https://github.com/ledfan/kotlin-geojsondsl
https://github.com/ledfan/kotlin-geojsondsl
Last synced: about 1 year ago
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- Host: GitHub
- URL: https://github.com/ledfan/kotlin-geojsondsl
- Owner: LEDfan
- License: apache-2.0
- Created: 2019-07-26T12:45:31.000Z (almost 7 years ago)
- Default Branch: master
- Last Pushed: 2021-07-14T05:27:16.000Z (almost 5 years ago)
- Last Synced: 2025-02-18T02:15:16.616Z (over 1 year ago)
- Language: Kotlin
- Size: 57.6 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
Kotlin GeoJSON DSL
==================
[](https://travis-ci.com/LEDfan/kotlin-geojsondsl)
This is a small Kotlin library to easily generate [GeoJSON](https://geojson.org/) using a DSL.
The library uses the [Klaxon](https://github.com/cbeust/klaxon) library.
## Minimal example
For example, the following Kotlin code:
```kotlin
println(feature {
withGeometry {
point(Coordinate(4.3516970, 50.8465573))
withProperty("city", "Brussels")
withProperty("country", "Belgium")
}
}.toJson().toJsonString(prettyPrint = true))
```
will print:
```json
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [50.8465573, 4.351697]
},
"properties": {
"country": "Belgium",
"city": "Brussels"
}
}
```
## Coordinate
The library does not depend on any specific geometry library. In order to represent a coordinate, the library uses the `ICoordinate` interface:
```kotlin
interface ICoordinate {
fun toJson(): JsonArray
}
```
Before you can use the library, you have to implement this interface, for example using:
```kotlin
data class Coordinate(val lat: Double, val lon: Double) : ICoordinate {
override fun toJson(): JsonArray {
return json {
array(
lon,
lat
)
} as JsonArray
}
}
```
### Feature
To create a feature object, simply call the `feature` function with a [trailling lambda](https://kotlinlang.org/docs/reference/lambdas.html#passing-a-lambda-to-the-last-parameter). In this lambda the following functions are available:
- `withGeometry` add a geometry to the feature
- `withGeometryCollection` add a collection of geometries to the feature
- `withProperty` add a property to the feature. The value can either be `Any` or a trailling lambda in which you can call the `array` or `obj` function os klaxon.
- `withId` add a id of type string or number to the feature
[Above](#minimal-example) you already find an example of `withGeometry`.
The following is an example of a GeometryCollection:
```kotlin
println(feature {
withGeometryCollection {
point(Coordinate(1.0, 2.0))
lineString {
withCoordinate(Coordinate(1.0, 2.0))
withCoordinate(Coordinate(3.0, 4.0))
}
}
}.toJson().toJsonString(prettyPrint = true))
```
which prints:
```json
{
"type": "Feature",
"geometry": {
"type": "GeometryCollection",
"geometries": [
{
"type": "Point",
"coordinates": [
2.0,
1.0
]
},
{
"type": "LineString",
"coordinates": [
[
2.0,
1.0
],
[
4.0,
3.0
]
]
}
]
},
"properties": {}
}
```
Examples of `withProperty`:
```kotlin
feature {
withGeometry {
point(Coordinate(10.0, 10.0))
}
withProperty("test1", "1") // simple property
withProperty("test2", "2") // simple property
withProperty("test3") {
// complex json array property
array(1, 2, 3)
}
withProperty("test4") {
// complex json object property
obj("a" to "b", "b" to array(1, 2))
}
}.toJson().toJsonString(prettyPrint = true))
```
which prints
```json
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [
10.0,
10.0
]
},
"properties": {
"test4": {
"a": "b",
"b": [
1,
2
]
},
"test2": "2",
"test3": [
1,
2,
3
],
"test1": "1"
}
}
```
### FeatureCollection
A featureCollection can be created similar to a feature by calling the `featureCollection` function. For example:
```kotlin
featureCollection {
withFeature {
withId("test")
withGeometry {
point(Coordinate(1.0, 1.0))
}
}
withFeature {
withId("test")
withGeometryCollection {
multiPoint {
withCoordinate(Coordinate(2.0, 3.0))
withCoordinate(Coordinate(4.0, 5.0))
}
point(Coordinate(5.0, 6.0))
}
}
}.toJson().toJsonString(prettyPrint = true))
```
```json
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"id": "test",
"geometry": {
"type": "Point",
"coordinates": [
1.0,
1.0
]
},
"properties": {}
},
{
"type": "Feature",
"id": "test",
"geometry": {
"type": "GeometryCollection",
"geometries": [
{
"type": "MultiPoint",
"coordinates": [
[
3.0,
2.0
],
[
5.0,
4.0
]
]
},
{
"type": "Point",
"coordinates": [
6.0,
5.0
]
}
]
},
"properties": {}
}
]
}
```
### Point
```kotlin
feature {
withGeometry {
point(Coordinate(1.0, 1.0))
}
}
```
```json
{"type":"Feature","geometry":{"type":"Point","coordinates":[10.0,10.0]},"properties":{}}
```
### MultiPoint
```kotlin
feature {
withGeometry {
multiPoint {
// only one coordinate is allowed
withCoordinate(Coordinate(10.0, 10.0))
withCoordinate(Coordinate(12.0, 12.0))
}
}
}
```
```json
{"type":"Feature","geometry":{"type":"MultiPoint","coordinates":[[10.0,10.0],[12.0,12.0]]},"properties":{}}
```
### LineString
```kotlin
feature {
withGeometry {
lineString {
withCoordinate(Coordinate(10.0, 10.0))
withCoordinate(Coordinate(10.0, 10.0))
}
}
}
```
```json
{"type":"Feature","geometry":{"type":"LineString","coordinates":[[10.0,10.0],[10.0,10.0]]},"properties":{}}
```
### MultiLineString
```kotlin
feature {
withGeometry {
multiLineString {
lineString {
withCoordinate(Coordinate(1.1, 2.2))
withCoordinate(Coordinate(3.3, 4.4))
}
lineString {
withCoordinate(Coordinate(5.5, 6.6))
withCoordinate(Coordinate(7.7, 8.8))
}
}
}
}
```
```json
{"type":"Feature","geometry":{"type":"MultiLineString","coordinates":[[[2.2,1.1],[4.4,3.3]],[[6.6,5.5],[8.8,7.7]]]},"properties":{}}
```
### Polygon
```kotlin
feature {
withGeometry {
polygon {
ring {
withCoordinate(Coordinate(1.1, 2.2))
withCoordinate(Coordinate(3.3, 4.4))
withCoordinate(Coordinate(3.3, 4.6))
withCoordinate(Coordinate(1.1, 2.2))
}
ring {
withCoordinate(Coordinate(0.5, 3.14))
withCoordinate(Coordinate(5.6, 4.2))
withCoordinate(Coordinate(8.8, 7.6))
withCoordinate(Coordinate(4.2, 5.2))
withCoordinate(Coordinate(0.5, 3.14))
}
}
}
}
```
```json
{
"type": "Feature",
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
2.2,
1.1
],
[
4.4,
3.3
],
[
4.6,
3.3
],
[
2.2,
1.1
]
],
[
[
3.14,
0.5
],
[
4.2,
5.6
],
[
7.6,
8.8
],
[
5.2,
4.2
],
[
3.14,
0.5
]
]
]
},
"properties": {}
}
```
### MultiPolygon
```kotlin
feature {
withGeometry {
multiPolygon {
polygon {
ring {
withCoordinate(Coordinate(1.1, 2.2))
withCoordinate(Coordinate(3.3, 4.4))
withCoordinate(Coordinate(3.3, 4.6))
withCoordinate(Coordinate(1.1, 2.2))
}
ring {
withCoordinate(Coordinate(0.5, 3.14))
withCoordinate(Coordinate(5.6, 4.2))
withCoordinate(Coordinate(8.8, 7.6))
withCoordinate(Coordinate(4.2, 5.2))
withCoordinate(Coordinate(0.5, 3.14))
}
}
polygon {
ring {
withCoordinate(Coordinate(1.1, 2.2))
withCoordinate(Coordinate(3.3, 4.4))
withCoordinate(Coordinate(3.3, 4.6))
withCoordinate(Coordinate(1.1, 2.2))
}
}
}
}
}
```
```json
{
"type": "Feature",
"geometry": {
"type": "MultiPolygon",
"coordinates": [
[
[
[
2.2,
1.1
],
[
4.4,
3.3
],
[
4.6,
3.3
],
[
2.2,
1.1
]
],
[
[
3.14,
0.5
],
[
4.2,
5.6
],
[
7.6,
8.8
],
[
5.2,
4.2
],
[
3.14,
0.5
]
]
],
[
[
[
2.2,
1.1
],
[
4.4,
3.3
],
[
4.6,
3.3
],
[
2.2,
1.1
]
]
]
]
},
"properties": {}
}
```
## License
> Copyright 2019 Tobia De Koninck
>
> 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.