两周做一个新的项目，人员比较紧张，除了需求和UI，前端后端一个人来干。文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
在项目需求确定后，UI隔了几天设计出了UI界面，拿到UI效果图后见有一个界面有波浪效果的我当时就蒙圈了，这都啥玩意啊？转念想到了最近在IT圈挺火的那个事件：产品要求安卓程序员实现根据用户手机壳颜色自动更换APP主题的需求后，顿时觉得画个波浪这个压根就不是事啊。文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
二次贝塞尔曲线文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
在微信官方的二次贝塞尔曲线画法连接文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
画波浪文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
思路：文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
在屏幕左边画一个波，然后让它一直向屏幕右边平移过去。其X的值由负数变为正数依次增大；然后一直重复此操作。文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
我画出来的波浪如下(感觉还是有那么一点波浪的感觉)：文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
界面代码为(index.wxml)：文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
<view class="page-body"> <view class="page-body-wrapper"> <canvas canvas-id="myCanvas3" class="canvas3"></canvas> </view> </view>
JS代码为(index.js)：文章源自菜鸟学院-https://www.cainiaoxueyuan.com/xcx/9060.html
Page({
onReady: function() {
this.position = {
x: 150,
y: 150,
vx: 2,
vy: 2
},
this.obj = {
offset: 0,
baseLine: 40,
direction: 1,
waveDirection: 1
},
// var offset = 5
this.drawQuadraticCurve3()
this.interval = setInterval(this.drawQuadraticCurve3, 1)
console.log(">>>>>>>>>" + this.obj.offset)
},
/**
* 画大波浪
*/
drawQuadraticCurve3: function() {
var obj = this.obj
var startX = 20,
itemWidth = 100,
offset = obj.offset,
baseLine = obj.baseLine,
waveHeight = 10,
direction = obj.direction,
waveDirection = obj.waveDirection
const ctx = wx.createCanvasContext('myCanvas3')
function getWaveHeigh(i) {
if (i % 2 == 0) {
// return baseLine + waveHeight
}
return baseLine - waveHeight
}
ctx.beginPath()
ctx.moveTo(-itemWidth * 6, baseLine)
ctx.setFillStyle('#4BF6EE')
for (var i = -6; i < 5; i++) {
startX = i * itemWidth;
var currentX = startX + (itemWidth / 2) + offset
var currentY = getWaveHeigh(i)
var currentEndX = startX + itemWidth + offset
ctx.quadraticCurveTo(currentEndX - 10,
currentY, currentEndX, baseLine)
ctx.stroke()
}
//填充海水
ctx.lineTo(0, 2000)
ctx.setFillStyle('#4BF6EE')
ctx.fill()
ctx.draw()
if (obj.waveDirection == 1) {
obj.offset = obj.offset + 1
} else if (obj.waveDirection == -1) {
obj.offset = obj.offset - 1
}
if (obj.offset == 400) {
obj.offset = 0
}
if (obj.offset == 50 || obj.offset == 1) {
// obj.waveDirection = obj.waveDirection * -1
}
// if (direction == 1) {
// obj.baseLine = obj.baseLine + 1
// } else if (direction == -1) {
// obj.baseLine = obj.baseLine - 1
// }
if (obj.baseLine >= 50 || obj.baseLine <= 40) {
console.log("<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<")
//obj.direction = (obj.direction * -1)
}
},
onUnload: function() {
clearInterval(this.interval)
}
})