///////////////////////////////////////////////////////////////////////////

//

// Copyright (c) 2004, Industrial Light & Magic, a division of Lucas

// Digital Ltd. LLC

// 

// All rights reserved.

// 

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

// *       Redistributions of source code must retain the above copyright

// notice, this list of conditions and the following disclaimer.

// *       Redistributions in binary form must reproduce the above

// copyright notice, this list of conditions and the following disclaimer

// in the documentation and/or other materials provided with the

// distribution.

// *       Neither the name of Industrial Light & Magic nor the names of

// its contributors may be used to endorse or promote products derived

// from this software without specific prior written permission. 

// 

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

//

///////////////////////////////////////////////////////////////////////////

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

//

//	Add a preview image to an OpenEXR file.

//

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

#include "makePreview.h"

#include <ImfInputFile.h>

#include <ImfOutputFile.h>

#include <ImfTiledOutputFile.h>

#include <ImfRgbaFile.h>

#include <ImfPreviewImage.h>

#include <ImfArray.h>

#include <ImathMath.h>

#include <ImathFun.h>

#include <math.h>

#include <iostream>

#include <algorithm>

#include <OpenEXRConfig.h>

using namespace OPENEXR_IMF_NAMESPACE;

using namespace IMATH_NAMESPACE;

using namespace std;

namespace {

float

knee (float x, float f)

{

    return log (x * f + 1) / f;

}

unsigned char

gamma (half h, float m)

{

    //

    // Conversion from half to unsigned char pixel data,

    // with gamma correction.  The conversion is the same

    // as in the exrdisplay program's ImageView class,

    // except with defog, kneeLow, and kneeHigh fixed

    // at 0.0, 0.0, and 5.0 respectively.

    //

    float x = max (0.f, h * m);

    if (x > 1)

	x = 1 + knee (x - 1, 0.184874f);

    return (unsigned char) (clamp (Math<float>::pow (x, 0.4545f) * 84.66f, 

				   0.f,

				   255.f));

}

void

generatePreview (const char inFileName[],

		 float exposure,

		 int previewWidth,

		 int &previewHeight,

		 Array2D <PreviewRgba> &previewPixels)

{

    //

    // Read the input file

    //

    RgbaInputFile in (inFileName);

    Box2i dw = in.dataWindow();

    float a = in.pixelAspectRatio();

    int w = dw.max.x - dw.min.x + 1;

    int h = dw.max.y - dw.min.y + 1;

    Array2D <Rgba> pixels (h, w);

    in.setFrameBuffer (&pixels[0][0] - dw.min.y * w - dw.min.x, 1, w);

    in.readPixels (dw.min.y, dw.max.y);

    //

    // Make a preview image

    //

    previewHeight = max (int (h / (w * a) * previewWidth + .5f), 1);

    previewPixels.resizeErase (previewHeight, previewWidth);

    float fx = (previewWidth  > 0)? (float (w - 1) / (previewWidth  - 1)): 1;

    float fy = (previewHeight > 0)? (float (h - 1) / (previewHeight - 1)): 1;

    float m  = Math<float>::pow (2.f, clamp (exposure + 2.47393f, -20.f, 20.f));

    for (int y = 0; y < previewHeight; ++y)

    {

	for (int x = 0; x < previewWidth; ++x)

	{

	    PreviewRgba &preview = previewPixels[y][x];

	    const Rgba &pixel = pixels[int (y * fy + .5f)][int (x * fx + .5f)];

	    preview.r = gamma (pixel.r, m);

	    preview.g = gamma (pixel.g, m);

	    preview.b = gamma (pixel.b, m);

	    preview.a = int (clamp (pixel.a * 255.f, 0.f, 255.f) + .5f);

	}

    }

}

} // namespace

void

makePreview (const char inFileName[],

	     const char outFileName[],

	     int previewWidth,

	     float exposure,

	     bool verbose)

{

    if (verbose)

	cout << "generating preview image" << endl;

    Array2D <PreviewRgba> previewPixels;

    int previewHeight;

    generatePreview (inFileName,

		     exposure,

		     previewWidth,

		     previewHeight,

		     previewPixels);

    InputFile in (inFileName);

    Header header = in.header();

    header.setPreviewImage

	(PreviewImage (previewWidth, previewHeight, &previewPixels[0][0]));

    if (verbose)

	cout << "copying " << inFileName << " to " << outFileName << endl;

    if (header.hasTileDescription())

    {

	TiledOutputFile out (outFileName, header);

	out.copyPixels (in);

    }

    else

    {

	OutputFile out (outFileName, header);

	out.copyPixels (in);

    }

    if (verbose)

	cout << "done." << endl;

}