Start font reading support.

src/fonts/FontReader.h

@@ -0,0 +1,54 @@
+#pragma once
+
+#include <string>
+#include <memory>
+#include <vector>
+#include "IFont.h"
+#include "File.h"
+
+class File;
+
+class FontReader
+{
+public:
+    ~FontReader();
+    void setPath(const std::string& path);
+
+    std::unique_ptr<IFont> read();
+
+private:
+
+    struct OffsetSubtable
+    {
+        uint32_t scaler_type{0};
+        uint16_t num_tables{0};
+        uint16_t search_range{0};
+        uint16_t entry_selector{0};
+        uint16_t range_shift{0};
+    };
+
+    struct Table
+    {
+        std::string name;
+        unsigned checksum{0};
+        unsigned offset{0};
+        unsigned length{0};
+    };
+
+    bool readOffsetSubtable();
+    void logOffsetSubtable();
+    void logTable(const Table& table);
+
+    void readTableDirectory();
+
+    void readTable();
+    void readHeadTable();
+
+    unsigned mCurrentOffset{0};
+    OffsetSubtable mOffsetSubtable;
+    std::vector<Table> mTables;
+
+    std::unique_ptr<IFont> mWorkingFont;
+    std::unique_ptr<File> mFile;
+    std::string mPath;
+};