// ==========================================================

// Bitmap conversion routines

//

// Design and implementation by

// - Hervé Drolon (drolon@infonie.fr)

//

// This file is part of FreeImage 3

//

// COVERED CODE IS PROVIDED UNDER THIS LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTY

// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES

// THAT THE COVERED CODE IS FREE OF DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE

// OR NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE COVERED

// CODE IS WITH YOU. SHOULD ANY COVERED CODE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT

// THE INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF ANY NECESSARY

// SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL

// PART OF THIS LICENSE. NO USE OF ANY COVERED CODE IS AUTHORIZED HEREUNDER EXCEPT UNDER

// THIS DISCLAIMER.

//

// Use at your own risk!

// ==========================================================

#include "FreeImage.h"

#include "Utilities.h"

// ----------------------------------------------------------

//   smart convert X to RGB16

// ----------------------------------------------------------

FIBITMAP * DLL_CALLCONV

FreeImage_ConvertToRGB16(FIBITMAP *dib) {

  FIBITMAP *src = NULL;

  FIBITMAP *dst = NULL;

  if(!FreeImage_HasPixels(dib)) return NULL;

  const FREE_IMAGE_TYPE src_type = FreeImage_GetImageType(dib);

  // check for allowed conversions 

  switch(src_type) {

    case FIT_BITMAP:

    {

      // convert to 24-bit if needed

      if((FreeImage_GetBPP(dib) == 24) || (FreeImage_GetBPP(dib) == 32)) {

        src = dib;

      } else {

        src = FreeImage_ConvertTo24Bits(dib);

        if(!src) return NULL;

      }

      break;

    }

    case FIT_UINT16:

      // allow conversion from unsigned 16-bit

      src = dib;

      break;

    case FIT_RGB16:

      // RGB16 type : clone the src

      return FreeImage_Clone(dib);

      break;

    case FIT_RGBA16:

      // allow conversion from 64-bit RGBA (ignore the alpha channel)

      src = dib;

      break;

    default:

      return NULL;

  }

  // allocate dst image

  const unsigned width = FreeImage_GetWidth(src);

  const unsigned height = FreeImage_GetHeight(src);

  dst = FreeImage_AllocateT(FIT_RGB16, width, height);

  if(!dst) {

    if(src != dib) {

      FreeImage_Unload(src);

    }

    return NULL;

  }

  // copy metadata from src to dst

  FreeImage_CloneMetadata(dst, src);

  // convert from src type to RGB16

  switch(src_type) {

    case FIT_BITMAP:

    {

      // Calculate the number of bytes per pixel (1 for 8-bit, 3 for 24-bit or 4 for 32-bit)

      const unsigned bytespp = FreeImage_GetLine(src) / FreeImage_GetWidth(src);

      for(unsigned y = 0; y < height; y++) {

        const BYTE *src_bits = (BYTE*)FreeImage_GetScanLine(src, y);

        FIRGB16 *dst_bits = (FIRGB16*)FreeImage_GetScanLine(dst, y);

        for(unsigned x = 0; x < width; x++) {

          dst_bits[x].red   = src_bits[FI_RGBA_RED] << 8;

          dst_bits[x].green = src_bits[FI_RGBA_GREEN] << 8;

          dst_bits[x].blue  = src_bits[FI_RGBA_BLUE] << 8;

          src_bits += bytespp;

        }

      }

    }

    break;

    case FIT_UINT16:

    {

      for(unsigned y = 0; y < height; y++) {

        const WORD *src_bits = (WORD*)FreeImage_GetScanLine(src, y);

        FIRGB16 *dst_bits = (FIRGB16*)FreeImage_GetScanLine(dst, y);

        for(unsigned x = 0; x < width; x++) {

          // convert by copying greyscale channel to each R, G, B channels

          dst_bits[x].red   = src_bits[x];

          dst_bits[x].green = src_bits[x];

          dst_bits[x].blue  = src_bits[x];

        }

      }

    }

    break;

    case FIT_RGBA16:

    {

      for(unsigned y = 0; y < height; y++) {

        const FIRGBA16 *src_bits = (FIRGBA16*)FreeImage_GetScanLine(src, y);

        FIRGB16 *dst_bits = (FIRGB16*)FreeImage_GetScanLine(dst, y);

        for(unsigned x = 0; x < width; x++) {

          // convert and skip alpha channel

          dst_bits[x].red   = src_bits[x].red;

          dst_bits[x].green = src_bits[x].green;

          dst_bits[x].blue  = src_bits[x].blue;

        }

      }

    }

    break;

    default:

      break;

  }

  if(src != dib) {

    FreeImage_Unload(src);

  }

  return dst;

}