SDL.fs

/// Wrappers and PInvoke of SDL2
/// Note I have only implemented the methods and constants I actually use - this is not a complete set of SDL by any means.
module SDL

open System.Runtime.InteropServices
open System

[<Literal>]
let libName = "SDL2"

let SDL_INIT_VIDEO = 0x00000020u

type SDL_WindowFlags =
| SDL_WINDOW_SHOWN = 0x00000004
| SDL_WINDOW_INPUT_FOCUS = 0x00000200

let SDL_TEXTUREACCESS_STREAMING = 1
let SDL_PIXELFORMAT_ARGB8888 = 372645892u

let SDL_KEYDOWN = 0x300u
let SDL_KEYUP = 769u
let SDLK_ESCAPE = 27u

[<type:StructLayout(LayoutKind.Sequential)>]
type SDL_Keysym = {
    scancode: SDL_Scancode
    sym: uint32
    ``mod``: SDL_Keymod
    unicode: uint32
} 
and SDL_Scancode = 
| SDL_SCANCODE_ESCAPE = 41
and SDL_Keymod =
| KMOD_NONE = 0x0000

[<type:StructLayout(LayoutKind.Sequential)>]
type SDL_KeyboardEvent =
    struct
        val ``type``: uint32
        val timestamp: uint32
        val windowID: uint32
        val state: byte
        val repeat: byte
        val private padding2: byte
        val private padding3: byte
        val keysym: SDL_Keysym
    end
    
[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern int SDL_Init(uint32 flags)
    
[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern int SDL_CreateWindowAndRenderer (int width, int height, SDL_WindowFlags flags, IntPtr& window, IntPtr& renderer)

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern uint32 SDL_GetTicks();

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern int SDL_PollEvent(SDL_KeyboardEvent& _event)

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern IntPtr SDL_CreateTexture (IntPtr renderer, uint32 format, int access, int width, int height)

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern int SDL_UpdateTexture(IntPtr texture, IntPtr rect, IntPtr pixels, int pitch);

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern int SDL_RenderClear(IntPtr renderer)

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern int SDL_RenderCopy(IntPtr renderer, IntPtr texture, IntPtr srcrect, IntPtr destrect);

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern unit SDL_RenderPresent(IntPtr renderer)

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern unit SDL_DestroyTexture(IntPtr texture)

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern unit SDL_DestroyRenderer(IntPtr renderer)

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern unit SDL_DestroyWindow(IntPtr window)

[<DllImport(libName, CallingConvention = CallingConvention.Cdecl)>]
extern unit SDL_Quit()