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Docs: Initial draft of fonts documentation (#2861)

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dear imgui
FONTS DOCUMENTATION
Also read https://www.dearimgui.org/faq for more fonts related infos.
## 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.
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.
You may also load external .TTF/.OTF files. The files in this folder are suggested fonts, provided as a convenience.
Please read the FAQ: https://www.dearimgui.org/faq
Please use the Discord server: http://discord.dearimgui.org and not the Github issue tracker for basic font loading questions.
Fonts are rasterized in a single texture at the time of calling either of
- `io.Fonts->GetTexDataAsAlpha8()`
- `GetTexDataAsRGBA32()/Build()`
**Please read the FAQ:** https://www.dearimgui.org/faq
Please use the Discord server: http://discord.dearimgui.org and not the GitHub issue tracker for basic font loading questions.
---------------------------------------
INDEX:
---------------------------------------
- Readme First / FAQ
- Fonts Loading Instructions
- Using Icons
- Using FreeType rasterizer
- Building Custom Glyph Ranges
- Using custom colorful icons
- Embedding Fonts in Source Code
- Credits/Licences for fonts included in repository
- Fonts Links
| Index |
|:---------------------------------------|
| [Readme First](#readme-first) |
| [Using Icons](#using-icons) |
| [Fonts Loading Instructions](#font-loading-instructions) |
| [FreeType Rasterizer, Small Font Sizes](#freeType-rasterizer-small-font-sizes) |
| [Building Custom Glyph Ranges](#building-custom-glyph-ranges) |
| [Using Custom Colorful Icons](#using-custom-colorful-icons) |
| [Embedding Fonts In Source Code](#embedding-fonts-in-source-code) |
| [Credits/Licenses For Fonts Included In This Folder](#creditslicenses-for-fonts-included-in-this-folder) |
| [Font Links](#font-links) |
---------------------------------------
README FIRST / FAQ
---------------------------------------
## 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.
- Fonts are rasterized in a single texture at the time of calling either of io.Fonts->GetTexDataAsAlpha8()/GetTexDataAsRGBA32()/Build().
- Make sure your font ranges data are persistent and available at the time the font atlas is being built.
- 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".
Read FAQ for details.
```
- If you want to include a backslash \ character in your string literal, you need to double them e.g. "folder\\\filename".
---------------------------------------
FONTS LOADING INSTRUCTIONS
---------------------------------------
## Using Icons
Load default font:
- Using an icon font (such as [FontAwesome](http://fontawesome.io) or [OpenFontIcons](https://github.com/traverseda/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:
```cpp
// Merge icons into default tool font
#include "IconsFontAwesome.h"
ImGuiIO& io = ImGui::GetIO();
io.Fonts->AddFontDefault();
Load .TTF/.OTF file with:
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:
```cpp
// 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:
```cpp
ImGuiIO& io = ImGui::GetIO();
io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels);
Load multiple fonts:
io.Fonts->AddFontDefault();
```
Load .TTF/.OTF file with:
```cpp
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::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):
```cpp
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](https://github.com/nothings/stb/blob/master/tests/oversample)**
- 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:
1. Reduce glyphs ranges by calculating them from source localization data.
You can use ImFontGlyphRangesBuilder for this purpose, this will be the biggest win!
2. You may reduce oversampling, e.g. config.OversampleH = config.OversampleV = 1, this will largely reduce your texture size.
3. Set io.Fonts.TexDesiredWidth to specify a texture width to minimize texture height (see comment in ImFontAtlas::Build function).
4. Set io.Fonts.Flags |= ImFontAtlasFlags_NoPowerOfTwoHeight; to disable rounding the texture height to the next power of two.
Combine two fonts into one:
```cpp
// Load a first font
ImFont* font = io.Fonts->AddFontDefault();
@ -92,28 +141,9 @@ Combine two fonts into one:
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();
Font atlas is too large?
- 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 users may run on hardware with lower specs than yours.
Some solutions:
- 1) Reduce glyphs ranges by calculating them from source localization data.
You can use ImFontGlyphRangesBuilder for this purpose, this will be the biggest win!
- 2) You may reduce oversampling, e.g. config.OversampleH = config.OversampleV = 1, this will largely reduce your texture size.
- 3) Set io.Fonts.TexDesiredWidth to specify a texture width to minimize texture height (see comment in ImFontAtlas::Build function).
- 4) Set io.Fonts.Flags |= ImFontAtlasFlags_NoPowerOfTwoHeight; to disable rounding the texture height to the next power of two.
- Read about oversampling here: https://github.com/nothings/stb/blob/master/tests/oversample
```
Add a fourth parameter to bake specific font ranges only:
```cpp
// Basic Latin, Extended Latin
io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels, NULL, io.Fonts->GetGlyphRangesDefault());
@ -122,79 +152,31 @@ Add a fourth parameter to bake specific font ranges only:
// 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.
```
See [Building Custom Glyph Ranges](#building-custom-glyph-ranges) section to create your own ranges.
Offset font vertically by altering the io.Font->DisplayOffset value:
```cpp
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.
---------------------------------------
USING ICONS
---------------------------------------
Using an icon font (such as FontAwesome: http://fontawesome.io or OpenFontIcons. https://github.com/traverseda/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
Those files contains a bunch of named #define which you can use to refer to specific icons of the font, e.g.:
#define ICON_FA_MUSIC "\xef\x80\x81"
#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");
Important to understand: 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.
---------------------------------------
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 that 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.
## 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.
```cpp
ImVector<ImWchar> ranges;
ImFontGlyphRangesBuilder builder;
builder.AddText("Hello world"); // Add a string (here "Hello world" contains 7 unique characters)
@ -204,21 +186,18 @@ For example: for a game where your script is known, if you can feed your entire
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
---------------------------------------
## Using Custom Colorful Icons
(This is a BETA api, use if you are familiar with dear imgui and with your rendering back-end)
**(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:
- 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];
@ -247,29 +226,25 @@ Pseudo-code:
}
}
}
```
---------------------------------------
EMBEDDING FONTS IN SOURCE CODE
---------------------------------------
## 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.
- 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, ...);
` 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 REPOSITORY
---------------------------------------
Some fonts are available in the misc/fonts/ folder:
## Credits/Licenses For Fonts Included In This Folder
Roboto-Medium.ttf
@ -309,10 +284,9 @@ Karla-Regular.ttf
---------------------------------------
FONTS LINKS
---------------------------------------
## Font Links
ICON FONTS
#### ICON FONTS
C/C++ header for icon fonts (#define with code points to use in source code string literals)
https://github.com/juliettef/IconFontCppHeaders
@ -332,7 +306,7 @@ ICON FONTS
IcoMoon - Custom Icon font builder
https://icomoon.io/app
REGULAR FONTS
#### REGULAR FONTS
Google Noto Fonts (worldwide languages)
https://www.google.com/get/noto/
@ -343,17 +317,15 @@ REGULAR FONTS
(Japanese) M+ fonts by Coji Morishita are free
http://mplus-fonts.sourceforge.jp/mplus-outline-fonts/index-en.html
MONOSPACE FONTS (PIXEL PERFECT)
#### MONOSPACE FONTS
Proggy Fonts, by Tristan Grimmer
(Pixel Perfect) Proggy Fonts, by Tristan Grimmer
http://www.proggyfonts.net or http://upperbounds.net
Sweet16, Sweet16 Mono, by Martin Sedlak (Latin + Supplemental + Extended A)
(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.
MONOSPACE FONTS (REGULAR)
Google Noto Mono Fonts
https://www.google.com/get/noto/