Extended font & glyph support (#114)

* Separate font utils, add glyph support (#113)
* Implement font glyph ranges builder
* Implement raw font config binds
* Implement font atlas module
* Rewrite font altas rebuilder in Managed

dear-imgui.cabal

@@ -124,8 +124,12 @@ library
     src
   exposed-modules:
     DearImGui
+    DearImGui.FontAtlas
     DearImGui.Raw
     DearImGui.Raw.DrawList
+    DearImGui.Raw.Font
+    DearImGui.Raw.Font.Config
+    DearImGui.Raw.Font.GlyphRanges
     DearImGui.Raw.ListClipper
     DearImGui.Raw.IO
   other-modules:
@@ -295,6 +299,14 @@ executable readme
   if (!flag(examples) || !flag(sdl) || !flag(opengl2))
     buildable: False
 
+executable fonts
+  import: common, build-flags
+  main-is: Main.hs
+  hs-source-dirs: examples/fonts
+  build-depends: sdl2, gl, dear-imgui, managed
+  if (!flag(examples) || !flag(sdl) || !flag(opengl2))
+    buildable: False
+
 executable image
   import: common, build-flags
   main-is: Image.hs

examples/fonts/Main.hs

@@ -0,0 +1,150 @@
+{-# language BlockArguments #-}
+{-# language LambdaCase #-}
+{-# language OverloadedStrings #-}
+{-# language RecordWildCards #-}
+{-# language NamedFieldPuns #-}
+{-# language DeriveTraversable #-}
+
+{- | Font usage example.
+
+Loads two non-standard fonts
+
+This example uses NotoSansJP-Regular.otf from Google Fonts
+Licensed under the SIL Open Font License, Version 1.1
+https://fonts.google.com/noto/specimen/Noto+Sans+JP
+-}
+
+module Main ( main ) where
+
+import Control.Exception
+import Control.Monad
+import Control.Monad.IO.Class
+import Control.Monad.Managed
+import Data.IORef
+import DearImGui
+import qualified DearImGui.FontAtlas as FontAtlas
+import DearImGui.OpenGL2
+import DearImGui.SDL
+import DearImGui.SDL.OpenGL
+import Graphics.GL
+import SDL
+
+-- Rebuild syntax enables us to keep fonts in any
+-- traversable type, so let's make our life a little easier.
+-- But feel free to use lists or maps.
+data FontSet a = FontSet
+  { droidFont :: a
+  , defaultFont :: a
+  , notoFont :: a
+  }
+  deriving (Functor, Foldable, Traversable)
+
+main :: IO ()
+main = do
+  -- Window initialization is similar to another examples.
+  initializeAll
+  runManaged do
+    window <- do
+      let title = "Hello, Dear ImGui!"
+      let config = defaultWindow { windowGraphicsContext = OpenGLContext defaultOpenGL }
+      managed $ bracket (createWindow title config) destroyWindow
+    glContext <- managed $ bracket (glCreateContext window) glDeleteContext
+    _ <- managed $ bracket createContext destroyContext
+    _ <- managed_ $ bracket_ (sdl2InitForOpenGL window glContext) sdl2Shutdown
+    _ <- managed_ $ bracket_ openGL2Init openGL2Shutdown
+
+    -- We use high-level syntax to build font atlas and
+    -- get handles to use in the main loop.
+    fontSet <- FontAtlas.rebuild FontSet
+      { -- The first mentioned font is loaded first
+        -- and set as a global default.
+        droidFont =
+          FontAtlas.FromTTF
+            "./imgui/misc/fonts/DroidSans.ttf"
+            15
+            Nothing
+            FontAtlas.Cyrillic
+
+        -- You also may use a default hardcoded font for
+        -- some purposes (i.e. as fallback)
+      , defaultFont =
+          FontAtlas.DefaultFont
+
+        -- To optimize atlas size, use ranges builder and
+        -- provide source localization data.
+      , notoFont =
+          FontAtlas.FromTTF
+            "./examples/fonts/NotoSansJP-Regular.otf"
+            20
+            Nothing
+            ( FontAtlas.RangesBuilder $ mconcat
+                [ FontAtlas.addRanges FontAtlas.Latin
+                , FontAtlas.addText "私をクリックしてください"
+                , FontAtlas.addText "こんにちは"
+                ]
+            )
+      }
+
+    liftIO $ do
+      fontFlag <- newIORef False
+      mainLoop window do
+        let FontSet{..} = fontSet
+        withWindowOpen "Hello, ImGui!" do
+          -- To use a font for widget text, you may either put it
+          -- into a 'withFont' block:
+          withFont defaultFont do
+            text "Hello, ImGui!"
+
+          text "Привет, ImGui!"
+
+          -- ...or you can explicitly push and pop a font.
+          -- Though it's not recommended.
+          toggled <- readIORef fontFlag
+
+          when toggled $
+            pushFont notoFont
+
+          -- Some of those are only present in Noto font range
+          -- and will render as `?`s.
+          text "こんにちは, ImGui!"
+
+          let buttonText = if toggled then "私をクリックしてください" else "Click Me!"
+          button buttonText >>= \clicked ->
+            when clicked $
+              modifyIORef' fontFlag not
+
+          when toggled
+            popFont
+
+        showDemoWindow
+
+mainLoop :: Window -> IO () -> IO ()
+mainLoop window frameAction = loop
+  where
+  loop = unlessQuit do
+    openGL2NewFrame
+    sdl2NewFrame
+    newFrame
+
+    frameAction
+
+    glClear GL_COLOR_BUFFER_BIT
+    render
+    openGL2RenderDrawData =<< getDrawData
+    glSwapWindow window
+
+    loop
+
+  unlessQuit action = do
+    shouldQuit <- checkEvents
+    if shouldQuit then pure () else action
+
+  checkEvents = do
+    pollEventWithImGui >>= \case
+      Nothing ->
+        return False
+      Just event ->
+        (isQuit event ||) <$> checkEvents
+
+  isQuit event =
+    SDL.eventPayload event == SDL.QuitEvent

examples/vulkan/Main.hs

@@ -134,12 +134,6 @@ app = do
     ImGui.createContext
     ImGui.destroyContext
 
-  logDebug "Adding fonts"
-  ImGui.clearFontAtlas
-  _default <- ImGui.addFontDefault
-  _custom <- ImGui.addFontFromFileTTF "imgui/misc/fonts/ProggyTiny.ttf" 10
-  ImGui.buildFontAtlas
-
   let
     preferredFormat :: Vulkan.SurfaceFormatKHR
     preferredFormat =

src/DearImGui.hs

@@ -86,6 +86,11 @@ module DearImGui
   , pushStyleVar
   , popStyleVar
 
+  , withFont
+  , Raw.Font.pushFont
+  , Raw.Font.popFont
+  , Raw.Font.Font
+
     -- * Cursor/Layout
   , Raw.separator
   , Raw.sameLine
@@ -247,13 +252,6 @@ module DearImGui
   , Raw.wantCaptureMouse
   , Raw.wantCaptureKeyboard
 
-    -- * Fonts
-  , Raw.Font
-  , addFontFromFileTTF
-  , Raw.addFontDefault
-  , Raw.buildFontAtlas
-  , Raw.clearFontAtlas
-
     -- * Utilities
 
     -- ** ListClipper
@@ -287,6 +285,9 @@ import System.IO
 -- dear-imgui
 import DearImGui.Enums
 import DearImGui.Structs
+import qualified DearImGui.Raw as Raw
+import qualified DearImGui.Raw.Font as Raw.Font
+import qualified DearImGui.Raw.ListClipper as Raw.ListClipper
 
 -- managed
 import qualified Control.Monad.Managed as Managed
@@ -303,9 +304,6 @@ import Control.Monad.IO.Class
 import UnliftIO (MonadUnliftIO)
 import UnliftIO.Exception (bracket, bracket_)
 
-import qualified DearImGui.Raw as Raw
-import qualified DearImGui.Raw.ListClipper as Raw.ListClipper
-
 -- vector
 import qualified Data.Vector as V
 import qualified Data.Vector.Storable as VS
@@ -1691,24 +1689,9 @@ popStyleVar :: (MonadIO m) => Int -> m ()
 popStyleVar n = liftIO do
   Raw.popStyleVar (fromIntegral n)
 
-
+-- | Render widgets inside the block using provided font.
--- | Load a font from TTF file.
+withFont :: MonadUnliftIO m => Raw.Font.Font -> m a -> m a
---
+withFont font = bracket_ (Raw.Font.pushFont font) Raw.Font.popFont
--- Specify font path and atlas glyph size.
---
--- Use 'addFontDefault' if you want to retain built-in font too.
---
--- Call 'buildFontAtlas' after adding all the fonts.
---
--- Call backend-specific `CreateFontsTexture` before using 'newFrame'.
-addFontFromFileTTF :: MonadIO m => FilePath -> Float -> m (Maybe Raw.Font)
-addFontFromFileTTF font size = liftIO do
-  res@(Raw.Font ptr) <- withCString font \fontPtr ->
-    Raw.addFontFromFileTTF fontPtr (CFloat size)
-  pure $
-    if castPtr ptr == nullPtr
-      then Nothing
-      else Just res
 
 -- | Clips a large list of items
 --

src/DearImGui/Context.hs

@@ -34,9 +34,12 @@ imguiContext = mempty
       , ( TypeName "ImVec3", [t| ImVec3 |] )
       , ( TypeName "ImVec4", [t| ImVec4 |] )
       , ( TypeName "ImU32", [t| ImU32 |] )
+      , ( TypeName "ImWchar", [t| ImWchar |] )
       , ( TypeName "ImDrawList", [t| ImDrawList |] )
       , ( TypeName "ImGuiContext", [t| ImGuiContext |] )
       , ( TypeName "ImFont", [t| ImFont |] )
+      , ( TypeName "ImFontConfig", [t| ImFontConfig |] )
+      , ( TypeName "ImFontGlyphRangesBuilder", [t| ImFontGlyphRangesBuilder |] )
       , ( TypeName "ImGuiListClipper", [t| ImGuiListClipper |] )
       ]
   }

src/DearImGui/FontAtlas.hs

@@ -0,0 +1,501 @@
+{-# LANGUAGE BlockArguments #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE TemplateHaskell #-}
+
+{-|
+Module: DearImGui.FontAtlas
+
+Font atlas builder, accompanied with lower-level functions.
+
+@
+import qualified DearImGui.FontAtlas as FontAtlas
+
+prepareAtlas =
+  FontAtlas.rebuild
+    [ FontAtlas.FileTTF "comic-sans-mono.ttf" 13 csOptions csRanges
+    , FontAtlas.Default
+    ]
+  where
+    csOptions = mconcat
+      [ FontAtlas.fontNo 1
+      , FontAtlas.glyphOffset (0, -1)
+      ]
+
+    csRanges = RangeBuilder $ mconcat
+      [ FontAtlas.addText "Hello world"
+      , FontRanges.addChar 'Ꙑ'
+      , FontRanges.addRanges FontRanges.Korean
+      ]
+@
+
+-}
+
+module DearImGui.FontAtlas
+  ( -- * Main types
+    Raw.Font(..)
+  , FontSource(..)
+    -- * Building atlas
+  , rebuild
+    -- ** Configuring sources
+  , ConfigSetup(..)
+  , fontDataOwnedByAtlas
+  , fontNo
+  , sizePixels
+  , oversampleH
+  , oversampleV
+  , pixelSnapH
+  , glyphExtraSpacing
+  , glyphOffset
+  , glyphRanges
+  , glyphMinAdvanceX
+  , glyphMaxAdvanceX
+  , mergeMode
+  , fontBuilderFlags
+  , rasterizerMultiply
+  , ellipsisChar
+
+    -- ** Configuring ranges
+  , Ranges(..)
+  , RangesBuilderSetup(..)
+  , addChar
+  , addText
+  , addRanges
+  , addRangesRaw
+
+  , pattern Latin
+  , pattern Korean
+  , pattern Japanese
+  , pattern ChineseFull
+  , pattern ChineseSimplifiedCommon
+  , pattern Cyrillic
+  , pattern Thai
+  , pattern Vietnamese
+
+    -- * Lower level types and functions
+  -- , Raw.FontConfig(..)
+  -- , Raw.GlyphRanges(..)
+  , build
+  , clear
+  , setupFont
+  , setupRanges
+  , withRanges
+  , withConfig
+  , addFontFromFileTTF
+  , addFontFromFileTTF_
+  )
+  where
+
+-- base
+import Data.Bool (bool)
+import Data.Maybe (fromMaybe)
+import Foreign
+import Foreign.C
+
+-- transformers
+import Control.Monad.IO.Class
+  ( MonadIO, liftIO )
+
+-- managed
+import Control.Monad.Managed
+  ( MonadManaged, managed )
+import qualified Control.Monad.Managed as Managed
+
+-- unlift
+import UnliftIO (MonadUnliftIO)
+import UnliftIO.Exception (bracket)
+
+-- dear-imgui
+import DearImGui.Raw.Font (Font(..))
+import qualified DearImGui.Raw.Font as Raw
+import DearImGui.Raw.Font.Config (FontConfig(..))
+import qualified DearImGui.Raw.Font.Config as FontConfig
+import DearImGui.Raw.Font.GlyphRanges (GlyphRanges(..), GlyphRangesBuilder(..))
+import qualified DearImGui.Raw.Font.GlyphRanges as GlyphRanges
+
+import DearImGui.Structs (ImVec2(..), ImWchar)
+
+-- | Font setup data
+data FontSource
+  = DefaultFont
+  | FromTTF FilePath Float (Maybe ConfigSetup) Ranges
+  -- TODO: FromMemory
+
+-- | Font config monoid interface to be used in 'FontSource'.
+--
+-- @
+-- mergeMode True <> fontNo 1
+-- @
+newtype ConfigSetup = ConfigSetup
+  { applyToConfig :: FontConfig -> IO ()
+  }
+
+instance Semigroup ConfigSetup where
+  ConfigSetup f <> ConfigSetup g =
+    ConfigSetup \fc -> f fc >> g fc
+instance Monoid ConfigSetup where
+  mempty = ConfigSetup (const mempty)
+
+-- | Glyph ranges settings, from presets to builder configuration.
+data Ranges
+  = RangesRaw GlyphRanges
+  | RangesBuiltin GlyphRanges.Builtin
+  | RangesBuilder RangesBuilderSetup
+
+-- | Basic Latin, Extended Latin
+pattern Latin :: Ranges
+pattern Latin = RangesBuiltin GlyphRanges.Latin
+
+-- | Default + Korean characters
+pattern Korean :: Ranges
+pattern Korean = RangesBuiltin GlyphRanges.Korean
+
+-- | Default + Hiragana, Katakana, Half-Width, Selection of 2999 Ideographs
+pattern Japanese :: Ranges
+pattern Japanese = RangesBuiltin GlyphRanges.Japanese
+
+-- | Default + Half-Width + Japanese Hiragana/Katakana + full set of about 21000 CJK Unified Ideographs
+pattern ChineseFull :: Ranges
+pattern ChineseFull = RangesBuiltin GlyphRanges.ChineseFull
+
+-- | Default + Half-Width + Japanese Hiragana/Katakana + set of 2500 CJK Unified Ideographs for common simplified Chinese
+pattern ChineseSimplifiedCommon :: Ranges
+pattern ChineseSimplifiedCommon = RangesBuiltin GlyphRanges.ChineseSimplifiedCommon
+
+-- | Default + about 400 Cyrillic characters
+pattern Cyrillic :: Ranges
+pattern Cyrillic = RangesBuiltin GlyphRanges.Cyrillic
+
+-- | Default + Thai characters
+pattern Thai :: Ranges
+pattern Thai = RangesBuiltin GlyphRanges.Thai
+
+-- | Default + Vietnamese characters
+pattern Vietnamese :: Ranges
+pattern Vietnamese = RangesBuiltin GlyphRanges.Vietnamese
+
+
+-- | Ranges builder monoid interface to be executed through 'buildRanges'.
+--
+-- @
+-- addRanges FontRanges.DefaultRanges <> addText "Привет"
+-- @
+newtype RangesBuilderSetup = RangesBuilderSetup
+  { applyToBuilder :: GlyphRangesBuilder -> IO ()
+  }
+
+instance Semigroup RangesBuilderSetup where
+  RangesBuilderSetup f <> RangesBuilderSetup g =
+    RangesBuilderSetup \fc -> f fc >> g fc
+
+instance Monoid RangesBuilderSetup where
+  mempty = RangesBuilderSetup (const mempty)
+
+-- | Rebuild font atlas with provided configuration
+-- and return corresponding structure of font handles
+-- to be used with 'withFont'.
+--
+-- Accepts any 'Traversable' instance, so you are free to use
+-- lists, maps or custom structures.
+rebuild :: (MonadIO m, Traversable t) => t FontSource -> m (t Font)
+rebuild sources = liftIO $ Managed.with action pure
+  where
+    action = do
+      clear
+      fonts <- traverse setupFont sources
+      build
+      return fonts
+
+-- | Reset font atlas, clearing internal data
+--
+-- Alias for 'Raw.clearFontAtlas'
+clear :: (MonadIO m) => m ()
+clear = Raw.clearFontAtlas
+
+-- | Build font atlas
+--
+-- Alias for 'Raw.buildFontAtlas'
+build :: (MonadIO m) => m ()
+build = Raw.buildFontAtlas
+
+-- | Load a font from TTF file.
+--
+-- Specify font path and atlas glyph size.
+--
+-- Use 'Raw.addFontDefault' if you want to retain built-in font too.
+--
+-- Call 'build' after adding all the fonts,
+-- particularly if you're loading them from memory or use custom glyphs.
+-- Or stick to `rebuild` function.
+--
+-- Call backend-specific `CreateFontsTexture` before using 'newFrame'.
+addFontFromFileTTF :: MonadIO m
+  => FilePath               -- ^ Font file path
+  -> Float                  -- ^ Font size in pixels
+  -> Maybe FontConfig   -- ^ Configuration data
+  -> Maybe GlyphRanges  -- ^ Glyph ranges to use
+  -> m (Maybe Font)     -- ^ Returns font handle, if added successfully
+addFontFromFileTTF font size config ranges = liftIO do
+  res@(Font ptr) <- withCString font \fontPtr ->
+    Raw.addFontFromFileTTF
+      fontPtr
+      (CFloat size)
+      (fromMaybe (FontConfig nullPtr) config)
+      (fromMaybe (GlyphRanges nullPtr) ranges)
+  pure $
+    if castPtr ptr == nullPtr
+      then Nothing
+      else Just res
+      -- FIXME: turn off asserts, so it would work
+
+addFontFromFileTTF_ :: MonadIO m
+  => FilePath           -- ^ Font file path
+  -> Float              -- ^ Font size in pixels
+  -> m (Maybe Raw.Font) -- ^ Returns font handle, if added successfully
+addFontFromFileTTF_ font size =
+  addFontFromFileTTF font size Nothing Nothing
+
+-- | Load a font with provided configuration, return its handle
+-- and defer range builder and config destructors, if needed.
+setupFont :: (MonadManaged m) => FontSource -> m Font
+setupFont = \case
+  DefaultFont ->
+    Raw.addFontDefault
+  FromTTF path size configSetup ranges -> do
+    glyphRanges' <- setupRanges ranges
+    config <- managed (withConfig configSetup)
+    mFont <- addFontFromFileTTF path size config glyphRanges'
+    case mFont of
+      Nothing ->
+        liftIO . fail $ "Couldn't load font from " <> path
+      Just font ->
+        pure font
+
+-- | Configure glyph ranges with provided configuration, return a handle
+-- and defer builder destructors, if needed.
+setupRanges :: (MonadManaged m) => Ranges -> m (Maybe GlyphRanges)
+setupRanges = \case
+  RangesRaw ranges ->
+    pure $ Just ranges
+  RangesBuiltin builtin ->
+    pure $ GlyphRanges.builtinSetup builtin
+  RangesBuilder settings -> do
+    built <- managed $ withRanges settings
+    pure $ Just built
+
+-- | Perform glyph ranges build based on provided configuration,
+-- and execute a computation with built glyph ranges.
+withRanges :: (MonadUnliftIO m) => RangesBuilderSetup -> (GlyphRanges -> m a) -> m a
+withRanges (RangesBuilderSetup setup) fn =
+  bracket acquire release execute
+  where
+    acquire = do
+      builder <- GlyphRanges.new
+      liftIO $ setup builder
+      rangesVec <- GlyphRanges.buildRangesVector builder
+      return (rangesVec, builder)
+
+    release (rangesVec, builder) = do
+      GlyphRanges.destroyRangesVector rangesVec
+      GlyphRanges.destroy builder
+
+    execute (rangesVec, _) =
+      fn (GlyphRanges.fromRangesVector rangesVec)
+
+-- | Configure font config with provided setup,
+-- and execute a computation with built object.
+-- return its handle and list of resource destructors.
+withConfig :: (MonadUnliftIO m) => Maybe ConfigSetup -> (Maybe FontConfig -> m a) -> m a
+withConfig mSetup action =
+  case mSetup of
+    Nothing ->
+      action Nothing
+    Just (ConfigSetup setup) ->
+      bracket acquire (FontConfig.destroy) (action . Just)
+      where
+        acquire = do
+          config <- FontConfig.new
+          liftIO $ setup config
+          return config
+
+-- | Single Unicode character
+addChar :: ImWchar -> RangesBuilderSetup
+addChar char =
+  RangesBuilderSetup \builder ->
+    GlyphRanges.addChar builder char
+
+-- | UTF-8 string
+addText :: String -> RangesBuilderSetup
+addText str =
+  RangesBuilderSetup \builder ->
+    withCString str (GlyphRanges.addText builder)
+
+-- | Existing ranges (as is)
+addRangesRaw :: GlyphRanges -> RangesBuilderSetup
+addRangesRaw ranges =
+  RangesBuilderSetup \builder ->
+    GlyphRanges.addRanges builder ranges
+
+-- | Existing ranges (through settings interface)
+addRanges :: Ranges -> RangesBuilderSetup
+addRanges = \case
+  RangesRaw ranges ->
+    addRangesRaw ranges
+  RangesBuilder settings ->
+    settings
+  RangesBuiltin builtin ->
+    addRangesRaw (GlyphRanges.getBuiltin builtin)
+
+-- | TTF/OTF data ownership taken by the container ImFontAtlas (will delete memory itself).
+--
+-- By default, it is @true@
+fontDataOwnedByAtlas :: Bool -> ConfigSetup
+fontDataOwnedByAtlas value =
+  ConfigSetup \fc ->
+    FontConfig.setFontDataOwnedByAtlas fc (bool 0 1 value)
+
+-- | Index of font within TTF/OTF file.
+--
+-- By default, it is @0@
+fontNo :: Int -> ConfigSetup
+fontNo value =
+  ConfigSetup \fc ->
+    FontConfig.setFontNo fc (fromIntegral value)
+
+-- | Size in pixels for rasterizer
+--
+-- More or less maps to the resulting font height.
+--
+-- Implicitly set by @addFont...@ functions.
+sizePixels :: Float -> ConfigSetup
+sizePixels value =
+  ConfigSetup \fc ->
+    FontConfig.setSizePixels fc (CFloat value)
+
+-- | Rasterize at higher quality for sub-pixel positioning.
+--
+-- Note: the difference between 2 and 3 is minimal so you can reduce this to 2 to save memory.
+-- Read https://github.com/nothings/stb/blob/master/tests/oversample/README.md for details.
+--
+-- By default, it is @3@
+oversampleH :: Int -> ConfigSetup
+oversampleH value =
+  ConfigSetup \fc ->
+    FontConfig.setOversampleH fc (fromIntegral value)
+
+-- | Rasterize at higher quality for sub-pixel positioning.
+--
+-- This is not really useful as we don't use sub-pixel positions on the Y axis.
+--
+-- By default, it is @1@
+oversampleV :: Int -> ConfigSetup
+oversampleV value =
+  ConfigSetup \fc ->
+    FontConfig.setOversampleV fc (fromIntegral value)
+
+-- | Align every glyph to pixel boundary.
+--
+-- Useful if you are merging a non-pixel aligned font with the default font.
+-- If enabled, you can set OversampleH/V to 1.
+--
+-- By default, it is @false@
+pixelSnapH :: Bool -> ConfigSetup
+pixelSnapH value =
+  ConfigSetup \fc ->
+    FontConfig.setPixelSnapH fc (bool 0 1 value)
+
+-- | Extra spacing (in pixels) between glyphs.
+--
+-- Only X axis is supported for now.
+--
+-- By default, it is @0, 0@
+glyphExtraSpacing :: (Float, Float) -> ConfigSetup
+glyphExtraSpacing (x, y) =
+  ConfigSetup \fc ->
+    Foreign.with (ImVec2 x y) (FontConfig.setGlyphExtraSpacing fc)
+
+-- | Offset all glyphs from this font input.
+--
+-- By default, it is @0, 0@
+glyphOffset :: (Float, Float) -> ConfigSetup
+glyphOffset (x, y) =
+  ConfigSetup \fc ->
+    Foreign.with (ImVec2 x y) (FontConfig.setGlyphOffset fc)
+
+-- | Pointer to a user-provided list of Unicode range.
+--
+-- 2 values per range, inclusive. Zero-terminated list.
+--
+-- THE ARRAY DATA NEEDS TO PERSIST AS LONG AS THE FONT IS ALIVE.
+--
+-- By default, it is @NULL@
+glyphRanges :: GlyphRanges -> ConfigSetup
+glyphRanges value =
+  ConfigSetup \fc ->
+    FontConfig.setGlyphRanges fc value
+
+-- | Minimum AdvanceX for glyphs.
+--
+-- Set Min to align font icons, set both Min/Max to enforce mono-space font.
+--
+-- By default, it is @0@
+glyphMinAdvanceX :: Float -> ConfigSetup
+glyphMinAdvanceX value =
+  ConfigSetup \fc ->
+    FontConfig.setGlyphMinAdvanceX fc (CFloat value)
+
+-- | Maximum AdvanceX for glyphs.
+--
+-- By default, it is @FLT_MAX@.
+glyphMaxAdvanceX :: Float -> ConfigSetup
+glyphMaxAdvanceX value =
+  ConfigSetup \fc ->
+    FontConfig.setGlyphMaxAdvanceX fc (CFloat value)
+
+-- | Merge into previous ImFont, so you can combine multiple inputs font into one ImFont.
+--
+-- e.g. ASCII font + icons + Japanese glyphs.
+-- You may want to use @GlyphOffset.y@ when merging font of different heights.
+--
+-- By default, it is @false@
+mergeMode :: Bool -> ConfigSetup
+mergeMode value =
+  ConfigSetup \fc ->
+    FontConfig.setMergeMode fc (bool 0 1 value)
+
+-- | Settings for custom font GlyphRanges.
+--
+-- THIS IS BUILDER IMPLEMENTATION DEPENDENT.
+--
+-- By default, it is @0@. Leave it so if unsure.
+fontBuilderFlags :: Int -> ConfigSetup
+fontBuilderFlags value =
+  ConfigSetup \fc ->
+    FontConfig.setFontBuilderFlags fc (fromIntegral value)
+
+-- | Brighten (>1.0f) or darken (<1.0f) font output.
+--
+-- Brightening small fonts may be a good workaround to make them more readable.
+--
+-- By default, it is @1.0f@.
+rasterizerMultiply :: Float -> ConfigSetup
+rasterizerMultiply value =
+  ConfigSetup \fc ->
+    FontConfig.setRasterizerMultiply fc (CFloat value)
+
+-- | Explicitly specify unicode codepoint of ellipsis character.
+--
+-- When fonts are being merged first specified ellipsis will be used.
+--
+-- By default, it is @-1@
+ellipsisChar :: ImWchar -> ConfigSetup
+ellipsisChar value =
+  ConfigSetup \fc ->
+    FontConfig.setEllipsisChar fc value

src/DearImGui/Raw.hs

@@ -211,14 +211,6 @@ module DearImGui.Raw
   , wantCaptureMouse
   , wantCaptureKeyboard
 
-    -- * Fonts in default font atlas
-  , Font(..)
-  , addFontDefault
-  , addFontFromFileTTF
-  , addFontFromMemoryTTF
-  , buildFontAtlas
-  , clearFontAtlas
-
     -- * Utilities
 
     -- ** Miscellaneous
@@ -1563,58 +1555,6 @@ wantCaptureKeyboard :: MonadIO m => m Bool
 wantCaptureKeyboard = liftIO do
   (0 /=) <$> [C.exp| bool { GetIO().WantCaptureKeyboard } |]
 
-
--- | Wraps @ImFont*@.
-newtype Font = Font (Ptr ImFont)
-
-addFontDefault :: MonadIO m => m Font
-addFontDefault = liftIO do
-  Font <$> [C.block|
-    ImFont* {
-      return GetIO().Fonts->AddFontDefault();
-    }
-  |]
-
-addFontFromFileTTF :: MonadIO m => CString -> CFloat -> m Font
-addFontFromFileTTF filenamePtr sizePixels = liftIO do
-  Font <$> [C.block|
-    ImFont* {
-      return GetIO().Fonts->AddFontFromFileTTF(
-        $(char* filenamePtr),
-        $(float sizePixels));
-    }
-  |]
-
--- | Transfer a buffer with TTF data to font atlas builder.
-addFontFromMemoryTTF :: MonadIO m => CStringLen -> CFloat -> m Font
-addFontFromMemoryTTF (castPtr -> fontDataPtr, fromIntegral -> fontSize) sizePixels = liftIO do
-  Font <$> [C.block|
-    ImFont* {
-      return GetIO().Fonts->AddFontFromMemoryTTF(
-        $(void* fontDataPtr),
-        $(int fontSize),
-        $(float sizePixels)
-      );
-    }
-  |]
-
-buildFontAtlas :: MonadIO m => m ()
-buildFontAtlas = liftIO do
-  [C.block|
-    void {
-      GetIO().Fonts->Build();
-    }
-  |]
-
-clearFontAtlas :: MonadIO m => m ()
-clearFontAtlas = liftIO do
-  [C.block|
-    void {
-      GetIO().Fonts->Clear();
-    }
-  |]
-
-
 -- | This draw list will be the first rendering one.
 --
 -- Useful to quickly draw shapes/text behind dear imgui contents.

src/DearImGui/Raw/Font.hs

@@ -0,0 +1,141 @@
+{-# LANGUAGE BlockArguments #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE ViewPatterns #-}
+
+
+{-| Fonts
+
+It includes default atlas management, font configuration and glyph ranges.
+
+-}
+
+module DearImGui.Raw.Font
+  ( -- * Types
+    Font(..)
+  , GlyphRanges(..)
+    -- * Adding fonts
+  , addFontDefault
+  , addFontFromFileTTF
+  , addFontFromMemoryTTF
+    -- * Using fonts
+  , pushFont
+  , popFont
+
+    -- * Atlas management
+  , clearFontAtlas
+  , buildFontAtlas
+  )
+  where
+
+-- base
+import Control.Monad.IO.Class
+  ( MonadIO, liftIO )
+import Foreign ( Ptr, castPtr )
+import Foreign.C
+
+-- dear-imgui
+import DearImGui.Context
+  ( imguiContext )
+import DearImGui.Structs
+import DearImGui.Raw.Font.Config
+  ( FontConfig(..) )
+import DearImGui.Raw.Font.GlyphRanges
+  ( GlyphRanges(..) )
+
+-- inline-c
+import qualified Language.C.Inline as C
+
+-- inline-c-cpp
+import qualified Language.C.Inline.Cpp as Cpp
+
+C.context (Cpp.cppCtx <> C.bsCtx <> imguiContext)
+C.include "imgui.h"
+Cpp.using "namespace ImGui"
+
+
+-- | Font runtime data handle
+--
+-- Wraps @ImFont*@.
+newtype Font = Font (Ptr ImFont)
+
+-- | Add the default font (@ProggyClean.ttf@, 13 px) to the atlas.
+addFontDefault :: MonadIO m
+  => m Font   -- ^ Returns font handle for future usage
+addFontDefault = liftIO do
+  Font <$> [C.block|
+    ImFont* {
+      return GetIO().Fonts->AddFontDefault();
+    }
+  |]
+
+-- | Add a custom OTF/TTF font from a file.
+addFontFromFileTTF :: MonadIO m
+  => CString     -- ^ Font file path
+  -> CFloat      -- ^ Font size in pixels
+  -> FontConfig  -- ^ Configuration data
+  -> GlyphRanges -- ^ Glyph ranges to use
+  -> m Font      -- ^ Returns font handle for future usage
+addFontFromFileTTF filenamePtr sizePixels (FontConfig fontConfig) (GlyphRanges glyphRanges) = liftIO do
+  Font <$> [C.block|
+    ImFont* {
+      return GetIO().Fonts->AddFontFromFileTTF(
+        $(char* filenamePtr),
+        $(float sizePixels),
+        $(ImFontConfig* fontConfig),
+        $(ImWchar* glyphRanges));
+    }
+  |]
+
+-- | Transfer a buffer with TTF data to font atlas builder.
+addFontFromMemoryTTF :: MonadIO m => CStringLen -> CFloat -> FontConfig -> GlyphRanges -> m Font
+addFontFromMemoryTTF (castPtr -> fontDataPtr, fromIntegral -> fontSize) sizePixels (FontConfig fontConfig) (GlyphRanges glyphRanges) = liftIO do
+  Font <$> [C.block|
+    ImFont* {
+      return GetIO().Fonts->AddFontFromMemoryTTF(
+        $(void* fontDataPtr),
+        $(int fontSize),
+        $(float sizePixels),
+        $(ImFontConfig* fontConfig),
+        $(ImWchar* glyphRanges)
+      );
+    }
+  |]
+
+
+-- | Pushes a font into the parameters stack,
+-- so ImGui would render following text using it.
+pushFont :: MonadIO m => Font -> m ()
+pushFont (Font font) = liftIO do
+  [C.exp| void { PushFont($(ImFont* font)); } |]
+
+-- | Pops a font pushed into the parameters stack
+--
+-- Should be called only after a corresponding 'pushFont' call.
+popFont :: MonadIO m => m ()
+popFont = liftIO do
+  [C.exp| void { PopFont(); } |]
+
+-- | Explicitly build pixels data for the atlas.
+buildFontAtlas :: MonadIO m => m ()
+buildFontAtlas = liftIO do
+  [C.block|
+    void {
+      GetIO().Fonts->Build();
+    }
+  |]
+
+-- | Clear all font atlas input and output data
+clearFontAtlas :: MonadIO m => m ()
+clearFontAtlas = liftIO do
+  [C.block|
+    void {
+      GetIO().Fonts->Clear();
+    }
+  |]

src/DearImGui/Raw/Font/Config.hs

@@ -0,0 +1,256 @@
+{-# LANGUAGE BlockArguments #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE ViewPatterns #-}
+
+
+{-| Font configuration
+
+IO functions to modify font config values.
+
+-}
+
+module DearImGui.Raw.Font.Config
+  ( FontConfig(..)
+  , new
+  , destroy
+    -- * Changing settings
+  , setFontDataOwnedByAtlas
+  , setFontNo
+  , setSizePixels
+  , setOversampleH
+  , setOversampleV
+  , setPixelSnapH
+  , setGlyphExtraSpacing
+  , setGlyphOffset
+  , setGlyphRanges
+  , setGlyphMinAdvanceX
+  , setGlyphMaxAdvanceX
+  , setMergeMode
+  , setFontBuilderFlags
+  , setRasterizerMultiply
+  , setEllipsisChar
+  )
+  where
+
+-- base
+import Control.Monad.IO.Class
+  ( MonadIO, liftIO )
+import Foreign ( Ptr )
+import Foreign.C
+
+-- dear-imgui
+import DearImGui.Context
+  ( imguiContext )
+import DearImGui.Structs
+import DearImGui.Raw.Font.GlyphRanges
+  ( GlyphRanges(..) )
+
+-- inline-c
+import qualified Language.C.Inline as C
+
+-- inline-c-cpp
+import qualified Language.C.Inline.Cpp as Cpp
+
+C.context (Cpp.cppCtx <> C.bsCtx <> imguiContext)
+C.include "imgui.h"
+Cpp.using "namespace ImGui"
+
+-- | Font configuration data handle
+--
+-- Wraps @ImFontConfig*@.
+newtype FontConfig = FontConfig (Ptr ImFontConfig)
+
+-- | Create an instance of config
+new :: MonadIO m => m FontConfig
+new = liftIO do
+  FontConfig <$> [C.block|
+    ImFontConfig* {
+      return IM_NEW(ImFontConfig);
+    }
+  |]
+
+-- | Destroy an instance of config
+--
+-- Should be used __after__ font atlas building.
+destroy :: MonadIO m => FontConfig -> m ()
+destroy (FontConfig config) = liftIO do
+  [C.block|
+    void {
+      IM_DELETE($(ImFontConfig* config));
+    }
+  |]
+
+
+-- | TTF/OTF data ownership taken by the container ImFontAtlas (will delete memory itself).
+--
+-- By default, it is @true@
+setFontDataOwnedByAtlas :: MonadIO m => FontConfig -> CBool -> m ()
+setFontDataOwnedByAtlas (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->FontDataOwnedByAtlas = $(bool value);
+    }
+  |]
+
+-- | Index of font within TTF/OTF file
+--
+-- By default, it is @0@
+setFontNo :: MonadIO m => FontConfig -> CInt -> m ()
+setFontNo (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->FontNo = $(int value);
+    }
+  |]
+
+-- | Size in pixels for rasterizer (more or less maps to the resulting font height).
+--
+-- Implicitly set by @addFont...@ functions.
+setSizePixels :: MonadIO m => FontConfig -> CFloat -> m ()
+setSizePixels (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->SizePixels = $(float value);
+    }
+  |]
+
+-- | Rasterize at higher quality for sub-pixel positioning. Note the difference between 2 and 3 is minimal so you can reduce this to 2 to save memory. Read https://github.com/nothings/stb/blob/master/tests/oversample/README.md for details.
+--
+-- By default, it is @3@
+setOversampleH :: MonadIO m => FontConfig -> CInt -> m ()
+setOversampleH (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->OversampleH = $(int value);
+    }
+  |]
+
+-- | Rasterize at higher quality for sub-pixel positioning. This is not really useful as we don't use sub-pixel positions on the Y axis.
+--
+-- By default, it is @1@
+setOversampleV :: MonadIO m => FontConfig -> CInt -> m ()
+setOversampleV (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->OversampleV = $(int value);
+    }
+  |]
+
+-- | Align every glyph to pixel boundary. Useful e.g. if you are merging a non-pixel aligned font with the default font. If enabled, you can set OversampleH/V to 1.
+--
+-- By default, it is @false@
+setPixelSnapH :: MonadIO m => FontConfig -> CBool -> m ()
+setPixelSnapH (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->PixelSnapH = $(bool value);
+    }
+  |]
+
+-- | Extra spacing (in pixels) between glyphs. Only X axis is supported for now.
+--
+-- By default, it is @0, 0@
+setGlyphExtraSpacing :: MonadIO m => FontConfig -> Ptr ImVec2 -> m ()
+setGlyphExtraSpacing (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->GlyphExtraSpacing = *$(ImVec2* value);
+    }
+  |]
+
+-- | Offset all glyphs from this font input.
+--
+-- By default, it is @0, 0@
+setGlyphOffset :: MonadIO m => FontConfig -> Ptr ImVec2 -> m ()
+setGlyphOffset (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->GlyphOffset = *$(ImVec2* value);
+    }
+  |]
+
+-- | Pointer to a user-provided list of Unicode range (2 value per range, values are inclusive, zero-terminated list). THE ARRAY DATA NEEDS TO PERSIST AS LONG AS THE FONT IS ALIVE.
+--
+-- By default, it is @NULL@
+setGlyphRanges :: MonadIO m => FontConfig -> GlyphRanges -> m ()
+setGlyphRanges (FontConfig fc) (GlyphRanges value) = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->GlyphRanges = $(ImWchar* value);
+    }
+  |]
+
+-- | Minimum AdvanceX for glyphs, set Min to align font icons, set both Min/Max to enforce mono-space font
+--
+-- By default, it is @0@
+setGlyphMinAdvanceX :: MonadIO m => FontConfig -> CFloat -> m ()
+setGlyphMinAdvanceX (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->GlyphMinAdvanceX = $(float value);
+    }
+  |]
+
+-- | Maximum AdvanceX for glyphs
+--
+-- By default, it is @FLT_MAX@
+setGlyphMaxAdvanceX :: MonadIO m => FontConfig -> CFloat -> m ()
+setGlyphMaxAdvanceX (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->GlyphMaxAdvanceX = $(float value);
+    }
+  |]
+
+-- | Merge into previous ImFont, so you can combine multiple inputs font into one ImFont (e.g. ASCII font + icons + Japanese glyphs). You may want to use GlyphOffset.y when merge font of different heights.
+--
+-- By default, it is @false@
+setMergeMode :: MonadIO m => FontConfig -> CBool -> m ()
+setMergeMode (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->MergeMode = $(bool value);
+    }
+  |]
+
+-- | Settings for custom font builder.
+-- THIS IS BUILDER IMPLEMENTATION DEPENDENT.
+--
+-- By default, it is @0@. Leave it so if unsure.
+setFontBuilderFlags :: MonadIO m => FontConfig -> CUInt -> m ()
+setFontBuilderFlags (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->FontBuilderFlags = $(unsigned int value);
+    }
+  |]
+
+-- | Brighten (>1.0f) or darken (<1.0f) font output.
+-- Brightening small fonts may be a good workaround to make them more readable.
+--
+-- By default, it is @1.0f@
+setRasterizerMultiply :: MonadIO m => FontConfig -> CFloat -> m ()
+setRasterizerMultiply (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->RasterizerMultiply = $(float value);
+    }
+  |]
+
+-- | Explicitly specify unicode codepoint of ellipsis character. When fonts are being merged first specified ellipsis will be used.
+--
+-- By default, it is @-1@
+setEllipsisChar :: MonadIO m => FontConfig -> ImWchar -> m ()
+setEllipsisChar (FontConfig fc) value = liftIO do
+  [C.block|
+    void {
+      $(ImFontConfig* fc)->EllipsisChar = $(ImWchar value);
+    }
+  |]

src/DearImGui/Raw/Font/GlyphRanges.hs

@@ -0,0 +1,295 @@
+{-# LANGUAGE BlockArguments #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE TemplateHaskell #-}
+
+{-| Font glyph ranges builder
+
+Helper to build glyph ranges from text/string data.
+Feed your application strings/characters to it then call 'buildRanges'.
+
+Low-level example of usage:
+
+@
+  -- import ImGui.Fonts
+  -- import ImGui.Raw.GlyphRangesBuilder as GRB
+
+  builder <- GRB.new
+
+  GRB.addRanges builder getGlyphRangesDefault
+  liftIO $ withCString "Привет" $ GRB.addText builder
+  rangesVec <- GRB.buildRanges builder
+  let ranges = GRB.fromRangesVector rangesVec
+
+  addFontFromFileTTF'
+    "./imgui/misc/fonts/DroidSans.ttf" 12
+    Nothing
+    (Just ranges)
+
+  -- it is strictly necessary to explicitly build the atlas
+  buildFontAtlas
+
+  -- resource destruction comes only after the building
+  GRB.destroyRangesVector rangesVec
+  GRB.destroy builder
+@
+
+-}
+
+module DearImGui.Raw.Font.GlyphRanges
+  ( GlyphRanges(..)
+
+    -- * Built-in ranges
+  , Builtin(..)
+  , getBuiltin
+  , builtinSetup
+
+    -- * Preparing a builder
+  , GlyphRangesBuilder(..)
+  , new
+  , destroy
+  , addChar
+  , addText
+  , addRanges
+
+    -- * Extracting data
+  , GlyphRangesVector(..)
+  , buildRangesVector
+  , fromRangesVector
+  , destroyRangesVector
+  )
+  where
+
+-- base
+import Control.Monad.IO.Class
+  ( MonadIO, liftIO )
+import Foreign ( Ptr )
+import Foreign.C
+import System.IO.Unsafe (unsafePerformIO)
+
+-- dear-imgui
+import DearImGui.Context
+  ( imguiContext )
+import DearImGui.Structs
+
+-- inline-c
+import qualified Language.C.Inline as C
+
+-- inline-c-cpp
+import qualified Language.C.Inline.Cpp as Cpp
+
+C.context (Cpp.cppCtx <> C.bsCtx <> imguiContext)
+C.include "imgui.h"
+Cpp.using "namespace ImGui"
+
+-- | Glyph ranges handle
+--
+-- Wraps @ImWchar*@.
+newtype GlyphRanges = GlyphRanges (Ptr ImWchar)
+
+-- | Builtin glyph ranges tags.
+data Builtin
+  = Latin
+  | Korean
+  | Japanese
+  | ChineseFull
+  | ChineseSimplifiedCommon
+  | Cyrillic
+  | Thai
+  | Vietnamese
+  deriving (Eq, Ord, Show, Enum, Bounded)
+
+-- | Get builtin glyph ranges from a tag.
+getBuiltin :: Builtin -> GlyphRanges
+getBuiltin = \case
+  Latin                   -> getGlyphRangesDefault
+  Korean                  -> getGlyphRangesKorean
+  Japanese                -> getGlyphRangesJapanese
+  ChineseFull             -> getGlyphRangesChineseFull
+  ChineseSimplifiedCommon -> getGlyphRangesChineseSimplifiedCommon
+  Cyrillic                -> getGlyphRangesCyrillic
+  Thai                    -> getGlyphRangesThai
+  Vietnamese              -> getGlyphRangesVietnamese
+
+-- | Special case of @getBuiltin@, but for font source setup.
+builtinSetup :: Builtin -> Maybe GlyphRanges
+builtinSetup = \case
+  Latin -> Nothing
+  others  -> Just (getBuiltin others)
+
+-- | Basic Latin, Extended Latin
+getGlyphRangesDefault :: GlyphRanges
+getGlyphRangesDefault = unsafePerformIO do
+  GlyphRanges <$> [C.block|
+    const ImWchar* {
+      return GetIO().Fonts->GetGlyphRangesDefault();
+    }
+  |]
+
+-- | Default + Korean characters
+getGlyphRangesKorean :: GlyphRanges
+getGlyphRangesKorean = unsafePerformIO do
+  GlyphRanges <$> [C.block|
+    const ImWchar* {
+      return GetIO().Fonts->GetGlyphRangesKorean();
+    }
+  |]
+
+-- | Default + Hiragana, Katakana, Half-Width, Selection of 2999 Ideographs
+getGlyphRangesJapanese :: GlyphRanges
+getGlyphRangesJapanese = unsafePerformIO do
+  GlyphRanges <$> [C.block|
+    const ImWchar* {
+      return GetIO().Fonts->GetGlyphRangesJapanese();
+    }
+  |]
+
+-- | Default + Half-Width + Japanese Hiragana/Katakana + full set of about 21000 CJK Unified Ideographs
+getGlyphRangesChineseFull :: GlyphRanges
+getGlyphRangesChineseFull = unsafePerformIO do
+  GlyphRanges <$> [C.block|
+    const ImWchar* {
+      return GetIO().Fonts->GetGlyphRangesChineseFull();
+    }
+  |]
+
+-- | Default + Half-Width + Japanese Hiragana/Katakana + set of 2500 CJK Unified Ideographs for common simplified Chinese
+getGlyphRangesChineseSimplifiedCommon :: GlyphRanges
+getGlyphRangesChineseSimplifiedCommon = unsafePerformIO do
+  GlyphRanges <$> [C.block|
+    const ImWchar* {
+      return GetIO().Fonts->GetGlyphRangesChineseSimplifiedCommon();
+    }
+  |]
+
+-- | Default + about 400 Cyrillic characters
+getGlyphRangesCyrillic :: GlyphRanges
+getGlyphRangesCyrillic = unsafePerformIO do
+  GlyphRanges <$> [C.block|
+    const ImWchar* {
+      return GetIO().Fonts->GetGlyphRangesCyrillic();
+    }
+  |]
+
+-- | Default + Thai characters
+getGlyphRangesThai :: GlyphRanges
+getGlyphRangesThai = unsafePerformIO do
+  GlyphRanges <$> [C.block|
+    const ImWchar* {
+      return GetIO().Fonts->GetGlyphRangesThai();
+    }
+  |]
+
+-- | Default + Vietnamese characters
+getGlyphRangesVietnamese :: GlyphRanges
+getGlyphRangesVietnamese = unsafePerformIO do
+  GlyphRanges <$> [C.block|
+    const ImWchar* {
+      return GetIO().Fonts->GetGlyphRangesVietnamese();
+    }
+  |]
+
+-- | Glyph ranges builder handle
+--
+-- Wraps @ImFontGlyphRangesBuilder*@.
+newtype GlyphRangesBuilder = GlyphRangesBuilder (Ptr ImFontGlyphRangesBuilder)
+
+-- | Glyph ranges vector handle to keep builder output
+--
+-- Wraps @ImVector<ImWchar>*@.
+newtype GlyphRangesVector = GlyphRangesVector (Ptr ())
+
+
+-- | Create an instance of builder
+new :: MonadIO m => m GlyphRangesBuilder
+new = liftIO do
+  GlyphRangesBuilder <$> [C.block|
+    ImFontGlyphRangesBuilder* {
+      return IM_NEW(ImFontGlyphRangesBuilder);
+    }
+  |]
+
+-- | Destroy an instance of builder
+--
+-- Should be used __after__ font atlas building.
+destroy :: MonadIO m => GlyphRangesBuilder -> m ()
+destroy (GlyphRangesBuilder builder) = liftIO do
+  [C.block|
+    void {
+      IM_DELETE($(ImFontGlyphRangesBuilder* builder));
+    }
+  |]
+
+
+-- | Add character
+addChar :: MonadIO m => GlyphRangesBuilder -> ImWchar -> m ()
+addChar (GlyphRangesBuilder builder) wChar = liftIO do
+  [C.block|
+    void {
+      $(ImFontGlyphRangesBuilder* builder)->AddChar($(ImWchar wChar));
+    }
+  |]
+
+-- | Add string (each character of the UTF-8 string are added)
+addText :: MonadIO m => GlyphRangesBuilder -> CString -> m ()
+addText (GlyphRangesBuilder builder) string = liftIO do
+  [C.block|
+    void {
+      $(ImFontGlyphRangesBuilder* builder)->AddText($(char* string));
+    }
+  |]
+-- FIXME: the function uses 'const char* text_end = NULL' parameter,
+--   which is pointer for the line ending. It is low level, though it
+--   could be utilized for string length parameter.
+
+-- | Add ranges, e.g. 'addRanges builder getGlyphRangesDefault'
+-- to force add all of ASCII/Latin+Ext
+addRanges :: MonadIO m => GlyphRangesBuilder -> GlyphRanges -> m()
+addRanges (GlyphRangesBuilder builder) (GlyphRanges ranges) = liftIO do
+  [C.block|
+    void {
+      $(ImFontGlyphRangesBuilder* builder)->AddRanges($(ImWchar* ranges));
+    }
+  |]
+
+
+-- | Build new ranges and create ranges vector instance,
+-- containing them
+buildRangesVector :: MonadIO m => GlyphRangesBuilder -> m (GlyphRangesVector)
+buildRangesVector (GlyphRangesBuilder builder) = liftIO do
+  GlyphRangesVector <$> [C.block|
+    void* {
+      ImVector<ImWchar>* ranges = IM_NEW(ImVector<ImWchar>);
+      $(ImFontGlyphRangesBuilder* builder)->BuildRanges(ranges);
+      return ranges;
+    }
+  |]
+
+-- | Extract glyph ranges from a vector
+--
+-- Should be used __before__ vector destruction.
+fromRangesVector :: GlyphRangesVector -> GlyphRanges
+fromRangesVector (GlyphRangesVector vecPtr) = unsafePerformIO do
+  GlyphRanges <$> [C.block|
+    ImWchar* {
+      return ((ImVector<ImWchar>*) $(void* vecPtr))->Data;
+    }
+  |]
+
+-- | Destroy a ranges vector instance
+--
+-- Should be used __after__ font atlas building.
+destroyRangesVector :: MonadIO m => GlyphRangesVector -> m ()
+destroyRangesVector (GlyphRangesVector vecPtr) = liftIO do
+  [C.block|
+    void {
+      IM_DELETE(((ImVector<ImWchar>*) $(void* vecPtr)));
+    }
+  |]

src/DearImGui/Structs.hs

@@ -5,7 +5,7 @@ module DearImGui.Structs where
 
 -- base
 import Data.Word
-  ( Word32 )
+  ( Word32, Word16 )
 import Foreign
   ( Storable(..), castPtr, plusPtr )
 
@@ -80,6 +80,12 @@ data ImGuiContext
 -- | Individual font handle.
 data ImFont
 
+-- | Font configuration handle.
+data ImFontConfig
+
+-- | Glyph ranges builder handle.
+data ImFontGlyphRangesBuilder
+
 -- | Opaque DrawList handle.
 data ImDrawList
 
@@ -88,3 +94,7 @@ data ImGuiListClipper
 
 -- | 32-bit unsigned integer (often used to store packed colors).
 type ImU32 = Word32
+
+-- | Single wide character (used mostly in glyph management)
+type ImWchar = Word16
+-- FIXME: consider IMGUI_USE_WCHAR32