Use OffscreenCanvasRenderingContext2D to draw rectangles, images, and text offscreen onto a canvas. Drawing offscreen onto a canvas is a process where content to draw onto the canvas is first drawn in the buffer, and then converted into a picture, and finally the picture is drawn on the canvas. This process increases the drawing efficiency.

 Canvas(this.context)
    .onReady(() =>{
          this.offContext.lineWidth = 5
          this.offContext.strokeRect(25, 25, 85, 105)
          var image = this.offContext.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
    })

 Canvas(this.context)
    .onReady(() =>{
          this.context.lineWidth = 5
          this.context.strokeRect(25, 25, 85, 105)
    })