nr-filter-blend.cpp

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// SPDX-License-Identifier: GPL-2.0-or-later
 * "This filter composites two objects together using commonly used
 * imaging software blending modes. It performs a pixel-wise combination
 * of two input images."
 * http://www.w3.org/TR/SVG11/filters.html#feBlend
 *
 * Authors:
 *   Niko Kiirala <niko@kiirala.com>
 *   Jasper van de Gronde <th.v.d.gronde@hccnet.nl>
 *   Krzysztof Kosiński <tweenk.pl@gmail.com>
 *
 * Copyright (C) 2007-2008 authors
 *
 * Released under GNU GPL v2+, read the file 'COPYING' for more information.
 */
 
#include <glibmm.h>
#include "display/cairo-templates.h"
#include "display/cairo-utils.h"
#include "display/nr-filter-blend.h"
#include "display/nr-filter-primitive.h"
#include "display/nr-filter-slot.h"
#include "display/nr-filter-types.h"
 
namespace Inkscape {
namespace Filters {
 
std::set<SPBlendMode> const FilterBlend::_valid_modes {
    // clang-format off
    SP_CSS_BLEND_NORMAL,      SP_CSS_BLEND_MULTIPLY,
    SP_CSS_BLEND_SCREEN,      SP_CSS_BLEND_DARKEN,
    SP_CSS_BLEND_LIGHTEN,     SP_CSS_BLEND_OVERLAY,
    SP_CSS_BLEND_COLORDODGE,  SP_CSS_BLEND_COLORBURN,
    SP_CSS_BLEND_HARDLIGHT,   SP_CSS_BLEND_SOFTLIGHT,
    SP_CSS_BLEND_DIFFERENCE,  SP_CSS_BLEND_EXCLUSION,
    SP_CSS_BLEND_HUE,         SP_CSS_BLEND_SATURATION,
    SP_CSS_BLEND_COLOR,       SP_CSS_BLEND_LUMINOSITY
    // clang-format on
        };
 
FilterBlend::FilterBlend()
    : _blend_mode(SP_CSS_BLEND_NORMAL)
    , _input2(NR_FILTER_SLOT_NOT_SET)
{
}
 
FilterBlend::~FilterBlend() = default;
 
static inline cairo_operator_t get_cairo_op(SPBlendMode _blend_mode)
{
    switch (_blend_mode) {
    case SP_CSS_BLEND_MULTIPLY:
        return CAIRO_OPERATOR_MULTIPLY;
    case SP_CSS_BLEND_SCREEN:
        return CAIRO_OPERATOR_SCREEN;
    case SP_CSS_BLEND_DARKEN:
        return CAIRO_OPERATOR_DARKEN;
    case SP_CSS_BLEND_LIGHTEN:
        return CAIRO_OPERATOR_LIGHTEN;
    // New in CSS Compositing and Blending Level 1
    case SP_CSS_BLEND_OVERLAY:
        return CAIRO_OPERATOR_OVERLAY;
    case SP_CSS_BLEND_COLORDODGE:
        return CAIRO_OPERATOR_COLOR_DODGE;
    case SP_CSS_BLEND_COLORBURN:
        return CAIRO_OPERATOR_COLOR_BURN;
    case SP_CSS_BLEND_HARDLIGHT:
        return CAIRO_OPERATOR_HARD_LIGHT;
    case SP_CSS_BLEND_SOFTLIGHT:
        return CAIRO_OPERATOR_SOFT_LIGHT;
    case SP_CSS_BLEND_DIFFERENCE:
        return CAIRO_OPERATOR_DIFFERENCE;
    case SP_CSS_BLEND_EXCLUSION:
        return CAIRO_OPERATOR_EXCLUSION;
    case SP_CSS_BLEND_HUE:
        return CAIRO_OPERATOR_HSL_HUE;
    case SP_CSS_BLEND_SATURATION:
        return CAIRO_OPERATOR_HSL_SATURATION;
    case SP_CSS_BLEND_COLOR:
        return CAIRO_OPERATOR_HSL_COLOR;
    case SP_CSS_BLEND_LUMINOSITY:
        return CAIRO_OPERATOR_HSL_LUMINOSITY;
 
    case SP_CSS_BLEND_NORMAL:
    default:
        return CAIRO_OPERATOR_OVER;
    }
}
 
void FilterBlend::render_cairo(FilterSlot &slot) const
{
    cairo_surface_t *input1 = slot.getcairo(_input);
    cairo_surface_t *input2 = slot.getcairo(_input2);
 
    // We may need to transform input surface to correct color interpolation space. The input surface
    // might be used as input to another primitive but it is likely that all the primitives in a given
    // filter use the same color interpolation space so we don't copy the input before converting.
    set_cairo_surface_ci(input1, color_interpolation);
    set_cairo_surface_ci(input2, color_interpolation);
 
    // input2 is the "background" image
    // out should be ARGB32 if any of the inputs is ARGB32
    cairo_surface_t *out = ink_cairo_surface_create_output(input1, input2);
    set_cairo_surface_ci(out, color_interpolation);
 
    ink_cairo_surface_blit(input2, out);
    cairo_t *out_ct = cairo_create(out);
    cairo_set_source_surface(out_ct, input1, 0, 0);
 
    // All of the blend modes are implemented in Cairo as of 1.10.
    // For a detailed description, see:
    // http://cairographics.org/operators/
    cairo_set_operator(out_ct, get_cairo_op(_blend_mode));
 
    cairo_paint(out_ct);
    cairo_destroy(out_ct);
 
    slot.set(_output, out);
    cairo_surface_destroy(out);
}
 
bool FilterBlend::can_handle_affine(Geom::Affine const &) const
{
    // blend is a per-pixel primitive and is immutable under transformations
    return true;
}
 
double FilterBlend::complexity(Geom::Affine const &) const
{
    return 1.1;
}
 
bool FilterBlend::uses_background() const
{
    return _input == NR_FILTER_BACKGROUNDIMAGE || _input == NR_FILTER_BACKGROUNDALPHA ||
           _input2 == NR_FILTER_BACKGROUNDIMAGE || _input2 == NR_FILTER_BACKGROUNDALPHA;
}
 
void FilterBlend::set_input(int slot)
{
    _input = slot;
}
 
void FilterBlend::set_input(int input, int slot)
{
    if (input == 0) _input = slot;
    if (input == 1) _input2 = slot;
}
 
void FilterBlend::set_mode(SPBlendMode mode)
{
    if (_valid_modes.count(mode)) {
        _blend_mode = mode;
    }
}
 
} /* namespace Filters */
} /* namespace Inkscape */
 
/*
  Local Variables:
  mode:c++
  c-file-style:"stroustrup"
  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
  indent-tabs-mode:nil
  fill-column:99
  End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :