[core] re-assign ids when lng jumps to avoid flicker

1 files changed, 7 insertions, 2 deletions

diff --git a/include/mbgl/tile/tile_id.hpp b/include/mbgl/tile/tile_id.hpp
index 3b52596f6c..dd2fba573d 100644
--- a/include/mbgl/tile/tile_id.hpp
+++ b/include/mbgl/tile/tile_id.hpp
@@ -85,9 +85,10 @@ public:
     std::array<UnwrappedTileID, 4> children() const;
     OverscaledTileID overscaleTo(uint8_t z) const;
     float pixelsToTileUnits(float pixelValue, float zoom) const;
+    UnwrappedTileID unwrapTo(int16_t wrap);
 
-    const int16_t wrap;
-    const CanonicalTileID canonical;
+    int16_t wrap;
+    CanonicalTileID canonical;
 };
 
 ::std::ostream& operator<<(::std::ostream& os, const UnwrappedTileID& rhs);
@@ -220,6 +221,10 @@ inline bool UnwrappedTileID::operator<(const UnwrappedTileID& rhs) const {
     return std::tie(wrap, canonical) < std::tie(rhs.wrap, rhs.canonical);
 }
 
+inline UnwrappedTileID UnwrappedTileID::unwrapTo(int16_t newWrap) {
+    return { newWrap, canonical };
+}
+
 inline bool UnwrappedTileID::isChildOf(const UnwrappedTileID& parent) const {
     return wrap == parent.wrap && canonical.isChildOf(parent.canonical);
 }