[core] OverscaledTileID::isChildOf should check wrap values.

Fixes issue #13478
mapbox · Nov 30, 2018 · f87ef3f · f87ef3f
1 parent 0151061
commit f87ef3f
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Showing 3 changed files with 10 additions and 2 deletions.
diff --git a/include/mbgl/tile/tile_id.hpp b/include/mbgl/tile/tile_id.hpp
@@ -181,7 +181,8 @@ inline uint32_t OverscaledTileID::overscaleFactor() const {
 }
 
 inline bool OverscaledTileID::isChildOf(const OverscaledTileID& rhs) const {
-    return overscaledZ > rhs.overscaledZ &&
+    return wrap == rhs.wrap &&
+           overscaledZ > rhs.overscaledZ &&
            (canonical == rhs.canonical || canonical.isChildOf(rhs.canonical));
 }
 

diff --git a/scripts/changelog_staging/tile-is-child.json b/scripts/changelog_staging/tile-is-child.json
@@ -0,0 +1,4 @@
+{
+  "core": "Fix OverscaledTileID::isChildOf to exclude tiles with different wrap. Incorrect child detection could cause flickering for symbols displaying in two wrapped world copies at the same time.",
+  "issue": 13478
+}
diff --git a/test/tile/tile_id.test.cpp b/test/tile/tile_id.test.cpp
@@ -186,6 +186,7 @@ TEST(TileID, Overscaled) {
     EXPECT_TRUE(OverscaledTileID(4, 2, 3).isChildOf(OverscaledTileID(3, 1, 1)));
     EXPECT_TRUE(OverscaledTileID(5, 0, { 4, 2, 3 }).isChildOf(OverscaledTileID(3, 1, 1)));
     EXPECT_TRUE(OverscaledTileID(6, 0, { 4, 2, 3 }).isChildOf(OverscaledTileID(3, 1, 1)));
+    EXPECT_FALSE(OverscaledTileID(6, -1, { 4, 2, 3 }).isChildOf(OverscaledTileID(3, 1, 1)));
     EXPECT_TRUE(OverscaledTileID(7, 0, { 4, 2, 3 }).isChildOf(OverscaledTileID(3, 1, 1)));
 
     EXPECT_FALSE(OverscaledTileID(2, 0, 0).isChildOf(OverscaledTileID(5, 0, { 4, 2, 3 })));
@@ -194,14 +195,16 @@ TEST(TileID, Overscaled) {
     EXPECT_FALSE(OverscaledTileID(5, 0, { 4, 2, 3 }).isChildOf(OverscaledTileID(5, 0, { 4, 2, 3 })));
     EXPECT_TRUE(OverscaledTileID(6, 0, { 4, 2, 3 }).isChildOf(OverscaledTileID(5, 0, { 4, 2, 3 })));
     EXPECT_TRUE(OverscaledTileID(7, 0, { 4, 2, 3 }).isChildOf(OverscaledTileID(5, 0, { 4, 2, 3 })));
+    EXPECT_FALSE(OverscaledTileID(7, 1, { 4, 2, 3 }).isChildOf(OverscaledTileID(5, 0, { 4, 2, 3 })));
 
     EXPECT_FALSE(OverscaledTileID(2, 0, 0).isChildOf(OverscaledTileID(6, 0, { 4, 2, 3 })));
     EXPECT_FALSE(OverscaledTileID(3, 1, 1).isChildOf(OverscaledTileID(6, 0, { 4, 2, 3 })));
     EXPECT_FALSE(OverscaledTileID(4, 2, 3).isChildOf(OverscaledTileID(6, 0, { 4, 2, 3 })));
     EXPECT_FALSE(OverscaledTileID(5, 0, { 4, 2, 3 }).isChildOf(OverscaledTileID(6, 0, { 4, 2, 3 })));
     EXPECT_FALSE(OverscaledTileID(6, 0, { 4, 2, 3 }).isChildOf(OverscaledTileID(6, 0, { 4, 2, 3 })));
     EXPECT_TRUE(OverscaledTileID(7, 0, { 4, 2, 3 }).isChildOf(OverscaledTileID(6, 0, { 4, 2, 3 })));
-
+    EXPECT_FALSE(OverscaledTileID(7, 0, { 4, 2, 3 }).isChildOf(OverscaledTileID(6, -1, { 4, 2, 3 })));
+
     EXPECT_FALSE(OverscaledTileID(2, 0, 0).isChildOf(OverscaledTileID(5, 0, { 4, 0, 0 })));
     EXPECT_FALSE(OverscaledTileID(3, 1, 1).isChildOf(OverscaledTileID(5, 0, { 4, 0, 0 })));
     EXPECT_FALSE(OverscaledTileID(4, 2, 3).isChildOf(OverscaledTileID(5, 0, { 4, 0, 0 })));