[android] Add getVisibleCoordinateBounds method.

2 files changed, 61 insertions, 0 deletions

diff --git a/platform/android/src/native_map_view.cpp b/platform/android/src/native_map_view.cpp
index 554a59de76..db3fbddeeb 100644
--- a/platform/android/src/native_map_view.cpp
+++ b/platform/android/src/native_map_view.cpp
@@ -529,6 +529,64 @@ void NativeMapView::setVisibleCoordinateBounds(JNIEnv& env, const jni::Array<jni
     map->easeTo(cameraOptions, animationOptions);
 }
 
+void NativeMapView::getVisibleCoordinateBounds(JNIEnv& env,
+                                     jint screenWidth,
+                                     jint screenHeight,
+                                     jni::Array<jdouble>& output,
+                                     jfloat pixelRatio_) {
+    mbgl::LatLng southEast = map->latLngForPixel(mbgl::ScreenCoordinate(screenWidth / pixelRatio_, screenHeight / pixelRatio_));
+    mbgl::LatLng northEast = map->latLngForPixel(mbgl::ScreenCoordinate(screenWidth / pixelRatio_, 0.0));
+    mbgl::LatLng southWest = map->latLngForPixel(mbgl::ScreenCoordinate(0.0, screenHeight / pixelRatio_));
+    mbgl::LatLng northWest = map->latLngForPixel(mbgl::ScreenCoordinate(0.0, 0.0));
+    mbgl::LatLng center = map->latLngForPixel(mbgl::ScreenCoordinate(screenWidth / (2 * pixelRatio_), screenHeight / (2 * pixelRatio_)));
+
+    double latitudes[] = {southEast.latitude(), northEast.latitude(), southWest.latitude(), northWest.latitude()};
+    double longitudes[] = {southEast.longitude(), northEast.longitude(), southWest.longitude(), northWest.longitude()};
+
+    auto latitudeMinMax = std::minmax_element(std::begin(latitudes), std::end(latitudes));
+
+    double latNorth = *(latitudeMinMax.second);
+    double latSouth = *(latitudeMinMax.first);
+
+    double lonEast = -180.0;
+    double lonWest = 180.0;
+    double centerLongitude = center.longitude();
+    auto longitudeMinMax = std::minmax_element(std::begin(longitudes), std::end(longitudes));
+
+    // check if the bounds is over dateline
+    if (std::abs(centerLongitude - (*(longitudeMinMax.first) + *(longitudeMinMax.second)) / 2) > 0.1) {
+        for (int i = 0; i < 4; i++) {
+            double longitude = longitudes[i];
+            if (longitude < 0) {
+                if (lonEast < longitude) {
+                    lonEast = longitude;
+                }
+            } else {
+                if (lonWest > longitude) {
+                    lonWest = longitude;
+                }
+            }
+        }
+    } else {
+        lonEast = *(longitudeMinMax.second);
+        lonWest = *(longitudeMinMax.first);
+    }
+
+    // lonEast should be no less than lonWest
+    lonEast = lonEast > lonWest ? lonEast : lonEast + 360;
+
+    std::vector<jdouble> buffer;
+    buffer.reserve(4);
+
+    // Order of the LatLngBounds: double latNorth, double lonEast, double latSouth, double lonWest
+    buffer.push_back(latNorth);
+    buffer.push_back(lonEast);
+    buffer.push_back(latSouth);
+    buffer.push_back(lonWest);
+
+    output.SetRegion<std::vector<jdouble>>(env, 0, buffer);
+}
+
 void NativeMapView::scheduleSnapshot(jni::JNIEnv&) {
     mapRenderer.requestSnapshot([&](PremultipliedImage image) {
         auto _env = android::AttachEnv();
@@ -1172,6 +1230,7 @@ void NativeMapView::registerNative(jni::JNIEnv& env) {
         METHOD(&NativeMapView::projectedMetersForLatLng, "nativeProjectedMetersForLatLng"),
         METHOD(&NativeMapView::pixelForLatLng, "nativePixelForLatLng"),
         METHOD(&NativeMapView::pixelsForLatLngs, "nativePixelsForLatLngs"),
+        METHOD(&NativeMapView::getVisibleCoordinateBounds, "nativeGetVisibleCoordinateBounds"),
         METHOD(&NativeMapView::latLngForProjectedMeters, "nativeLatLngForProjectedMeters"),
         METHOD(&NativeMapView::latLngForPixel, "nativeLatLngForPixel"),
         METHOD(&NativeMapView::latLngsForPixels, "nativeLatLngsForPixels"),
diff --git a/platform/android/src/native_map_view.hpp b/platform/android/src/native_map_view.hpp
index 622c454b7d..0823e53509 100755
--- a/platform/android/src/native_map_view.hpp
+++ b/platform/android/src/native_map_view.hpp
@@ -139,6 +139,8 @@ public:
 
     void setVisibleCoordinateBounds(JNIEnv&, const jni::Array<jni::Object<LatLng>>&, const jni::Object<RectF>&, jni::jdouble, jni::jlong);
 
+    void getVisibleCoordinateBounds(JNIEnv& env, jint screenWidth, jint screenHeight, jni::Array<jdouble>& output, jfloat pixelRatio_);
+
     void scheduleSnapshot(jni::JNIEnv&);
 
     jni::Local<jni::Object<CameraPosition>> getCameraPosition(jni::JNIEnv&);