[android] #3758 - Projection / Visible Region implementation.

[android] #3758 - add VisibleRegion + unit tests, removed boundingbox, cleanup jni, cleanup test app, renamed CoordinateSpan to LatLng.

1 files changed, 72 insertions, 0 deletions

diff --git a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/Projection.java b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/Projection.java
new file mode 100644
index 0000000000..e53d430b69
--- /dev/null
+++ b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/Projection.java
@@ -0,0 +1,72 @@
+package com.mapbox.mapboxsdk.maps;
+
+import android.graphics.PointF;
+import android.support.annotation.NonNull;
+
+import com.mapbox.mapboxsdk.geometry.LatLng;
+import com.mapbox.mapboxsdk.geometry.LatLngBounds;
+import com.mapbox.mapboxsdk.geometry.VisibleRegion;
+
+/**
+ * A projection is used to translate between on screen location and geographic coordinates on
+ * the surface of the Earth (LatLng). Screen location is in screen pixels (not display pixels)
+ * with respect to the top left corner of the map (and not necessarily of the whole screen).
+ */
+public class Projection {
+
+    private MapView mMapView;
+
+    Projection(@NonNull MapView mapView) {
+        this.mMapView = mapView;
+    }
+
+    /**
+     * Returns the geographic location that corresponds to a screen location.
+     * The screen location is specified in screen pixels (not display pixels) relative to the
+     * top left of the map (not the top left of the whole screen).
+     *
+     * @param point A Point on the screen in screen pixels.
+     * @return The LatLng corresponding to the point on the screen, or null if the ray through
+     * the given screen point does not intersect the ground plane.
+     */
+    public LatLng fromScreenLocation(PointF point) {
+        return mMapView.fromScreenLocation(point);
+    }
+
+    /**
+     * Gets a projection of the viewing frustum for converting between screen coordinates and
+     * geo-latitude/longitude coordinates.
+     *
+     * @return The projection of the viewing frustum in its current state.
+     */
+    public VisibleRegion getVisibleRegion() {
+        LatLngBounds.Builder builder = new LatLngBounds.Builder();
+
+        int viewportWidth = mMapView.getWidth();
+        int viewportHeight = mMapView.getHeight();
+
+        LatLng topLeft = fromScreenLocation(new PointF(0, 0));
+        LatLng topRight = fromScreenLocation(new PointF(viewportWidth, 0));
+        LatLng bottomRight = fromScreenLocation(new PointF(viewportWidth, viewportHeight));
+        LatLng bottomLeft = fromScreenLocation(new PointF(0, viewportHeight));
+
+        builder.include(topLeft)
+                .include(topRight)
+                .include(bottomRight)
+                .include(bottomLeft);
+
+        return new VisibleRegion(topLeft,topRight,bottomLeft,bottomRight,builder.build());
+    }
+
+    /**
+     * Returns a screen location that corresponds to a geographical coordinate (LatLng).
+     * The screen location is in screen pixels (not display pixels) relative to the top left
+     * of the map (not of the whole screen).
+     *
+     * @param location A LatLng on the map to convert to a screen location.
+     * @return A Point representing the screen location in screen pixels.
+     */
+    public PointF toScreenLocation(LatLng location) {
+        return mMapView.toScreenLocation(location);
+    }
+}