廢話不多說,先上一張效果圖!
建立兩個(gè)canvas標(biāo)簽,先繪制底層的淺灰色圓圈背景,再繪制上層的紅色進(jìn)度條。
<view class="wrap">
<view class="circle-box">
<canvas class="circle" style="width:200px; height:200px;" canvas-id="canvasArcCir">
</canvas>
<canvas class="circle" style="z-index: -5; width:200px; height:200px;" canvas-id="canvasCircle">
</canvas>
<view class="draw_btn" bindtap="drawCircle">開始動(dòng)態(tài)繪制</view>
</view>
</view>
特別注意:底層的canvas最好使用
z-index:-5;
放置于底層
page {
width: 100%;
height: 100%;
background-color: #fff;
}
.circle-box {
text-align: center;
margin-top: 10vw;
}
.circle {
position: absolute;
left: 0;
right: 0;
margin: auto;
}
.draw_btn {
width: 35vw;
position: absolute;
top: 33vw;
right: 0;
left: 0;
margin: auto;
border: 1px #000 solid;
border-radius: 5vw;
}
//獲取應(yīng)用實(shí)例
var app = getApp()
var interval;
var varName;
var ctx = wx.createCanvasContext('canvasArcCir');
Page({
data: {
},
drawCircle: function () {
clearInterval(varName);
function drawArc(s, e) {
ctx.setFillStyle('white');
ctx.clearRect(0, 0, 200, 200);
ctx.draw();
var x = 100, y = 100, radius = 96;
ctx.setLineWidth(5);
ctx.setStrokeStyle('#d81e06');
ctx.setLineCap('round');
ctx.beginPath();
ctx.arc(x, y, radius, s, e, false);
ctx.stroke()
ctx.draw()
}
var step = 1, startAngle = 1.5 * Math.PI, endAngle = 0;
var animation_interval = 1000, n = 60;
var animation = function () {
if (step <= n) {
endAngle = step * 2 * Math.PI / n + 1.5 * Math.PI;
drawArc(startAngle, endAngle);
step++;
} else {
clearInterval(varName);
}
};
varName = setInterval(animation, animation_interval);
},
onReady: function () {
//創(chuàng)建并返回繪圖上下文context對(duì)象。
var cxt_arc = wx.createCanvasContext('canvasCircle');
cxt_arc.setLineWidth(6);
cxt_arc.setStrokeStyle('#eaeaea');
cxt_arc.setLineCap('round');
cxt_arc.beginPath();
cxt_arc.arc(100, 100, 96, 0, 2 * Math.PI, false);
cxt_arc.stroke();
cxt_arc.draw();
},
onLoad: function (options) {
}
})
1、關(guān)于小程序canvas繪制,請(qǐng)觀看微信小程序官方文檔繪制
2、開始繪制的路徑可以根據(jù) JS代碼中的變量startAngle 來選擇從哪里開始繪制
最后有什么問題可以留言,大家一起討論共同進(jìn)步~~
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