Header writing to a separate function

src/OpenStreetMap-esp32.cpp

@@ -377,7 +377,7 @@ bool OpenStreetMap::downloadAndDecodeTile(CachedTile &tile, uint32_t x, uint32_t
     if (!readTileDataToBuffer(stream, buffer, contentSize, result))
     {
         http.end();
-        log_e("%s", result);
+        log_e("%s", result.c_str());
         return false;
     }
 
@@ -412,37 +412,8 @@ bool OpenStreetMap::downloadAndDecodeTile(CachedTile &tile, uint32_t x, uint32_t
     return true;
 }
 
-bool OpenStreetMap::saveMap(const char *filename, LGFX_Sprite &map, String &result, uint8_t sdPin, uint32_t frequency)
+bool OpenStreetMap::writeHeader(const LGFX_Sprite &map, File &file)
 {
-    log_i("Saving map as %s", filename);
-
-    if (!map.getBuffer())
-    {
-        result = "No data in map";
-        return false;
-    }
-
-    MemoryBuffer rowBuffer(map.width() * 3);
-    if (!rowBuffer.isAllocated())
-    {
-        result = "Row buffer allocation failed";
-        return false;
-    }
-
-    if (!SD.begin(sdPin, SPI, frequency))
-    {
-        result = "SD Card mount failed";
-        return false;
-    }
-
-    File file = SD.open(filename, FILE_WRITE);
-    if (!file)
-    {
-        result = "Failed to open file";
-        SD.end();
-        return false;
-    }
-
     // BMP Header (54 bytes)
     uint16_t bfType = 0x4D42;                              // "BM"
     uint32_t biSizeImage = map.width() * map.height() * 3; // 3 bytes per pixel (RGB888)
@@ -460,32 +431,57 @@ bool OpenStreetMap::saveMap(const char *filename, LGFX_Sprite &map, String &resu
     uint32_t biClrUsed = 0;
     uint32_t biClrImportant = 0;
 
-    // Write BMP header (Ensuring little-endian format)
-    auto writeLE = [&](uint32_t value, uint8_t size)
+    auto writeLE = [&](uint32_t value, uint8_t size) -> bool
     {
         for (uint8_t i = 0; i < size; i++)
-            file.write(static_cast<uint8_t>(value >> (8 * i)));
+            if (file.write(static_cast<uint8_t>(value >> (8 * i))) != 1)
+                return false;
+
+        return true;
     };
 
-    writeLE(bfType, 2);
-    writeLE(bfSize, 4);
-    writeLE(0, 2); // bfReserved
-    writeLE(0, 2);
-    writeLE(bfOffBits, 4);
-
-    writeLE(biSize, 4);
-    writeLE(biWidth, 4);
-    writeLE(biHeight, 4);
-    writeLE(biPlanes, 2);
-    writeLE(biBitCount, 2);
-    writeLE(biCompression, 4);
-    writeLE(biSizeImage, 4);
-    writeLE(biXPelsPerMeter, 4);
-    writeLE(biYPelsPerMeter, 4);
-    writeLE(biClrUsed, 4);
-    writeLE(biClrImportant, 4);
-
-    uint8_t *buf = rowBuffer.get();
+    bool success = true;
+
+    if (!(success &= writeLE(bfType, 2)))
+        return false;
+    if (!(success &= writeLE(bfSize, 4)))
+        return false;
+    if (!(success &= writeLE(0, 2)))
+        return false;
+    if (!(success &= writeLE(0, 2)))
+        return false;
+    if (!(success &= writeLE(bfOffBits, 4)))
+        return false;
+    if (!(success &= writeLE(biSize, 4)))
+        return false;
+    if (!(success &= writeLE(biWidth, 4)))
+        return false;
+    if (!(success &= writeLE(biHeight, 4)))
+        return false;
+    if (!(success &= writeLE(biPlanes, 2)))
+        return false;
+    if (!(success &= writeLE(biBitCount, 2)))
+        return false;
+    if (!(success &= writeLE(biCompression, 4)))
+        return false;
+    if (!(success &= writeLE(biSizeImage, 4)))
+        return false;
+    if (!(success &= writeLE(biXPelsPerMeter, 4)))
+        return false;
+    if (!(success &= writeLE(biYPelsPerMeter, 4)))
+        return false;
+    if (!(success &= writeLE(biClrUsed, 4)))
+        return false;
+    if (!(success &= writeLE(biClrImportant, 4)))
+        return false;
+
+    return success;
+}
+
+bool OpenStreetMap::writeMap(LGFX_Sprite &map, File &file, MemoryBuffer &buffer)
+{
+    uint8_t *buf = buffer.get();
+    const size_t size = buffer.size();
     for (uint16_t y = 0; y < map.height(); y++)
     {
         for (uint16_t x = 0; x < map.width(); x++)
@@ -499,7 +495,57 @@ bool OpenStreetMap::saveMap(const char *filename, LGFX_Sprite &map, String &resu
             buf[x * 3 + 1] = green8;
             buf[x * 3 + 2] = red8;
         }
-        file.write(buf, rowBuffer.size());
+        if (file.write(buf, size) != size)
+            return false;
+    }
+    return true;
+}
+
+bool OpenStreetMap::saveMap(const char *filename, LGFX_Sprite &map, String &result, uint8_t sdPin, uint32_t frequency)
+{
+    log_i("Saving map as %s", filename);
+
+    if (!map.getBuffer())
+    {
+        result = "No data in map";
+        return false;
+    }
+
+    MemoryBuffer rowBuffer(map.width() * 3);
+    if (!rowBuffer.isAllocated())
+    {
+        result = "Row buffer allocation failed";
+        return false;
+    }
+
+    if (!SD.begin(sdPin, SPI, frequency))
+    {
+        result = "SD Card mount failed";
+        return false;
+    }
+
+    File file = SD.open(filename, FILE_WRITE);
+    if (!file)
+    {
+        result = "Failed to open file";
+        SD.end();
+        return false;
+    }
+
+    if (!writeHeader(map, file))
+    {
+        result = "Failed to write bmp header";
+        file.close();
+        SD.end();
+        return false;
+    }
+
+    if (!writeMap(map, file, rowBuffer))
+    {
+        result = "Failed to write map data";
+        file.close();
+        SD.end();
+        return false;
     }
 
     file.close();

src/OpenStreetMap-esp32.h

@@ -70,6 +70,8 @@ class OpenStreetMap
     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);
+    bool writeHeader(const LGFX_Sprite &map, File &file);
+    bool writeMap(LGFX_Sprite &map, File &file, MemoryBuffer &buffer);
 
     std::vector<CachedTile> tilesCache;
     uint16_t *currentTileBuffer = nullptr;
@@ -84,7 +86,7 @@ class OpenStreetMap
     int32_t startTileIndexX = 0;
     int32_t startTileIndexY = 0;
 
-    uint16_t numberOfColums = 0;    
+    uint16_t numberOfColums = 0;
 };
 
 #endif