downEventCallback method

void downEventCallback(
  1. double x,
  2. double y
)

滑动开始回调

Implementation

void downEventCallback(double x, double y) {
  x = x / scaleNum;
  y = y / scaleNum;
  curPath.moveTo(x, y);
  curPath.lineTo(x, y);
  paintState.value = !paintState.value;
}