font_loader.cc

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#include "app/core/platform/font_loader.h"
 
#include <string>
#include <unordered_set>
#include <vector>
 
#include "absl/strings/str_format.h"
#include "app/gui/icons.h"
#include "imgui/imgui.h"
 
#ifdef _WIN32
#include <Windows.h>
 
int CALLBACK EnumFontFamExProc(const LOGFONT* lpelfe, const TEXTMETRIC* lpntme,
                               DWORD FontType, LPARAM lParam) {
  // Step 3: Load the font into ImGui
  ImGuiIO& io = ImGui::GetIO();
  io.Fonts->AddFontFromFileTTF(lpelfe->lfFaceName, 16.0f);
 
  return 1;
}
 
void LoadSystemFonts() {
  HKEY hKey;
  std::vector<std::string> fontPaths;
 
  // Open the registry key where fonts are listed
  if (RegOpenKeyEx(
          HKEY_LOCAL_MACHINE,
          TEXT("SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Fonts"), 0,
          KEY_READ, &hKey) == ERROR_SUCCESS) {
    DWORD valueCount;
    DWORD maxValueNameSize;
    DWORD maxValueDataSize;
 
    // Query the number of entries and the maximum size of the names and values
    RegQueryInfoKey(hKey, NULL, NULL, NULL, NULL, NULL, NULL, &valueCount,
                    &maxValueNameSize, &maxValueDataSize, NULL, NULL);
 
    char* valueName = new char[maxValueNameSize + 1];  // +1 for null terminator
    BYTE* valueData = new BYTE[maxValueDataSize + 1];  // +1 for null terminator
 
    // Enumerate all font entries
    for (DWORD i = 0; i < valueCount; i++) {
      DWORD valueNameSize = maxValueNameSize + 1;  // +1 for null terminator
      DWORD valueDataSize = maxValueDataSize + 1;  // +1 for null terminator
      DWORD valueType;
 
      // Clear buffers
      memset(valueName, 0, valueNameSize);
      memset(valueData, 0, valueDataSize);
 
      // Get the font name and file path
      if (RegEnumValue(hKey, i, valueName, &valueNameSize, NULL, &valueType,
                       valueData, &valueDataSize) == ERROR_SUCCESS) {
        if (valueType == REG_SZ) {
          // Add the font file path to the vector
          std::string fontPath(reinterpret_cast<char*>(valueData),
                               valueDataSize);
 
          fontPaths.push_back(fontPath);
        }
      }
    }
 
    delete[] valueName;
    delete[] valueData;
 
    RegCloseKey(hKey);
  }
 
  ImGuiIO& io = ImGui::GetIO();
 
  // List of common font face names
  static const std::unordered_set<std::string> commonFontFaceNames = {
      "arial",
      "times",
      "cour",
      "verdana",
      "tahoma",
      "comic",
      "Impact",
      "ariblk",
      "Trebuchet MS",
      "Georgia",
      "Palatino Linotype",
      "Lucida Sans Unicode",
      "Tahoma",
      "Lucida Console"};
 
  for (auto& fontPath : fontPaths) {
    // Check if the font path has a "C:\" prefix
    if (fontPath.substr(0, 2) != "C:") {
      // Add "C:\Windows\Fonts\" prefix to the font path
      fontPath = absl::StrFormat("C:\\Windows\\Fonts\\%s", fontPath.c_str());
    }
 
    // Check if the font file has a .ttf or .TTF extension
    std::string extension = fontPath.substr(fontPath.find_last_of(".") + 1);
    if (extension == "ttf" || extension == "TTF") {
      // Get the font face name from the font path
      std::string fontFaceName =
          fontPath.substr(fontPath.find_last_of("\\/") + 1);
      fontFaceName = fontFaceName.substr(0, fontFaceName.find_last_of("."));
 
      // Check if the font face name is in the common font face names list
      if (commonFontFaceNames.find(fontFaceName) != commonFontFaceNames.end()) {
        io.Fonts->AddFontFromFileTTF(fontPath.c_str(), 16.0f);
 
        // Merge icon set
        // Icon configuration
        static const ImWchar icons_ranges[] = {ICON_MIN_MD, 0xf900, 0};
        ImFontConfig icons_config;
        static const float ICON_FONT_SIZE = 18.0f;
        icons_config.MergeMode = true;
        icons_config.GlyphOffset.y = 5.0f;
        icons_config.GlyphMinAdvanceX = 13.0f;
        icons_config.PixelSnapH = true;
        io.Fonts->AddFontFromFileTTF(FONT_ICON_FILE_NAME_MD, ICON_FONT_SIZE,
                                     &icons_config, icons_ranges);
      }
    }
  }
}
 
#elif defined(__linux__)
 
void LoadSystemFonts() {
  // Load Linux System Fonts into ImGui
  // ...
}
 
#endif