diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 16:29:01 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 16:29:01 +0000 |
commit | 35a96bde514a8897f6f0fcc41c5833bf63df2e2a (patch) | |
tree | 657d15a03cc46bd099fc2c6546a7a4ad43815d9f /src/livarot/AlphaLigne.h | |
parent | Initial commit. (diff) | |
download | inkscape-35a96bde514a8897f6f0fcc41c5833bf63df2e2a.tar.xz inkscape-35a96bde514a8897f6f0fcc41c5833bf63df2e2a.zip |
Adding upstream version 1.0.2.upstream/1.0.2upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/livarot/AlphaLigne.h')
-rw-r--r-- | src/livarot/AlphaLigne.h | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/src/livarot/AlphaLigne.h b/src/livarot/AlphaLigne.h new file mode 100644 index 0000000..a192e1c --- /dev/null +++ b/src/livarot/AlphaLigne.h @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/** @file + * TODO: insert short description here + *//* + * Authors: + * see git history + * Fred + * + * Copyright (C) 2018 Authors + * Released under GNU GPL v2+, read the file 'COPYING' for more information. + */ + +#ifndef my_alpha_ligne +#define my_alpha_ligne + +#include "LivarotDefs.h" + +/* + * pixel coverage of a line, libart style: each pixel coverage is obtained from the coverage of the previous one by + * adding a delta given by a step. the goal is to have only a limited number of positions where the delta != 0, so that + * you only have to store a limited number of steps. + */ + +// a step +struct alpha_step { + int x; // position + float delta; // increase or decrease in pixel coverage with respect to the coverage of the previous pixel +}; + + +class AlphaLigne { +public: + // bounds of the line + // necessary since the visible portion of the canvas is bounded, and you need to compute + // the value of the pixel "just before the visible portion of the line" + int min,max; + int length; + + // before is the step containing the delta relative to a pixel infinitely far on the left of the line + // thus the initial pixel coverage is before.delta + alpha_step before,after; + // array of steps + int nbStep,maxStep; + alpha_step* steps; + + // bounds of the portion of the line that has received some coverage + int curMin,curMax; + + // iMin and iMax are the bounds of the visible portion of the line + AlphaLigne(int iMin,int iMax); + virtual ~AlphaLigne(); + + // empties the line + void Reset(); + + // add some coverage. + // pente is (eval-sval)/(epos-spos), because you can compute it once per edge, and thus spare the + // CPU some potentially costly divisions + int AddBord(float spos,float sval,float epos,float eval,float iPente); + // version where you don't have the pente parameter + int AddBord(float spos,float sval,float epos,float eval); + + // sorts the steps in increasing order. needed before you raster the line + void Flatten(); + + // debug dump of the steps + void Affiche(); + + // private + void AddRun(int st,float pente); + + // raster the line in the buffer given in "dest", with the rasterization primitive worker + // worker() is given the color parameter each time it is called. the type of the function is + // defined in LivarotDefs.h + void Raster(raster_info &dest,void* color,RasterInRunFunc worker); + + // also private. that's the comparison function given to qsort() + static int CmpStep(const void * p1, const void * p2) { + alpha_step* d1=(alpha_step*)p1; + alpha_step* d2=(alpha_step*)p2; + return d1->x - d2->x ; + }; +}; + + +#endif + |