Further compression and png work.

src/compression/ZlibEncoder.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include "AbstractEncoder.h"
+
+#include <memory>
+#include <vector>
+
+class ZlibEncoder : public AbstractEncoder
+{
+
+public:
+    ZlibEncoder(BitStream* inputStream, BitStream* outputStream);
+    ~ZlibEncoder();
+
+    void setCompressionMethod(unsigned char method);
+
+    void setExtraFlags(unsigned char extraFlags);
+
+    bool encode() override;
+
+    bool decode() override;
+
+private:
+    unsigned char mCmf{0};
+    unsigned char mFlg{0};
+    unsigned char mCompressionMethod{8};
+    unsigned char mCompressionInfo{0};
+    unsigned char mFlagCheck{0};
+    unsigned char mFlagDict{0};
+    unsigned char mFlagLevel{0};
+    unsigned char mCheckValue{0};
+
+    std::unique_ptr<AbstractEncoder> mWorkingEncoder;
+};