/*

 * Copyright 2011 Google Inc.

 *

 * Use of this source code is governed by a BSD-style license that can be

 * found in the LICENSE file.

 */

#include "include/effects/SkColorMatrixFilter.h"

static SkScalar byte_to_unit_float(U8CPU byte) {

    if (0xFF == byte) {

        // want to get this exact

        return 1;

    } else {

        return byte * 0.00392156862745f;

    }

}

sk_sp<SkColorFilter> SkColorMatrixFilter::MakeLightingFilter(SkColor mul, SkColor add) {

    const SkColor opaqueAlphaMask = SK_ColorBLACK;

    // omit the alpha and compare only the RGB values

    if (0 == (add & ~opaqueAlphaMask)) {

        return SkColorFilters::Blend(mul | opaqueAlphaMask, SkBlendMode::kModulate);

    }

    SkColorMatrix matrix;

    matrix.setScale(byte_to_unit_float(SkColorGetR(mul)),

                    byte_to_unit_float(SkColorGetG(mul)),

                    byte_to_unit_float(SkColorGetB(mul)),

                    1);

    matrix.postTranslate(byte_to_unit_float(SkColorGetR(add)),

                         byte_to_unit_float(SkColorGetG(add)),

                         byte_to_unit_float(SkColorGetB(add)),

                         0);

    return SkColorFilters::Matrix(matrix);

}