element-draw.uvue

<template>
  <!-- #ifdef APP -->
  <scroll-view class="page-scroll-view">
  <!-- #endif -->
    <view>
      <view class="drawing" id="draw-text-view"></view>
      <view class="drawing" id="draw-line-view"></view>
      <view class="drawing" id="draw-circle-view"></view>
      <view class="drawing" id="draw-dash-line"></view>
      <view class="drawing" id="draw-house"></view>
      <view class="drawing" id="draw-style"></view>
      <view class="drawing" id="draw-odd"></view>
      <view class="drawing" id="draw-arcto"></view>
    </view>
  <!-- #ifdef APP -->
  </scroll-view>
  <!-- #endif -->
</template>

<script>
  var y = 160
  export default {
    data() {
      return {
        texts: [
          'HBuilderX，轻巧、极速，极客编辑器',
          'uni-app x，终极跨平台方案',
          'uniCloud，js serverless云服务',
          'uts，大一统语言',
          'uniMPSdk，让你的App具备小程序能力',
          'uni-admin，开源、现成的全端管理后台',
          'uni-id，开源、全端的账户中心',
          'uni-pay，开源、云端一体、全平台的支付',
          'uni-ai，聚合ai能力',
          'uni-cms，开源、云端一体、全平台的内容管理平台',
          'uni-im，开源、云端一体、全平台的im即时消息',
          'uni统计，开源、完善、全平台的统计报表',
          '......'
        ] as string[]
      }
    },
    onShow() {
    },

    onReady() {
      this.drawText()
      this.drawLines()
      this.drawCircles()
      this.drawStar()
      this.drawhouse()
      this.drawPoint()
      this.drawRect()
      this.drawArcTo()
    },
    onUnload() {
      y = 160
    },
    methods: {
      drawText() {
        let element = uni.getElementById('draw-text-view')!
        let ctx = element.getDrawableContext()!
        let width = element.getBoundingClientRect().width
        ctx.reset()
        ctx.font = "15px Arial"
        ctx.textAlign = "center"
        for (var i = 0; i < this.texts.length; i++) {
          let value = this.texts[i]
          if (i % 2 == 0) {
            ctx.fillText(value, width / 2, (20 * (i + 1)))
          } else {
            ctx.lineWidth = 0.5
            ctx.strokeText(value, width / 2, (20 * (i + 1)))
          }
        }
        ctx.update()
      },
      drawLines() {
        let ctx = uni.getElementById('draw-line-view')!.getDrawableContext()!
        ctx.reset()
        ctx.lineWidth = 10;

        ["round", "bevel", "miter"].forEach((join, i) => {
          ctx.lineJoin = join;
          ctx.beginPath();
          ctx.moveTo(5, 10 + i * 40);
          ctx.lineTo(50, 50 + i * 40);
          ctx.lineTo(90, 10 + i * 40);
          ctx.lineTo(130, 50 + i * 40);
          ctx.lineTo(170, 10 + i * 40);
          ctx.stroke();
        });
        ctx.lineWidth = 1
        var space = 170
        ctx.strokeStyle = '#09f';
        ctx.beginPath();
        ctx.moveTo(10 + space, 10);
        ctx.lineTo(140 + space, 10);
        ctx.moveTo(10 + space, 140);
        ctx.lineTo(140 + space, 140);
        ctx.stroke();
        // Draw lines
        ctx.strokeStyle = 'black';
        ['butt', 'round', 'square'].forEach((lineCap, i) => {
          ctx.lineWidth = 15;
          ctx.lineCap = lineCap;
          ctx.beginPath();
          ctx.moveTo(25 + space + i * 50, 10);
          ctx.lineTo(25 + space + i * 50, 140);
          ctx.stroke();
        });
        ctx.lineWidth = 1;
        this.drawDashedLine([], ctx);
        this.drawDashedLine([2, 2], ctx);
        this.drawDashedLine([10, 10], ctx);
        this.drawDashedLine([20, 5], ctx);
        this.drawDashedLine([15, 3, 3, 3], ctx);
        this.drawDashedLine([20, 3, 3, 3, 3, 3, 3, 3], ctx);
        ctx.lineDashOffset = 18;
        this.drawDashedLine([12, 3, 3], ctx);
        ctx.lineDashOffset = 0
        ctx.setLineDash([0])
        ctx.update()
      },
      drawDashedLine(pattern : Array<number>, ctx : DrawableContext) {
        ctx.beginPath();
        ctx.setLineDash(pattern);
        ctx.moveTo(0, y);
        ctx.lineTo(300, y);
        ctx.stroke();
        y += 15;
      },
      drawCircles() {
        let ctx = uni.getElementById('draw-circle-view')!.getDrawableContext()!
        ctx.reset()
        // Draw shapes
        for (var i = 0; i < 4; i++) {
          for (var j = 0; j < 3; j++) {
            ctx.beginPath();
            var x = 25 + j * 50;               // x coordinate
            var y = 25 + i * 50;               // y coordinate
            var radius = 20;                    // Arc radius
            var startAngle = 0;                     // Starting point on circle
            var endAngle = Math.PI + (Math.PI * j) / 2; // End point on circle
            var clockwise = i % 2 == 0 ? false : true; // clockwise or anticlockwise

            ctx.arc(x, y, radius, startAngle, endAngle, clockwise);

            if (i > 1) {
              ctx.fill();
            } else {
              ctx.stroke();
            }
          }
        }
        ctx.update()
      },

      drawStar() {
        let ctx = uni.getElementById('draw-dash-line')!.getDrawableContext()!
        ctx.reset()
        ctx.beginPath();
        var horn = 5; // 画5个角
        var angle = 360 / horn; // 五个角的度数
        // 两个圆的半径
        var R = 50;
        var r = 20;
        // 坐标
        var x = 100;
        var y = 100;
        for (var i = 0; i < horn; i++) {
          // 角度转弧度：角度/180*Math.PI
          // 外圆顶点坐标
          ctx.lineTo(Math.cos((18 + i * angle) / 180.0 * Math.PI) * R + x, -Math.sin((18 + i * angle) / 180.0 * Math.PI) * R + y);
          // 內圆顶点坐标
          ctx.lineTo(Math.cos((54 + i * angle) / 180.0 * Math.PI) * r + x, -Math.sin((54 + i * angle) / 180.0 * Math.PI) * r + y);
        }
        // closePath：关闭路径，将路径的终点与起点相连
        ctx.closePath();
        ctx.lineWidth = 3;
        ctx.fillStyle = '#E4EF00';
        ctx.strokeStyle = "red";
        ctx.fill();
        ctx.stroke();

        ctx.lineWidth = 10;
        ctx.beginPath()
        ctx.moveTo(170, 100)
        ctx.lineTo(255, 15)
        ctx.lineTo(340, 100)
        ctx.closePath()
        ctx.fill()
        ctx.strokeStyle = "blue"
        ctx.stroke()
        ctx.beginPath()
        ctx.moveTo(170, 145)
        ctx.lineTo(255, 45)
        ctx.lineTo(340, 145)
        ctx.closePath()
        ctx.fill()
        ctx.strokeStyle = "gray"
        ctx.stroke()
        // 未设置beginPath，导致上下表现一致，与前端一致
        ctx.moveTo(170, 190)
        ctx.lineTo(255, 90)
        ctx.lineTo(340, 190)
        ctx.closePath()
        ctx.fillStyle = "orange"
        ctx.fill()
        ctx.strokeStyle = "khaki"
        ctx.stroke()
        ctx.update()
      },
      hex(num : number) : string {
        if (num == 0) {
          return "00"
        }
        let hexChars = "0123456789ABCDEF";
        let result = "";
        while (num > 0) {
          let remainder = Math.floor(num) % 16;
          result = hexChars[remainder] + result;
          num = Math.floor(Math.floor(num) / 16);
        }
        if (result.length == 1) {
          return "0" + result
        }
        return result
      },
      drawhouse() {
        let ctx = uni.getElementById('draw-house')!.getDrawableContext()!
        ctx.reset()
        ctx.lineWidth = 10;

        // Wall
        ctx.strokeRect(75, 140, 150, 110);

        // Door
        ctx.fillRect(130, 190, 40, 60);

        // Roof
        ctx.beginPath();
        ctx.moveTo(50, 140);
        ctx.lineTo(150, 60);
        ctx.lineTo(250, 140);
        ctx.closePath();
        ctx.stroke();
        ctx.update()
      },
      drawPoint() {
        let ctx = uni.getElementById('draw-style')!.getDrawableContext()!
        ctx.reset()
        for (let i = 0; i < 6; i++) {
          for (let j = 0; j < 6; j++) {
            ctx.strokeStyle = `rgb(0,${Math.floor(255 - 42.5 * i)},${Math.floor(255 - 42.5 * j)})`;
            ctx.beginPath();
            ctx.arc(12.5 + j * 25, 12.5 + i * 25, 10, 0, Math.PI * 2, true);
            ctx.stroke();
          }
        }
        for (let i = 0; i < 6; i++) {
          for (let j = 0; j < 6; j++) {
            ctx.fillStyle = `rgb(${Math.floor(255 - 42.5 * i)},${Math.floor(255 - 42.5 * j)},0)`;
            ctx.fillRect(180 + j * 25, i * 25, 25, 25);
          }
        }
        ctx.update()
      },
      drawRect() {
        let ctx = uni.getElementById('draw-odd')!.getDrawableContext()!
        ctx.reset()
        // Create path
        ctx.moveTo(30, 90);
        ctx.lineTo(110, 20);
        ctx.lineTo(240, 130);
        ctx.lineTo(60, 130);
        ctx.lineTo(190, 20);
        ctx.lineTo(270, 90);
        ctx.closePath();

        // Fill path
        ctx.fillStyle = "green";
        ctx.fill("evenodd");
        ctx.update()

      },
      drawArcTo() {
        let ctx = uni.getElementById('draw-arcto')!.getDrawableContext()!
        ctx.reset()
        ctx.beginPath();
        ctx.moveTo(50, 20);
        ctx.bezierCurveTo(230, 30, 150, 60, 50, 100);
        ctx.stroke();

        ctx.fillStyle = "blue";
        // start point
        ctx.fillRect(50, 20, 10, 10);
        // end point
        ctx.fillRect(50, 100, 10, 10);

        ctx.fillStyle = "red";
        // control point one
        ctx.fillRect(230, 30, 10, 10);
        // control point two
        ctx.fillRect(150, 70, 10, 10);
        ctx.update()
      }
    }
  }
</script>

<style>
  .drawing {
    height: 275px;
    background-color: lightgray;
    margin-bottom: 15px;
  }
</style>