[core, ios, osx] Tilt around visual center point

The tilt gesture on both iOS and OS X now respects the content insets. On iOS, in user tracking mode, it additionally respects the user dot’s position if it’s aligned to the top or bottom of the view.

3 files changed, 18 insertions, 1 deletions

diff --git a/src/mbgl/map/map.cpp b/src/mbgl/map/map.cpp
index 51106db88b..a45a9ffaff 100644
--- a/src/mbgl/map/map.cpp
+++ b/src/mbgl/map/map.cpp
@@ -357,7 +357,11 @@ void Map::resetNorth(const Duration& duration) {
 #pragma mark - Pitch
 
 void Map::setPitch(double pitch, const Duration& duration) {
-    transform->setPitch(pitch * M_PI / 180, duration);
+    setPitch(pitch, {NAN, NAN}, duration);
+}
+
+void Map::setPitch(double pitch, const PrecisionPoint& anchor, const Duration& duration) {
+    transform->setPitch(pitch * M_PI / 180, anchor, duration);
     update(Update::Repaint);
 }
 
diff --git a/src/mbgl/map/transform.cpp b/src/mbgl/map/transform.cpp
index b4743c0719..208f9a089a 100644
--- a/src/mbgl/map/transform.cpp
+++ b/src/mbgl/map/transform.cpp
@@ -523,12 +523,17 @@ double Transform::getAngle() const {
 #pragma mark - Pitch
 
 void Transform::setPitch(double pitch, const Duration& duration) {
+    setPitch(pitch, {NAN, NAN}, duration);
+}
+
+void Transform::setPitch(double pitch, const PrecisionPoint& anchor, const Duration& duration) {
     if (std::isnan(pitch)) {
         return;
     }
 
     CameraOptions camera;
     camera.pitch = pitch;
+    camera.anchor = anchor;
     easeTo(camera, duration);
 }
 
diff --git a/src/mbgl/map/transform.hpp b/src/mbgl/map/transform.hpp
index bef6c6c87e..8c9ea08885 100644
--- a/src/mbgl/map/transform.hpp
+++ b/src/mbgl/map/transform.hpp
@@ -102,7 +102,15 @@ public:
     double getAngle() const;
 
     // Pitch
+    /** Sets the pitch angle.
+        @param angle The new pitch angle, measured in radians toward the
+            horizon. */
     void setPitch(double pitch, const Duration& = Duration::zero());
+    /** Sets the pitch angle, keeping the given point fixed within the view.
+        @param angle The new pitch angle, measured in radians toward the
+            horizon.
+        @param anchor A point relative to the top-left corner of the view. */
+    void setPitch(double pitch, const PrecisionPoint& anchor, const Duration& = Duration::zero());
     double getPitch() const;
 
     // North Orientation