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

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();
+    }
+  |]