add initial Font class

src/gui/Font.cc

@@ -0,0 +1,91 @@
+#include "Font.h"
+
+#define round_up_26_6(val) (((val) + 63) >> 6u)
+
+static FT_Library ft_library_handle;
+static bool ft_initialized;
+
+bool Initialize_FreeType()
+{
+    if (ft_initialized)
+    {
+        return true;
+    }
+
+    if (FT_Init_FreeType(&ft_library_handle) != 0)
+    {
+        return false;
+    }
+
+    ft_initialized = true;
+    return true;
+}
+
+bool Font::load(const char * fname, int size)
+{
+    if (!Initialize_FreeType())
+    {
+        return false;
+    }
+
+    if (FT_New_Face(ft_library_handle, fname, 0, &m_face) != 0)
+    {
+        return false;
+    }
+
+    FT_Set_Pixel_Sizes(m_face, 0, size);
+
+    return preload_glyphs();
+}
+
+bool Font::preload_glyphs()
+{
+    static const char preload_glyph_list[] = "HMgjqxy_|^";
+
+    int max_top = -9999;
+    int min_bottom = 9999;
+    m_advance = 0;
+
+    for (size_t i = 0u; i < sizeof(preload_glyph_list) - 1u; i++)
+    {
+        std::shared_ptr<Glyph> g = get_glyph(preload_glyph_list[i]);
+        if (g == NULL)
+        {
+            return false;
+        }
+        if (m_face->glyph->bitmap_top > max_top)
+        {
+            max_top = m_face->glyph->bitmap_top;
+        }
+        int bitmap_bottom = m_face->glyph->bitmap_top - m_face->glyph->bitmap.rows;
+        if (bitmap_bottom < min_bottom)
+        {
+            min_bottom = bitmap_bottom;
+        }
+        if (g->get_advance() > m_advance)
+        {
+            m_advance = g->get_advance();
+        }
+    }
+
+    m_line_height = round_up_26_6(m_face->size->metrics.height);
+    m_baseline_offset = (m_line_height - (max_top - min_bottom)) / 2 - min_bottom;
+
+    return true;
+}
+
+std::shared_ptr<Glyph> Font::get_glyph(FT_ULong character)
+{
+    auto it = m_glyphs.find(character);
+    if (it != m_glyphs.end())
+    {
+        return it->second;
+    }
+    std::shared_ptr<Glyph> glyph = std::make_shared<Glyph>();
+    if (!glyph->load(m_face, character))
+    {
+        glyph = nullptr;
+    }
+    m_glyphs[character] = glyph;
+    return glyph;
+}

src/gui/Font.h

@@ -0,0 +1,24 @@
+#ifndef FONT_H
+#define FONT_H
+
+#include <unordered_map>
+#include <memory>
+#include "Glyph.h"
+
+class Font
+{
+public:
+    bool load(const char * fname, int size);
+    std::shared_ptr<Glyph> get_glyph(FT_ULong character);
+
+protected:
+    bool preload_glyphs();
+
+    FT_Face m_face;
+    std::unordered_map<FT_ULong, std::shared_ptr<Glyph>> m_glyphs;
+    int m_advance;
+    int m_line_height;
+    int m_baseline_offset;
+};
+
+#endif