draw abstract method

void draw(
  1. Canvas canvas,
  2. Size size,
  3. bool deeper
)

绘制核心方法 canvas 画布对象 size 画布尺寸 deeper 当前是否为底层绘制（true为历史记录层，false为实时绘制层）

Core drawing method canvas Canvas object size Canvas size deeper Whether this is deep layer drawing (true for history layer, false for real-time layer)

Implementation

void draw(Canvas canvas, Size size, bool deeper);