docs/FONTS.md

Fonts

The code in imgui.cpp embeds a copy of ‘ProggyClean.ttf’ (by Tristan Grimmer), a 13 pixels high, pixel-perfect font used by default. We embed it font in source code so you can use Dear ImGui without any file system access.

You may also load external .TTF/.OTF files. The files in this folder are suggested fonts, provided as a convenience.

Fonts are rasterized in a single texture at the time of calling either of

io.Fonts->GetTexDataAsAlpha8()
GetTexDataAsRGBA32()/Build()

Also read the FAQ: https://www.dearimgui.org/faq

If you have other loading/merging/adding fonts, you can post on the Dear ImGui Getting Started forum.

Index
Readme First
Using Icons
Fonts Loading Instructions
FreeType Rasterizer, Small Font Sizes
Building Custom Glyph Ranges
Using Custom Colorful Icons
Embedding Fonts In Source Code
Credits/Licenses For Fonts Included In This Folder
Font Links

Readme First

You can use the style editor ImGui::ShowStyleEditor() in the “Fonts” section to browse your fonts and understand what's going on if you have an issue.
Make sure your font ranges data are persistent (available during the call to GetTexDataAsAlpha8()/GetTexDataAsRGBA32()/Build().
Use C++11 u8“my text” syntax to encode literal strings as UTF-8. e.g.:
```
  u8"hello"
  u8"こんにちは"   // this will be encoded as UTF-8
```
If you want to include a backslash \ character in your string literal, you need to double them e.g. “folder\\filename”.
Please use the Discourse forum and not the Github issue tracker for basic font loading questions.

Using Icons

Using an icon font (such as FontAwesome or OpenFontIcons) is an easy and practical way to use icons in your Dear ImGui application.
A common pattern is to merge the icon font within your main font, so you can embed icons directly from your strings without having to change fonts back and forth.
To refer to the icon UTF-8 codepoints from your C++ code, you may use those headers files created by Juliette Foucaut: https://github.com/juliettef/IconFontCppHeaders

The C++11 version of those files uses the u8"" utf-8 encoding syntax + \u

#define ICON_FA_SEARCH u8"\uf002"

The pre-C++11 version has the values directly encoded as utf-8:

#define ICON_FA_SEARCH "\xEF\x80\x82"

Example Setup:

  // Merge icons into default tool font
  #include "IconsFontAwesome.h"
  ImGuiIO& io = ImGui::GetIO();
  io.Fonts->AddFontDefault();

  ImFontConfig config;
  config.MergeMode = true;
  config.GlyphMinAdvanceX = 13.0f; // Use if you want to make the icon monospaced
  static const ImWchar icon_ranges[] = { ICON_MIN_FA, ICON_MAX_FA, 0 };
  io.Fonts->AddFontFromFileTTF("fonts/fontawesome-webfont.ttf", 13.0f, &config, icon_ranges);

Example Usage:

  // Usage, e.g.
  ImGui::Text("%s among %d items", ICON_FA_SEARCH, count);
  ImGui::Button(ICON_FA_SEARCH " Search");
  // C string _literals_ can be concatenated at compilation time, e.g. "hello" " world"
  // ICON_FA_SEARCH is defined as a string literal so this is the same as "A" "B" becoming "AB"

See Links below for other icons fonts and related tools.

Font Loading Instructions

Load default font:

  ImGuiIO& io = ImGui::GetIO();
  io.Fonts->AddFontDefault();

Load .TTF/.OTF file with:

  ImGuiIO& io = ImGui::GetIO();
  ImFont* font1 = io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels);
  ImFont* font2 = io.Fonts->AddFontFromFileTTF("anotherfont.otf", size_pixels);

  // Select font at runtime
  ImGui::Text("Hello");	// use the default font (which is the first loaded font)
  ImGui::PushFont(font2);
  ImGui::Text("Hello with another font");
  ImGui::PopFont();

For advanced options create a ImFontConfig structure and pass it to the AddFont function (it will be copied internally):

  ImFontConfig config;
  config.OversampleH = 2;
  config.OversampleV = 1;
  config.GlyphExtraSpacing.x = 1.0f;
  ImFont* font = io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels, &config);

Read about oversampling here

If you have very large number of glyphs or multiple fonts, the texture may become too big for your graphics API.
The typical result of failing to upload a texture is if every glyphs appears as white rectangles.
In particular, using a large range such as GetGlyphRangesChineseSimplifiedCommon() is not recommended unless you set OversampleH/OversampleV to 1 and use a small font size.
Mind the fact that some graphics drivers have texture size limitation.
If you are building a PC application, mind the fact that your users may use hardware with lower limitations than yours.

Some solutions:

Reduce glyphs ranges by calculating them from source localization data. You can use ImFontGlyphRangesBuilder for this purpose, this will be the biggest win!
You may reduce oversampling, e.g. config.OversampleH = config.OversampleV = 1, this will largely reduce your texture size.
Set io.Fonts.TexDesiredWidth to specify a texture width to minimize texture height (see comment in ImFontAtlas::Build function).
Set io.Fonts.Flags |= ImFontAtlasFlags_NoPowerOfTwoHeight; to disable rounding the texture height to the next power of two.

Combine two fonts into one:

  // Load a first font
  ImFont* font = io.Fonts->AddFontDefault();

  // Add character ranges and merge into the previous font
  // The ranges array is not copied by the AddFont* functions and is used lazily
  // so ensure it is available at the time of building or calling GetTexDataAsRGBA32().
  static const ImWchar icons_ranges[] = { 0xf000, 0xf3ff, 0 }; // Will not be copied by AddFont* so keep in scope.
  ImFontConfig config;
  config.MergeMode = true;
  io.Fonts->AddFontFromFileTTF("DroidSans.ttf", 18.0f, &config, io.Fonts->GetGlyphRangesJapanese());
  io.Fonts->AddFontFromFileTTF("fontawesome-webfont.ttf", 18.0f, &config, icons_ranges);
  io.Fonts->Build();

Add a fourth parameter to bake specific font ranges only:

  // Basic Latin, Extended Latin
  io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels, NULL, io.Fonts->GetGlyphRangesDefault());

  // Default + Selection of 2500 Ideographs used by Simplified Chinese
  io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels, NULL, io.Fonts->GetGlyphRangesChineseSimplifiedCommon());

  // Default + Hiragana, Katakana, Half-Width, Selection of 1946 Ideographs
  io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels, NULL, io.Fonts->GetGlyphRangesJapanese());

See Building Custom Glyph Ranges section to create your own ranges. Offset font vertically by altering the io.Font->DisplayOffset value:

  ImFont* font = io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels);
  font->DisplayOffset.y = 1;   // Render 1 pixel down

Freetype Rasterizer, Small Font Sizes

Dear ImGui uses imstb_truetype.h to rasterize fonts (with optional oversampling). This technique and its implementation are not ideal for fonts rendered at small sizes, which may appear a little blurry or hard to read.
There is an implementation of the ImFontAtlas builder using FreeType that you can use in the misc/freetype/ folder.
FreeType supports auto-hinting which tends to improve the readability of small fonts.

Note

This code currently creates textures that are unoptimally too large (could be fixed with some work).
Also note that correct sRGB space blending will have an important effect on your font rendering quality.

Building Custom Glyph Ranges

You can use the ImFontGlyphRangesBuilder helper to create glyph ranges based on text input. For example: for a game where your script is known, if you can feed your entire script to it and only build the characters the game needs.

  ImVector<ImWchar> ranges;
  ImFontGlyphRangesBuilder builder;
  builder.AddText("Hello world");                        // Add a string (here "Hello world" contains 7 unique characters)
  builder.AddChar(0x7262);                               // Add a specific character
  builder.AddRanges(io.Fonts->GetGlyphRangesJapanese()); // Add one of the default ranges
  builder.BuildRanges(&ranges);                          // Build the final result (ordered ranges with all the unique characters submitted)

  io.Fonts->AddFontFromFileTTF("myfontfile.ttf", size_in_pixels, NULL, ranges.Data);
  io.Fonts->Build();                                     // Build the atlas while 'ranges' is still in scope and not deleted.

Using Custom Colorful Icons

(This is a BETA api, use if you are familiar with dear imgui and with your rendering back-end)

You can use the ImFontAtlas::AddCustomRect() and ImFontAtlas::AddCustomRectFontGlyph() api to register rectangles that will be packed into the font atlas texture. Register them before building the atlas, then call Build().
You can then use ImFontAtlas::GetCustomRectByIndex(int) to query the position/size of your rectangle within the texture, and blit/copy any graphics data of your choice into those rectangles.

Pseudo-code:

  // Add font, then register two custom 13x13 rectangles mapped to glyph 'a' and 'b' of this font
  ImFont* font = io.Fonts->AddFontDefault();
  int rect_ids[2];
  rect_ids[0] = io.Fonts->AddCustomRectFontGlyph(font, 'a', 13, 13, 13+1);
  rect_ids[1] = io.Fonts->AddCustomRectFontGlyph(font, 'b', 13, 13, 13+1);

  // Build atlas
  io.Fonts->Build();

  // Retrieve texture in RGBA format
  unsigned char* tex_pixels = NULL;
  int tex_width, tex_height;
  io.Fonts->GetTexDataAsRGBA32(&tex_pixels, &tex_width, &tex_height);

  for (int rect_n = 0; rect_n < IM_ARRAYSIZE(rect_ids); rect_n++)
  {
      int rect_id = rects_ids[rect_n];
      if (const ImFontAtlas::CustomRect* rect = io.Fonts->GetCustomRectByIndex(rect_id))
      {
          // Fill the custom rectangle with red pixels (in reality you would draw/copy your bitmap data here!)
          for (int y = 0; y < rect->Height; y++)
          {
              ImU32* p = (ImU32*)tex_pixels + (rect->Y + y) * tex_width + (rect->X);
              for (int x = rect->Width; x > 0; x--)
                  *p++ = IM_COL32(255, 0, 0, 255);
          }
      }
  }

Embedding Fonts In Source Code

Compile and use ‘binary_to_compressed_c.cpp’ to create a compressed C style array that you can embed in source code.
See the documentation in binary_to_compressed_c.cpp for instruction on how to use the tool.
You may find a precompiled version binary_to_compressed_c.exe for Windows instead of demo binaries package (see README).
The tool can optionally output Base85 encoding to reduce the size of source code but the read-only arrays in the actual binary will be about 20% bigger.

Then load the font with: ImFont* font = io.Fonts->AddFontFromMemoryCompressedTTF(compressed_data, compressed_data_size, size_pixels, ...); or ImFont* font = io.Fonts- AddFontFromMemoryCompressedBase85TTF(compressed_data_base85, size_pixels, ...);

Credits/Licenses For Fonts Included In This Folder

Roboto-Medium.ttf

Apache License 2.0 by Christian Robertson https://fonts.google.com/specimen/Roboto

Cousine-Regular.ttf

DroidSans.ttf

ProggyClean.ttf

Font Links

ICON FONTS

C/C++ header for icon fonts (#define with code points to use in source code string literals) https://github.com/juliettef/IconFontCppHeaders

FontAwesome https://fortawesome.github.io/Font-Awesome

OpenFontIcons https://github.com/traverseda/OpenFontIcons

Google Icon Fonts https://design.google.com/icons/

Kenney Icon Font (Game Controller Icons) https://github.com/nicodinh/kenney-icon-font

IcoMoon - Custom Icon font builder https://icomoon.io/app

REGULAR FONTS

Google Noto Fonts (worldwide languages) https://www.google.com/get/noto/

Open Sans Fonts https://fonts.google.com/specimen/Open+Sans

(Japanese) M+ fonts by Coji Morishita are free http://mplus-fonts.sourceforge.jp/mplus-outline-fonts/index-en.html

MONOSPACE FONTS

(Pixel Perfect) Proggy Fonts, by Tristan Grimmer http://www.proggyfonts.net or http://upperbounds.net

(Pixel Perfect) Sweet16, Sweet16 Mono, by Martin Sedlak (Latin + Supplemental + Extended A) https://github.com/kmar/Sweet16Font Also include .inl file to use directly in dear imgui.

Google Noto Mono Fonts https://www.google.com/get/noto/

Typefaces for source code beautification https://github.com/chrissimpkins/codeface

Programmation fonts http://s9w.github.io/font_compare/

Inconsolata http://www.levien.com/type/myfonts/inconsolata.html

Adobe Source Code Pro: Monospaced font family for user interface and coding environments https://github.com/adobe-fonts/source-code-pro

Monospace/Fixed Width Programmer's Fonts http://www.lowing.org/fonts/

Or use Arial Unicode or other Unicode fonts provided with Windows for full characters coverage (not sure of their licensing).