/// <summary>
/// 缩放任务组到指定的等级
/// </summary>
/// <param name="zoom"></param>
/// <returns></returns>
internal ZoomTask ScaleTo(int zoom)
{
// 计算缩放等级
var level = Math.Pow(2, zoom - Zoom);
var newGroup = new ZoomTask(zoom);
foreach (var tasks in m_taskDict.Values)
{
foreach (var task in tasks)
{
newGroup.AddTask(new MapLine
{
StartX = (long)Math.Floor(task.StartX * level),
EndX = (long)Math.Floor(task.EndX * level),
Y = (long)Math.Floor(task.Y * level),
Zoom = zoom
});
}
}
return(newGroup);
}
/// <summary>
/// 计算下载任务列表
/// </summary>
private void CalculateQuest()
{
// 先按多边形分组，一组点可能组成多个多边形
var points = m_points;
IList <MercatorRegion> regionList = new List <MercatorRegion>();
while (points.Any())
{
var index = points.ToList().LastIndexOf(points.First());
if (index == 0)
{
if (points.Any())
{
File.AppendAllLines("points.txt", points.Select(o => $"{o.X},{o.Y}"));
}
break;
}
var region = new MercatorRegion(points.Take(index + 1));
regionList.Add(region);
points = points.Skip(index + 1).ToList();
}
if (!regionList.Any())
{
throw new ArgumentException("无法构建成多边形，请检查点是否闭合");
}
// 只计算最大层，其余层通过缩小计算得出
var tileRegionList = regionList.Select(o => o.GetTileRegion(MaxZoom));
var segments = tileRegionList.Aggregate(Enumerable.Empty <TileSegment>(), (current, region) => current.Concat(region.GetTileSegments())).ToList();
var minY = (long)Math.Floor(segments.Min(o => o.MinY));
var maxY = (long)Math.Floor(segments.Max(o => o.MaxY));
// 每个Y值计算一次交点
var taskGroup = new ZoomTask(MaxZoom);
for (var i = minY; i <= maxY; i++)
{
var y = i;
var matchSegments = segments.Where(o => (o.MaxY >= y) && (o.MinY <= y));
var intersectList = new List <TilePoint>();
foreach (var s in matchSegments)
{
intersectList.Add(s.IntersectY(y));
}
// 分解任务
intersectList = intersectList.OrderBy(o => o.X).ToList();
for (var index = 0; index < intersectList.Count; index += 2)
{
var x1 = (long)Math.Floor(intersectList[index].X);
var x2 = (long)Math.Floor(intersectList[index + 1].X);
var task = new MapLine
{
StartX = x1,
EndX = x2,
Y = y,
Zoom = MaxZoom
};
taskGroup.AddTask(task);
}
}
// 将线段两点加入任务组
foreach (var s in segments)
{
taskGroup.AddTask(GetTaskFromTilePoint(s.Point1, MaxZoom));
taskGroup.AddTask(GetTaskFromTilePoint(s.Point2, MaxZoom));
}
// 将线段所有x轴点加入任务组
var minX = (long)Math.Floor(segments.Min(o => o.MinX));
var maxX = (long)Math.Floor(segments.Max(o => o.MaxX));
for (var i = minX; i <= maxX; i++)
{
var x = i;
var matchSegments = segments.Where(o => (o.MaxX >= x) && (o.MinX <= x));
foreach (var s in matchSegments)
{
taskGroup.AddTask(GetTaskFromTilePoint(s.IntersectX(x), MaxZoom));
}
}
// 整合任务组
m_zoomTasks.Add(taskGroup);
var tg = taskGroup;
for (var index = MaxZoom - 1; index >= MinZoom; index--)
{
tg = tg.ScaleTo(index);
m_zoomTasks.Add(tg);
}
}
/// <summary>
/// 计算下载任务列表
/// </summary>
private void Calculate()
{
var minZoom = m_supportZooms.Min();
var maxZoom = m_supportZooms.Max();
// 只计算最大层，其余层通过缩小计算得出
var tileRegionList = m_regions.Select(o => o.GetTileRegion(maxZoom));
var segments =
tileRegionList.Aggregate(Enumerable.Empty <TileSegment>(), (current, region) => current.Concat(region.GetTileSegments())).ToList();
// 每个Y值计算一次交点
var zoomTask = new ZoomTask(maxZoom);
var pointDict = new ConcurrentDictionary <double, ConcurrentBag <TilePoint> >();
foreach (var segment in segments)
{
foreach (var tp in segment.GetTilePointIntersectY())
{
if (!pointDict.ContainsKey(tp.Y))
{
pointDict.TryAdd(tp.Y, new ConcurrentBag <TilePoint>());
}
pointDict[tp.Y].Add(tp);
}
}
foreach (var group in pointDict)
{
var points = group.Value.OrderBy(o => o.X).ToList();
for (var index = 0; index < points.Count; index += 2)
{
var x1 = (long)Math.Floor(points[index].X);
var x2 = (long)Math.Floor(points[index + 1].X);
var task = new MapLine
{
StartX = x1,
EndX = x2,
Y = (long)group.Key,
Zoom = maxZoom
};
zoomTask.AddTask(task);
}
}
// 将线段两点加入任务组
foreach (var s in segments)
{
zoomTask.AddTask(GetTaskFromTilePoint(s.Point1, maxZoom));
zoomTask.AddTask(GetTaskFromTilePoint(s.Point2, maxZoom));
}
// 将线段所有x轴点加入任务组
var minX = (long)Math.Floor(segments.Min(o => o.MinX));
var maxX = (long)Math.Floor(segments.Max(o => o.MaxX));
foreach (var segment in segments)
{
foreach (var tp in segment.GetTilePointIntersectX())
{
zoomTask.AddTask(GetTaskFromTilePoint(tp, maxZoom));
}
}
// 整合任务组
m_zoomTasks.Add(zoomTask);
var tg = zoomTask;
for (var index = maxZoom - 1; index >= minZoom; index--)
{
tg = tg.ScaleTo(index);
m_zoomTasks.Add(tg);
}
}