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pixblock-transform.cpp

#define __NR_PIXBLOCK_SCALER_CPP__

/*
 * Functions for blitting pixblocks using matrix transformation
 *
 * Author:
 *   Niko Kiirala <niko@kiirala.com>
 *
 * Copyright (C) 2006,2009 Niko Kiirala
 *
 * Released under GNU GPL, read the file 'COPYING' for more information
 */

#include <glib.h>
#include <cmath>
#if defined (SOLARIS) && (SOLARIS == 8)
#include "round.h"
using Inkscape::round;
#endif 
using std::floor;

#include "display/nr-filter-utils.h"

#include "libnr/nr-blit.h"
#include "libnr/nr-pixblock.h"
#include <2geom/matrix.h>

namespace NR {

struct RGBA {
    double r, g, b, a;
};
struct RGBAi {
    int r, g, b, a;
};

/**
 * Sanity check function for indexing pixblocks.
 * Catches reading and writing outside the pixblock area.
 * When enabled, decreases filter rendering speed massively.
 */
inline void _check_index(NRPixBlock const * const pb, int const location, int const line)
{
    if(false) {
        int max_loc = pb->rs * (pb->area.y1 - pb->area.y0);
        if (location < 0 || (location + 4) > max_loc)
            g_warning("Location %d out of bounds (0 ... %d) at line %d", location, max_loc, line);
    }
}

void transform_nearest(NRPixBlock *to, NRPixBlock *from, Geom::Matrix const &trans)
{
    if (NR_PIXBLOCK_BPP(from) != 4 || NR_PIXBLOCK_BPP(to) != 4) {
        g_warning("A non-32-bpp image passed to transform_nearest: scaling aborted.");
        return;
    }

    bool free_from_on_exit = false;
    if (from->mode != to->mode){
        NRPixBlock *o_from = from;
        from = new NRPixBlock;
        nr_pixblock_setup_fast(from, to->mode, o_from->area.x0, o_from->area.y0, o_from->area.x1, o_from->area.y1, false);
        nr_blit_pixblock_pixblock(from, o_from);
        free_from_on_exit = true;
    }

    // Precalculate sizes of source and destination pixblocks
    int from_width = from->area.x1 - from->area.x0;
    int from_height = from->area.y1 - from->area.y0;
    int to_width = to->area.x1 - to->area.x0;
    int to_height = to->area.y1 - to->area.y0;

    Geom::Matrix itrans = trans.inverse();

    // Loop through every pixel of destination image, a line at a time
    for (int to_y = 0 ; to_y < to_height ; to_y++) {
        for (int to_x = 0 ; to_x < to_width ; to_x++) {
            RGBAi result = {0,0,0,0};

            int from_x = (int)floor(itrans[0] * (to_x + 0.5 + to->area.x0)
                                    + itrans[2] * (to_y + 0.5 + to->area.y0)
                                    + itrans[4]);
            from_x -= from->area.x0;
            int from_y = (int)floor(itrans[1] * (to_x + 0.5 + to->area.x0)
                                    + itrans[3] * (to_y + 0.5 + to->area.y0)
                                    + itrans[5]);
            from_y -= from->area.y0;

            if (from_x >= 0 && from_x < from_width
                && from_y >= 0 && from_y < from_height) {
                _check_index(from, from_y * from->rs + from_x * 4, __LINE__);
                result.r = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4];
                result.g = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4 + 1];
                result.b = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4 + 2];
                result.a = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4 + 3];
            }

            _check_index(to, to_y * to->rs + to_x * 4, __LINE__);
            NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4] = result.r;
            NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 1] = result.g;
            NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 2] = result.b;
            NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 3] = result.a;
        }
    }
    if (free_from_on_exit) {
        nr_pixblock_release(from);
        delete from;
    }
}

/** Calculates cubically interpolated value of the four given pixel values.
 * The pixel values should be from four adjacent pixels in source image or
 * four adjacent interpolated values. len should be the x- or y-coordinate
 * (depending on interpolation direction) of the center of the target pixel
 * in source image coordinates.
 */
__attribute__ ((const))
inline static double sample(double const a, double const b,
                            double const c, double const d,
                            double const len)
{
    double lena = 1.5 + (len - round(len));
    double lenb = 0.5 + (len - round(len));
    double lenc = 0.5 - (len - round(len));
    double lend = 1.5 - (len - round(len));
    double const f = -0.5; // corresponds to cubic Hermite spline
    double sum = 0;
    sum += ((((f * lena) - 5.0 * f) * lena + 8.0 * f) * lena - 4 * f) * a;
    sum += (((f + 2.0) * lenb - (f + 3.0)) * lenb * lenb + 1.0) * b;
    sum += (((f + 2.0) * lenc - (f + 3.0)) * lenc * lenc + 1.0) * c;
    sum += ((((f * lend) - 5.0 * f) * lend + 8.0 * f) * lend - 4 * f) * d;

    return sum;
}

void transform_bicubic(NRPixBlock *to, NRPixBlock *from, Geom::Matrix const &trans)
{
    if (NR_PIXBLOCK_BPP(from) != 4 || NR_PIXBLOCK_BPP(to) != 4) {
        g_warning("A non-32-bpp image passed to transform_bicubic: scaling aborted.");
        return;
    }

    bool free_from_on_exit = false;
    if (from->mode != to->mode){
        NRPixBlock *o_from = from;
        from = new NRPixBlock;
        nr_pixblock_setup_fast(from, to->mode, o_from->area.x0, o_from->area.y0, o_from->area.x1, o_from->area.y1, false);
        nr_blit_pixblock_pixblock(from, o_from);
        free_from_on_exit = true;
    }
    
    // Precalculate sizes of source and destination pixblocks
    int from_width = from->area.x1 - from->area.x0;
    int from_height = from->area.y1 - from->area.y0;
    int to_width = to->area.x1 - to->area.x0;
    int to_height = to->area.y1 - to->area.y0;

    Geom::Matrix itrans = trans.inverse();

    // Loop through every pixel of destination image, a line at a time
    for (int to_y = 0 ; to_y < to_height ; to_y++) {
        for (int to_x = 0 ; to_x < to_width ; to_x++) {
            double from_x = itrans[0] * (to_x + 0.5 + to->area.x0)
                + itrans[2] * (to_y + 0.5 + to->area.y0)
                + itrans[4] - from->area.x0;
            double from_y = itrans[1] * (to_x + 0.5 + to->area.x0)
                + itrans[3] * (to_y + 0.5 + to->area.y0)
                + itrans[5] - from->area.y0;

            if (from_x < 0 || from_x >= from_width ||
                from_y < 0 || from_y >= from_height) {
                continue;
            }

            RGBA line[4];

            int from_line[4];
            for (int i = 0 ; i < 4 ; i++) {
                int fy_line = (int)round(from_y) + i - 2;
                if (fy_line >= 0) {
                    if (fy_line < from_height) {
                        from_line[i] = fy_line * from->rs;
                    } else {
                        from_line[i] = (from_height - 1) * from->rs;
                    }
                } else {
                    from_line[i] = 0;
                }                
            }

            for (int i = 0 ; i < 4 ; i++) {
                int k = (int)round(from_x) + i - 2;
                if (k < 0) k = 0;
                if (k >= from_width) k = from_width - 1;
                k *= 4;
                _check_index(from, from_line[0] + k, __LINE__);
                _check_index(from, from_line[1] + k, __LINE__);
                _check_index(from, from_line[2] + k, __LINE__);
                _check_index(from, from_line[3] + k, __LINE__);
                line[i].r = sample(NR_PIXBLOCK_PX(from)[from_line[0] + k],
                                   NR_PIXBLOCK_PX(from)[from_line[1] + k],
                                   NR_PIXBLOCK_PX(from)[from_line[2] + k],
                                   NR_PIXBLOCK_PX(from)[from_line[3] + k],
                                   from_y);
                line[i].g = sample(NR_PIXBLOCK_PX(from)[from_line[0] + k + 1],
                                   NR_PIXBLOCK_PX(from)[from_line[1] + k + 1],
                                   NR_PIXBLOCK_PX(from)[from_line[2] + k + 1],
                                   NR_PIXBLOCK_PX(from)[from_line[3] + k + 1],
                                   from_y);
                line[i].b = sample(NR_PIXBLOCK_PX(from)[from_line[0] + k + 2],
                                   NR_PIXBLOCK_PX(from)[from_line[1] + k + 2],
                                   NR_PIXBLOCK_PX(from)[from_line[2] + k + 2],
                                   NR_PIXBLOCK_PX(from)[from_line[3] + k + 2],
                                   from_y);
                line[i].a = sample(NR_PIXBLOCK_PX(from)[from_line[0] + k + 3],
                                   NR_PIXBLOCK_PX(from)[from_line[1] + k + 3],
                                   NR_PIXBLOCK_PX(from)[from_line[2] + k + 3],
                                   NR_PIXBLOCK_PX(from)[from_line[3] + k + 3],
                                   from_y);
            }
            RGBA result;
            result.r = round(sample(line[0].r, line[1].r, line[2].r, line[3].r,
                                    from_x));
            result.g = round(sample(line[0].g, line[1].g, line[2].g, line[3].g,
                                    from_x));
            result.b = round(sample(line[0].b, line[1].b, line[2].b, line[3].b,
                                    from_x));
            result.a = round(sample(line[0].a, line[1].a, line[2].a, line[3].a,
                                    from_x));

            using Inkscape::Filters::clamp;
            using Inkscape::Filters::clamp_alpha;
            _check_index(to, to_y * to->rs + to_x * 4, __LINE__);
            if (to->mode == NR_PIXBLOCK_MODE_R8G8B8A8P) {
                /* Make sure, none of the RGB channels exceeds 100% intensity
                 * in premultiplied output */
                int const alpha = clamp((int)result.a);
                NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4] = 
                    clamp_alpha((int)result.r, alpha);
                NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 1] = 
                    clamp_alpha((int)result.g, alpha);
                NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 2] = 
                    clamp_alpha((int)result.b, alpha);
                NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 3] = alpha;
            } else {
                /* Clamp the output to unsigned char range */
                NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4]
                    = clamp((int)result.r);
                NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 1]
                    = clamp((int)result.g);
                NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 2]
                    = clamp((int)result.b);
                NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 3]
                    = clamp((int)result.a);
            }
        }
    }
    if (free_from_on_exit) {
        nr_pixblock_release(from);
        delete from;
    }
}

} /* namespace NR */
/*
  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:encoding=utf-8:textwidth=99 :

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