Download tiles in a separate function (#9)

* Downloading tiles to a separate function

Author: CelliesProjects

src/OpenStreetMap-esp32.cpp

@@ -261,22 +261,11 @@ bool OpenStreetMap::fetchMap(LGFX_Sprite &mapSprite, double longitude, double la
         }
     }
 
-    // normalize the coordinates
     longitude = fmod(longitude + 180.0, 360.0) - 180.0;
     latitude = std::clamp(latitude, -90.0, 90.0);
 
     tileList requiredTiles;
     computeRequiredTiles(longitude, latitude, zoom, requiredTiles);
-
-#define SHOW_REQUIRED_TILES false
-#if defined(SHOW_REQUIRED_TILES) && (SHOW_REQUIRED_TILES == true)
-    log_i("Required Tiles:");
-    for (size_t i = 0; i < requiredTiles.size(); ++i)
-    {
-        log_i("    Tile [%zu]: X=%d, Y=%d", i, requiredTiles[i].first, requiredTiles[i].second);
-    }
-#endif
-
     if (tilesCache.capacity() < requiredTiles.size())
     {
         log_e("Caching error: Need %i cache slots, but only %i are provided", requiredTiles.size(), tilesCache.capacity());
@@ -316,104 +305,108 @@ bool OpenStreetMap::readTileDataToBuffer(WiFiClient *stream, MemoryBuffer &buffe
     return true;
 }
 
-bool OpenStreetMap::downloadAndDecodeTile(CachedTile &tile, uint32_t x, uint32_t y, uint8_t zoom, String &result)
+std::optional<std::unique_ptr<MemoryBuffer>> OpenStreetMap::downloadTile(const String &url, String &result, size_t &size)
 {
-    const uint32_t worldTileWidth = 1 << zoom;
-    if (x >= worldTileWidth || y >= worldTileWidth)
-    {
-        result = "Out of range tile coordinates";
-        return false;
-    }
-
-    const String url = "https://tile.openstreetmap.org/" + String(zoom) + "/" + String(x) + "/" + String(y) + ".png";
-
     HTTPClient http;
     http.setUserAgent("OpenStreetMap-esp32/1.0 (+https://github.com/CelliesProjects/OpenStreetMap-esp32)");
     if (!http.begin(url))
     {
         result = "Failed to initialize HTTP client";
-        return false;
+        return std::nullopt;
     }
 
     const int httpCode = http.GET();
     if (httpCode != HTTP_CODE_OK)
     {
         http.end();
-
-        if (httpCode == HTTP_CODE_NOT_FOUND)
-        {
-            result = "HTTP Error 404 - not found tile " + String(x) + "," + String(y) + "," + String(zoom);
-            return false;
-        }
-
         result = "HTTP Error: " + String(httpCode);
-        return false;
+        return std::nullopt;
     }
 
     const size_t contentSize = http.getSize();
     if (contentSize < 1)
     {
         http.end();
         result = "Empty or chunked response";
-        return false;
+        return std::nullopt;
     }
 
     WiFiClient *stream = http.getStreamPtr();
     if (!stream)
     {
         http.end();
         result = "Failed to get HTTP stream";
-        return false;
+        return std::nullopt;
     }
 
-    MemoryBuffer buffer(contentSize);
-    if (!buffer.isAllocated())
+    auto buffer = std::make_unique<MemoryBuffer>(contentSize);
+    if (!buffer->isAllocated())
     {
         http.end();
         result = "Failed to allocate buffer";
-        return false;
+        return std::nullopt;
     }
 
-    if (!readTileDataToBuffer(stream, buffer, contentSize, result))
+    if (!readTileDataToBuffer(stream, *buffer, contentSize, result))
     {
         http.end();
-        log_e("%s", result.c_str());
-        return false;
+        return std::nullopt;
     }
 
     http.end();
+    size = contentSize;
+    result = "Downloaded tile " + url;
+    return buffer;
+}
 
-    const int16_t rc = png.openRAM(buffer.get(), contentSize, PNGDraw);
-    if (rc != PNG_SUCCESS)
+bool OpenStreetMap::downloadAndDecodeTile(CachedTile &tile, uint32_t x, uint32_t y, uint8_t zoom, String &result)
+{
+    const uint32_t worldTileWidth = 1 << zoom;
+    if (x >= worldTileWidth || y >= worldTileWidth)
     {
-        result = "PNG Decoder Error: " + String(rc);
+        result = "Out of range tile coordinates";
         return false;
     }
 
-    if (png.getWidth() != OSM_TILESIZE || png.getHeight() != OSM_TILESIZE)
+    const String url = "https://tile.openstreetmap.org/" + String(zoom) + "/" + String(x) + "/" + String(y) + ".png";
+
     {
-        result = "Unexpected tile size: w=" + String(png.getWidth()) + " h=" + String(png.getWidth());
-        return false;
-    }
+        size_t contentSize;
+        auto buffer = downloadTile(url, result, contentSize);
+        if (!buffer)
+            return false;
 
-    currentInstance = this;
-    currentTileBuffer = tile.buffer;
-    const int decodeResult = png.decode(0, PNG_FAST_PALETTE);
-    currentTileBuffer = nullptr;
-    currentInstance = nullptr;
+        const int16_t rc = png.openRAM(buffer.value()->get(), contentSize, PNGDraw);
+        if (rc != PNG_SUCCESS)
+        {
+            result = "PNG Decoder Error: " + String(rc);
+            return false;
+        }
 
-    if (decodeResult != PNG_SUCCESS)
-    {
-        result = "Decoding " + url + " failed with code: " + String(decodeResult);
-        tile.valid = false;
-        return false;
+        if (png.getWidth() != OSM_TILESIZE || png.getHeight() != OSM_TILESIZE)
+        {
+            result = "Unexpected tile size: w=" + String(png.getWidth()) + " h=" + String(png.getWidth());
+            return false;
+        }
+
+        currentInstance = this;
+        currentTileBuffer = tile.buffer;
+        const int decodeResult = png.decode(0, PNG_FAST_PALETTE);
+        currentTileBuffer = nullptr;
+        currentInstance = nullptr;
+
+        if (decodeResult != PNG_SUCCESS)
+        {
+            result = "Decoding " + url + " failed with code: " + String(decodeResult);
+            tile.valid = false;
+            return false;
+        }
     }
 
     tile.x = x;
     tile.y = y;
     tile.z = zoom;
     tile.valid = true;
-
     result = "Added: " + url;
     return true;
 }

src/OpenStreetMap-esp32.h

@@ -29,6 +29,8 @@
 #include <WiFiClient.h>
 #include <SD.h>
 #include <vector>
+#include <optional>
+#include <memory>
 #include <LovyanGFX.hpp>
 #include <PNGdec.h>
 
@@ -67,6 +69,7 @@ class OpenStreetMap
     void updateCache(const tileList &requiredTiles, uint8_t zoom);
     bool isTileCached(uint32_t x, uint32_t y, uint8_t z);
     CachedTile *findUnusedTile(const tileList &requiredTiles, uint8_t zoom);
+    std::optional<std::unique_ptr<MemoryBuffer>> downloadTile(const String &url, String &result, size_t &size);
     bool downloadAndDecodeTile(CachedTile &tile, uint32_t x, uint32_t y, uint8_t zoom, String &result);
     bool readTileDataToBuffer(WiFiClient *stream, MemoryBuffer &buffer, size_t contentSize, String &result);
     bool composeMap(LGFX_Sprite &mapSprite, const tileList &requiredTiles, uint8_t zoom);