tile38/geojson/feature.go

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package geojson
import (
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"encoding/binary"
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"github.com/tidwall/gjson"
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"github.com/tidwall/tile38/geojson/geohash"
)
// Feature is a geojson object with the type "Feature"
type Feature struct {
Geometry Object
BBox *BBox
bboxDefined bool
idprops string // raw id and properties seperated by a '\0'
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}
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func fillFeatureMap(json string) (Feature, error) {
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var g Feature
v := gjson.Get(json, "geometry")
switch v.Type {
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default:
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return g, errInvalidGeometryMember
case gjson.Null:
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return g, errGeometryMemberRequired
case gjson.JSON:
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var err error
g.Geometry, err = objectMap(v.Raw, feat)
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if err != nil {
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return g, err
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}
}
var err error
g.BBox, err = fillBBox(json)
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if err != nil {
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return g, err
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}
g.bboxDefined = g.BBox != nil
if !g.bboxDefined {
cbbox := g.CalculatedBBox()
g.BBox = &cbbox
}
var propsExists bool
props := gjson.Get(json, "properties")
switch props.Type {
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default:
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return g, errInvalidPropertiesMember
case gjson.Null:
case gjson.JSON:
propsExists = true
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}
id := gjson.Get(json, "id")
if id.Exists() || propsExists {
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g.idprops = makeCompositeRaw(id.Raw, props.Raw)
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}
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return g, err
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}
// Geohash converts the object to a geohash value.
func (g Feature) Geohash(precision int) (string, error) {
p := g.CalculatedPoint()
return geohash.Encode(p.Y, p.X, precision)
}
// CalculatedPoint is a point representation of the object.
func (g Feature) CalculatedPoint() Position {
return g.CalculatedBBox().center()
}
// CalculatedBBox is exterior bbox containing the object.
func (g Feature) CalculatedBBox() BBox {
if g.BBox != nil {
return *g.BBox
}
return g.Geometry.CalculatedBBox()
}
// PositionCount return the number of coordinates.
func (g Feature) PositionCount() int {
res := g.Geometry.PositionCount()
if g.BBox != nil {
return 2 + res
}
return res
}
// Weight returns the in-memory size of the object.
func (g Feature) Weight() int {
res := g.PositionCount() * sizeofPosition
res += len(g.idprops)
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return res
}
// MarshalJSON allows the object to be encoded in json.Marshal calls.
func (g Feature) MarshalJSON() ([]byte, error) {
return g.appendJSON(nil), nil
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}
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func (g Feature) getRaw() (id, props string) {
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if len(g.idprops) == 0 {
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return "", ""
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}
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switch g.idprops[0] {
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default:
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lnp := int(g.idprops[0]) + 1
return g.idprops[1:lnp], g.idprops[lnp:]
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case 255:
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lnp := int(binary.LittleEndian.Uint64([]byte(g.idprops[1:9]))) + 9
return g.idprops[9:lnp], g.idprops[lnp:]
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}
}
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func makeCompositeRaw(idRaw, propsRaw string) string {
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idRaw = stripWhitespace(idRaw)
propsRaw = stripWhitespace(propsRaw)
if len(idRaw) == 0 && len(propsRaw) == 0 {
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return ""
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}
var raw []byte
if len(idRaw) > 0xFF-1 {
raw = make([]byte, len(idRaw)+len(propsRaw)+9)
raw[0] = 0xFF
binary.LittleEndian.PutUint64(raw[1:9], uint64(len(idRaw)))
copy(raw[9:], idRaw)
copy(raw[len(idRaw)+9:], propsRaw)
} else {
raw = make([]byte, len(idRaw)+len(propsRaw)+1)
raw[0] = byte(len(idRaw))
copy(raw[1:], idRaw)
copy(raw[len(idRaw)+1:], propsRaw)
}
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return string(raw)
}
func (g Feature) appendJSON(json []byte) []byte {
json = append(json, `{"type":"Feature","geometry":`...)
json = append(json, g.Geometry.JSON()...)
if g.bboxDefined {
json = appendBBoxJSON(json, g.BBox)
}
idRaw, propsRaw := g.getRaw()
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if propsRaw != "" {
json = append(json, `,"properties":`...)
json = append(json, propsRaw...)
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}
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if idRaw != "" {
json = append(json, `,"id":`...)
json = append(json, idRaw...)
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}
return append(json, '}')
}
// JSON is the json representation of the object. This might not be exactly the same as the original.
func (g Feature) JSON() string {
return string(g.appendJSON(nil))
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}
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// String returns a string representation of the object. This might be JSON or something else.
func (g Feature) String() string {
return g.JSON()
}
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// Bytes is the bytes representation of the object.
func (g Feature) Bytes() []byte {
return []byte(g.JSON())
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}
func (g Feature) bboxPtr() *BBox {
return g.BBox
}
func (g Feature) hasPositions() bool {
if g.bboxDefined {
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return true
}
return g.Geometry.hasPositions()
}
// WithinBBox detects if the object is fully contained inside a bbox.
func (g Feature) WithinBBox(bbox BBox) bool {
if g.bboxDefined {
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return rectBBox(g.CalculatedBBox()).InsideRect(rectBBox(bbox))
}
return g.Geometry.WithinBBox(bbox)
}
// IntersectsBBox detects if the object intersects a bbox.
func (g Feature) IntersectsBBox(bbox BBox) bool {
if g.bboxDefined {
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return rectBBox(g.CalculatedBBox()).IntersectsRect(rectBBox(bbox))
}
return g.Geometry.IntersectsBBox(bbox)
}
// Within detects if the object is fully contained inside another object.
func (g Feature) Within(o Object) bool {
return withinObjectShared(g, o,
func(v Polygon) bool {
return g.Geometry.Within(o)
},
func(v MultiPolygon) bool {
return g.Geometry.Within(o)
},
)
}
// Intersects detects if the object intersects another object.
func (g Feature) Intersects(o Object) bool {
return intersectsObjectShared(g, o,
func(v Polygon) bool {
return g.Geometry.Intersects(o)
},
func(v MultiPolygon) bool {
return g.Geometry.Intersects(o)
},
)
}
// Nearby detects if the object is nearby a position.
func (g Feature) Nearby(center Position, meters float64) bool {
return nearbyObjectShared(g, center.X, center.Y, meters)
}
// IsBBoxDefined returns true if the object has a defined bbox.
func (g Feature) IsBBoxDefined() bool {
return g.bboxDefined
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}
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// IsGeometry return true if the object is a geojson geometry object. false if it something else.
func (g Feature) IsGeometry() bool {
return true
}