样式不会影响下面的绘画样式（代码加在上一次绘画和下一次绘画中间。）
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>
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> 2、`can.closePath()` //将图形起点和终点用线连接起来使之成为封闭的图形。
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### 7、旋转画布
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```js
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can.rotate(2*Math.PI/360*45); // 一定要写在开始绘图之前
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can.fillRect(0,0,200, 10);
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```
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> 旋转整个画布的坐标系（参考坐标为画布的(0,0)位置）
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### 8、缩放画布
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```js
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can.scale(0.5,2);
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can.fillRect(0,0,200, 10);
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```
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**整个画布**：x方向缩放为原来的0.5，y方向拉伸为原来的2倍。
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### 9、画布位移
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```js
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can.translate(100,100)
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can.fillRect(0,0,200, 10);
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```
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### 10、保存与恢复画布状态
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```js
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can.save() // 存档：保存当前画布坐标系状态
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can.restore() // 读档：恢复之前保存的画布坐标系状态
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```
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### 11、示例1：指针时钟
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```html
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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>clock</title>
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<style type="text/css">
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#can {
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width: 1000px;
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height: 600px;
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background: linear-gradient(45deg, green, skyblue);
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}
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</style>
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</head>
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<body>
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<canvas id="can" width="2000" height="1200"></canvas>
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</body>
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<script type="text/javascript">
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let dom = document.getElementById('can');
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let can = dom.getContext('2d');
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// 把画布的圆心移动到画布的中心
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can.translate(dom.width / 2, dom.height / 2);
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// 保存当前的画布坐标系
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can.save()
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run();
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function run() {
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setInterval(function() {
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clearCanvas();
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draw();
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}, 10);
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}
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// 绘图
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function draw() {
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let time = new Date();
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let hour = time.getHours();
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let min = time.getMinutes();
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let sec = time.getSeconds();
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let minSec = time.getMilliseconds();
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drawPannl();
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drawHour(hour, min, sec);
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drawMin(min, sec);
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drawSec(sec, minSec);
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drawPoint();
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}
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// 最简单的方法：由于canvas每当高度或宽度被重设时，画布内容就会被清空
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function clearCanvas() {
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dom.height = dom.height;
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can.translate(dom.width / 2, dom.height / 2);
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can.save()
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}
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// 画表盘
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function drawPannl() {
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can.beginPath();
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can.restore()
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can.save()
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can.lineWidth = 10;
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can.strokeStyle = 'skyblue';
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can.arc(0, 0, 400, 0, 2 * Math.PI);
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can.stroke();
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for (let i = 0; i < 12; i++) {
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can.beginPath();
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can.lineWidth = 16;
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can.strokeStyle = 'greenyellow';
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can.rotate(2 * Math.PI / 12)
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can.moveTo(0, -395);
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can.lineTo(0, -340);
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can.stroke();
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}
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for (let i = 0; i < 60; i++) {
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can.beginPath();
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can.lineWidth = 10;
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can.strokeStyle = '#fff';
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can.rotate(2 * Math.PI / 60)
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can.moveTo(0, -395);
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can.lineTo(0, -370);
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can.stroke();
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}
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}
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// 画时针
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function drawHour(h, m, s) {
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can.beginPath();
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can.restore()
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can.save()
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can.lineWidth = 24;
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can.strokeStyle = 'palevioletred';
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can.lineCap = 'round'
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can.rotate(2 * Math.PI / (12 * 60 * 60) * (h * 60 * 60 + m * 60 + s))
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can.moveTo(0, 0);
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can.lineTo(0, -200);
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can.stroke();
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}
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// 画分针
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function drawMin(m, s) {
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can.beginPath();
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can.restore()
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can.save()
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can.lineWidth = 14;
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can.strokeStyle = '#09f';
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can.lineCap = 'round'
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can.rotate(2 * Math.PI / (60 * 60) * (m * 60 + s))
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can.moveTo(0, 0);
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can.lineTo(0, -260);
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can.stroke();
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}
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// 画秒针
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function drawSec(s, ms) {
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can.beginPath();
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can.restore()
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can.save()
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can.lineWidth = 8;
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can.strokeStyle = '#f00';
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can.lineCap = 'round'
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can.rotate(2 * Math.PI / (60 * 1000) * (s * 1000 + ms));
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can.moveTo(0, 50);
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can.lineTo(0, -320);
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can.stroke();
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}
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// 画中心点
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function drawPoint() {
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can.beginPath();
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can.restore()
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can.save()
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can.lineWidth = 10;
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can.fillStyle = 'red';
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can.arc(0, 0, 12, 0, 2 * Math.PI);
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can.fill();
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}
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</script>
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</html>
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```
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### 12、示例2：圆弧时钟
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```html
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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>clock</title>
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<style type="text/css">
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#can {
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width: 1000px;
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height: 600px;
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background: linear-gradient(45deg, rgb(94, 53, 6), black);
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}
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</style>
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</head>
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<body>
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<canvas id="can" width="2000" height="1200"></canvas>
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</body>
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<script type="text/javascript">
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let dom = document.getElementById('can');
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let can = dom.getContext('2d');
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// 把画布的圆心移动到画布的中心
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can.translate(dom.width / 2, dom.height / 2);
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// 保存当前的画布坐标系
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can.save();
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// 圆形指针起始角度
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let startDeg = 2 * Math.PI / 360 * 270;
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run();
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// draw();
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function run() {
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setInterval(function() {
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clearCanvas();
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draw();
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}, 20);
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}
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// 绘图
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function draw() {
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let time = new Date();
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// let hour = time.getHours();
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let hour = time.getHours() > 10 ? time.getHours() - 12 : time.getHours();
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let min = time.getMinutes();
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let sec = time.getSeconds();
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let minSec = time.getMilliseconds();
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drawPannl();
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drawTime(hour, min, sec, minSec);
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drawHour(hour, min, sec);
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drawMin(min, sec);
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drawSec(sec, minSec);
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drawPoint();
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}
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// 最简单的方法：由于canvas每当高度或宽度被重设时，画布内容就会被清空
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function clearCanvas() {
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dom.height = dom.height;
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can.translate(dom.width / 2, dom.height / 2);
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can.save()
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}
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// 画表盘
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function drawPannl() {
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can.restore()
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can.save()
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// 设置时表盘
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can.beginPath();
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can.lineWidth = 50;
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can.strokeStyle = 'rgba(255,23,87,0.2)';
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can.arc(0, 0, 400, 0, 2 * Math.PI);
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can.stroke();
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// 设置分表盘
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can.beginPath();
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can.strokeStyle = 'rgba(169,242,15,0.2)';
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can.arc(0, 0, 345, 0, 2 * Math.PI);
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can.stroke();
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// 设置秒表盘
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can.beginPath();
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can.strokeStyle = 'rgba(21,202,230,0.2)';
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can.arc(0, 0, 290, 0, 2 * Math.PI);
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can.stroke();
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// 小时刻度
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// for (let i = 0; i < 12; i++) {
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// can.beginPath();
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// can.lineWidth = 16;
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// can.strokeStyle = 'rgba(0,0,0,0.2)';
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// can.rotate(2 * Math.PI / 12)
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// can.moveTo(0, -375);
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// can.lineTo(0, -425);
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// can.stroke();
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// }
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// 分针刻度
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// for (let i = 0; i < 60; i++) {
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// can.beginPath();
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// can.lineWidth = 10;
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// can.strokeStyle = '#fff';
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// can.rotate(2 * Math.PI / 60)
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// can.moveTo(0, -395);
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// can.lineTo(0, -370);
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// can.stroke();
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// }
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}
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// 画时针
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function drawHour(h, m, s) {
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let rotateDeg = 2 * Math.PI / (12 * 60 * 60) * (h * 60 * 60 + m * 60 + s);
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can.beginPath();
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can.restore()
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can.save()
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// 时针圆弧
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can.lineWidth = 50;
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can.strokeStyle = 'rgb(255,23,87)';
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can.lineCap = 'round';
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can.shadowColor = "rgb(255,23,87)"; // 设置阴影颜色
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can.shadowBlur = 20; // 设置阴影范围
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can.arc(0, 0, 400, startDeg, startDeg + rotateDeg);
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can.stroke();
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// 时针指针
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can.beginPath();
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can.lineWidth = 24;
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can.strokeStyle = 'rgb(255,23,87)';
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can.lineCap = 'round'
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can.rotate(rotateDeg)
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can.moveTo(0, 0);
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can.lineTo(0, -100);
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can.stroke();
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}
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// 画分针
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function drawMin(m, s) {
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let rotateDeg = 2 * Math.PI / (60 * 60) * (m * 60 + s);
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can.beginPath();
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can.restore()
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can.save()
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// 分针圆弧
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can.lineWidth = 50;
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can.strokeStyle = 'rgb(169,242,15)';
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can.lineCap = 'round'
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can.shadowColor = "rgb(169,242,15)";
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can.shadowBlur = 20;
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can.arc(0, 0, 345, startDeg, startDeg + rotateDeg);
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can.stroke();
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// 分针指针
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can.beginPath();
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can.lineWidth = 14;
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can.strokeStyle = 'rgb(169,242,15)';
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can.lineCap = 'round'
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can.rotate(rotateDeg)
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can.moveTo(0, 0);
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can.lineTo(0, -160);
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can.stroke();
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}
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// 画秒针
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function drawSec(s, ms) {
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let rotateDeg = 2 * Math.PI / (60 * 1000) * (s * 1000 + ms);
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can.beginPath();
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can.restore()
|
||
can.save()
|
||
|
||
can.lineWidth = 50;
|
||
can.strokeStyle = 'rgb(21,202,230)';
|
||
can.lineCap = 'round'
|
||
can.arc(0, 0, 290, startDeg, startDeg + rotateDeg);
|
||
can.stroke();
|
||
|
||
can.beginPath();
|
||
can.lineWidth = 8;
|
||
can.strokeStyle = 'rgb(21,202,230)';
|
||
can.lineCap = 'round'
|
||
can.shadowColor = "rgb(21,202,230)";
|
||
can.shadowBlur = 20;
|
||
can.rotate(rotateDeg);
|
||
can.moveTo(0, 50);
|
||
can.lineTo(0, -220);
|
||
can.stroke();
|
||
}
|
||
|
||
|
||
// 画中心点
|
||
function drawPoint() {
|
||
can.beginPath();
|
||
can.restore()
|
||
can.save()
|
||
|
||
can.lineWidth = 10;
|
||
can.fillStyle = 'red';
|
||
can.arc(0, 0, 12, 0, 2 * Math.PI);
|
||
can.fill();
|
||
}
|
||
|
||
// 显示数字时钟
|
||
function drawTime(h, m, s, ms) {
|
||
can.font = '60px Calibri';
|
||
can.fillStyle = '#0f0'
|
||
can.shadowColor = "#fff";
|
||
can.shadowBlur = 20;
|
||
can.fillText(`${h}:${m}:${s}.${ms}`, -140, -100);
|
||
}
|
||
</script>
|
||
|
||
</html>
|
||
```
|
||
|
||
 |