Added image wrapper (#74)

Raw.image and sdl2/gl example "image"

Wrappers should be backend-specific due to different handling of `userTextureIDPtr`.

examples/sdl/Image.hs

@@ -0,0 +1,133 @@
+{-# language BlockArguments #-}
+{-# language LambdaCase #-}
+{-# language OverloadedStrings #-}
+
+module Main ( main ) where
+
+import Control.Exception
+import Control.Monad.IO.Class
+import Control.Monad.Managed
+import DearImGui
+import qualified DearImGui.Raw as Raw
+import DearImGui.OpenGL3
+import DearImGui.SDL
+import DearImGui.SDL.OpenGL
+import Graphics.GL
+import qualified SDL as SDL
+
+--  For the texture creation
+import Foreign
+import Foreign.Ptr
+import qualified Numeric.LinearAlgebra as M
+import Foreign.Marshal.Alloc
+import Data.IORef
+import qualified Data.Vector.Storable as VS
+
+data Texture = Texture {textureID :: GLuint, textureWidth :: GLsizei, textureHeight :: GLsizei}
+
+-- |Creates a texture in memory
+--
+-- Reserves space on the texture-memory for width*height
+create2DTexture :: Int -> Int -> IO Texture
+create2DTexture width height = do
+  alloca $ \ptr -> do
+    glGenTextures 1 ptr
+    tID <- peek ptr
+    return Texture {textureID = tID, textureWidth = fromIntegral width, textureHeight = fromIntegral height}
+    
+
+--createDummyTexture :: IORef Texture -> M.Matrix (Float) -> IO ()
+--createDummyTexture texture matrix = do
+createDummyTexture :: Texture -> IO ()
+createDummyTexture texture = do
+  let width = textureWidth texture
+  let height = textureWidth texture
+  glEnable GL_TEXTURE_2D
+  glBindTexture GL_TEXTURE_2D $ textureID texture
+  glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MIN_FILTER GL_LINEAR
+  glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MAG_FILTER GL_LINEAR
+  glTexParameteri GL_TEXTURE_2D GL_TEXTURE_WRAP_S GL_REPEAT
+  glTexParameteri GL_TEXTURE_2D GL_TEXTURE_WRAP_T GL_REPEAT
+  let dat = VS.generate (3*(fromIntegral width)*(fromIntegral height)) (\i -> fromIntegral $ 17 + (50 * (i `mod` 3)):: GLubyte) :: VS.Vector GLubyte -- some blueish
+  VS.unsafeWith dat $ \dataPtr -> do
+    glTexImage2D GL_TEXTURE_2D 0 GL_RGB width height 0 GL_RGB GL_UNSIGNED_BYTE (castPtr dataPtr)
+    return()
+  glBindTexture GL_TEXTURE_2D 0
+  return ()
+
+
+gui :: IO ()
+gui = do
+
+
+  -- Initialize SDL
+  SDL.initializeAll
+
+
+
+  runManaged do
+    -- Create a window using SDL. As we're using OpenGL, we need to enable OpenGL too.
+    w <- do
+      let title = "Hello, Dear ImGui!"
+      let config = SDL.defaultWindow { SDL.windowGraphicsContext = SDL.OpenGLContext SDL.defaultOpenGL, SDL.windowResizable = True }
+      managed $ bracket (SDL.createWindow title config) SDL.destroyWindow
+
+    -- Create an OpenGL context
+    glContext <- managed $ bracket (SDL.glCreateContext w) SDL.glDeleteContext
+
+    -- Create an ImGui context
+    _ <- managed $ bracket createContext destroyContext
+
+    -- Initialize ImGui's SDL2 backend
+    _ <- managed_ $ bracket_ (sdl2InitForOpenGL w glContext) sdl2Shutdown
+
+    -- Initialize ImGui's OpenGL backend
+    _ <- managed_ $ bracket_ openGL3Init (do 
+      putStrLn "ImguiOpenGL shut down"
+      openGL3Shutdown)
+
+
+    liftIO $ do 
+      txt <- create2DTexture 500 500 
+      createDummyTexture txt
+      err <- glGetError
+      putStrLn $  "Error-code: " ++ show err
+     
+    liftIO $ do
+      mainLoop w 1 -- 1 is actually the Ptr address
+
+
+mainLoop :: SDL.Window ->  GLuint -> IO ()
+mainLoop w c = do
+  -- Process the event loop
+  untilNothingM pollEventWithImGui
+
+  -- Tell ImGui we're starting a new frame
+  openGL3NewFrame
+  sdl2NewFrame
+  newFrame
+
+  -- Build the GUI
+  bracket_ (begin "GL") end $ do
+--    image (intPtrToPtr $ fromIntegral c) (ImVec2 500 500)(ImVec2 0 0)(ImVec2 1 1)(ImVec4 1 1 1 1)(ImVec4 0 0 0 0)
+    Foreign.with (ImVec2 500 500) \sizePtr ->
+      Foreign.with (ImVec2 0 0) \uv0Ptr -> 
+        Foreign.with (ImVec2 1 1) \uv1Ptr -> 
+          Foreign.with (ImVec4 1 1 1 1) \tintColPtr -> 
+            Foreign.with (ImVec4 0 0 0 0) \borderColPtr -> do
+              Raw.image (intPtrToPtr $ fromIntegral c) sizePtr uv0Ptr uv1Ptr tintColPtr borderColPtr
+
+  -- Render
+  render
+  glClear GL_COLOR_BUFFER_BIT
+
+  openGL3RenderDrawData =<< getDrawData
+
+  SDL.glSwapWindow w
+
+  mainLoop w c
+
+  where
+    untilNothingM m = m >>= maybe (return ()) (\_ -> untilNothingM m)
+
+main = do gui