/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * 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 <headless/CairoCommon.hxx>
#include <dlfcn.h>
#include <vcl/BitmapTools.hxx>
#include <svdata.hxx>
#include <tools/helpers.hxx>
#include <basegfx/utils/canvastools.hxx>
#include <basegfx/matrix/b2dhommatrixtools.hxx>
#include <basegfx/polygon/b2dpolypolygontools.hxx>
#include <basegfx/polygon/b2dpolygontools.hxx>
#include <unotools/configmgr.hxx>
#include <sal/log.hxx>
#include <osl/module.h>

#if CAIRO_VERSION < CAIRO_VERSION_ENCODE(1, 12, 0)
#error "require at least cairo 1.12.0"
#endif

void dl_cairo_surface_set_device_scale(cairo_surface_t* surface, double x_scale, double y_scale)
{
#if !HAVE_DLAPI
    cairo_surface_set_device_scale(surface, x_scale, y_scale);
#else
    static auto func = reinterpret_cast<void (*)(cairo_surface_t*, double, double)>(
        osl_getAsciiFunctionSymbol(nullptr, "cairo_surface_set_device_scale"));
    if (func)
        func(surface, x_scale, y_scale);
#endif
}

void dl_cairo_surface_get_device_scale(cairo_surface_t* surface, double* x_scale, double* y_scale)
{
#if !HAVE_DLAPI
    cairo_surface_get_device_scale(surface, x_scale, y_scale);
#else
    static auto func = reinterpret_cast<void (*)(cairo_surface_t*, double*, double*)>(
        osl_getAsciiFunctionSymbol(nullptr, "cairo_surface_get_device_scale"));
    if (func)
        func(surface, x_scale, y_scale);
    else
    {
        if (x_scale)
            *x_scale = 1.0;
        if (y_scale)
            *y_scale = 1.0;
    }
#endif
}

basegfx::B2DRange getFillDamage(cairo_t* cr)
{
    double x1, y1, x2, y2;

    // this is faster than cairo_fill_extents, at the cost of some overdraw
    cairo_path_extents(cr, &x1, &y1, &x2, &y2);

    // support B2DRange::isEmpty()
    if (0.0 != x1 || 0.0 != y1 || 0.0 != x2 || 0.0 != y2)
    {
        return basegfx::B2DRange(x1, y1, x2, y2);
    }

    return basegfx::B2DRange();
}

basegfx::B2DRange getClipBox(cairo_t* cr)
{
    double x1, y1, x2, y2;

    cairo_clip_extents(cr, &x1, &y1, &x2, &y2);

    // support B2DRange::isEmpty()
    if (0.0 != x1 || 0.0 != y1 || 0.0 != x2 || 0.0 != y2)
    {
        return basegfx::B2DRange(x1, y1, x2, y2);
    }

    return basegfx::B2DRange();
}

basegfx::B2DRange getClippedFillDamage(cairo_t* cr)
{
    basegfx::B2DRange aDamageRect(getFillDamage(cr));
    aDamageRect.intersect(getClipBox(cr));
    return aDamageRect;
}

basegfx::B2DRange getStrokeDamage(cairo_t* cr)
{
    double x1, y1, x2, y2;

    // less accurate, but much faster
    cairo_path_extents(cr, &x1, &y1, &x2, &y2);

    // support B2DRange::isEmpty()
    if (0.0 != x1 || 0.0 != y1 || 0.0 != x2 || 0.0 != y2)
    {
        return basegfx::B2DRange(x1, y1, x2, y2);
    }

    return basegfx::B2DRange();
}

basegfx::B2DRange getClippedStrokeDamage(cairo_t* cr)
{
    basegfx::B2DRange aDamageRect(getStrokeDamage(cr));
    aDamageRect.intersect(getClipBox(cr));
    return aDamageRect;
}

// Remove bClosePath: Checked that the already used mechanism for Win using
// Gdiplus already relies on rPolygon.isClosed(), so should be safe to replace
// this.
// For PixelSnap we need the ObjectToDevice transformation here now. This is a
// special case relative to the also executed LineDraw-Offset of (0.5, 0.5) in
// DeviceCoordinates: The LineDraw-Offset is applied *after* the snap, so we
// need the ObjectToDevice transformation *without* that offset here to do the
// same. The LineDraw-Offset will be applied by the callers using a linear
// transformation for Cairo now
// For support of PixelSnapHairline we also need the ObjectToDevice transformation
// and a method (same as in gdiimpl.cxx for Win and Gdiplus). This is needed e.g.
// for Chart-content visualization. CAUTION: It's not the same as PixelSnap (!)
// tdf#129845 add reply value to allow counting a point/byte/size measurement to
// be included
size_t AddPolygonToPath(cairo_t* cr, const basegfx::B2DPolygon& rPolygon,
                        const basegfx::B2DHomMatrix& rObjectToDevice, bool bPixelSnap,
                        bool bPixelSnapHairline)
{
    // short circuit if there is nothing to do
    const sal_uInt32 nPointCount(rPolygon.count());
    size_t nSizeMeasure(0);

    if (0 == nPointCount)
    {
        return nSizeMeasure;
    }

    const bool bHasCurves(rPolygon.areControlPointsUsed());
    const bool bClosePath(rPolygon.isClosed());
    const bool bObjectToDeviceUsed(!rObjectToDevice.isIdentity());
    basegfx::B2DHomMatrix aObjectToDeviceInv;
    basegfx::B2DPoint aLast;

    for (sal_uInt32 nPointIdx = 0, nPrevIdx = 0;; nPrevIdx = nPointIdx++)
    {
        int nClosedIdx = nPointIdx;
        if (nPointIdx >= nPointCount)
        {
            // prepare to close last curve segment if needed
            if (bClosePath && (nPointIdx == nPointCount))
            {
                nClosedIdx = 0;
            }
            else
            {
                break;
            }
        }

        basegfx::B2DPoint aPoint(rPolygon.getB2DPoint(nClosedIdx));

        if (bPixelSnap)
        {
            // snap device coordinates to full pixels
            if (bObjectToDeviceUsed)
            {
                // go to DeviceCoordinates
                aPoint *= rObjectToDevice;
            }

            // snap by rounding
            aPoint.setX(basegfx::fround(aPoint.getX()));
            aPoint.setY(basegfx::fround(aPoint.getY()));

            if (bObjectToDeviceUsed)
            {
                if (aObjectToDeviceInv.isIdentity())
                {
                    aObjectToDeviceInv = rObjectToDevice;
                    aObjectToDeviceInv.invert();
                }

                // go back to ObjectCoordinates
                aPoint *= aObjectToDeviceInv;
            }
        }

        if (bPixelSnapHairline)
        {
            // snap horizontal and vertical lines (mainly used in Chart for
            // 'nicer' AAing)
            aPoint = impPixelSnap(rPolygon, rObjectToDevice, aObjectToDeviceInv, nClosedIdx);
        }

        if (!nPointIdx)
        {
            // first point => just move there
            cairo_move_to(cr, aPoint.getX(), aPoint.getY());
            aLast = aPoint;
            continue;
        }

        bool bPendingCurve(false);

        if (bHasCurves)
        {
            bPendingCurve = rPolygon.isNextControlPointUsed(nPrevIdx);
            bPendingCurve |= rPolygon.isPrevControlPointUsed(nClosedIdx);
        }

        if (!bPendingCurve) // line segment
        {
            cairo_line_to(cr, aPoint.getX(), aPoint.getY());
            nSizeMeasure++;
        }
        else // cubic bezier segment
        {
            basegfx::B2DPoint aCP1 = rPolygon.getNextControlPoint(nPrevIdx);
            basegfx::B2DPoint aCP2 = rPolygon.getPrevControlPoint(nClosedIdx);

            // tdf#99165 if the control points are 'empty', create the mathematical
            // correct replacement ones to avoid problems with the graphical sub-system
            // tdf#101026 The 1st attempt to create a mathematically correct replacement control
            // vector was wrong. Best alternative is one as close as possible which means short.
            if (aCP1.equal(aLast))
            {
                aCP1 = aLast + ((aCP2 - aLast) * 0.0005);
            }

            if (aCP2.equal(aPoint))
            {
                aCP2 = aPoint + ((aCP1 - aPoint) * 0.0005);
            }

            cairo_curve_to(cr, aCP1.getX(), aCP1.getY(), aCP2.getX(), aCP2.getY(), aPoint.getX(),
                           aPoint.getY());
            // take some bigger measure for curve segments - too expensive to subdivide
            // here and that precision not needed, but four (2 points, 2 control-points)
            // would be a too low weight
            nSizeMeasure += 10;
        }

        aLast = aPoint;
    }

    if (bClosePath)
    {
        cairo_close_path(cr);
    }

    return nSizeMeasure;
}

basegfx::B2DPoint impPixelSnap(const basegfx::B2DPolygon& rPolygon,
                               const basegfx::B2DHomMatrix& rObjectToDevice,
                               basegfx::B2DHomMatrix& rObjectToDeviceInv, sal_uInt32 nIndex)
{
    const sal_uInt32 nCount(rPolygon.count());

    // get the data
    const basegfx::B2ITuple aPrevTuple(
        basegfx::fround(rObjectToDevice * rPolygon.getB2DPoint((nIndex + nCount - 1) % nCount)));
    const basegfx::B2DPoint aCurrPoint(rObjectToDevice * rPolygon.getB2DPoint(nIndex));
    const basegfx::B2ITuple aCurrTuple(basegfx::fround(aCurrPoint));
    const basegfx::B2ITuple aNextTuple(
        basegfx::fround(rObjectToDevice * rPolygon.getB2DPoint((nIndex + 1) % nCount)));

    // get the states
    const bool bPrevVertical(aPrevTuple.getX() == aCurrTuple.getX());
    const bool bNextVertical(aNextTuple.getX() == aCurrTuple.getX());
    const bool bPrevHorizontal(aPrevTuple.getY() == aCurrTuple.getY());
    const bool bNextHorizontal(aNextTuple.getY() == aCurrTuple.getY());
    const bool bSnapX(bPrevVertical || bNextVertical);
    const bool bSnapY(bPrevHorizontal || bNextHorizontal);

    if (bSnapX || bSnapY)
    {
        basegfx::B2DPoint aSnappedPoint(bSnapX ? aCurrTuple.getX() : aCurrPoint.getX(),
                                        bSnapY ? aCurrTuple.getY() : aCurrPoint.getY());

        if (rObjectToDeviceInv.isIdentity())
        {
            rObjectToDeviceInv = rObjectToDevice;
            rObjectToDeviceInv.invert();
        }

        aSnappedPoint *= rObjectToDeviceInv;

        return aSnappedPoint;
    }

    return rPolygon.getB2DPoint(nIndex);
}

SystemDependentData_CairoPath::SystemDependentData_CairoPath(size_t nSizeMeasure, cairo_t* cr,
                                                             bool bNoJoin, bool bAntiAlias,
                                                             const std::vector<double>* pStroke)
    : basegfx::SystemDependentData(Application::GetSystemDependentDataManager())
    , mpCairoPath(nullptr)
    , mbNoJoin(bNoJoin)
    , mbAntiAlias(bAntiAlias)
{
    static const bool bFuzzing = utl::ConfigManager::IsFuzzing();

    // tdf#129845 only create a copy of the path when nSizeMeasure is
    // bigger than some decent threshold
    if (!bFuzzing && nSizeMeasure > 50)
    {
        mpCairoPath = cairo_copy_path(cr);

        if (nullptr != pStroke)
        {
            maStroke = *pStroke;
        }
    }
}

SystemDependentData_CairoPath::~SystemDependentData_CairoPath()
{
    if (nullptr != mpCairoPath)
    {
        cairo_path_destroy(mpCairoPath);
        mpCairoPath = nullptr;
    }
}

sal_Int64 SystemDependentData_CairoPath::estimateUsageInBytes() const
{
    // tdf#129845 by using the default return value of zero when no path
    // was created, SystemDependentData::calculateCombinedHoldCyclesInSeconds
    // will do the right thing and not buffer this entry at all
    sal_Int64 nRetval(0);

    if (nullptr != mpCairoPath)
    {
        // per node
        // - num_data incarnations of
        // - sizeof(cairo_path_data_t) which is a union of defines and point data
        //   thus may 2 x sizeof(double)
        nRetval = mpCairoPath->num_data * sizeof(cairo_path_data_t);
    }

    return nRetval;
}

void add_polygon_path(cairo_t* cr, const basegfx::B2DPolyPolygon& rPolyPolygon,
                      const basegfx::B2DHomMatrix& rObjectToDevice, bool bPixelSnap)
{
    // try to access buffered data
    std::shared_ptr<SystemDependentData_CairoPath> pSystemDependentData_CairoPath(
        rPolyPolygon.getSystemDependentData<SystemDependentData_CairoPath>());

    if (pSystemDependentData_CairoPath)
    {
        // re-use data
        cairo_append_path(cr, pSystemDependentData_CairoPath->getCairoPath());
    }
    else
    {
        // create data
        size_t nSizeMeasure(0);

        for (const auto& rPoly : rPolyPolygon)
        {
            // PixelOffset used: Was dependent of 'm_aLineColor != SALCOLOR_NONE'
            // Adapt setupPolyPolygon-users to set a linear transformation to achieve PixelOffset
            nSizeMeasure += AddPolygonToPath(cr, rPoly, rObjectToDevice, bPixelSnap, false);
        }

        // copy and add to buffering mechanism
        // for decisions how/what to buffer, see Note in WinSalGraphicsImpl::drawPolyPolygon
        pSystemDependentData_CairoPath
            = rPolyPolygon.addOrReplaceSystemDependentData<SystemDependentData_CairoPath>(
                nSizeMeasure, cr, false, false, nullptr);
    }
}

cairo_user_data_key_t* CairoCommon::getDamageKey()
{
    static cairo_user_data_key_t aDamageKey;
    return &aDamageKey;
}

cairo_t* CairoCommon::getCairoContext(bool bXorModeAllowed, bool bAntiAlias) const
{
    cairo_t* cr;
    if (m_ePaintMode == PaintMode::Xor && bXorModeAllowed)
        cr = createTmpCompatibleCairoContext();
    else
        cr = cairo_create(m_pSurface);
    cairo_set_line_width(cr, 1);
    cairo_set_fill_rule(cr, CAIRO_FILL_RULE_EVEN_ODD);
    cairo_set_antialias(cr, bAntiAlias ? CAIRO_ANTIALIAS_DEFAULT : CAIRO_ANTIALIAS_NONE);
    cairo_set_operator(cr, CAIRO_OPERATOR_OVER);

    // ensure no linear transformation and no PathInfo in local cairo_path_t
    cairo_identity_matrix(cr);
    cairo_new_path(cr);

    return cr;
}

void CairoCommon::releaseCairoContext(cairo_t* cr, bool bXorModeAllowed,
                                      const basegfx::B2DRange& rExtents) const
{
    const bool bXoring = (m_ePaintMode == PaintMode::Xor && bXorModeAllowed);

    if (rExtents.isEmpty())
    {
        //nothing changed, return early
        if (bXoring)
        {
            cairo_surface_t* surface = cairo_get_target(cr);
            cairo_surface_destroy(surface);
        }
        cairo_destroy(cr);
        return;
    }

    basegfx::B2IRange aIntExtents(basegfx::unotools::b2ISurroundingRangeFromB2DRange(rExtents));
    sal_Int32 nExtentsLeft(aIntExtents.getMinX()), nExtentsTop(aIntExtents.getMinY());
    sal_Int32 nExtentsRight(aIntExtents.getMaxX()), nExtentsBottom(aIntExtents.getMaxY());
    sal_Int32 nWidth = m_aFrameSize.getX();
    sal_Int32 nHeight = m_aFrameSize.getY();
    nExtentsLeft = std::max<sal_Int32>(nExtentsLeft, 0);
    nExtentsTop = std::max<sal_Int32>(nExtentsTop, 0);
    nExtentsRight = std::min<sal_Int32>(nExtentsRight, nWidth);
    nExtentsBottom = std::min<sal_Int32>(nExtentsBottom, nHeight);

    cairo_surface_t* surface = cairo_get_target(cr);
    cairo_surface_flush(surface);

    //For the most part we avoid the use of XOR these days, but there
    //are some edge cases where legacy stuff still supports it, so
    //emulate it (slowly) here.
    if (bXoring)
        doXorOnRelease(nExtentsLeft, nExtentsTop, nExtentsRight, nExtentsBottom, surface, nWidth);

    cairo_destroy(cr); // unref

    DamageHandler* pDamage
        = static_cast<DamageHandler*>(cairo_surface_get_user_data(m_pSurface, getDamageKey()));

    if (pDamage)
    {
        pDamage->damaged(pDamage->handle, nExtentsLeft, nExtentsTop, nExtentsRight - nExtentsLeft,
                         nExtentsBottom - nExtentsTop);
    }
}

void CairoCommon::doXorOnRelease(sal_Int32 nExtentsLeft, sal_Int32 nExtentsTop,
                                 sal_Int32 nExtentsRight, sal_Int32 nExtentsBottom,
                                 cairo_surface_t* const surface, sal_Int32 nWidth) const
{
    //For the most part we avoid the use of XOR these days, but there
    //are some edge cases where legacy stuff still supports it, so
    //emulate it (slowly) here.
    cairo_surface_t* target_surface = m_pSurface;
    if (cairo_surface_get_type(target_surface) != CAIRO_SURFACE_TYPE_IMAGE)
    {
        //in the unlikely case we can't use m_pSurface directly, copy contents
        //to another temp image surface
        target_surface = cairo_surface_map_to_image(target_surface, nullptr);
    }

    cairo_surface_flush(target_surface);
    unsigned char* target_surface_data = cairo_image_surface_get_data(target_surface);
    unsigned char* xor_surface_data = cairo_image_surface_get_data(surface);

    cairo_format_t nFormat = cairo_image_surface_get_format(target_surface);
    assert(nFormat == CAIRO_FORMAT_ARGB32 && "need to implement CAIRO_FORMAT_A1 after all here");
    sal_Int32 nStride = cairo_format_stride_for_width(nFormat, nWidth * m_fScale);
    sal_Int32 nUnscaledExtentsLeft = nExtentsLeft * m_fScale;
    sal_Int32 nUnscaledExtentsRight = nExtentsRight * m_fScale;
    sal_Int32 nUnscaledExtentsTop = nExtentsTop * m_fScale;
    sal_Int32 nUnscaledExtentsBottom = nExtentsBottom * m_fScale;

    // Handle headless size forced to (1,1) by SvpSalFrame::GetSurfaceFrameSize().
    int target_surface_width = cairo_image_surface_get_width(target_surface);
    if (nUnscaledExtentsLeft > target_surface_width)
        nUnscaledExtentsLeft = target_surface_width;
    if (nUnscaledExtentsRight > target_surface_width)
        nUnscaledExtentsRight = target_surface_width;
    int target_surface_height = cairo_image_surface_get_height(target_surface);
    if (nUnscaledExtentsTop > target_surface_height)
        nUnscaledExtentsTop = target_surface_height;
    if (nUnscaledExtentsBottom > target_surface_height)
        nUnscaledExtentsBottom = target_surface_height;

#if !ENABLE_WASM_STRIP_PREMULTIPLY
    vcl::bitmap::lookup_table const& unpremultiply_table = vcl::bitmap::get_unpremultiply_table();
    vcl::bitmap::lookup_table const& premultiply_table = vcl::bitmap::get_premultiply_table();
#endif
    for (sal_Int32 y = nUnscaledExtentsTop; y < nUnscaledExtentsBottom; ++y)
    {
        unsigned char* true_row = target_surface_data + (nStride * y);
        unsigned char* xor_row = xor_surface_data + (nStride * y);
        unsigned char* true_data = true_row + (nUnscaledExtentsLeft * 4);
        unsigned char* xor_data = xor_row + (nUnscaledExtentsLeft * 4);
        for (sal_Int32 x = nUnscaledExtentsLeft; x < nUnscaledExtentsRight; ++x)
        {
            sal_uInt8 a = true_data[SVP_CAIRO_ALPHA];
            sal_uInt8 xor_a = xor_data[SVP_CAIRO_ALPHA];
#if ENABLE_WASM_STRIP_PREMULTIPLY
            sal_uInt8 b = vcl::bitmap::unpremultiply(a, true_data[SVP_CAIRO_BLUE])
                          ^ vcl::bitmap::unpremultiply(xor_a, xor_data[SVP_CAIRO_BLUE]);
            sal_uInt8 g = vcl::bitmap::unpremultiply(a, true_data[SVP_CAIRO_GREEN])
                          ^ vcl::bitmap::unpremultiply(xor_a, xor_data[SVP_CAIRO_GREEN]);
            sal_uInt8 r = vcl::bitmap::unpremultiply(a, true_data[SVP_CAIRO_RED])
                          ^ vcl::bitmap::unpremultiply(xor_a, xor_data[SVP_CAIRO_RED]);
            true_data[SVP_CAIRO_BLUE] = vcl::bitmap::premultiply(a, b);
            true_data[SVP_CAIRO_GREEN] = vcl::bitmap::premultiply(a, g);
            true_data[SVP_CAIRO_RED] = vcl::bitmap::premultiply(a, r);
#else
            sal_uInt8 b = unpremultiply_table[a][true_data[SVP_CAIRO_BLUE]]
                          ^ unpremultiply_table[xor_a][xor_data[SVP_CAIRO_BLUE]];
            sal_uInt8 g = unpremultiply_table[a][true_data[SVP_CAIRO_GREEN]]
                          ^ unpremultiply_table[xor_a][xor_data[SVP_CAIRO_GREEN]];
            sal_uInt8 r = unpremultiply_table[a][true_data[SVP_CAIRO_RED]]
                          ^ unpremultiply_table[xor_a][xor_data[SVP_CAIRO_RED]];
            true_data[SVP_CAIRO_BLUE] = premultiply_table[a][b];
            true_data[SVP_CAIRO_GREEN] = premultiply_table[a][g];
            true_data[SVP_CAIRO_RED] = premultiply_table[a][r];
#endif
            true_data += 4;
            xor_data += 4;
        }
    }
    cairo_surface_mark_dirty(target_surface);

    if (target_surface != m_pSurface)
    {
        cairo_surface_unmap_image(m_pSurface, target_surface);
    }

    cairo_surface_destroy(surface);
}

cairo_t* CairoCommon::createTmpCompatibleCairoContext() const
{
    cairo_surface_t* target = cairo_surface_create_similar_image(m_pSurface, CAIRO_FORMAT_ARGB32,
                                                                 m_aFrameSize.getX() * m_fScale,
                                                                 m_aFrameSize.getY() * m_fScale);

    dl_cairo_surface_set_device_scale(target, m_fScale, m_fScale);

    return cairo_create(target);
}

void CairoCommon::applyColor(cairo_t* cr, Color aColor, double fTransparency)
{
    if (cairo_surface_get_content(m_pSurface) == CAIRO_CONTENT_COLOR_ALPHA)
    {
        cairo_set_source_rgba(cr, aColor.GetRed() / 255.0, aColor.GetGreen() / 255.0,
                              aColor.GetBlue() / 255.0, 1.0 - fTransparency);
    }
    else
    {
        double fSet = aColor == COL_BLACK ? 1.0 : 0.0;
        cairo_set_source_rgba(cr, 1, 1, 1, fSet);
        cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
    }
}

void CairoCommon::clipRegion(cairo_t* cr, const vcl::Region& rClipRegion)
{
    RectangleVector aRectangles;
    if (!rClipRegion.IsEmpty())
    {
        rClipRegion.GetRegionRectangles(aRectangles);
    }
    if (!aRectangles.empty())
    {
        bool bEmpty = true;
        for (auto const& rectangle : aRectangles)
        {
            if (rectangle.GetWidth() <= 0 || rectangle.GetHeight() <= 0)
            {
                SAL_WARN("vcl.gdi", "bad clip rect of: " << rectangle);
                continue;
            }
            cairo_rectangle(cr, rectangle.Left(), rectangle.Top(), rectangle.GetWidth(),
                            rectangle.GetHeight());
            bEmpty = false;
        }
        if (!bEmpty)
            cairo_clip(cr);
    }
}

void CairoCommon::clipRegion(cairo_t* cr) { CairoCommon::clipRegion(cr, m_aClipRegion); }

bool CairoCommon::drawPolyLine(cairo_t* cr, basegfx::B2DRange* pExtents, const Color& rLineColor,
                               bool bAntiAlias, const basegfx::B2DHomMatrix& rObjectToDevice,
                               const basegfx::B2DPolygon& rPolyLine, double fTransparency,
                               double fLineWidth, const std::vector<double>* pStroke,
                               basegfx::B2DLineJoin eLineJoin, css::drawing::LineCap eLineCap,
                               double fMiterMinimumAngle, bool bPixelSnapHairline)
{
    // short circuit if there is nothing to do
    if (0 == rPolyLine.count() || fTransparency < 0.0 || fTransparency >= 1.0)
    {
        return true;
    }

    static const bool bFuzzing = utl::ConfigManager::IsFuzzing();
    if (bFuzzing)
    {
        const basegfx::B2DRange aRange(basegfx::utils::getRange(rPolyLine));
        if (aRange.getMaxX() - aRange.getMinX() > 0x10000000
            || aRange.getMaxY() - aRange.getMinY() > 0x10000000)
        {
            SAL_WARN("vcl.gdi", "drawPolyLine, skipping suspicious range of: "
                                    << aRange << " for fuzzing performance");
            return true;
        }
    }

    // need to check/handle LineWidth when ObjectToDevice transformation is used
    const bool bObjectToDeviceIsIdentity(rObjectToDevice.isIdentity());

    // tdf#124848 calculate-back logical LineWidth for a hairline
    // since this implementation hands over the transformation to
    // the graphic sub-system
    if (fLineWidth == 0)
    {
        fLineWidth = 1.0;

        if (!bObjectToDeviceIsIdentity)
        {
            basegfx::B2DHomMatrix aObjectToDeviceInv(rObjectToDevice);
            aObjectToDeviceInv.invert();
            fLineWidth = (aObjectToDeviceInv * basegfx::B2DVector(fLineWidth, 0)).getLength();
        }
    }

    // PixelOffset used: Need to reflect in linear transformation
    cairo_matrix_t aMatrix;
    basegfx::B2DHomMatrix aDamageMatrix(basegfx::utils::createTranslateB2DHomMatrix(0.5, 0.5));

    if (bObjectToDeviceIsIdentity)
    {
        // Set PixelOffset as requested
        cairo_matrix_init_translate(&aMatrix, 0.5, 0.5);
    }
    else
    {
        // Prepare ObjectToDevice transformation. Take PixelOffset for Lines into
        // account: Multiply from left to act in DeviceCoordinates
        aDamageMatrix = aDamageMatrix * rObjectToDevice;
        cairo_matrix_init(&aMatrix, aDamageMatrix.get(0, 0), aDamageMatrix.get(1, 0),
                          aDamageMatrix.get(0, 1), aDamageMatrix.get(1, 1), aDamageMatrix.get(0, 2),
                          aDamageMatrix.get(1, 2));
    }

    // set linear transformation
    cairo_set_matrix(cr, &aMatrix);

    // setup line attributes
    cairo_line_join_t eCairoLineJoin = CAIRO_LINE_JOIN_MITER;
    switch (eLineJoin)
    {
        case basegfx::B2DLineJoin::Bevel:
            eCairoLineJoin = CAIRO_LINE_JOIN_BEVEL;
            break;
        case basegfx::B2DLineJoin::Round:
            eCairoLineJoin = CAIRO_LINE_JOIN_ROUND;
            break;
        case basegfx::B2DLineJoin::NONE:
        case basegfx::B2DLineJoin::Miter:
            eCairoLineJoin = CAIRO_LINE_JOIN_MITER;
            break;
    }

    // convert miter minimum angle to miter limit
    double fMiterLimit = 1.0 / sin(std::max(fMiterMinimumAngle, 0.01 * M_PI) / 2.0);

    // setup cap attribute
    cairo_line_cap_t eCairoLineCap(CAIRO_LINE_CAP_BUTT);

    switch (eLineCap)
    {
        default: // css::drawing::LineCap_BUTT:
        {
            eCairoLineCap = CAIRO_LINE_CAP_BUTT;
            break;
        }
        case css::drawing::LineCap_ROUND:
        {
            eCairoLineCap = CAIRO_LINE_CAP_ROUND;
            break;
        }
        case css::drawing::LineCap_SQUARE:
        {
            eCairoLineCap = CAIRO_LINE_CAP_SQUARE;
            break;
        }
    }

    cairo_set_source_rgba(cr, rLineColor.GetRed() / 255.0, rLineColor.GetGreen() / 255.0,
                          rLineColor.GetBlue() / 255.0, 1.0 - fTransparency);

    cairo_set_line_join(cr, eCairoLineJoin);
    cairo_set_line_cap(cr, eCairoLineCap);

    constexpr int MaxNormalLineWidth = 64;
    if (fLineWidth > MaxNormalLineWidth)
    {
        const double fLineWidthPixel
            = bObjectToDeviceIsIdentity
                  ? fLineWidth
                  : (rObjectToDevice * basegfx::B2DVector(fLineWidth, 0)).getLength();
        if (fLineWidthPixel > MaxNormalLineWidth)
        {
            SAL_WARN("vcl.gdi", "drawPolyLine, suspicious input line width of: "
                                    << fLineWidth << ", will be " << fLineWidthPixel
                                    << " pixels thick");
            if (bFuzzing)
            {
                basegfx::B2DHomMatrix aObjectToDeviceInv(rObjectToDevice);
                aObjectToDeviceInv.invert();
                fLineWidth
                    = (aObjectToDeviceInv * basegfx::B2DVector(MaxNormalLineWidth, 0)).getLength();
            }
        }
    }
    cairo_set_line_width(cr, fLineWidth);
    cairo_set_miter_limit(cr, fMiterLimit);

    // try to access buffered data
    std::shared_ptr<SystemDependentData_CairoPath> pSystemDependentData_CairoPath(
        rPolyLine.getSystemDependentData<SystemDependentData_CairoPath>());

    // MM01 need to do line dashing as fallback stuff here now
    const double fDotDashLength(
        nullptr != pStroke ? std::accumulate(pStroke->begin(), pStroke->end(), 0.0) : 0.0);
    const bool bStrokeUsed(0.0 != fDotDashLength);
    assert(!bStrokeUsed || (bStrokeUsed && pStroke));

    // MM01 decide if to stroke directly
    static const bool bDoDirectCairoStroke(true);

    // MM01 activate to stroke directly
    if (bDoDirectCairoStroke && bStrokeUsed)
    {
        cairo_set_dash(cr, pStroke->data(), pStroke->size(), 0.0);
    }

    if (!bDoDirectCairoStroke && pSystemDependentData_CairoPath)
    {
        // MM01 - check on stroke change. Used against not used, or if both used,
        // equal or different?
        const bool bStrokeWasUsed(!pSystemDependentData_CairoPath->getStroke().empty());

        if (bStrokeWasUsed != bStrokeUsed
            || (bStrokeUsed && *pStroke != pSystemDependentData_CairoPath->getStroke()))
        {
            // data invalid, forget
            pSystemDependentData_CairoPath.reset();
        }
    }

    // check for basegfx::B2DLineJoin::NONE to react accordingly
    const bool bNoJoin(
        (basegfx::B2DLineJoin::NONE == eLineJoin && basegfx::fTools::more(fLineWidth, 0.0)));

    if (pSystemDependentData_CairoPath)
    {
        // check data validity
        if (nullptr == pSystemDependentData_CairoPath->getCairoPath()
            || pSystemDependentData_CairoPath->getNoJoin() != bNoJoin
            || pSystemDependentData_CairoPath->getAntiAlias() != bAntiAlias
            || bPixelSnapHairline /*tdf#124700*/)
        {
            // data invalid, forget
            pSystemDependentData_CairoPath.reset();
        }
    }

    if (pSystemDependentData_CairoPath)
    {
        // re-use data
        cairo_append_path(cr, pSystemDependentData_CairoPath->getCairoPath());
    }
    else
    {
        // create data
        size_t nSizeMeasure(0);

        // MM01 need to do line dashing as fallback stuff here now
        basegfx::B2DPolyPolygon aPolyPolygonLine;

        if (!bDoDirectCairoStroke && bStrokeUsed)
        {
            // apply LineStyle
            basegfx::utils::applyLineDashing(rPolyLine, // source
                                             *pStroke, // pattern
                                             &aPolyPolygonLine, // target for lines
                                             nullptr, // target for gaps
                                             fDotDashLength); // full length if available
        }
        else
        {
            // no line dashing or direct stroke, just copy
            aPolyPolygonLine.append(rPolyLine);
        }

        // MM01 checked/verified for Cairo
        for (sal_uInt32 a(0); a < aPolyPolygonLine.count(); a++)
        {
            const basegfx::B2DPolygon aPolyLine(aPolyPolygonLine.getB2DPolygon(a));

            if (!bNoJoin)
            {
                // PixelOffset now reflected in linear transformation used
                nSizeMeasure
                    += AddPolygonToPath(cr, aPolyLine,
                                        rObjectToDevice, // ObjectToDevice *without* LineDraw-Offset
                                        !bAntiAlias, bPixelSnapHairline);
            }
            else
            {
                const sal_uInt32 nPointCount(aPolyLine.count());
                const sal_uInt32 nEdgeCount(aPolyLine.isClosed() ? nPointCount : nPointCount - 1);
                basegfx::B2DPolygon aEdge;

                aEdge.append(aPolyLine.getB2DPoint(0));
                aEdge.append(basegfx::B2DPoint(0.0, 0.0));

                for (sal_uInt32 i(0); i < nEdgeCount; i++)
                {
                    const sal_uInt32 nNextIndex((i + 1) % nPointCount);
                    aEdge.setB2DPoint(1, aPolyLine.getB2DPoint(nNextIndex));
                    aEdge.setNextControlPoint(0, aPolyLine.getNextControlPoint(i));
                    aEdge.setPrevControlPoint(1, aPolyLine.getPrevControlPoint(nNextIndex));

                    // PixelOffset now reflected in linear transformation used
                    nSizeMeasure += AddPolygonToPath(
                        cr, aEdge,
                        rObjectToDevice, // ObjectToDevice *without* LineDraw-Offset
                        !bAntiAlias, bPixelSnapHairline);

                    // prepare next step
                    aEdge.setB2DPoint(0, aEdge.getB2DPoint(1));
                }
            }
        }

        // copy and add to buffering mechanism
        if (!bPixelSnapHairline /*tdf#124700*/)
        {
            pSystemDependentData_CairoPath
                = rPolyLine.addOrReplaceSystemDependentData<SystemDependentData_CairoPath>(
                    nSizeMeasure, cr, bNoJoin, bAntiAlias, pStroke);
        }
    }

    // extract extents
    if (pExtents)
    {
        *pExtents = getClippedStrokeDamage(cr);
        // transform also extents (ranges) of damage so they can be correctly redrawn
        pExtents->transform(aDamageMatrix);
    }

    // draw and consume
    cairo_stroke(cr);

    return true;
}

namespace
{
basegfx::B2DRange renderWithOperator(cairo_t* cr, const SalTwoRect& rTR, cairo_surface_t* source,
                                     cairo_operator_t eOperator = CAIRO_OPERATOR_SOURCE)
{
    cairo_rectangle(cr, rTR.mnDestX, rTR.mnDestY, rTR.mnDestWidth, rTR.mnDestHeight);

    basegfx::B2DRange extents = getClippedFillDamage(cr);

    cairo_clip(cr);

    cairo_translate(cr, rTR.mnDestX, rTR.mnDestY);
    if (rTR.mnSrcWidth != 0 && rTR.mnSrcHeight != 0)
    {
        double fXScale = static_cast<double>(rTR.mnDestWidth) / rTR.mnSrcWidth;
        double fYScale = static_cast<double>(rTR.mnDestHeight) / rTR.mnSrcHeight;
        cairo_scale(cr, fXScale, fYScale);
    }

    cairo_save(cr);
    cairo_set_source_surface(cr, source, -rTR.mnSrcX, -rTR.mnSrcY);

    if (cairo_status(cr) == CAIRO_STATUS_SUCCESS)
    {
        //tdf#133716 borders of upscaled images should not be blurred
        cairo_pattern_t* sourcepattern = cairo_get_source(cr);
        cairo_pattern_set_extend(sourcepattern, CAIRO_EXTEND_PAD);
    }

    cairo_set_operator(cr, eOperator);
    cairo_paint(cr);
    cairo_restore(cr);

    return extents;
}

} // end anonymous ns

basegfx::B2DRange CairoCommon::renderSource(cairo_t* cr, const SalTwoRect& rTR,
                                            cairo_surface_t* source)
{
    return renderWithOperator(cr, rTR, source, CAIRO_OPERATOR_SOURCE);
}

void CairoCommon::copyWithOperator(const SalTwoRect& rTR, cairo_surface_t* source,
                                   cairo_operator_t eOp, bool bAntiAlias)
{
    cairo_t* cr = getCairoContext(false, bAntiAlias);
    clipRegion(cr);

    basegfx::B2DRange extents = renderWithOperator(cr, rTR, source, eOp);

    releaseCairoContext(cr, false, extents);
}

void CairoCommon::copySource(const SalTwoRect& rTR, cairo_surface_t* source, bool bAntiAlias)
{
    copyWithOperator(rTR, source, CAIRO_OPERATOR_SOURCE, bAntiAlias);
}

void CairoCommon::copyBitsCairo(const SalTwoRect& rTR, cairo_surface_t* pSourceSurface,
                                bool bAntiAlias)
{
    SalTwoRect aTR(rTR);

    cairo_surface_t* pCopy = nullptr;

    if (pSourceSurface == getSurface())
    {
        //self copy is a problem, so dup source in that case
        pCopy
            = cairo_surface_create_similar(pSourceSurface, cairo_surface_get_content(getSurface()),
                                           aTR.mnSrcWidth * m_fScale, aTR.mnSrcHeight * m_fScale);
        dl_cairo_surface_set_device_scale(pCopy, m_fScale, m_fScale);
        cairo_t* cr = cairo_create(pCopy);
        cairo_set_source_surface(cr, pSourceSurface, -aTR.mnSrcX, -aTR.mnSrcY);
        cairo_rectangle(cr, 0, 0, aTR.mnSrcWidth, aTR.mnSrcHeight);
        cairo_fill(cr);
        cairo_destroy(cr);

        pSourceSurface = pCopy;

        aTR.mnSrcX = 0;
        aTR.mnSrcY = 0;
    }

    copySource(aTR, pSourceSurface, bAntiAlias);

    if (pCopy)
        cairo_surface_destroy(pCopy);
}

namespace
{
cairo_pattern_t* create_stipple()
{
    static unsigned char data[16] = { 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00,
                                      0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0xFF };
    cairo_surface_t* surface = cairo_image_surface_create_for_data(data, CAIRO_FORMAT_A8, 4, 4, 4);
    cairo_pattern_t* pattern = cairo_pattern_create_for_surface(surface);
    cairo_surface_destroy(surface);
    cairo_pattern_set_extend(pattern, CAIRO_EXTEND_REPEAT);
    cairo_pattern_set_filter(pattern, CAIRO_FILTER_NEAREST);
    return pattern;
}
} // end anonymous ns

void CairoCommon::invert(const basegfx::B2DPolygon& rPoly, SalInvert nFlags, bool bAntiAlias)
{
    cairo_t* cr = getCairoContext(false, bAntiAlias);
    clipRegion(cr);

    // To make releaseCairoContext work, use empty extents
    basegfx::B2DRange extents;

    AddPolygonToPath(cr, rPoly, basegfx::B2DHomMatrix(), !bAntiAlias, false);

    cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);

    cairo_set_operator(cr, CAIRO_OPERATOR_DIFFERENCE);

    if (nFlags & SalInvert::TrackFrame)
    {
        cairo_set_line_width(cr, 2.0);
        const double dashLengths[2] = { 4.0, 4.0 };
        cairo_set_dash(cr, dashLengths, 2, 0);

        extents = getClippedStrokeDamage(cr);
        //see tdf#106577 under wayland, some pixel droppings seen, maybe we're
        //out by one somewhere, or cairo_stroke_extents is confused by
        //dashes/line width
        if (!extents.isEmpty())
        {
            extents.grow(1);
        }

        cairo_stroke(cr);
    }
    else
    {
        extents = getClippedFillDamage(cr);

        cairo_clip(cr);

        if (nFlags & SalInvert::N50)
        {
            cairo_pattern_t* pattern = create_stipple();
            cairo_surface_t* surface = cairo_surface_create_similar(
                m_pSurface, cairo_surface_get_content(m_pSurface), extents.getWidth() * m_fScale,
                extents.getHeight() * m_fScale);

            dl_cairo_surface_set_device_scale(surface, m_fScale, m_fScale);
            cairo_t* stipple_cr = cairo_create(surface);
            cairo_set_source_rgb(stipple_cr, 1.0, 1.0, 1.0);
            cairo_mask(stipple_cr, pattern);
            cairo_pattern_destroy(pattern);
            cairo_destroy(stipple_cr);
            cairo_mask_surface(cr, surface, extents.getMinX(), extents.getMinY());
            cairo_surface_destroy(surface);
        }
        else
        {
            cairo_paint(cr);
        }
    }

    releaseCairoContext(cr, false, extents);
}

cairo_format_t getCairoFormat(const BitmapBuffer& rBuffer)
{
    cairo_format_t nFormat;
#ifdef HAVE_CAIRO_FORMAT_RGB24_888
    assert(rBuffer.mnBitCount == 32 || rBuffer.mnBitCount == 24 || rBuffer.mnBitCount == 1);
#else
    assert(rBuffer.mnBitCount == 32 || rBuffer.mnBitCount == 1);
#endif

    if (rBuffer.mnBitCount == 32)
        nFormat = CAIRO_FORMAT_ARGB32;
#ifdef HAVE_CAIRO_FORMAT_RGB24_888
    else if (rBuffer.mnBitCount == 24)
        nFormat = CAIRO_FORMAT_RGB24_888;
#endif
    else
        nFormat = CAIRO_FORMAT_A1;
    return nFormat;
}

namespace
{
bool isCairoCompatible(const BitmapBuffer* pBuffer)
{
    if (!pBuffer)
        return false;

        // We use Cairo that supports 24-bit RGB.
#ifdef HAVE_CAIRO_FORMAT_RGB24_888
    if (pBuffer->mnBitCount != 32 && pBuffer->mnBitCount != 24 && pBuffer->mnBitCount != 1)
#else
    if (pBuffer->mnBitCount != 32 && pBuffer->mnBitCount != 1)
#endif
        return false;

    cairo_format_t nFormat = getCairoFormat(*pBuffer);
    return (cairo_format_stride_for_width(nFormat, pBuffer->mnWidth) == pBuffer->mnScanlineSize);
}
}

cairo_surface_t* CairoCommon::createCairoSurface(const BitmapBuffer* pBuffer)
{
    if (!isCairoCompatible(pBuffer))
        return nullptr;

    cairo_format_t nFormat = getCairoFormat(*pBuffer);
    cairo_surface_t* target = cairo_image_surface_create_for_data(
        pBuffer->mpBits, nFormat, pBuffer->mnWidth, pBuffer->mnHeight, pBuffer->mnScanlineSize);
    if (cairo_surface_status(target) != CAIRO_STATUS_SUCCESS)
    {
        cairo_surface_destroy(target);
        return nullptr;
    }
    return target;
}

std::unique_ptr<BitmapBuffer> FastConvert24BitRgbTo32BitCairo(const BitmapBuffer* pSrc)
{
    if (pSrc == nullptr)
        return nullptr;

    assert(pSrc->mnFormat == SVP_24BIT_FORMAT);
    const tools::Long nWidth = pSrc->mnWidth;
    const tools::Long nHeight = pSrc->mnHeight;
    std::unique_ptr<BitmapBuffer> pDst(new BitmapBuffer);
    pDst->mnFormat = (ScanlineFormat::N32BitTcArgb | ScanlineFormat::TopDown);
    pDst->mnWidth = nWidth;
    pDst->mnHeight = nHeight;
    pDst->mnBitCount = 32;
    pDst->maColorMask = pSrc->maColorMask;
    pDst->maPalette = pSrc->maPalette;

    tools::Long nScanlineBase;
    const bool bFail = o3tl::checked_multiply<tools::Long>(pDst->mnBitCount, nWidth, nScanlineBase);
    if (bFail)
    {
        SAL_WARN("vcl.gdi", "checked multiply failed");
        pDst->mpBits = nullptr;
        return nullptr;
    }

    pDst->mnScanlineSize = AlignedWidth4Bytes(nScanlineBase);
    if (pDst->mnScanlineSize < nScanlineBase / 8)
    {
        SAL_WARN("vcl.gdi", "scanline calculation wraparound");
        pDst->mpBits = nullptr;
        return nullptr;
    }

    try
    {
        pDst->mpBits = new sal_uInt8[pDst->mnScanlineSize * nHeight];
    }
    catch (const std::bad_alloc&)
    {
        // memory exception, clean up
        pDst->mpBits = nullptr;
        return nullptr;
    }

    for (tools::Long y = 0; y < nHeight; ++y)
    {
        sal_uInt8* pS = pSrc->mpBits + y * pSrc->mnScanlineSize;
        sal_uInt8* pD = pDst->mpBits + y * pDst->mnScanlineSize;
        for (tools::Long x = 0; x < nWidth; ++x)
        {
#if defined(ANDROID) && !HAVE_FEATURE_ANDROID_LOK
            static_assert((SVP_CAIRO_FORMAT & ~ScanlineFormat::TopDown)
                              == ScanlineFormat::N32BitTcRgba,
                          "Expected SVP_CAIRO_FORMAT set to N32BitTcBgra");
            static_assert((SVP_24BIT_FORMAT & ~ScanlineFormat::TopDown)
                              == ScanlineFormat::N24BitTcRgb,
                          "Expected SVP_24BIT_FORMAT set to N24BitTcRgb");
            pD[0] = pS[0];
            pD[1] = pS[1];
            pD[2] = pS[2];
            pD[3] = 0xff; // Alpha
#elif defined OSL_BIGENDIAN
            static_assert((SVP_CAIRO_FORMAT & ~ScanlineFormat::TopDown)
                              == ScanlineFormat::N32BitTcArgb,
                          "Expected SVP_CAIRO_FORMAT set to N32BitTcBgra");
            static_assert((SVP_24BIT_FORMAT & ~ScanlineFormat::TopDown)
                              == ScanlineFormat::N24BitTcRgb,
                          "Expected SVP_24BIT_FORMAT set to N24BitTcRgb");
            pD[0] = 0xff; // Alpha
            pD[1] = pS[0];
            pD[2] = pS[1];
            pD[3] = pS[2];
#else
            static_assert((SVP_CAIRO_FORMAT & ~ScanlineFormat::TopDown)
                              == ScanlineFormat::N32BitTcBgra,
                          "Expected SVP_CAIRO_FORMAT set to N32BitTcBgra");
            static_assert((SVP_24BIT_FORMAT & ~ScanlineFormat::TopDown)
                              == ScanlineFormat::N24BitTcBgr,
                          "Expected SVP_24BIT_FORMAT set to N24BitTcBgr");
            pD[0] = pS[0];
            pD[1] = pS[1];
            pD[2] = pS[2];
            pD[3] = 0xff; // Alpha
#endif

            pS += 3;
            pD += 4;
        }
    }

    return pDst;
}

void Toggle1BitTransparency(const BitmapBuffer& rBuf)
{
    assert(rBuf.maPalette.GetBestIndex(BitmapColor(COL_BLACK)) == 0);
    // TODO: make upper layers use standard alpha
    if (getCairoFormat(rBuf) == CAIRO_FORMAT_A1)
    {
        const int nImageSize = rBuf.mnHeight * rBuf.mnScanlineSize;
        unsigned char* pDst = rBuf.mpBits;
        for (int i = nImageSize; --i >= 0; ++pDst)
            *pDst = ~*pDst;
    }
}

namespace
{
// check for env var that decides for using downscale pattern
const char* pDisableDownScale(getenv("SAL_DISABLE_CAIRO_DOWNSCALE"));
bool bDisableDownScale(nullptr != pDisableDownScale);
}

cairo_surface_t* SurfaceHelper::implCreateOrReuseDownscale(unsigned long nTargetWidth,
                                                           unsigned long nTargetHeight)
{
    const unsigned long nSourceWidth(cairo_image_surface_get_width(pSurface));
    const unsigned long nSourceHeight(cairo_image_surface_get_height(pSurface));

    // zoomed in, need to stretch at paint, no pre-scale useful
    if (nTargetWidth >= nSourceWidth || nTargetHeight >= nSourceHeight)
    {
        return pSurface;
    }

    // calculate downscale factor
    unsigned long nWFactor(1);
    unsigned long nW((nSourceWidth + 1) / 2);
    unsigned long nHFactor(1);
    unsigned long nH((nSourceHeight + 1) / 2);

    while (nW > nTargetWidth && nW > 1)
    {
        nW = (nW + 1) / 2;
        nWFactor *= 2;
    }

    while (nH > nTargetHeight && nH > 1)
    {
        nH = (nH + 1) / 2;
        nHFactor *= 2;
    }

    if (1 == nWFactor && 1 == nHFactor)
    {
        // original size *is* best binary size, use it
        return pSurface;
    }

    // go up one scale again - look for no change
    nW = (1 == nWFactor) ? nTargetWidth : nW * 2;
    nH = (1 == nHFactor) ? nTargetHeight : nH * 2;

    // check if we have a downscaled version of required size
    // bail out if the multiplication for the key would overflow
    if (nW >= SAL_MAX_UINT32 || nH >= SAL_MAX_UINT32)
        return pSurface;
    const sal_uInt64 key((nW * static_cast<sal_uInt64>(SAL_MAX_UINT32)) + nH);
    auto isHit(maDownscaled.find(key));

    if (isHit != maDownscaled.end())
    {
        return isHit->second;
    }

    // create new surface in the targeted size
    cairo_surface_t* pSurfaceTarget
        = cairo_surface_create_similar(pSurface, cairo_surface_get_content(pSurface), nW, nH);

    // made a version to scale self first that worked well, but would've
    // been hard to support CAIRO_FORMAT_A1 including bit shifting, so
    // I decided to go with cairo itself - use CAIRO_FILTER_FAST or
    // CAIRO_FILTER_GOOD though. Please modify as needed for
    // performance/quality
    cairo_t* cr = cairo_create(pSurfaceTarget);
    const double fScaleX(static_cast<double>(nW) / static_cast<double>(nSourceWidth));
    const double fScaleY(static_cast<double>(nH) / static_cast<double>(nSourceHeight));
    cairo_scale(cr, fScaleX, fScaleY);
    cairo_set_source_surface(cr, pSurface, 0.0, 0.0);
    cairo_pattern_set_filter(cairo_get_source(cr), CAIRO_FILTER_GOOD);
    cairo_paint(cr);
    cairo_destroy(cr);

    // need to set device_scale for downscale surfaces to get
    // them handled correctly
    cairo_surface_set_device_scale(pSurfaceTarget, fScaleX, fScaleY);

    // add entry to cached entries
    maDownscaled[key] = pSurfaceTarget;

    return pSurfaceTarget;
}

bool SurfaceHelper::isTrivial() const
{
    constexpr unsigned long nMinimalSquareSizeToBuffer(64 * 64);
    const unsigned long nSourceWidth(cairo_image_surface_get_width(pSurface));
    const unsigned long nSourceHeight(cairo_image_surface_get_height(pSurface));

    return nSourceWidth * nSourceHeight < nMinimalSquareSizeToBuffer;
}

SurfaceHelper::SurfaceHelper()
    : pSurface(nullptr)
{
}

SurfaceHelper::~SurfaceHelper()
{
    cairo_surface_destroy(pSurface);
    for (auto& candidate : maDownscaled)
    {
        cairo_surface_destroy(candidate.second);
    }
}

cairo_surface_t* SurfaceHelper::getSurface(unsigned long nTargetWidth,
                                           unsigned long nTargetHeight) const
{
    if (bDisableDownScale || 0 == nTargetWidth || 0 == nTargetHeight || !pSurface || isTrivial())
    {
        // caller asks for original or disabled or trivial (smaller then a minimal square size)
        // also excludes zero cases for width/height after this point if need to prescale
        return pSurface;
    }

    return const_cast<SurfaceHelper*>(this)->implCreateOrReuseDownscale(nTargetWidth,
                                                                        nTargetHeight);
}

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