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 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
 *   with this work for additional information regarding copyright
 *   ownership. The ASF licenses this file to you under the Apache
 *   License, Version 2.0 (the "License"); you may not use this file
 *   except in compliance with the License. You may obtain a copy of
 *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
 */

#include <tools/color.hxx>

#include <vcl/BitmapColor.hxx>
#include <vcl/BitmapWriteAccess.hxx>

#include <bitmap/BlendFrameCache.hxx>

BlendFrameCache::BlendFrameCache(Size const& rSize, sal_uInt8 nAlpha, Color const& rColorTopLeft,
                                 Color const& rColorTopRight, Color const& rColorBottomRight,
                                 Color const& rColorBottomLeft)
    : m_aLastSize(rSize)
    , m_nLastAlpha(nAlpha)
    , m_aLastColorTopLeft(rColorTopLeft)
    , m_aLastColorTopRight(rColorTopRight)
    , m_aLastColorBottomRight(rColorBottomRight)
    , m_aLastColorBottomLeft(rColorBottomLeft)
{
    if (rSize.Width() <= 1 || rSize.Height() <= 1)
        return;

    sal_uInt8 aEraseTrans(0xff);
    Bitmap aContent(rSize, vcl::PixelFormat::N24_BPP);
    AlphaMask aAlpha(rSize, &aEraseTrans);

    aContent.Erase(COL_BLACK);

    {
        BitmapScopedWriteAccess pContent(aContent);
        BitmapScopedWriteAccess pAlpha(aAlpha);

        if (!pContent || !pAlpha)
            return;

        Scanline pScanContent = pContent->GetScanline(0);
        Scanline pScanAlpha = pContent->GetScanline(0);

        // x == 0, y == 0, top-left corner
        pContent->SetPixelOnData(pScanContent, 0, rColorTopLeft);
        pAlpha->SetPixelOnData(pScanAlpha, 0, BitmapColor(nAlpha));

        tools::Long x(0);
        const tools::Long nW(rSize.Width());

        // y == 0, top line left to right
        for (x = 1; x < nW - 1; x++)
        {
            Color aMix(rColorTopLeft);

            aMix.Merge(rColorTopRight, 255 - sal_uInt8((x * 255) / nW));
            pContent->SetPixelOnData(pScanContent, x, aMix);
            pAlpha->SetPixelOnData(pScanAlpha, x, BitmapColor(nAlpha));
        }

        // x == nW - 1, y == 0, top-right corner
        // #i123690# Caution! When nW is 1, x == nW is possible (!)
        if (x < nW)
        {
            pContent->SetPixelOnData(pScanContent, x, rColorTopRight);
            pAlpha->SetPixelOnData(pScanAlpha, x, BitmapColor(nAlpha));
        }

        tools::Long y(0);
        const tools::Long nH(rSize.Height());

        // x == 0 and nW - 1, left and right line top-down
        for (y = 1; y < nH - 1; y++)
        {
            pScanContent = pContent->GetScanline(y);
            pScanAlpha = pContent->GetScanline(y);
            Color aMixA(rColorTopLeft);

            aMixA.Merge(rColorBottomLeft, 255 - sal_uInt8((y * 255) / nH));
            pContent->SetPixelOnData(pScanContent, 0, aMixA);
            pAlpha->SetPixelOnData(pScanAlpha, 0, BitmapColor(nAlpha));

            // #i123690# Caution! When nW is 1, x == nW is possible (!)
            if (x < nW)
            {
                Color aMixB(rColorTopRight);

                aMixB.Merge(rColorBottomRight, 255 - sal_uInt8((y * 255) / nH));
                pContent->SetPixelOnData(pScanContent, x, aMixB);
                pAlpha->SetPixelOnData(pScanAlpha, x, BitmapColor(nAlpha));
            }
        }

        // #i123690# Caution! When nH is 1, y == nH is possible (!)
        if (y < nH)
        {
            // x == 0, y == nH - 1, bottom-left corner
            pContent->SetPixelOnData(pScanContent, 0, rColorBottomLeft);
            pAlpha->SetPixelOnData(pScanAlpha, 0, BitmapColor(nAlpha));

            // y == nH - 1, bottom line left to right
            for (x = 1; x < nW - 1; x++)
            {
                Color aMix(rColorBottomLeft);

                aMix.Merge(rColorBottomRight, 255 - sal_uInt8(((x - 0) * 255) / nW));
                pContent->SetPixelOnData(pScanContent, x, aMix);
                pAlpha->SetPixelOnData(pScanAlpha, x, BitmapColor(nAlpha));
            }

            // x == nW - 1, y == nH - 1, bottom-right corner
            // #i123690# Caution! When nW is 1, x == nW is possible (!)
            if (x < nW)
            {
                pContent->SetPixelOnData(pScanContent, x, rColorBottomRight);
                pAlpha->SetPixelOnData(pScanAlpha, x, BitmapColor(nAlpha));
            }
        }
    }

    m_aLastResult = BitmapEx(aContent, aAlpha);
}

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