imgui/misc/freetype

imgui_freetype

Build font atlases using FreeType instead of stb_truetype (which is the default font rasterizer).
by @vuhdo, @mikesart, @ocornut.

Usage

1. Get latest FreeType binaries or build yourself (under Windows you may use vcpkg with vcpkg install freetype --triplet=x64-windows, vcpkg integrate install).
2. Add imgui_freetype.h/cpp alongside your project files.
3. Add #define IMGUI_ENABLE_FREETYPE in your imconfig.h file

About Gamma Correct Blending

FreeType assumes blending in linear space rather than gamma space. See FreeType note for FT_Render_Glyph. For correct results you need to be using sRGB and convert to linear space in the pixel shader output. The default Dear ImGui styles will be impacted by this change (alpha values will need tweaking).

Testbed for toying with settings (for developers)

See https://gist.github.com/ocornut/b3a9ecf13502fd818799a452969649ad

Known issues

• Oversampling settings are ignored but also not so much necessary with the higher quality rendering.

Comparison

Small, thin anti-aliased fonts typically benefit a lot from FreeType's hinting:

Colorful glyphs/emojis

You can use the ImGuiFreeTypeBuilderFlags_LoadColor flag to load certain colorful glyphs. See the "Using Colorful Glyphs/Emojis" section of FONTS.md.

Using OpenType SVG fonts (SVGinOT)

• SVG in Open Type is a standard by Adobe and Mozilla for color OpenType and Open Font Format fonts. It allows font creators to embed complete SVG files within a font enabling full color and even animations.
• Popular fonts such as twemoji and fonts made with scfbuild is SVGinOT
• Two alternatives are possible to render SVG fonts: use "lunasvg" or "plutosvg". plutosvg will support some more fonts (e.g. NotoColorEmoji-Regular) and may load them faster.

Using lunasvg

Requires: lunasvg v2.3.2 and above

• Add #define IMGUI_ENABLE_FREETYPE_LUNASVG in your imconfig.h.
• Get latest lunasvg binaries or build yourself. Under Windows you may use vcpkg with: vcpkg install lunasvg --triplet=x64-windows.

Using plutosvg (and plutovg)

• Add #define IMGUI_ENABLE_FREETYPE_PLUTOSVG in your imconfig.h.
• Compile and link with plutosvg and plutovg (which is required by plutosvg)

Compilation hints for plutovg

• Compile all source files in plutovg/source/*.c
• Add include directory: plutovg/include + plutovg/stb

Compilation hints for plutosvg

• Compile plutosvg/source/plutosvg.c
• Add include directory: plutosvg/source
• Add define: PLUTOSVG_HAS_FREETYPE
• Link with: plutovg, freetype