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Diffstat (limited to 'vendor/github.com/golang/geo/s2/region.go')
| -rw-r--r-- | vendor/github.com/golang/geo/s2/region.go | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/vendor/github.com/golang/geo/s2/region.go b/vendor/github.com/golang/geo/s2/region.go new file mode 100644 index 000000000..9ea3de1ca --- /dev/null +++ b/vendor/github.com/golang/geo/s2/region.go @@ -0,0 +1,71 @@ +// Copyright 2014 Google Inc. All rights reserved. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package s2 + +// A Region represents a two-dimensional region on the unit sphere. +// +// The purpose of this interface is to allow complex regions to be +// approximated as simpler regions. The interface is restricted to methods +// that are useful for computing approximations. +type Region interface { + // CapBound returns a bounding spherical cap. This is not guaranteed to be exact. + CapBound() Cap + + // RectBound returns a bounding latitude-longitude rectangle that contains + // the region. The bounds are not guaranteed to be tight. + RectBound() Rect + + // ContainsCell reports whether the region completely contains the given region. + // It returns false if containment could not be determined. + ContainsCell(c Cell) bool + + // IntersectsCell reports whether the region intersects the given cell or + // if intersection could not be determined. It returns false if the region + // does not intersect. + IntersectsCell(c Cell) bool + + // ContainsPoint reports whether the region contains the given point or not. + // The point should be unit length, although some implementations may relax + // this restriction. + ContainsPoint(p Point) bool + + // CellUnionBound returns a small collection of CellIDs whose union covers + // the region. The cells are not sorted, may have redundancies (such as cells + // that contain other cells), and may cover much more area than necessary. + // + // This method is not intended for direct use by client code. Clients + // should typically use Covering, which has options to control the size and + // accuracy of the covering. Alternatively, if you want a fast covering and + // don't care about accuracy, consider calling FastCovering (which returns a + // cleaned-up version of the covering computed by this method). + // + // CellUnionBound implementations should attempt to return a small + // covering (ideally 4 cells or fewer) that covers the region and can be + // computed quickly. The result is used by RegionCoverer as a starting + // point for further refinement. + CellUnionBound() []CellID +} + +// Enforce Region interface satisfaction. +var ( + _ Region = Cap{} + _ Region = Cell{} + _ Region = (*CellUnion)(nil) + _ Region = (*Loop)(nil) + _ Region = Point{} + _ Region = (*Polygon)(nil) + _ Region = (*Polyline)(nil) + _ Region = Rect{} +) |