Add a RAII wrapper around pngdec (#15)

* Add a RAII wrapper around pngdec

Author: CelliesProjects

src/OpenStreetMap-esp32.cpp

@@ -383,10 +383,10 @@ bool OpenStreetMap::fetchTile(CachedTile &tile, uint32_t x, uint32_t y, uint8_t
         if (!buffer)
             return false;
 
-        const int16_t rc = png.openRAM(buffer.value()->get(), buffer.value()->size(), PNGDraw);
-        if (rc != PNG_SUCCESS)
+        PNGDecoderRAII png(PNGDraw);
+        if (!png.open(buffer.value()->get(), buffer.value()->size()))
         {
-            result = "PNG Decoder Error: " + String(rc);
+            result = "PNG Decoder Error";
             return false;
         }
 

src/OpenStreetMap-esp32.h

@@ -25,18 +25,16 @@
 #define OPENSTREETMAP_ESP32_H
 
 #include <Arduino.h>
-#include <HTTPClient.h>
 #include <WiFiClient.h>
 #include <SD.h>
 #include <vector>
 #include <optional>
-#include <memory>
 #include <LovyanGFX.hpp>
-#include <PNGdec.h>
 
 #include "CachedTile.h"
 #include "MemoryBuffer.h"
 #include "HTTPClientRAII.h"
+#include "pngdecRAII.h"
 
 constexpr uint16_t OSM_TILESIZE = 256;
 constexpr uint16_t OSM_TILE_TIMEOUT_MS = 2500;
@@ -77,7 +75,6 @@ class OpenStreetMap
 
     std::vector<CachedTile> tilesCache;
     uint16_t *currentTileBuffer = nullptr;
-    PNG png;
 
     uint16_t mapWidth = 320;
     uint16_t mapHeight = 240;

src/pngdecRAII.h

@@ -0,0 +1,79 @@
+/*
+    Copyright (c) 2025 Cellie https://github.com/CelliesProjects/OpenStreetMap-esp32
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+    SPDX-License-Identifier: MIT
+    */
+
+#ifndef PNGDEC_RAII_H
+#define PNGDEC_RAII_H
+
+#include <PNGdec.h>
+
+class PNGDecoderRAII
+{
+public:
+    explicit PNGDecoderRAII(PNG_DRAW_CALLBACK *drawCallback)
+        : callback(drawCallback), isOpen(false) {}
+
+    PNGDecoderRAII(const PNGDecoderRAII &) = delete;
+    PNGDecoderRAII &operator=(const PNGDecoderRAII &) = delete;
+
+    ~PNGDecoderRAII()
+    {
+        close();
+    }
+
+    bool open(uint8_t *pngData, size_t dataSize)
+    {
+        if (isOpen)
+            close();
+
+        int result = png.openRAM(pngData, dataSize, callback);
+        isOpen = (result == PNG_SUCCESS);
+        return isOpen;
+    }
+
+    int decode(void *pPriv = NULL, uint8_t options = 0)
+    {
+        if (!isOpen)
+            return PNG_INVALID_PARAMETER;
+
+        return png.decode(pPriv, options);
+    }
+
+    int getWidth() const { return png.getWidth(); }
+    int getHeight() const { return png.getHeight(); }
+
+    void close()
+    {
+        if (isOpen)
+        {
+            png.close();
+            isOpen = false;
+        }
+    }
+
+private:
+    PNGdec png;
+    PNG_DRAW_CALLBACK *callback;
+    bool isOpen;
+};
+
+#endif // PNGDEC_RAII_H