add Font::Glyph class

src/gui/Font.cc

@@ -1,5 +1,8 @@
 #include "Font.h"
 #include <iostream>
+#include <stdint.h>
+
+#define round_up_26_6(val) (((val) + 63) >> 6u)
 
 namespace jes
 {
@@ -26,6 +29,76 @@ namespace jes
 
         FT_Set_Pixel_Sizes(m_face, 0, size);
 
+        m_line_height = round_up_26_6(m_face->size->metrics.height);
+
+        m_loaded = true;
+        return true;
+    }
+
+    Font::GlyphRef Font::load_glyph(FT_ULong char_code)
+    {
+        GlyphRef glyph = new Glyph();
+        if (glyph->load(m_face, char_code))
+            return glyph;
+        return NULL;
+    }
+
+    Font::Glyph::Glyph()
+    {
+        m_loaded = false;
+    }
+
+    Font::Glyph::~Glyph()
+    {
+        if (m_loaded)
+        {
+            glDeleteTextures(1, &m_texture_id);
+        }
+    }
+
+    bool Font::Glyph::load(FT_Face face, FT_ULong char_code)
+    {
+        if (FT_Load_Char(face, char_code, FT_LOAD_RENDER) != 0)
+            return false;
+
+        int width = face->glyph->bitmap.width;
+        int height = face->glyph->bitmap.rows;
+        m_left = face->glyph->bitmap_left;
+        m_top = face->glyph->bitmap_top;
+        m_advance = round_up_26_6(face->glyph->advance.x);
+        uint8_t * texture = new uint8_t[width * height];
+        for (int i = 0; i < height; i++)
+        {
+            memcpy(&texture[width * i],
+                   &face->glyph->bitmap.buffer[width * (height - i - 1)],
+                   width);
+        }
+
+        glGenTextures(1, &m_texture_id);
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_2D, m_texture_id);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, width, height, 0, GL_ALPHA, GL_UNSIGNED_BYTE, texture);
+        delete[] texture;
+
+        float w = width - 1;
+        float h = height - 1;
+        float s = 1.0 / (width * 2);
+        float t = 1.0 / (height * 2);
+        GLfloat box[4][4] = {
+            {0, 0, s, t},
+            {w, 0, 1 - s, t},
+            {0, h, s, 1 - t},
+            {w, h, 1 - s, 1 - t},
+        };
+        glGenBuffers(1, &m_vbo_id);
+        glBindBuffer(GL_ARRAY_BUFFER, m_vbo_id);
+        glBufferData(GL_ARRAY_BUFFER, sizeof(box), box, GL_STATIC_DRAW);
+
         m_loaded = true;
         return true;
     }

src/gui/Font.h

@@ -4,20 +4,54 @@
 #include "jes/Ref.h"
 #include <ft2build.h>
 #include FT_FREETYPE_H
+#include "gl3w.h"
+#include <unordered_map>
 
 namespace jes
 {
     class Font
     {
     public:
+        class Glyph
+        {
+        public:
+            Glyph();
+            ~Glyph();
+            bool load(FT_Face face, FT_ULong char_code);
+            int get_top() { return m_top; }
+            int get_left() { return m_left; }
+            int get_advance() { return m_advance; }
+            void draw()
+            {
+                glBindTexture(GL_TEXTURE_2D, m_texture_id);
+                glEnableVertexAttribArray(0);
+                glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
+                glBindBuffer(GL_ARRAY_BUFFER, m_vbo_id);
+                glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+            }
+        protected:
+            bool m_loaded;
+            int m_top;
+            int m_left;
+            int m_advance;
+            GLuint m_texture_id;
+            GLuint m_vbo_id;
+        };
+        typedef Ref<Glyph> GlyphRef;
+
         Font();
         ~Font();
         bool load(FT_Library ft, const char * fname, size_t size);
-        int get_line_height() { return round_up_26_6(m_face->size->metrics.height); }
+        int get_line_height() { return m_line_height; }
+        int get_advance() { return m_advance; }
     protected:
-        int round_up_26_6(int val) { return (val + 63) >> 6u; }
+        GlyphRef load_glyph(FT_ULong char_code);
+
         FT_Face m_face;
+        int m_line_height;
+        int m_advance;
         bool m_loaded;
+        std::unordered_map<FT_ULong, GlyphRef> m_glyphs;
     };
 
     typedef Ref<Font> FontRef;