Prevent duplicate tile fetch jobs (#106)

Avoid duplicate tile downloads at low zoom levels by reusing already queued jobs

* Prevents wrapping tiles from being redundantly fetched multiple times
* `makeJobList()` now checks if a tile is already queued and reuses its buffer
* Maintains 1:1 alignment between `requiredTiles` and `tilePointers`

Author: CelliesProjects

src/OpenStreetMap-esp32.cpp

@@ -225,15 +225,24 @@ void OpenStreetMap::makeJobList(const tileList &requiredTiles, std::vector<TileJ
         if (isTileCached(x, y, zoom, tilePointers)) // isTileCached will push_back a valid ptr if tile is cached
             continue;
 
+        // Check if this tile is already in the job list
+        auto existing = std::find_if(jobs.begin(), jobs.end(), [&](const TileJob &job)
+                                     { return job.x == x && job.y == static_cast<uint32_t>(y) && job.z == zoom; });
+        if (existing != jobs.end())
+        {
+            tilePointers.push_back(existing->tile->buffer); // reuse buffer from already queued job
+            continue;
+        }
+
         CachedTile *tileToReplace = findUnusedTile(requiredTiles, zoom);
         if (!tileToReplace)
         {
             tilePointers.push_back(nullptr); // again, keep 1:1 aligned
             continue;
         }
 
-        tilePointers.push_back(tileToReplace->buffer);                      // push_back the still-to-download tile ptr
-        jobs.push_back({x, static_cast<uint32_t>(y), zoom, tileToReplace}); // push_back tile ptr to the job list
+        tilePointers.push_back(tileToReplace->buffer);                      // store buffer for rendering
+        jobs.push_back({x, static_cast<uint32_t>(y), zoom, tileToReplace}); // queue job
     }
 }