setVertex method
根据索引设置顶点
Implementation
void setVertex(int index, Point<double> vertex) {
switch (index) {
case 0:
topLeft = vertex;
break;
case 1:
topRight = vertex;
break;
case 2:
bottomRight = vertex;
break;
case 3:
bottomLeft = vertex;
break;
default:
throw ArgumentError('顶点索引必须在0-3之间');
}
}