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：

kotlin 复制代码

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

java 复制代码

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

鸿蒙 画布来了 我不允许你不会

作者：徐庆

具体实现 ：

最后总结

鸿蒙画布来了我不允许你不会

具体实现：