WPF中手写地图控件（3）——动态加载地图图片

瓦片增加一个Loading动画

可以查看我的另一个博客WPF中自定义Loading图

从中心扩散

进行从里到外的扩散，方向是上左下右。如下图所示

于是我们可以定义一个拥有坐标X跟Y的集合，他允许这个集合，内部使用枚举器的MoveNext自动排序，中心的在前，外面在后。

public class SpiralArray : IEnumerable<(int, int)>
{protected (int, int) Range;public SpiralArray((int, int) range){Range = range;}public IEnumerator<(int, int)> GetEnumerator(){return new SpiralArrayIEnumerator(Range);}IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}public class SpiralArrayIEnumerator : IEnumerator<(int, int)>
{public int Start;public int End;public int CenterX;public int CenterY;private bool IsOver = false;private int Direction = 0;// 0 上 1 左 2 : 下 3 : 右private int Step = 0;private int CurrentMoveSteps = 0;private int ChangedDirectionTimes = 0;  //改变方向次数/// <summary>/// 构造函数/// </summary>/// <param name="range"></param>public SpiralArrayIEnumerator((int, int) range){Start = range.Item1;End = range.Item2;Reset();}public (int, int) Current { get; set; }object IEnumerator.Current => Current;public void Dispose(){}public bool MoveNext(){if(Step == 0){Current = (CenterX, CenterY);CurrentMoveSteps = 0;Step = 1;return true;}else{// 走一步CurrentMoveSteps++;// 改变方向if(CurrentMoveSteps > Step){Direction = (Direction + 1) % 4;CurrentMoveSteps = 1;ChangedDirectionTimes++;if(ChangedDirectionTimes >= 2){// 步长 + 1Step++;ChangedDirectionTimes = 0;}}Move();if(Current.Item1 >= End || Current.Item2 >= End || Current.Item1 < Start || Current.Item2 < Start)return false;return true;}}/// <summary>/// 移动一步/// </summary>private void Move(){switch (Direction){// 上case 0:Current = (Current.Item1, Current.Item2 - 1);break;// 左case 1:Current = (Current.Item1 - 1, Current.Item2);break;// 下case 2:Current = (Current.Item1, Current.Item2 + 1);break;// 右case 3:Current = (Current.Item1 + 1, Current.Item2);break;default:break;}}public void Reset(){CenterX = (End + Start) / 2;CenterY = (End + Start) / 2;Current = (CenterX, CenterY);Direction = 0;Step = 0;ChangedDirectionTimes = 0;IsOver = false;}
}