File indexing completed on 2024-12-22 04:11:38 

0001 /*
0002  *  SPDX-FileCopyrightText: 2016 Wolthera van Hövell tot Westerflier <griffinvalley@gmail.com>
0003  *  SPDX-FileCopyrightText: 2012 José Luis Vergara <pentalis@gmail.com>
0004  *
0005  * SPDX-License-Identifier: LGPL-2.1-or-later
0006 */
0007 
0008 #ifndef _KOCOMPOSITEOPDESTINATIONATOP_H_
0009 #define _KOCOMPOSITEOPDESTINATIONATOP_H_
0010 
0011 #include "KoCompositeOpBase.h"
0012 
0013 /**
0014  *  Generic implementation of the Destination-atop composite op, based off the behind composite op.
0015  *  This is necessary for Open Raster support.
0016  *  https://www.w3.org/TR/compositing-1/
0017  */
0018 template<class CS_Traits>
0019 class KoCompositeOpDestinationAtop : public KoCompositeOpBase<CS_Traits, KoCompositeOpDestinationAtop<CS_Traits> >
0020 {
0021     typedef KoCompositeOpBase<CS_Traits, KoCompositeOpDestinationAtop<CS_Traits> > base_class;
0022     typedef typename CS_Traits::channels_type channels_type;
0023 
0024     static const qint8 channels_nb = CS_Traits::channels_nb;
0025     static const qint8 alpha_pos   = CS_Traits::alpha_pos;
0026 
0027 public:
0028     KoCompositeOpDestinationAtop(const KoColorSpace * cs)
0029         : base_class(cs, COMPOSITE_DESTINATION_ATOP, KoCompositeOp::categoryMix()) { }
0030 
0031 public:
0032     template<bool alphaLocked, bool allChannelFlags>
0033     inline static channels_type composeColorChannels(const channels_type* src, channels_type srcAlpha,
0034                                                      channels_type*       dst, channels_type dstAlpha,
0035                                                      channels_type  maskAlpha, channels_type  opacity,
0036                                                      const QBitArray& channelFlags                    )  {
0037         using namespace Arithmetic;
0038 
0039         channels_type appliedAlpha       = mul(maskAlpha, srcAlpha, opacity);
0040 
0041         channels_type newDstAlpha        = appliedAlpha;
0042 
0043         if (dstAlpha != zeroValue<channels_type>() && srcAlpha != zeroValue<channels_type>()) {
0044             // blend the color channels as if we were painting on the layer below
0045             for (qint8 channel = 0; channel < channels_nb; ++channel)
0046                 if(channel != alpha_pos && (allChannelFlags || channelFlags.testBit(channel))) {
0047                     dst[channel] = lerp(src[channel],dst[channel],dstAlpha);
0048                 }
0049         }
0050         else if (srcAlpha != zeroValue<channels_type>()) {
0051             // don't blend if the color of the destination is undefined (has zero opacity)
0052             // copy the source channel instead
0053             for (qint8 channel = 0; channel < channels_nb; ++channel)
0054                 if(channel != alpha_pos && (allChannelFlags || channelFlags.testBit(channel)))
0055                     dst[channel] = src[channel];
0056         }
0057 
0058         return newDstAlpha;
0059     }
0060 };
0061 
0062 #endif  // _KOCOMPOSITEOPDESTINATIONATOP_H_