{"id":379,"date":"2022-08-30T16:50:00","date_gmt":"2022-08-30T08:50:00","guid":{"rendered":"https:\/\/www.keioi.cn\/?p=379"},"modified":"2022-08-30T15:55:08","modified_gmt":"2022-08-30T07:55:08","slug":"%e5%be%ae%e4%bf%a1%e5%b0%8f%e7%a8%8b%e5%ba%8fcanvas%e7%94%bb%e6%9d%bf%e8%87%aa%e7%94%b1%e7%94%bb%e7%ba%bf%ef%bc%88%e6%96%b0api%ef%bc%89","status":"publish","type":"post","link":"https:\/\/www.keioi.cn\/archives\/379","title":{"rendered":"\u5fae\u4fe1\u5c0f\u7a0b\u5e8fcanvas\u753b\u677f\u81ea\u7531\u753b\u7ebf\uff08\u65b0api\uff09"},"content":{"rendered":"\n

\u5728\u5fae\u4fe1\u5c0f\u7a0b\u5e8f\u5f00\u53d1\u5de5\u5177\u65b0\u5efapage\u9875<\/p>\n\n\n\n

\u5728wxml\u6587\u4ef6\u91cc\u8bbe\u7f6e<\/p>\n\n\n\n

<view class=”main”><\/p>\n\n\n\n

  <view class=”cvs”><\/p>\n\n\n\n

    <canvas id=”mycanvas” type=”2d” bindtouchstart=”paints” bindtouchmove=”paintm” style=”width:{{w}}px;height:{{h}}px”><\/p>\n\n\n\n

    <\/canvas><\/p>\n\n\n\n

  <\/view><\/p>\n\n\n\n

<\/view><\/p>\n\n\n\n

bindtouchstart=”paints”  \uff0c  \u5f00\u59cb\u89e6\u5c4f\u5bf9\u5e94\u51fd\u6570<\/p>\n\n\n\n

bindtouchmove=”paintm”  \uff0c\u5728\u5c4f\u5e55\u79fb\u52a8\u753b\u5bf9\u5e94\u51fd\u6570<\/p>\n\n\n\n

\u5728css\u6587\u4ef6\u8bbe\u7f6e<\/p>\n\n\n\n

.main{<\/p>\n\n\n\n

  display: flex;<\/p>\n\n\n\n

  flex-direction: column;<\/p>\n\n\n\n

  align-items: center;<\/p>\n\n\n\n

  justify-items: center;<\/p>\n\n\n\n

}<\/p>\n\n\n\n

.cvs{<\/p>\n\n\n\n

  margin-top:20rpx ;<\/p>\n\n\n\n

}<\/p>\n\n\n\n

canvas{<\/p>\n\n\n\n

  border: 1px solid #1f8d10 ;<\/p>\n\n\n\n

}<\/p>\n\n\n\n

js\u6587\u4ef6<\/p>\n\n\n\n

data\u91cc\u5b9a\u4e49\u53d8\u91cf<\/p>\n\n\n\n

data: {<\/p>\n\n\n\n

    ctx: “”,<\/p>\n\n\n\n

    w: 300,<\/p>\n\n\n\n

    h: 150,<\/p>\n\n\n\n

  },<\/p>\n\n\n\n

\u5982\u56fe<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

<\/p>\n\n\n\n

\u73b0\u5728\u5f00\u59cb\u5728js\u6587\u4ef6\u91cc\u9762\u5199\u753b\u7ebf\u51fd\u6570<\/p>\n\n\n\n

\u5148\u5199\u4e00\u4e2a\u51fd\u6570\u53d6\u5230canvas \u7ed8\u56fe\u4e0a\u4e0b\u6587<\/p>\n\n\n\n

canvasinit: function () {<\/p>\n\n\n\n

    wx.createSelectorQuery()<\/p>\n\n\n\n

      .select(‘#mycanvas’)<\/p>\n\n\n\n

      .fields({<\/p>\n\n\n\n

        node: true<\/p>\n\n\n\n

      })<\/p>\n\n\n\n

      .exec((res) => {<\/p>\n\n\n\n

        const canvas = res[0].node<\/p>\n\n\n\n

        const context = canvas.getContext(‘2d’)<\/p>\n\n\n\n

        this.setData({<\/p>\n\n\n\n

          ctx: context<\/p>\n\n\n\n

        })<\/p>\n\n\n\n

      })<\/p>\n\n\n\n

  },<\/p>\n\n\n\n

.select(‘#mycanvas’) \u91cc\u9762\u7684mycanvas\u5bf9\u5e94wxml\u6587\u4ef6canvas\u7684id<\/p>\n\n\n\n

this.setData({<\/p>\n\n\n\n

          ctx: context<\/p>\n\n\n\n

})      \u53d6\u5230\u4e0a\u4e0b\u6587\u8d4b\u503c\u7ed9\u53d8\u91cf\u65b9\u4fbf\u4f7f\u7528<\/p>\n\n\n\n

\u8fd9\u4e2a\u51fd\u6570\u5c31\u53ef\u4ee5\u53d6\u5230\u753b\u677fcanvas\u5bf9\u5e94\u7684\u7ed8\u56fe\u4e0a\u4e0b\u6587<\/p>\n\n\n\n

\u5199\u5728\u753b\u677f\u4e0a\u753b\u7ebf\u7684\u51fd\u6570\uff1b<\/p>\n\n\n\n

\/\/\u753b\u677f\u5f00\u59cb\u4f4d\u7f6e<\/p>\n\n\n\n

paints: function (e) {<\/p>\n\n\n\n

    let x = e.touches[0].x<\/p>\n\n\n\n

    let y = e.touches[0].y<\/p>\n\n\n\n

    const ctx = this.data.ctx<\/p>\n\n\n\n

    ctx.lineCap = “round”<\/p>\n\n\n\n

    ctx.lineJoin = “round”<\/p>\n\n\n\n

    ctx.strokeStyle = “#1b76c0”<\/p>\n\n\n\n

    ctx.lineWidth = 5<\/p>\n\n\n\n

    ctx.moveTo(x, y)<\/p>\n\n\n\n

  },<\/p>\n\n\n\n

 let x = e.touches[0].x<\/p>\n\n\n\n

 let y = e.touches[0].y  \uff0c\u8fd9\u4e2a\u662f\u53d6\u5230\u5f00\u59cb\u89e6\u5230\u753b\u677f\u7684\u5750\u6807\uff0c<\/p>\n\n\n\n

 ctx.lineCap = “round”<\/p>\n\n\n\n

 ctx.lineJoin = “round”  \uff0c\u5b9a\u4e49\u7ebf\u6761\u548c\u4ea4\u70b9\u6837\u5f0f\u5706\u5f62<\/p>\n\n\n\n

ctx.moveTo(x, y)  \uff0c \u79fb\u52a8\u5230\u753b\u677f\u5750\u6807\u5904<\/p>\n\n\n\n

\/\/\u753b\u677f\u4e0a\u79fb\u52a8<\/p>\n\n\n\n

paintm: function (e) {<\/p>\n\n\n\n

    let x = e.touches[0].x<\/p>\n\n\n\n

    let y = e.touches[0].y<\/p>\n\n\n\n

    const ctx = this.data.ctx<\/p>\n\n\n\n

    ctx.lineTo(x, y)<\/p>\n\n\n\n

    ctx.stroke()<\/p>\n\n\n\n

  },<\/p>\n\n\n\n

 let x = e.touches[0].x<\/p>\n\n\n\n

 let y = e.touches[0].y  \uff0c\u8fd9\u4e2a\u662f\u53d6\u5230\u5728\u753b\u677f\u79fb\u52a8\u7684\u5750\u6807\uff0c<\/p>\n\n\n\n

ctx.lineTo(x, y) \uff0c \u753b\u7ebf\u5750\u6807\u70b9<\/p>\n\n\n\n

ctx.stroke() \uff0c\u753b\u7ebf<\/p>\n\n\n\n

\u8981\u628acanvasinit\u51fd\u6570\u653e\u5230onload\u91cc\u9762\uff0c\u9875\u9762\u52a0\u8f7d\u5c31\u53d6\u5230canvas\u4e0a\u4e0b\u6587\u3002<\/p>\n\n\n\n

\u5982\u56fe<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

\u5f53\u5b9a\u4e49\u5bbd\u9ad8\u4e3a300\uff0c150\u7684\u65f6\u5019\u662f\u6b63\u5e38\u7684\uff0c\u5f53\u968f\u4fbf\u6539\u4e86\u5bbd\u9ad8\u540e\u6bd4\u5982300\uff0c300\u51fa\u73b0\u5f02\u5e38\uff0c\u753b\u7ebf\u4f4d\u7f6e\u4e0d\u5bf9\u4e86\u3002<\/p>\n\n\n\n

\u5982\u4e0b<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

<\/p>\n\n\n\n

\u8fd9\u662f\u7269\u7406\u50cf\u7d20\u548c\u903b\u8f91\u50cf\u7d20\u4e0d\u76f8\u7b49\u60c5\u51b5\u9020\u6210\u3002<\/p>\n\n\n\n

\u8981\u5728canvasinit\u51fd\u6570\u52a0\u6dfb\u52a0\u4ee3\u7801\uff0c\u83b7\u53d6\u8bbe\u5907\u7684\u50cf\u7d20\u6bd4\uff0c\u4e58\u4e0a canvas \u7684\u5b9e\u9645\u5927\u5c0f\uff0c\u5982\u4e0b<\/p>\n\n\n\n

canvasinit: function () {<\/p>\n\n\n\n

    wx.createSelectorQuery()<\/p>\n\n\n\n

      .select(‘#mycanvas’)<\/p>\n\n\n\n

      .fields({<\/p>\n\n\n\n

        node: true,<\/p>\n\n\n\n

        size: true<\/p>\n\n\n\n

      })<\/p>\n\n\n\n

      .exec((res) => {<\/p>\n\n\n\n

        const canvas = res[0].node<\/p>\n\n\n\n

        const context = canvas.getContext(‘2d’)<\/p>\n\n\n\n

        const renderW = res[0].width<\/p>\n\n\n\n

        const renderH = res[0].height<\/p>\n\n\n\n

        const dpr = wx.getWindowInfo().pixelRatio<\/p>\n\n\n\n

        canvas.width = renderW * dpr<\/p>\n\n\n\n

        canvas.height = renderH * dpr<\/p>\n\n\n\n

        context.scale(dpr, dpr)<\/p>\n\n\n\n

        this.setData({<\/p>\n\n\n\n

          ctx: context<\/p>\n\n\n\n

        })<\/p>\n\n\n\n

      })<\/p>\n\n\n\n

  },<\/p>\n\n\n\n

\u8fd9\u6837\u5bbd\u9ad8\u53d8\u4e86\u753b\u7ebf\u4e5f\u6b63\u5e38\u4e86\u3002<\/p>\n\n\n\n

\u6269\u5c55<\/strong><\/p>\n\n\n\n

\u5728\u52a0\u8f7d\u9875\u9762\u65f6\u6839\u636e\u53d6\u5230\u624b\u673a\u8bbe\u5907\u7684\u5bbd\u9ad8\uff0c\u5b9a\u4e49<\/p>\n\n\n\n

canvas\u7684\u5bbd\u9ad8<\/p>\n\n\n\n

\u5728onload\u51fd\u6570\u91cc\u9762\u6dfb\u52a0<\/p>\n\n\n\n

const w=wx.getWindowInfo().screenWidth-40<\/p>\n\n\n\n

const h=wx.getWindowInfo().screenHeight-200<\/p>\n\n\n\n

    this.setData({<\/p>\n\n\n\n

      w:w,<\/p>\n\n\n\n

      h:h<\/p>\n\n\n\n

    })<\/p>\n\n\n\n

\u53d6\u5230\u8bbe\u5907\u5bbd\u9ad8\uff0c\u76f8\u5bf9\u4e8e\u8bbe\u5907\uff0c\u9002\u5f53\u51cf\u5c11\u4e00\u70b9canvas\u7684\u5bbd\u9ad8\uff0c\u8fd9\u6837\u7a7a\u767d\u5904\u52a0\u5165\u4e00\u4e9b\u6309\u94ae\u9009\u9879\u3002\u5982\u56fe<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

<\/p>\n\n\n\n

<\/p>\n","protected":false},"excerpt":{"rendered":"

\u5728\u5fae\u4fe1\u5c0f\u7a0b\u5e8f\u5f00\u53d1\u5de5\u5177\u65b0\u5efapage...<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[],"class_list":["post-379","post","type-post","status-publish","format-standard","hentry","category-js"],"_links":{"self":[{"href":"https:\/\/www.keioi.cn\/api\/wp\/v2\/posts\/379","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.keioi.cn\/api\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.keioi.cn\/api\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.keioi.cn\/api\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.keioi.cn\/api\/wp\/v2\/comments?post=379"}],"version-history":[{"count":1,"href":"https:\/\/www.keioi.cn\/api\/wp\/v2\/posts\/379\/revisions"}],"predecessor-version":[{"id":384,"href":"https:\/\/www.keioi.cn\/api\/wp\/v2\/posts\/379\/revisions\/384"}],"wp:attachment":[{"href":"https:\/\/www.keioi.cn\/api\/wp\/v2\/media?parent=379"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.keioi.cn\/api\/wp\/v2\/categories?post=379"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.keioi.cn\/api\/wp\/v2\/tags?post=379"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}