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canvas绘制线条

框架类型 问题类型 API/组件名称 终端类型 微信版本 基础库版本
小程序 Bug canvas 客户端 7.0.3 2.6.2

- 当前 Bug 的表现(可附上截图)



- 预期表现

一根实线一根虚线


- 提供一个最简复现 Demo

// 手指开始移动/选中点(线)

start: function (e) {

console.log(e)

var that = this

let touchPoint = e.changedTouches[0]

let length = this.data.pointList.length


for (let i = 0; i < length; i++) {

let point = this.data.pointList[i]

if (Math.abs(touchPoint.x - point.x) < width) {

that.setData({

current: point

})

point.isSelected = true

break

}

}

if (that.data.current && that.data.current == last) {

startMove = true

startPoint = touchPoint

} else {

if (last) {

last.isSelected = false

}

last = that.data.current

this.draw()

}

},

// 手指移动

move: function (e) {

if (startMove) {

let touchPoint = e.changedTouches[0]

this.data.current.x = parseFloat(this.data.current.x) + parseFloat(touchPoint.x) - parseFloat(startPoint.x) // 移动线只改变x值

this.data.current.y = this.data.current.y // 0

if (this.data.pointList[0].isSelected == true) {

this.data.pointList[1].x = this.data.pointList[0].x

} else if (this.data.pointList[1].isSelected == true) {

this.data.pointList[0].x = this.data.pointList[1].x

}

startPoint = touchPoint

var current = this.data.current;

this.draw()

// console.log(this.data.current)

this.setData({

current: current

})

}

},

//手指结束移动

end: function (e) {

startMove = false

},

draw(callback) {

this.drawImage()

this.drawLine()

this.drawDashLine()

ctx.draw(false, callback)

},

// 画底图

drawImage: function () {

ctx.drawImage(this.data.src, 0, 0, this.data.cnavasWidth, this.data.canvasHeight)

},

// 画实线

drawLine: function () {

// ctx.strokeStyle = '#ffa29b'

lineList.map(pointMap => {

ctx.beginPath()

ctx.setLineWidth(5)

ctx.strokeStyle = this.data.pointList[pointMap[0]].isSelected == true || this.data.pointList[pointMap[1]].isSelected == true ? 'blue' : '#ffa29b'

ctx.moveTo(this.data.pointList[pointMap[0]].x, this.data.pointList[pointMap[0]].y)

ctx.lineTo(this.data.pointList[pointMap[1]].x, this.data.pointList[pointMap[1]].y)

ctx.stroke()

})

},

// 画虚线

drawDashLine: function() {

ctx.beginPath()

ctx.strokeStyle = '#ffa29b'

ctx.setLineDash([5, 5], 5)

ctx.moveTo(wx.getStorageSync('leftPoint'),0)

ctx.lineTo(wx.getStorageSync('leftPoint'), app.globalData.windowHeight - (app.globalData.height * 6 + 10 + 150) / (750 / app.globalData.windowWidth) + 100)

ctx.stroke()

},

backTake() {

wx.redirectTo({

url: '/pages/camera/hipcamerathree/hipcamerathree',

})

},

// 保存canvas绘制内容

savePhoto() {

for (var i in this.data.pointList) {

this.data.pointList[i].isSelected = false

}

wx.setStorageSync('hiplistjsonthree', this.data.pointList)

var that = this

this.draw(() => {

// 绘图

wx.canvasToTempFilePath({

x: 0,

y: 0,

width: that.data.cnavasWidth,

height: that.data.canvasHeight,

destWidth: that.data.cnavasWidth,

destHeight: that.data.canvasHeight,

fileType: 'jpg',

canvasId: 'mycanvas',

success(res) {

wx.compressImage({

src: res.tempFilePath,

quality: 45,

success(res) {

wx.uploadFile({

url: 'https://apich.xiaoxiaowu.info/user/Upload',

filePath: res.tempFilePath,

name: 'avatar',

success(e) {

console.log('上传成功', e.data)

var data = JSON.parse(e.data)

// wx.setStorageSync('hipImgThree', data.url)

wx.setStorage({

key: 'hipImgThree',

data: data.url,

success(res) {

wx.reLaunch({

url: '/pages/testevaluation/testevaluation?index=4&&hipListThree=' + JSON.stringify(that.data.pointList),

})

}

})

}

})

}

})

}

}, this)

})

},


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