Small png cleaning.

src/image/PngWriter.h

@@ -9,6 +9,7 @@
 using Path = std::filesystem::path;
 
 class BitStream;
+class BufferBitStream;
 class File;
 
 class PngWriter
@@ -27,6 +28,10 @@ private:
     void writeSignature();
     void writeHeader();
 
+    void writeDataChunks(const BufferBitStream& buffer);
+
+    void writeEndChunk();
+
     //void writeIDatChunk();
 
     Path mPath;