///<summary>获得块的经纬度范围</summary>
public static Rect GetTileJW(int layer, int idxx, int idxy)
{
int ycount = (int)Math.Pow(2, layer);
double angle = MapHelper.DegToRad(360.0 / ycount);
double tileLength = 2.0 * Math.PI / Math.Pow(2, layer); //2*pi/power(2,layer) 假定半径为1, 平面地图坐标系下该层划分块的长和宽度
double xStart = (idxx * angle - Math.PI) / Math.PI * 180; // 指定索引号块的起始经度
double xEnd = ((idxx + 1) * angle - Math.PI) / Math.PI * 180; // 指定索引号块的起始经度
double yStart = (Math.Atan(Math.Exp(Math.PI - (idxy + 1) * tileLength)) * 2 - Math.PI / 2) / Math.PI * 180; //指定索引号块的结束纬度
double yEnd = (Math.Atan(Math.Exp(Math.PI - idxy * tileLength)) * 2 - Math.PI / 2) / Math.PI * 180; //atan(exp(PI-idxy*2*pi/power(2,layer)))*2-pi/2 指定索引号块的起始纬度
return(new Rect(xStart, yStart, xEnd - xStart, yEnd - yStart));
}
///<summary>计算局部平面场景模式下的相关参数，设置相关参数后调用</summary>
public void calPlaneModePara()
{
if (tileReadMode == ETileReadMode.内置瓦片服务 || tileReadMode == ETileReadMode.自定义Web瓦片)
{
//计算最合适的对应层，再加2层作为起始层
double minjd = StartLocation.Longitude;
double minwd = StartLocation.Latitude;
double maxjd = EndLocation.Longitude;
double maxwd = EndLocation.Latitude;
double spanjd = maxjd - minjd;
double spanwd = maxwd - minwd;
int ycount; double angle, tileLength, xStart, xEnd, yStart, yEnd;
int si = 0; double cz = double.PositiveInfinity;
for (int i = 0; i < 18; i++)
{
int idxx = 0; int idxy = 0;
ycount = (int)Math.Pow(2, i);
angle = MapHelper.DegToRad(360.0 / ycount);
tileLength = 2.0 * Math.PI / Math.Pow(2, i); //2*pi/power(2,layer) 假定半径为1, 平面地图坐标系下该层划分块的长和宽度
xStart = (idxx * angle - Math.PI) / Math.PI * 180; // 指定索引号块的起始经度
xEnd = ((idxx + 1) * angle - Math.PI) / Math.PI * 180; // 指定索引号块的起始经度
yStart = (Math.Atan(Math.Exp(Math.PI - (idxy + 1) * tileLength)) * 2 - Math.PI / 2) / Math.PI * 180; //指定索引号块的结束纬度
yEnd = (Math.Atan(Math.Exp(Math.PI - idxy * tileLength)) * 2 - Math.PI / 2) / Math.PI * 180; //atan(exp(PI-idxy*2*pi/power(2,layer)))*2-pi/2 指定索引号块的起始纬度
double tmp = Math.Abs(xEnd - xStart - spanjd) + Math.Abs(yStart - yEnd - spanwd);
if (tmp < cz)
{
cz = tmp; si = i;
}
}
StartLayer = si + 2;
//计算合适的瓦片序号
ycount = (int)Math.Pow(2, StartLayer);
angle = MapHelper.DegToRad(360.0 / ycount);
StartIdxX = (int)((minjd / 180 * Math.PI + Math.PI) / angle);
tileLength = 2.0 * Math.PI / Math.Pow(2, StartLayer); //2*pi/power(2,layer) 假定半径为1, 平面地图坐标系下该层划分块的长和宽度
StartIdxY = (int)((Math.PI - Math.Log(Math.Tan((minwd / 180 * Math.PI + Math.PI / 2) / 2))) / tileLength);
EndIdxX = (int)((maxjd / 180 * Math.PI + Math.PI) / angle);
tileLength = 2.0 * Math.PI / Math.Pow(2, StartLayer); //2*pi/power(2,layer) 假定半径为1, 平面地图坐标系下该层划分块的长和宽度
EndIdxY = (int)((Math.PI - Math.Log(Math.Tan((maxwd / 180 * Math.PI + Math.PI / 2) / 2))) / tileLength);
//计算新的准确的起止经纬
System.Windows.Rect tmprect = Helpler.GetTileJW(StartLayer, StartIdxX, StartIdxY);
StartLocation = new GeoPoint(tmprect.Bottom, tmprect.Left);
tmprect = Helpler.GetTileJW(StartLayer, EndIdxX, EndIdxY);
EndLocation = new GeoPoint(tmprect.Top, tmprect.Right);
//以12，0，赤道为基准计算单位转换坐标
System.Windows.Rect rect12 = Helpler.GetTileJW(12, 0, (int)Math.Pow(2, 11));
UnitLongLen = 1 / rect12.Width;
UnitLatLen = 1 / rect12.Height * AdjustAspect;
}
else //自定义瓦片
{
StartLayer = 0;
StartIdxX = 0;
StartIdxY = 0;
EndIdxX = 1;
EndIdxY = 1;
UnitLatLen = 100 / (EndLocation.Latitude - StartLocation.Latitude);
UnitLongLen = 100 / (EndLocation.Longitude - StartLocation.Longitude);
}
}