From dbb42e741d29ab213f2a51fc8d9568c02f844647 Mon Sep 17 00:00:00 2001
From: fschildt <florian.schildt@protonmail.com>
Date: Sat, 27 Sep 2025 12:40:31 +0200
Subject: add font glyph drawing

---
 src/common/Font.cpp | 117 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/common/Font.hpp |  43 +++++++++++++++++++
 2 files changed, 160 insertions(+)
 create mode 100644 src/common/Font.cpp
 create mode 100644 src/common/Font.hpp

(limited to 'src/common')

diff --git a/src/common/Font.cpp b/src/common/Font.cpp
new file mode 100644
index 0000000..31a6720
--- /dev/null
+++ b/src/common/Font.cpp
@@ -0,0 +1,117 @@
+#include <common/Font.hpp>
+
+#include <fstream>
+#include <iostream>
+
+
+Font::~Font()
+{
+    Deinit();
+}
+
+
+bool
+Font::Init(const char* path, int font_size)
+{
+    std::ifstream file(path, std::ios::in|std::ios::binary|std::ios::ate);
+    if (!file.is_open()) {
+        return false;
+    }
+
+
+    std::streampos end = file.tellg();
+    size_t size = static_cast<size_t>(end);
+    char *content = new char[size + 1];
+
+    file.seekg(0, std::ios::beg);
+    file.read(content, end);
+    file.close();
+    content[size] = '\0';
+
+
+    // set font info
+    if (!stbtt_InitFont(&m_font_info, (unsigned char*)content, 0))
+    {
+        std::cout << "stbtt_InitFont failed.\n";
+        printf("stbtt_InitFont failed\n");
+        delete[] content;
+        return false;
+    }
+
+
+    // font settings (scale + vmetrics)
+    float scale = stbtt_ScaleForPixelHeight(&m_font_info, (float)font_size);
+    int baseline, ascent, descent, line_gap;
+    stbtt_GetFontVMetrics(&m_font_info, &ascent, &descent, &line_gap);
+    baseline = int(scale * (float)-descent);
+    ascent   = int(scale * (float)ascent);
+    descent  = int(scale * (float)descent);
+    line_gap = int(scale * (float)line_gap);
+
+
+    m_font_scale = scale;
+    m_font_baseline = baseline;
+    m_font_yadvance = ascent - descent + line_gap;
+    m_file_content = content;
+
+
+    return true;
+}
+
+
+void
+Font::LoadGlyph(Glyph& glyph, uint32_t codepoint)
+{
+    int bbx0, bby0, bbx1, bby1;
+    stbtt_GetCodepointBitmapBox(&m_font_info, (int)codepoint, m_font_scale, m_font_scale, &bbx0, &bby0, &bbx1, &bby1);
+    int width = bbx1 - bbx0;
+    int height = bby1 - bby0;
+
+
+    size_t size = size_t(width * height);
+    uint8_t* bitmap_flipped = new uint8_t[size];
+    uint8_t* bitmap_correct = new uint8_t[size];
+
+
+    stbtt_MakeCodepointBitmap(&m_font_info, bitmap_flipped, width, height, width, m_font_scale, m_font_scale, (int)codepoint);
+
+    uint8_t* dest = bitmap_correct;
+    for (int y = 0; y < height; ++y)
+    {
+        uint8_t* src = bitmap_flipped + size_t((height-1-y)*width);
+        for (int x = 0; x < width; ++x)
+        {
+            *dest++ = *src++;
+        }
+    }
+    delete[] bitmap_flipped;
+
+    glyph.bitmap.width = width;
+    glyph.bitmap.height = height;
+    glyph.bitmap.pixels = std::unique_ptr<uint8_t>(bitmap_correct);
+
+
+    int xadvance;
+    int left_side_bearing;
+    stbtt_GetCodepointHMetrics(&m_font_info, (int)codepoint, &xadvance, &left_side_bearing);
+    xadvance          = (int)(m_font_scale * (float)xadvance);
+    left_side_bearing = (int)(m_font_scale * (float)left_side_bearing);
+
+
+    glyph.xoff = static_cast<int>(m_font_scale * (float)bbx0) + left_side_bearing;
+    glyph.yoff = -bby1;
+    glyph.xadvance = xadvance;
+
+}
+
+
+void
+Font::Deinit()
+{
+    if (m_file_content) {
+        delete[] m_file_content;
+        m_file_content = nullptr;
+    }
+}
+
+
diff --git a/src/common/Font.hpp b/src/common/Font.hpp
new file mode 100644
index 0000000..a594add
--- /dev/null
+++ b/src/common/Font.hpp
@@ -0,0 +1,43 @@
+#pragma once
+
+#include <filesystem>
+#include <stb_truetype.h>
+
+
+struct MonoBitmap {
+    int32_t width;
+    int32_t height;
+    std::unique_ptr<uint8_t> pixels;
+};
+
+
+struct Glyph {
+    int32_t xoff;
+    int32_t yoff;
+    int32_t xadvance;
+    MonoBitmap bitmap;
+};
+
+
+class Font {
+public:
+    ~Font();
+
+    bool Init(const char* path, int font_size);
+    void Deinit();
+
+    void LoadGlyph(Glyph& glyph, uint32_t codepoint);
+
+
+private:
+    const char* m_file_content = nullptr;
+
+    float m_font_scale;
+    int m_font_baseline;
+    int m_font_yadvance;
+
+    stbtt_fontinfo m_font_info;
+    Glyph m_glyphs['~' - ' ' + 1];
+};
+
+
-- 
cgit v1.2.3