mirror of
https://github.com/Drezil/dear-imgui.hs.git
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109 lines
2.8 KiB
Haskell
109 lines
2.8 KiB
Haskell
{-# LANGUAGE BlockArguments #-}
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{-# LANGUAGE FlexibleContexts #-}
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{-# LANGUAGE NamedFieldPuns #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE PatternSynonyms #-}
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{-# LANGUAGE QuasiQuotes #-}
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{-# LANGUAGE TemplateHaskell #-}
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{-|
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Module: DearImGui.SDL
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SDL2 specific functions backend for Dear ImGui.
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Modules for initialising a backend with SDL2 can be found under the corresponding backend,
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e.g. "DearImGui.SDL.OpenGL".
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-}
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module DearImGui.SDL (
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-- ** SDL2
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sdl2NewFrame
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, sdl2Shutdown
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, pollEventWithImGui
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, pollEventsWithImGui
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-- *** Raw
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, dispatchRawEvent
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)
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where
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-- base
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import Control.Monad
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( void, when )
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import Foreign.Marshal.Alloc
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( alloca )
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import Foreign.Ptr
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( Ptr, castPtr )
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-- inline-c
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import qualified Language.C.Inline as C
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-- inline-c-cpp
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import qualified Language.C.Inline.Cpp as Cpp
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-- sdl2
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import SDL
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import SDL.Raw.Enum as Raw
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import qualified SDL.Raw.Event as Raw
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import qualified SDL.Raw.Types as Raw
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-- transformers
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import Control.Monad.IO.Class
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( MonadIO, liftIO )
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C.context (Cpp.cppCtx <> C.bsCtx)
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C.include "imgui.h"
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C.include "backends/imgui_impl_sdl2.h"
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C.include "SDL.h"
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Cpp.using "namespace ImGui"
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-- | Wraps @ImGui_ImplSDL2_NewFrame@.
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sdl2NewFrame :: MonadIO m => m ()
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sdl2NewFrame = liftIO do
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[C.exp| void { ImGui_ImplSDL2_NewFrame(); } |]
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-- | Wraps @ImGui_ImplSDL2_Shutdown@.
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sdl2Shutdown :: MonadIO m => m ()
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sdl2Shutdown = liftIO do
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[C.exp| void { ImGui_ImplSDL2_Shutdown(); } |]
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-- | Call the SDL2 'pollEvent' function, while also dispatching the event to
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-- Dear ImGui. You should use this in your application instead of 'pollEvent'.
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pollEventWithImGui :: MonadIO m => m (Maybe Event)
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pollEventWithImGui = liftIO do
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alloca \evPtr -> do
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pumpEvents
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-- We use NULL first to check if there's an event.
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nEvents <- Raw.peepEvents evPtr 1 Raw.SDL_PEEKEVENT Raw.SDL_FIRSTEVENT Raw.SDL_LASTEVENT
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when (nEvents > 0) do
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void $ dispatchRawEvent evPtr
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pollEvent
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-- | Dispatch a raw 'Raw.Event' value to Dear ImGui.
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--
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-- You may want this function instead of 'pollEventWithImGui' if you do not use
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-- @sdl2@'s higher-level 'Event' type (e.g. your application has its own polling
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-- mechanism).
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--
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-- __It is your application's responsibility to both manage the input__
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-- __pointer's memory and to fill the memory location with a raw 'Raw.Event'__
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-- __value.__
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dispatchRawEvent :: MonadIO m => Ptr Raw.Event -> m Bool
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dispatchRawEvent evPtr = liftIO do
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let evPtr' = castPtr evPtr :: Ptr ()
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(0 /=) <$> [C.exp| bool { ImGui_ImplSDL2_ProcessEvent((const SDL_Event*) $(void* evPtr')) } |]
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-- | Like the SDL2 'pollEvents' function, while also dispatching the events to
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-- Dear ImGui. See 'pollEventWithImGui'.
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pollEventsWithImGui :: MonadIO m => m [Event]
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pollEventsWithImGui = do
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e <- pollEventWithImGui
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case e of
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Nothing -> pure []
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Just e' -> ( e' : ) <$> pollEventsWithImGui
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