forked from minhngoc25a/freetype2
286 lines
6.8 KiB
C
286 lines
6.8 KiB
C
/***************************************************************************/
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/* */
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/* afangles.c */
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/* */
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/* Routines used to compute vector angles with limited accuracy */
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/* and very high speed. It also contains sorting routines (body). */
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/* */
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/* Copyright 2003-2018 by */
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/* David Turner, Robert Wilhelm, and Werner Lemberg. */
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/* */
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/* This file is part of the FreeType project, and may only be used, */
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/* modified, and distributed under the terms of the FreeType project */
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/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
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/* this file you indicate that you have read the license and */
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/* understand and accept it fully. */
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/* */
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/***************************************************************************/
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#include "aftypes.h"
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/*
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* We are not using `af_angle_atan' anymore, but we keep the source
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* code below just in case...
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*/
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#if 0
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/*
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* The trick here is to realize that we don't need a very accurate angle
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* approximation. We are going to use the result of `af_angle_atan' to
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* only compare the sign of angle differences, or check whether its
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* magnitude is very small.
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*
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* The approximation
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*
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* dy * PI / (|dx|+|dy|)
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*
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* should be enough, and much faster to compute.
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*/
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FT_LOCAL_DEF( AF_Angle )
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af_angle_atan( FT_Fixed dx,
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FT_Fixed dy )
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{
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AF_Angle angle;
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FT_Fixed ax = dx;
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FT_Fixed ay = dy;
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if ( ax < 0 )
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ax = -ax;
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if ( ay < 0 )
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ay = -ay;
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ax += ay;
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if ( ax == 0 )
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angle = 0;
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else
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{
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angle = ( AF_ANGLE_PI2 * dy ) / ( ax + ay );
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if ( dx < 0 )
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{
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if ( angle >= 0 )
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angle = AF_ANGLE_PI - angle;
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else
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angle = -AF_ANGLE_PI - angle;
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}
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}
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return angle;
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}
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#elif 0
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/* the following table has been automatically generated with */
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/* the `mather.py' Python script */
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#define AF_ATAN_BITS 8
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static const FT_Byte af_arctan[1L << AF_ATAN_BITS] =
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{
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0, 0, 1, 1, 1, 2, 2, 2,
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3, 3, 3, 3, 4, 4, 4, 5,
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5, 5, 6, 6, 6, 7, 7, 7,
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8, 8, 8, 9, 9, 9, 10, 10,
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10, 10, 11, 11, 11, 12, 12, 12,
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13, 13, 13, 14, 14, 14, 14, 15,
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15, 15, 16, 16, 16, 17, 17, 17,
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18, 18, 18, 18, 19, 19, 19, 20,
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20, 20, 21, 21, 21, 21, 22, 22,
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22, 23, 23, 23, 24, 24, 24, 24,
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25, 25, 25, 26, 26, 26, 26, 27,
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27, 27, 28, 28, 28, 28, 29, 29,
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29, 30, 30, 30, 30, 31, 31, 31,
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31, 32, 32, 32, 33, 33, 33, 33,
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34, 34, 34, 34, 35, 35, 35, 35,
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36, 36, 36, 36, 37, 37, 37, 38,
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38, 38, 38, 39, 39, 39, 39, 40,
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40, 40, 40, 41, 41, 41, 41, 42,
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42, 42, 42, 42, 43, 43, 43, 43,
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44, 44, 44, 44, 45, 45, 45, 45,
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46, 46, 46, 46, 46, 47, 47, 47,
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47, 48, 48, 48, 48, 48, 49, 49,
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49, 49, 50, 50, 50, 50, 50, 51,
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51, 51, 51, 51, 52, 52, 52, 52,
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52, 53, 53, 53, 53, 53, 54, 54,
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54, 54, 54, 55, 55, 55, 55, 55,
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56, 56, 56, 56, 56, 57, 57, 57,
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57, 57, 57, 58, 58, 58, 58, 58,
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59, 59, 59, 59, 59, 59, 60, 60,
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60, 60, 60, 61, 61, 61, 61, 61,
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61, 62, 62, 62, 62, 62, 62, 63,
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63, 63, 63, 63, 63, 64, 64, 64
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};
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FT_LOCAL_DEF( AF_Angle )
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af_angle_atan( FT_Fixed dx,
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FT_Fixed dy )
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{
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AF_Angle angle;
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/* check trivial cases */
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if ( dy == 0 )
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{
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angle = 0;
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if ( dx < 0 )
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angle = AF_ANGLE_PI;
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return angle;
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}
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else if ( dx == 0 )
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{
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angle = AF_ANGLE_PI2;
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if ( dy < 0 )
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angle = -AF_ANGLE_PI2;
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return angle;
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}
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angle = 0;
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if ( dx < 0 )
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{
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dx = -dx;
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dy = -dy;
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angle = AF_ANGLE_PI;
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}
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if ( dy < 0 )
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{
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FT_Pos tmp;
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tmp = dx;
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dx = -dy;
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dy = tmp;
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angle -= AF_ANGLE_PI2;
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}
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if ( dx == 0 && dy == 0 )
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return 0;
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if ( dx == dy )
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angle += AF_ANGLE_PI4;
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else if ( dx > dy )
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angle += af_arctan[FT_DivFix( dy, dx ) >> ( 16 - AF_ATAN_BITS )];
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else
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angle += AF_ANGLE_PI2 -
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af_arctan[FT_DivFix( dx, dy ) >> ( 16 - AF_ATAN_BITS )];
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if ( angle > AF_ANGLE_PI )
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angle -= AF_ANGLE_2PI;
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return angle;
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}
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#endif /* 0 */
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FT_LOCAL_DEF( void )
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af_sort_pos( FT_UInt count,
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FT_Pos* table )
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{
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FT_UInt i, j;
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FT_Pos swap;
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for ( i = 1; i < count; i++ )
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{
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for ( j = i; j > 0; j-- )
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{
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if ( table[j] >= table[j - 1] )
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break;
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swap = table[j];
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table[j] = table[j - 1];
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table[j - 1] = swap;
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}
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}
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}
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FT_LOCAL_DEF( void )
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af_sort_and_quantize_widths( FT_UInt* count,
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AF_Width table,
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FT_Pos threshold )
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{
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FT_UInt i, j;
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FT_UInt cur_idx;
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FT_Pos cur_val;
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FT_Pos sum;
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AF_WidthRec swap;
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if ( *count == 1 )
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return;
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/* sort */
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for ( i = 1; i < *count; i++ )
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{
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for ( j = i; j > 0; j-- )
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{
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if ( table[j].org >= table[j - 1].org )
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break;
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swap = table[j];
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table[j] = table[j - 1];
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table[j - 1] = swap;
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}
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}
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cur_idx = 0;
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cur_val = table[cur_idx].org;
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/* compute and use mean values for clusters not larger than */
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/* `threshold'; this is very primitive and might not yield */
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/* the best result, but normally, using reference character */
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/* `o', `*count' is 2, so the code below is fully sufficient */
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for ( i = 1; i < *count; i++ )
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{
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if ( table[i].org - cur_val > threshold ||
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i == *count - 1 )
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{
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sum = 0;
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/* fix loop for end of array */
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if ( table[i].org - cur_val <= threshold &&
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i == *count - 1 )
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i++;
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for ( j = cur_idx; j < i; j++ )
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{
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sum += table[j].org;
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table[j].org = 0;
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}
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table[cur_idx].org = sum / (FT_Pos)j;
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if ( i < *count - 1 )
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{
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cur_idx = i + 1;
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cur_val = table[cur_idx].org;
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}
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}
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}
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cur_idx = 1;
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/* compress array to remove zero values */
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for ( i = 1; i < *count; i++ )
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{
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if ( table[i].org )
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table[cur_idx++] = table[i];
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}
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*count = cur_idx;
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}
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/* END */
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