鸿蒙 画布来了 我不允许你不会

前言：

作者：徐庆

团队：坚果派 公众号："大前端之旅" 润开鸿生态技术专家，华为HDE，CSDN博客专家，CSDN超级个体，CSDN特邀嘉宾，InfoQ签约作者，OpenHarmony布道师，电子发烧友专家博客，51CTO博客专家，擅长HarmonyOS/OpenHarmony应用开发、熟悉服务卡片开发。欢迎合作。

具体实现 ：

import pointer from '@ohos.multimodalInput.pointer';
@Entry
@Component
struct Index {
  private settings: RenderingContextSettings = new RenderingContextSettings(true);
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings);
  private path2Db: Path2D = new Path2D()

  private pointX1:number
  private pointY1:number

  private pointX2:number
  private pointY2:number

  drawAction(){


  }
  onPageShow(){
    //画笔粗细
    this.context.lineWidth = 5
    //画笔颜色
    this.context.strokeStyle = '#0000ff'

  }

  build() {
    Row() {
      Column() {

        Canvas(this.context)
          .width('100%')
          .height('100%')
          .backgroundColor('#F5DC62')
          .onTouch((event)=>{

            var pointX = event.touches[0].x;
            var pointY = event.touches[0].y;

            if (event.type === TouchType.Down) {
              // this.eventType = 'Down'
              this.path2Db.moveTo(event.touches[0].x, event.touches[0].y);

              this.pointX1 = pointX
              this.pointY1 = pointY

              this.pointX2 = pointX
              this.pointY2 = pointY


            }
            if (event.type === TouchType.Up) {
              // this.eventType = 'Up'
            }
            if (event.type === TouchType.Move) {
              // this.eventType = 'Move'
              // this.path2Db.lineTo(event.touches[0].x, event.touches[0].y);

              let curX = (pointX + this.pointX1)/2
              let curY = (pointY + this.pointY1)/2

              this.path2Db.bezierCurveTo(this.pointX1,this.pointY1,this.pointX2,this.pointY2,curX,curY)

              this.pointX1 = pointX
              this.pointY1 = pointY

              this.pointX2 = curX
              this.pointY2 = curY

              this.context.stroke(this.path2Db)

            }
            console.log("X:",event.touches[0].x.toString())
            console.log("Y:",event.touches[0].y.toString())

          })

      }
      .width('100%')
    }
    .height('100%')
  }
}

查看源码

Path2D extends CanvasPath 

Path2D 是继承我们 CanvasPath 父类

最后总结

我们通过定义了2个点的x 坐标和y坐标 然后通过Canvas 组件绘制 Path2D 来里更新我们绘制的点的坐标来实现画图的线。线都同通过无数的点构成的 我们只需要把这些绘制点的坐标更新显示出来即可 今天的文章就讲到这里 有兴趣的同学可以继续研究 如果你觉得文章还不错麻烦给我三连 关注点赞和转发 如果了解更多鸿蒙开发的知识 可以关注坚果派公众号 。 谢谢