[autofit] Add a lot of comments and do some minor formatting.
This commit is contained in:
Werner Lemberg
parent
dd6c38fac7
commit
c5bda503b9
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@ -4,7 +4,7 @@
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/* */
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/* Auto-fitter hinting routines (body). */
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/* */
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/* Copyright 2003, 2004, 2005, 2006, 2007, 2009, 2010 by */
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/* Copyright 2003-2007, 2009-2011 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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@ -21,6 +21,8 @@
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#include FT_INTERNAL_CALC_H
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/* Get new segment for given axis. */
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FT_LOCAL_DEF( FT_Error )
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af_axis_hints_new_segment( AF_AxisHints axis,
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FT_Memory memory,
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@ -61,6 +63,8 @@
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}
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/* Get new edge for given axis, direction, and position. */
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FT_LOCAL( FT_Error )
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af_axis_hints_new_edge( AF_AxisHints axis,
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FT_Int fpos,
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@ -169,20 +173,20 @@
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printf( "Table of points:\n" );
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printf( " [ index | xorg | yorg | xscale | yscale "
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"| xfit | yfit | flags ]\n" );
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printf( " [ index | xorg | yorg | xscale | yscale"
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" | xfit | yfit | flags ]\n" );
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for ( point = points; point < limit; point++ )
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{
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printf( " [ %5d | %5d | %5d | %-5.2f | %-5.2f "
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"| %-5.2f | %-5.2f | %c%c%c%c%c%c ]\n",
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printf( " [ %5d | %5d | %5d | %-5.2f | %-5.2f"
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" | %-5.2f | %-5.2f | %c%c%c%c%c%c ]\n",
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point - points,
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point->fx,
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point->fy,
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point->ox/64.0,
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point->oy/64.0,
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point->x/64.0,
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point->y/64.0,
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point->ox / 64.0,
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point->oy / 64.0,
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point->x / 64.0,
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point->y / 64.0,
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( point->flags & AF_FLAG_WEAK_INTERPOLATION ) ? 'w' : ' ',
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( point->flags & AF_FLAG_INFLECTION ) ? 'i' : ' ',
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( point->flags & AF_FLAG_EXTREMA_X ) ? '<' : ' ',
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@ -222,7 +226,8 @@
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}
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/* A function to dump the array of linked segments. */
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/* Dump the array of linked segments. */
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void
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af_glyph_hints_dump_segments( AF_GlyphHints hints )
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{
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@ -260,6 +265,8 @@
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}
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/* Dump the array of linked edges. */
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void
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af_glyph_hints_dump_edges( AF_GlyphHints hints )
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{
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@ -276,7 +283,7 @@
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/*
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* note: AF_DIMENSION_HORZ corresponds to _vertical_ edges
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* since they have constant a X coordinate.
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* since they have a constant X coordinate.
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*/
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printf ( "Table of %s edges:\n",
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dimension == AF_DIMENSION_HORZ ? "vertical" : "horizontal" );
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@ -329,7 +336,8 @@
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#endif /* !AF_DEBUG */
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/* compute the direction value of a given vector */
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/* Compute the direction value of a given vector. */
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FT_LOCAL_DEF( AF_Direction )
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af_direction_compute( FT_Pos dx,
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FT_Pos dy )
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@ -369,6 +377,8 @@
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}
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}
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/* return no direction if arm lengths differ too much */
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/* (value 14 is heuristic) */
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ss *= 14;
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if ( FT_ABS( ll ) <= FT_ABS( ss ) )
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dir = AF_DIR_NONE;
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@ -397,7 +407,7 @@
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/*
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* note that we don't need to free the segment and edge
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* buffers, since they are really within the hints->points array
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* buffers since they are really within the hints->points array
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*/
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for ( dim = 0; dim < AF_DIMENSION_MAX; dim++ )
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{
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@ -408,8 +418,8 @@
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axis->max_segments = 0;
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FT_FREE( axis->segments );
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axis->num_edges = 0;
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axis->max_edges = 0;
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axis->num_edges = 0;
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axis->max_edges = 0;
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FT_FREE( axis->edges );
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}
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@ -426,6 +436,8 @@
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}
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/* Reset metrics. */
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FT_LOCAL_DEF( void )
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af_glyph_hints_rescale( AF_GlyphHints hints,
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AF_ScriptMetrics metrics )
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@ -435,6 +447,9 @@
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}
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/* Recompute all AF_Point in AF_GlyphHints from the definitions */
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/* in a source outline. */
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FT_LOCAL_DEF( FT_Error )
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af_glyph_hints_reload( AF_GlyphHints hints,
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FT_Outline* outline )
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@ -457,12 +472,12 @@
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hints->axis[1].num_segments = 0;
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hints->axis[1].num_edges = 0;
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/* first of all, reallocate the contours array when necessary */
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/* first of all, reallocate the contours array if necessary */
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new_max = (FT_UInt)outline->n_contours;
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old_max = hints->max_contours;
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if ( new_max > old_max )
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{
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new_max = ( new_max + 3 ) & ~3;
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new_max = ( new_max + 3 ) & ~3; /* round up to a multiple of 4 */
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if ( FT_RENEW_ARRAY( hints->contours, old_max, new_max ) )
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goto Exit;
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@ -479,7 +494,7 @@
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old_max = hints->max_points;
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if ( new_max > old_max )
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{
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new_max = ( new_max + 2 + 7 ) & ~7;
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new_max = ( new_max + 2 + 7 ) & ~7; /* round up to a multiple of 8 */
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if ( FT_RENEW_ARRAY( hints->points, old_max, new_max ) )
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goto Exit;
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@ -545,7 +560,7 @@
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point->flags = AF_FLAG_CUBIC;
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break;
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default:
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point->flags = 0;
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point->flags = AF_FLAG_NONE;
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}
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point->prev = prev;
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@ -563,7 +578,7 @@
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}
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}
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/* set-up the contours array */
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/* set up the contours array */
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{
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AF_Point* contour = hints->contours;
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AF_Point* contour_limit = contour + hints->num_contours;
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@ -611,6 +626,8 @@
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in_dir = af_direction_compute( out_x, out_y );
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point->out_dir = (FT_Char)in_dir;
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/* check for weak points */
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if ( point->flags & ( AF_FLAG_CONIC | AF_FLAG_CUBIC ) )
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{
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Is_Weak_Point:
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@ -639,6 +656,8 @@
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}
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/* Store the hinted outline in an FT_Outline structure. */
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FT_LOCAL_DEF( void )
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af_glyph_hints_save( AF_GlyphHints hints,
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FT_Outline* outline )
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@ -671,6 +690,9 @@
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****************************************************************/
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/* Align all points of an edge to the same coordinate value, */
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/* either horizontally or vertically. */
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FT_LOCAL_DEF( void )
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af_glyph_hints_align_edge_points( AF_GlyphHints hints,
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AF_Dimension dim )
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@ -704,7 +726,6 @@
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break;
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point = point->next;
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}
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}
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}
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@ -744,8 +765,8 @@
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****************************************************************/
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/* hint the strong points -- this is equivalent to the TrueType `IP' */
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/* hinting instruction */
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/* Hint the strong points -- this is equivalent to the TrueType `IP' */
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/* hinting instruction. */
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FT_LOCAL_DEF( void )
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af_glyph_hints_align_strong_points( AF_GlyphHints hints,
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@ -827,11 +848,12 @@
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max = edge_limit - edges;
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#if 1
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/* for small edge counts, a linear search is better */
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/* for a small number of edges, a linear search is better */
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if ( max <= 8 )
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{
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FT_PtrDist nn;
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for ( nn = 0; nn < max; nn++ )
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if ( edges[nn].fpos >= u )
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break;
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@ -863,6 +885,7 @@
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}
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}
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/* point is not on an edge */
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{
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AF_Edge before = edges + min - 1;
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AF_Edge after = edges + min + 0;
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@ -898,6 +921,10 @@
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****************************************************************/
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/* Shift the original coordinates of all points between `p1' and */
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/* `p2' to get hinted coordinates, using the same difference as */
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/* given by `ref'. */
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static void
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af_iup_shift( AF_Point p1,
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AF_Point p2,
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@ -906,6 +933,7 @@
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AF_Point p;
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FT_Pos delta = ref->u - ref->v;
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if ( delta == 0 )
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return;
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@ -917,6 +945,13 @@
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}
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/* Interpolate the original coordinates of all points between `p1' and */
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/* `p2' to get hinted coordinates, using `ref1' and `ref2' as the */
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/* reference points. The `u' and `v' members are the current and */
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/* original coordinate values, respectively. */
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/* */
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/* Details can be found in the TrueType bytecode specification. */
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static void
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af_iup_interp( AF_Point p1,
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AF_Point p2,
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@ -985,6 +1020,9 @@
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}
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/* Hint the weak points -- this is equivalent to the TrueType `IUP' */
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/* hinting instruction. */
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FT_LOCAL_DEF( void )
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af_glyph_hints_align_weak_points( AF_GlyphHints hints,
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AF_Dimension dim )
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@ -1050,17 +1088,18 @@
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for (;;)
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{
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FT_ASSERT( point <= end_point &&
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FT_ASSERT( point <= end_point &&
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( point->flags & touch_flag ) != 0 );
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/* skip any touched neighbhours */
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while ( point < end_point && ( point[1].flags & touch_flag ) != 0 )
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/* skip any touched neighbours */
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while ( point < end_point &&
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( point[1].flags & touch_flag ) != 0 )
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point++;
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last_touched = point;
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/* find the next touched point, if any */
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point ++;
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point++;
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for (;;)
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{
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if ( point > end_point )
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@ -1080,9 +1119,8 @@
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EndContour:
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/* special case: only one point was touched */
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if ( last_touched == first_touched )
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{
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af_iup_shift( first_point, end_point, first_touched );
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}
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else /* interpolate the last part */
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{
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if ( last_touched < end_point )
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@ -4,7 +4,7 @@
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/* */
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/* Auto-fitter hinting routines (specification). */
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/* */
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/* Copyright 2003, 2004, 2005, 2006, 2007, 2008, 2010 by */
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/* Copyright 2003-2008, 2010-2011 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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@ -25,10 +25,10 @@
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FT_BEGIN_HEADER
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/*
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* The definition of outline glyph hints. These are shared by all
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* script analysis routines (until now).
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*/
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/*
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* The definition of outline glyph hints. These are shared by all
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* script analysis routines (until now).
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*/
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typedef enum AF_Dimension_
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{
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@ -55,6 +55,128 @@ FT_BEGIN_HEADER
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} AF_Direction;
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/*
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* The following explanations are mostly taken from the article
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*
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* Real-Time Grid Fitting of Typographic Outlines
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*
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* by David Turner and Werner Lemberg
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*
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* http://www.tug.org/TUGboat/Articles/tb24-3/lemberg.pdf
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*
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*
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* Segments
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*
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* `af_{cjk,latin,...}_hints_compute_segments' are the functions to
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* find segments in an outline. A segment is a series of consecutive
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* points that are approximately aligned along a coordinate axis. The
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* analysis to do so is specific to a script.
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*
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* A segment must have at least two points, except in the case of
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* `fake' segments that are generated to hint metrics appropriately,
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* and which consist of a single point.
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*
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*
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* Edges
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*
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* As soon as segments are defined, the auto-hinter groups them into
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* edges. An edge corresponds to a single position on the main
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* dimension that collects one or more segments (allowing for a small
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* threshold).
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*
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* The auto-hinter first tries to grid fit edges, then to align
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* segments on the edges unless it detects that they form a serif.
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*
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* `af_{cjk,latin,...}_hints_compute_edges' are the functions to find
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* edges; they are specific to a script.
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*
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*
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* Stems
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*
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* Segments need to be `linked' to other ones in order to detect stems.
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* A stem is made of two segments that face each other in opposite
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* directions and that are sufficiently close to each other. Using
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* vocabulary from the TrueType specification, stem segments form a
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* `black distance'.
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*
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* Each segment has at most one `best' candidate to form a black
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* distance, or no candidate at all. Notice that two distinct segments
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* can have the same candidate, which frequently means a serif.
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*
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* A stem is recognized by the following condition:
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*
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* best segment_1 = segment_2 && best segment_2 = segment_1
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*
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* The best candidate is stored in field `link' in structure
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* `AF_Segment'.
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*
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* Stems are detected by `af_{cjk,latin,...}_hint_edges'.
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*
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*
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* Serifs
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*
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* On the opposite, a serif has
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*
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* best segment_1 = segment_2 && best segment_2 != segment_1
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*
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* where segment_1 corresponds to the serif segment.
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*
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* The best candidate is stored in field `serif' in structure
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* `AF_Segment' (and `link' is set to NULL).
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*
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* Serifs are detected by `af_{cjk,latin,...}_hint_edges'.
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*
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*
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* Touched points
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*
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* A point is called `touched' if it has been processed somehow by the
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* auto-hinter. It basically means that it shouldn't be moved again
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* (or moved only under certain constraints to preserve the already
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* applied processing).
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*
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*
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* Flat and round segments
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*
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* Segments are `round' or `flat', depending on the series of points
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* that define them. A segment is round if the next and previous point
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* of an extremum (which can be either a single point or sequence of
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* points) are both conic or cubic control points. Otherwise, a
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* segment with an extremum is flat.
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*
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*
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* Strong Points
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*
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* Experience has shown that points which are not part of an edge need
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* to be interpolated linearly between their two closest edges, even if
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* these are not part of the contour of those particular points.
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* Typical candidates for this are
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*
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* - angle points (i.e., points where the `in' and `out' direction
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* differ greatly)
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*
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* - inflection points (i.e., where the `in' and `out' angles are the
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* same, but the curvature changes sign)
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*
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* `af_glyph_hints_align_strong_points' is the function which takes
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* care of such situations; it is equivalent to the TrueType `IP'
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* hinting instruction.
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*
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*
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* Weak Points
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*
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* Other points in the outline must be interpolated using the
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* coordinates of their previous and next unfitted contour neighbours.
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* These are called `weak points' and are touched by the function
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* `af_glyph_hints_align_weak_points', equivalent to the TrueType `IUP'
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* hinting instruction. Typical candidates are control points and
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* points on the contour without a major direction.
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*
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* The major effect is to reduce possible distortion caused by
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* alignment of edges and strong points, thus weak points are processed
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* after strong points.
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*/
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/* point hint flags */
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typedef enum AF_Flags_
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{
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@ -155,32 +277,31 @@ FT_BEGIN_HEADER
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FT_Fixed scale; /* used to speed up interpolation between edges */
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AF_Width blue_edge; /* non-NULL if this is a blue edge */
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||||
AF_Edge link;
|
||||
AF_Edge serif;
|
||||
FT_Short num_linked;
|
||||
AF_Edge link; /* link edge */
|
||||
AF_Edge serif; /* primary edge for serifs */
|
||||
FT_Short num_linked; /* number of linked edges */
|
||||
FT_Int score; /* used during stem matching */
|
||||
|
||||
FT_Int score;
|
||||
|
||||
AF_Segment first;
|
||||
AF_Segment last;
|
||||
AF_Segment first; /* first segment in edge */
|
||||
AF_Segment last; /* last segment in edge */
|
||||
|
||||
} AF_EdgeRec;
|
||||
|
||||
|
||||
typedef struct AF_AxisHintsRec_
|
||||
{
|
||||
FT_Int num_segments;
|
||||
FT_Int max_segments;
|
||||
AF_Segment segments;
|
||||
FT_Int num_segments; /* number of used segments */
|
||||
FT_Int max_segments; /* number of allocated segments */
|
||||
AF_Segment segments; /* segments array */
|
||||
#ifdef AF_SORT_SEGMENTS
|
||||
FT_Int mid_segments;
|
||||
#endif
|
||||
|
||||
FT_Int num_edges;
|
||||
FT_Int max_edges;
|
||||
AF_Edge edges;
|
||||
FT_Int num_edges; /* number of used edges */
|
||||
FT_Int max_edges; /* number of allocated edges */
|
||||
AF_Edge edges; /* edges array */
|
||||
|
||||
AF_Direction major_dir;
|
||||
AF_Direction major_dir; /* either vertical or horizontal */
|
||||
|
||||
} AF_AxisHintsRec, *AF_AxisHints;
|
||||
|
||||
|
|
@ -197,13 +318,13 @@ FT_BEGIN_HEADER
|
|||
|
||||
FT_Pos edge_distance_threshold;
|
||||
|
||||
FT_Int max_points;
|
||||
FT_Int num_points;
|
||||
AF_Point points;
|
||||
FT_Int max_points; /* number of allocated points */
|
||||
FT_Int num_points; /* number of used points */
|
||||
AF_Point points; /* points array */
|
||||
|
||||
FT_Int max_contours;
|
||||
FT_Int num_contours;
|
||||
AF_Point* contours;
|
||||
FT_Int max_contours; /* number of allocated contours */
|
||||
FT_Int num_contours; /* number of used contours */
|
||||
AF_Point* contours; /* contours array */
|
||||
|
||||
AF_AxisHintsRec axis[AF_DIMENSION_MAX];
|
||||
|
||||
|
|
@ -214,7 +335,7 @@ FT_BEGIN_HEADER
|
|||
|
||||
FT_Pos xmin_delta; /* used for warping */
|
||||
FT_Pos xmax_delta;
|
||||
|
||||
|
||||
} AF_GlyphHintsRec;
|
||||
|
||||
|
||||
|
|
@ -274,12 +395,6 @@ FT_BEGIN_HEADER
|
|||
af_glyph_hints_init( AF_GlyphHints hints,
|
||||
FT_Memory memory );
|
||||
|
||||
|
||||
|
||||
/*
|
||||
* recompute all AF_Point in a AF_GlyphHints from the definitions
|
||||
* in a source outline
|
||||
*/
|
||||
FT_LOCAL( void )
|
||||
af_glyph_hints_rescale( AF_GlyphHints hints,
|
||||
AF_ScriptMetrics metrics );
|
||||
|
|
|
|||
Loading…
Reference in New Issue