add Glyph class

src/gui/Glyph.cc

@@ -0,0 +1,52 @@
+#include "Glyph.h"
+
+#define round_up_26_6(val) (((val) + 63) >> 6u)
+
+bool Glyph::load(FT_Face face, FT_ULong char_code)
+{
+    if (FT_Load_Char(face, char_code, FT_LOAD_RENDER) != 0)
+        return false;
+
+    m_texture = glcxx::Texture::create();
+    m_texture->bind(GL_TEXTURE_2D);
+    int width = face->glyph->bitmap.width;
+    int rounded_width = glcxx::Texture::next_power_of_2(width);
+    int height = face->glyph->bitmap.rows;
+    int rounded_height = glcxx::Texture::next_power_of_2(height);
+    m_advance = round_up_26_6(face->glyph->advance.x);
+    uint8_t * texture = new uint8_t[rounded_width * rounded_height];
+    memset(texture, 0, rounded_width * rounded_height);
+    for (int i = 0; i < height; i++)
+    {
+        memcpy(&texture[rounded_width * i],
+               &face->glyph->bitmap.buffer[width * (height - i - 1)],
+               width);
+    }
+
+    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, rounded_width, rounded_height, 0, GL_ALPHA, GL_UNSIGNED_BYTE, texture);
+    delete[] texture;
+
+    m_array = glcxx::Array::create();
+    m_array->bind();
+
+    int left = face->glyph->bitmap_left;
+    int top = face->glyph->bitmap_top;
+    float s_max = width / (float)rounded_width;
+    float t_max = height / (float)rounded_height;
+    m_buffer = glcxx::Buffer::create(GL_ARRAY_BUFFER, GL_STATIC_DRAW, {
+        (GLfloat)left, (GLfloat)(top - height),           0.0,   0.0,
+        (GLfloat)(left + width), (GLfloat)(top - height), s_max, 0.0,
+        (GLfloat)left, (GLfloat)top,                      0.0,   t_max,
+        (GLfloat)(left + width), (GLfloat)top,            s_max, t_max,
+    });
+
+    glEnableVertexAttribArray(0);
+    glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
+
+    return true;
+}

src/gui/Glyph.h

@@ -0,0 +1,26 @@
+#ifndef GLYPH_H
+#define GLYPH_H
+
+#include <ft2build.h>
+#include FT_FREETYPE_H
+#include "glcxx.hpp"
+
+class Glyph
+{
+public:
+    bool load(FT_Face face, FT_ULong char_code);
+    int get_advance() { return m_advance; }
+    void render()
+    {
+        m_array->bind();
+        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    }
+
+protected:
+    int m_advance;
+    std::shared_ptr<glcxx::Texture> m_texture;
+    std::shared_ptr<glcxx::Buffer> m_buffer;
+    std::shared_ptr<glcxx::Array> m_array;
+};
+
+#endif