Feat/wms tile overlay

maps-app/src/main/java/com/google/maps/android/compose/WmsTileOverlayActivity.kt

@@ -48,7 +48,7 @@ class WmsTileOverlayActivity : ComponentActivity() {
                     urlFormatter = { xMin, yMin, xMax, yMax, _ ->
                         "https://basemap.nationalmap.gov/arcgis/services/USGSShadedReliefOnly/MapServer/WmsServer?" +
                             "SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap" +
-                            "&FORMAT=image/png&TRANSPARENT=true&LAYERS=0" +
+                            "&FORMAT=image/png&STYLES=default&TRANSPARENT=true&LAYERS=0" +
                             "&SRS=EPSG:3857&WIDTH=256&HEIGHT=256" +
                             "&BBOX=$xMin,$yMin,$xMax,$yMax"
                     },

maps-compose-utils/src/main/java/com/google/maps/android/compose/wms/WmsTileOverlay.kt

@@ -35,6 +35,10 @@ import com.google.maps.android.compose.rememberTileOverlayState
  * @param onClick a lambda invoked when the tile overlay is clicked.
  * @param tileWidth the width of the tiles in pixels (default 256).
  * @param tileHeight the height of the tiles in pixels (default 256).
+ * @param datasetXMinBound the minimum X coordinate of the dataset in EPSG:3857 (default null).
+ * @param datasetYMinBound the minimum Y coordinate of the dataset in EPSG:3857 (default null).
+ * @param datasetXMaxBound the maximum X coordinate of the dataset in EPSG:3857 (default null).
+ * @param datasetYMaxBound the maximum Y coordinate of the dataset in EPSG:3857 (default null).
  */
 @Composable
 public fun WmsTileOverlay(
@@ -46,13 +50,21 @@ public fun WmsTileOverlay(
     zIndex: Float = 0f,
     onClick: (TileOverlay) -> Unit = {},
     tileWidth: Int = 256,
-    tileHeight: Int = 256
+    tileHeight: Int = 256,
+    datasetXMinBound: Double? = null,
+    datasetYMinBound: Double? = null,
+    datasetXMaxBound: Double? = null,
+    datasetYMaxBound: Double? = null
 ) {
     val tileProvider = remember(urlFormatter, tileWidth, tileHeight) {
         WmsUrlTileProvider(
             width = tileWidth,
             height = tileHeight,
-            urlFormatter = urlFormatter
+            urlFormatter = urlFormatter,
+            datasetXMinBound = datasetXMinBound,
+            datasetYMinBound = datasetYMinBound,
+            datasetXMaxBound = datasetXMaxBound,
+            datasetYMaxBound = datasetYMaxBound
         )
     }
     TileOverlay(

maps-compose-utils/src/main/java/com/google/maps/android/compose/wms/WmsUrlTileProvider.kt

@@ -19,7 +19,6 @@ package com.google.maps.android.compose.wms
 import com.google.android.gms.maps.model.UrlTileProvider
 import java.net.MalformedURLException
 import java.net.URL
-import kotlin.math.pow
 
 /**
  * A [UrlTileProvider] for Web Map Service (WMS) layers that use the EPSG:3857 (Web Mercator)
@@ -29,10 +28,18 @@ import kotlin.math.pow
  * @param height the height of the tile in pixels.
  * @param urlFormatter a lambda that returns the WMS URL for the given bounding box coordinates
  * (xMin, yMin, xMax, yMax) and zoom level.
+ * @param datasetXMinBound the minimum X coordinate of the dataset in EPSG:3857 (default null).
+ * @param datasetYMinBound the minimum Y coordinate of the dataset in EPSG:3857 (default null).
+ * @param datasetXMaxBound the maximum X coordinate of the dataset in EPSG:3857 (default null).
+ * @param datasetYMaxBound the maximum Y coordinate of the dataset in EPSG:3857 (default null).
  */
 public class WmsUrlTileProvider(
     width: Int = 256,
     height: Int = 256,
+    private val datasetXMinBound: Double? = null,
+    private val datasetYMinBound: Double? = null,
+    private val datasetXMaxBound: Double? = null,
+    private val datasetYMaxBound: Double? = null,
     private val urlFormatter: (
         xMin: Double,
         yMin: Double,
@@ -41,9 +48,17 @@ public class WmsUrlTileProvider(
         zoom: Int
     ) -> String
 ) : UrlTileProvider(width, height) {
+    private val bounded: Boolean = datasetXMinBound != null || datasetYMinBound != null || datasetXMaxBound != null || datasetYMaxBound != null
 
     override fun getTileUrl(x: Int, y: Int, zoom: Int): URL? {
-        val bbox = getBoundingBox(x, y, zoom)
+        val bbox = getBoundingBox(x, y, zoom) // doubleArrayOf(xMin, yMin, xMax, yMax)
+        // Return null if the tile is entirely outside the specified bounds of the dataset
+        if(bounded && // skip checking for datasets where no bounds are specified
+            (datasetXMaxBound != null && bbox[0] > datasetXMaxBound) || // xMin greater than datasets xMax. No overlap.
+            (datasetYMaxBound != null && bbox[1] > datasetYMaxBound) || // yMin greater than datasets yMax. No overlap.
+            (datasetXMinBound != null && bbox[2] < datasetXMinBound) || // xMax less than datasets xMin. No overlap.
+            (datasetYMinBound != null && bbox[3] < datasetYMinBound) // yMax less than datasets yMin. No overlap.
+        ){return null}
         val urlString = urlFormatter(bbox[0], bbox[1], bbox[2], bbox[3], zoom)
         return try {
             URL(urlString)
@@ -54,9 +69,11 @@ public class WmsUrlTileProvider(
 
     private companion object {
         /**
-         * The Earth's circumference in meters at the equator according to EPSG:3857.
+         * The Earth's bound and circumference in meters at the equator according to EPSG:3857.
          */
-        private const val EARTH_CIRCUMFERENCE = 2 * 20037508.34789244
+        private const val BOUND = 20037508.34789244
+        private const val EARTH_CIRCUMFERENCE = 2 * BOUND
+
     }
 
     /**
@@ -65,16 +82,16 @@ public class WmsUrlTileProvider(
      * @return an array containing [xMin, yMin, xMax, yMax] in meters.
      */
     internal fun getBoundingBox(x: Int, y: Int, zoom: Int): DoubleArray {
-        val numTiles = 2.0.pow(zoom.toDouble())
+        val numTiles: Int = 1 shl zoom // Powers of 2 are equivalent to bit-shifts
         val tileSizeMeters = EARTH_CIRCUMFERENCE / numTiles
 
-        val xMin = -20037508.34789244 + (x * tileSizeMeters)
-        val xMax = -20037508.34789244 + ((x + 1) * tileSizeMeters)
+        val xMin = -BOUND + (x * tileSizeMeters)
+        val xMax = xMin + tileSizeMeters
 
         // Y is inverted in TMS/Google Maps tiles vs WMS BBOX
         // Top of map (y=0) is +20037508.34789244
-        val yMax = 20037508.34789244 - (y * tileSizeMeters)
-        val yMin = 20037508.34789244 - ((y + 1) * tileSizeMeters)
+        val yMax = BOUND - (y * tileSizeMeters)
+        val yMin = yMax - tileSizeMeters
 
         return doubleArrayOf(xMin, yMin, xMax, yMax)
     }

maps-compose-utils/src/test/java/com/google/maps/android/compose/wms/WmsUrlTileProviderTest.kt

@@ -17,6 +17,8 @@
 package com.google.maps.android.compose.wms
 
 import org.junit.Assert.assertArrayEquals
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertNull
 import org.junit.Test
 
 public class WmsUrlTileProviderTest {
@@ -62,4 +64,33 @@ public class WmsUrlTileProviderTest {
         val expected = doubleArrayOf(-worldSize / 2, 0.0, 0.0, worldSize / 2)
         assertArrayEquals(expected, bbox, 0.001)
     }
+
+    @Test
+    public fun testGetTileUrlBeyondBounds() {
+        val provider = WmsUrlTileProvider(datasetXMinBound = 1.0) { _, _, _, _, _ -> "https://example.com" }
+        val halfOfRes = {zoom : Int -> 1 shl (zoom - 1)}
+        for (z in 1..3) {
+            for (x in 0..<halfOfRes(z)) { //since xMinBound is the line 1.0 the boxes made to reach 0.0 will not intersect
+                for (y in 0..2 * halfOfRes(z)) {
+                    val tileUrl = provider.getTileUrl(x, y, z)
+                    assertNull(tileUrl)
+                }
+            }
+        }
+    }
+
+    @Test
+    public fun testGetTileUrlWithinBounds() {
+        val provider = WmsUrlTileProvider(datasetXMaxBound = -1.0) { _, _, _, _, _ -> "https://example.com" }
+        val halfOfRes = {zoom : Int -> 1 shl (zoom - 1)}
+        for (z in 1..3) {
+            for (x in 0..<halfOfRes(z)) { //since xMaxBound is the line 1.0 the boxes made to reach 0.0 will be contained
+                for (y in 0..2 * halfOfRes(z)) {
+                    val tileUrl = provider.getTileUrl(x, y, z)
+                    assertNotNull(tileUrl)
+                }
+            }
+        }
+    }
+
 }