using System;
using System.Runtime.InteropServices;
using System.Drawing;
using System.Drawing.Imaging;

namespace ImageLoader {
    /// <summary>
    /// Image library class, used for loading images via DevIL.dll
    /// </summary>
    public unsafe class ImageLib {
        #region DllImports
        [DllImport("devil.dll")]
        private static extern void ilInit(); //initializes DevIL
        [DllImport("devil.dll")]
        private static extern void ilGenImages( //generates an image to work with
            int Num,
            uint* Images
        );
        [DllImport("devil.dll")]
        private static extern void ilBindImage( //binds DevIL functions to this image
            uint Image
        );
        [DllImport("devil.dll")]
        private static extern bool ilLoadImage( //load the image
            string FileName
        );
        [DllImport("devil.dll")]
        private static extern int ilGetInteger( //get a value
            uint Mode
        );
        [DllImport("devil.dll")]
        private static extern bool ilConvertImage( //convert the image
            uint DestFormat,
            uint DestType
        );
        [DllImport("devil.dll")]
        private static extern void ilCopyPixels( //copy pixels to a buffer
          uint XOff,
          uint YOff,
          uint ZOff,
          uint Width,
          uint Height,
          uint Depth,
          uint Format,
          uint Type,
          IntPtr Data
        );
        [DllImport("devil.dll")]
        private static extern void ilDeleteImages( //delete generated images
            int Num,
            uint *Images
        );
        #endregion

        /// <summary>
        /// Loads an image using DevIL.dll
        /// </summary>
        /// <param name="filename">The image to load</param>
        /// <returns>A nice and crisp .NET bitmap</returns>
        public static Bitmap LoadImage(string filename) {
            //example of use:
            //pictureBox1.Image = ImageLib.LoadImage("image.dds");

            uint imageID = 0;
            //initialize DevIL
            ilInit();

            //generate 1 image id
            ilGenImages(1, &imageID);

            //bind functions to generated image
            ilBindImage(imageID);

            //load image from file
            ilLoadImage(filename);

            //get width/height of image
            int width = ilGetInteger((uint)DevILValue.IL_IMAGE_WIDTH);
            int height = ilGetInteger((uint)DevILValue.IL_IMAGE_HEIGHT);

            //create a bitmap
            Bitmap bitmap1 = new Bitmap(width, height, PixelFormat.Format32bppArgb);
            //used for Bitmap.LockBits()
            Rectangle rectangle1 = new Rectangle(0, 0, width, height);

            //create BitmapData class to obtain a pointer to the first byte of data
            //lock bits to system memory
            BitmapData data1 = bitmap1.LockBits(rectangle1, ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);

            //get the pointer to the data
            IntPtr ptr = data1.Scan0;

            //convert the image to BGRA format
            //not sure why BGRA, i would expect RGBA, this might be wrong
            ilConvertImage((uint)DevILImage.IL_BGRA, (uint)DevILData.IL_UNSIGNED_BYTE);

            //copy the DevIL image bitmap data to the address pointed to by ptr
            ilCopyPixels(0, 0, 0, (uint)width, (uint)height, 1, (uint)DevILImage.IL_BGRA, (uint)DevILData.IL_UNSIGNED_BYTE, ptr);

            //unlock bits from memory
            bitmap1.UnlockBits(data1);

            //clean up by deleting image
            ilDeleteImages(1, &imageID);

            //return a nice and clean .NET bitmap
            return bitmap1;
        }

    }
    public enum DevILValue : uint {
        IL_ORIGIN_SET = 0x0600,
        IL_ORIGIN_LOWER_LEFT = 0x0601,
        IL_ORIGIN_UPPER_LEFT = 0x0602,
        IL_ORIGIN_MODE = 0x0603,

        IL_FORMAT_SET = 0x0610,
        IL_FORMAT_MODE = 0x0611,
        IL_TYPE_SET = 0x0612,
        IL_TYPE_MODE = 0x0613,

        IL_FILE_MODE = 0x0621,
        IL_CONV_PAL = 0x0630,

        IL_VERSION_NUM = 0x0DE2,
        IL_IMAGE_WIDTH = 0x0DE4,
        IL_IMAGE_HEIGHT = 0x0DE5,
        IL_IMAGE_DEPTH = 0x0DE6,
        IL_IMAGE_SIZE_OF_DATA = 0x0DE7,
        IL_IMAGE_BPP = 0x0DE8,
        IL_IMAGE_BYTES_PER_PIXEL = 0x0DE8,
        IL_IMAGE_BITS_PER_PIXEL = 0x0DE9,
        IL_IMAGE_FORMAT = 0x0DEA,
        IL_IMAGE_TYPE = 0x0DEB,
        IL_PALETTE_TYPE = 0x0DEC,
        IL_PALETTE_SIZE = 0x0DED,
        IL_PALETTE_BPP = 0x0DEE,
        IL_PALETTE_NUM_COLS = 0x0DEF,
        IL_PALETTE_BASE_TYPE = 0x0DF0,
        IL_NUM_IMAGES = 0x0DF1,
        IL_NUM_MIPMAPS = 0x0DF2,
        IL_NUM_LAYERS = 0x0DF3,
        IL_ACTIVE_IMAGE = 0x0DF4,
        IL_ACTIVE_MIPMAP = 0x0DF5,
        IL_ACTIVE_LAYER = 0x0DF6,
        IL_CUR_IMAGE = 0x0DF7,
        IL_IMAGE_DURATION = 0x0DF8,
        IL_IMAGE_PLANESIZE = 0x0DF9,
        IL_IMAGE_BPC = 0x0DFA,
        IL_IMAGE_OFFX = 0x0DFB,
        IL_IMAGE_OFFY = 0x0DFC,
        IL_IMAGE_CUBEFLAGS = 0x0DFD,
        IL_IMAGE_ORIGIN = 0x0DFE,
        IL_IMAGE_CHANNELS = 0x0DFF,
    }
    public enum DevILImage : uint {
        IL_COLOUR_INDEX = 0x1900,
        IL_COLOR_INDEX = 0x1900,
        IL_RGB = 0x1907,
        IL_RGBA = 0x1908,
        IL_BGR = 0x80E0,
        IL_BGRA = 0x80E1,
        IL_LUMINANCE = 0x1909,
    }
    public enum DevILData : uint {
        IL_BYTE = 0x1400,
        IL_UNSIGNED_BYTE = 0x1401,
        IL_SHORT = 0x1402,
        IL_UNSIGNED_SHORT = 0x1403,
        IL_INT = 0x1404,
        IL_UNSIGNED_INT = 0x1405,
        IL_FLOAT = 0x1406,
        IL_DOUBLE = 0x140A,
    }
}