ref: f9b34b580707c0de388c07b9097b9400d651cbb0
dir: /src/autohint/ahoptim.c/
/***************************************************************************/ /* */ /* ahoptim.c */ /* */ /* FreeType auto hinting outline optimization (body). */ /* */ /* Copyright 2000-2001, 2002 Catharon Productions Inc. */ /* Author: David Turner */ /* */ /* This file is part of the Catharon Typography Project and shall only */ /* be used, modified, and distributed under the terms of the Catharon */ /* Open Source License that should come with this file under the name */ /* `CatharonLicense.txt'. By continuing to use, modify, or distribute */ /* this file you indicate that you have read the license and */ /* understand and accept it fully. */ /* */ /* Note that this license is compatible with the FreeType license. */ /* */ /***************************************************************************/ /*************************************************************************/ /* */ /* This module is in charge of optimising the outlines produced by the */ /* auto-hinter in direct mode. This is required at small pixel sizes in */ /* order to ensure coherent spacing, among other things.. */ /* */ /* The technique used in this module is a simplified simulated */ /* annealing. */ /* */ /*************************************************************************/ #include <ft2build.h> #include FT_INTERNAL_OBJECTS_H /* for FT_ALLOC_ARRAY() and FT_FREE() */ #include "ahoptim.h" /* define this macro to use brute force optimization -- this is slow, */ /* but a good way to perfect the distortion function `by hand' through */ /* tweaking */ #define AH_BRUTE_FORCE #define xxxAH_DEBUG_OPTIM #undef LOG #ifdef AH_DEBUG_OPTIM #define LOG( x ) optim_log ## x #else #define LOG( x ) #endif /* AH_DEBUG_OPTIM */ #ifdef AH_DEBUG_OPTIM #include <stdarg.h> #include <stdlib.h> #define FLOAT( x ) ( (float)( (x) / 64.0 ) ) static void optim_log( const char* fmt, ... ) { va_list ap; va_start( ap, fmt ); vprintf( fmt, ap ); va_end( ap ); } static void AH_Dump_Stems( AH_Optimizer* optimizer ) { int n; AH_Stem* stem; stem = optimizer->stems; for ( n = 0; n < optimizer->num_stems; n++, stem++ ) { LOG(( " %c%2d [%.1f:%.1f]={%.1f:%.1f}=" "<%1.f..%1.f> force=%.1f speed=%.1f\n", optimizer->vertical ? 'V' : 'H', n, FLOAT( stem->edge1->opos ), FLOAT( stem->edge2->opos ), FLOAT( stem->edge1->pos ), FLOAT( stem->edge2->pos ), FLOAT( stem->min_pos ), FLOAT( stem->max_pos ), FLOAT( stem->force ), FLOAT( stem->velocity ) )); } } static void AH_Dump_Stems2( AH_Optimizer* optimizer ) { int n; AH_Stem* stem; stem = optimizer->stems; for ( n = 0; n < optimizer->num_stems; n++, stem++ ) { LOG(( " %c%2d [%.1f]=<%1.f..%1.f> force=%.1f speed=%.1f\n", optimizer->vertical ? 'V' : 'H', n, FLOAT( stem->pos ), FLOAT( stem->min_pos ), FLOAT( stem->max_pos ), FLOAT( stem->force ), FLOAT( stem->velocity ) )); } } static void AH_Dump_Springs( AH_Optimizer* optimizer ) { int n; AH_Spring* spring; AH_Stem* stems; spring = optimizer->springs; stems = optimizer->stems; LOG(( "%cSprings ", optimizer->vertical ? 'V' : 'H' )); for ( n = 0; n < optimizer->num_springs; n++, spring++ ) { LOG(( " [%d-%d:%.1f:%1.f:%.1f]", spring->stem1 - stems, spring->stem2 - stems, FLOAT( spring->owidth ), FLOAT( spring->stem2->pos - ( spring->stem1->pos + spring->stem1->width ) ), FLOAT( spring->tension ) )); } LOG(( "\n" )); } #endif /* AH_DEBUG_OPTIM */ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /**** ****/ /**** COMPUTE STEMS AND SPRINGS IN AN OUTLINE ****/ /**** ****/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ static int valid_stem_segments( AH_Segment* seg1, AH_Segment* seg2 ) { return seg1->serif == 0 && seg2 && seg2->link == seg1 && seg1->pos < seg2->pos && seg1->min_coord <= seg2->max_coord && seg2->min_coord <= seg1->max_coord; } /* compute all stems in an outline */ static int optim_compute_stems( AH_Optimizer* optimizer ) { AH_Outline* outline = optimizer->outline; FT_Fixed scale; FT_Memory memory = optimizer->memory; FT_Error error = 0; FT_Int dimension; AH_Edge* edges; AH_Edge* edge_limit; AH_Stem** p_stems; FT_Int* p_num_stems; edges = outline->horz_edges; edge_limit = edges + outline->num_hedges; scale = outline->y_scale; p_stems = &optimizer->horz_stems; p_num_stems = &optimizer->num_hstems; for ( dimension = 1; dimension >= 0; dimension-- ) { AH_Stem* stems = 0; FT_Int num_stems = 0; AH_Edge* edge; /* first of all, count the number of stems in this direction */ for ( edge = edges; edge < edge_limit; edge++ ) { AH_Segment* seg = edge->first; do { if (valid_stem_segments( seg, seg->link ) ) num_stems++; seg = seg->edge_next; } while ( seg != edge->first ); } /* now allocate the stems and build their table */ if ( num_stems > 0 ) { AH_Stem* stem; if ( FT_NEW_ARRAY( stems, num_stems ) ) goto Exit; stem = stems; for ( edge = edges; edge < edge_limit; edge++ ) { AH_Segment* seg = edge->first; AH_Segment* seg2; do { seg2 = seg->link; if ( valid_stem_segments( seg, seg2 ) ) { AH_Edge* edge1 = seg->edge; AH_Edge* edge2 = seg2->edge; stem->edge1 = edge1; stem->edge2 = edge2; stem->opos = edge1->opos; stem->pos = edge1->pos; stem->owidth = edge2->opos - edge1->opos; stem->width = edge2->pos - edge1->pos; /* compute min_coord and max_coord */ { FT_Pos min_coord = seg->min_coord; FT_Pos max_coord = seg->max_coord; if ( seg2->min_coord > min_coord ) min_coord = seg2->min_coord; if ( seg2->max_coord < max_coord ) max_coord = seg2->max_coord; stem->min_coord = min_coord; stem->max_coord = max_coord; } /* compute minimum and maximum positions for stem -- */ /* note that the left-most/bottom-most stem has always */ /* a fixed position */ if ( stem == stems || edge1->blue_edge || edge2->blue_edge ) { /* this stem cannot move; it is snapped to a blue edge */ stem->min_pos = stem->pos; stem->max_pos = stem->pos; } else { /* this edge can move; compute its min and max positions */ FT_Pos pos1 = stem->opos; FT_Pos pos2 = pos1 + stem->owidth - stem->width; FT_Pos min1 = pos1 & -64; FT_Pos min2 = pos2 & -64; stem->min_pos = min1; stem->max_pos = min1 + 64; if ( min2 < min1 ) stem->min_pos = min2; else stem->max_pos = min2 + 64; /* XXX: just to see what it does */ stem->max_pos += 64; /* just for the case where direct hinting did some */ /* incredible things (e.g. blue edge shifts) */ if ( stem->min_pos > stem->pos ) stem->min_pos = stem->pos; if ( stem->max_pos < stem->pos ) stem->max_pos = stem->pos; } stem->velocity = 0; stem->force = 0; stem++; } seg = seg->edge_next; } while ( seg != edge->first ); } } *p_stems = stems; *p_num_stems = num_stems; edges = outline->vert_edges; edge_limit = edges + outline->num_vedges; scale = outline->x_scale; p_stems = &optimizer->vert_stems; p_num_stems = &optimizer->num_vstems; } Exit: #ifdef AH_DEBUG_OPTIM AH_Dump_Stems( optimizer ); #endif return error; } /* returns the spring area between two stems, 0 if none */ static FT_Pos stem_spring_area( AH_Stem* stem1, AH_Stem* stem2 ) { FT_Pos area1 = stem1->max_coord - stem1->min_coord; FT_Pos area2 = stem2->max_coord - stem2->min_coord; FT_Pos min = stem1->min_coord; FT_Pos max = stem1->max_coord; FT_Pos area; /* order stems */ if ( stem2->opos <= stem1->opos + stem1->owidth ) return 0; if ( min < stem2->min_coord ) min = stem2->min_coord; if ( max < stem2->max_coord ) max = stem2->max_coord; area = ( max-min ); if ( 2 * area < area1 && 2 * area < area2 ) area = 0; return area; } /* compute all springs in an outline */ static int optim_compute_springs( AH_Optimizer* optimizer ) { /* basically, a spring exists between two stems if most of their */ /* surface is aligned */ FT_Memory memory = optimizer->memory; AH_Stem* stems; AH_Stem* stem_limit; AH_Stem* stem; int dimension; int error = 0; FT_Int* p_num_springs; AH_Spring** p_springs; stems = optimizer->horz_stems; stem_limit = stems + optimizer->num_hstems; p_springs = &optimizer->horz_springs; p_num_springs = &optimizer->num_hsprings; for ( dimension = 1; dimension >= 0; dimension-- ) { FT_Int num_springs = 0; AH_Spring* springs = 0; /* first of all, count stem springs */ for ( stem = stems; stem + 1 < stem_limit; stem++ ) { AH_Stem* stem2; for ( stem2 = stem+1; stem2 < stem_limit; stem2++ ) if ( stem_spring_area( stem, stem2 ) ) num_springs++; } /* then allocate and build the springs table */ if ( num_springs > 0 ) { AH_Spring* spring; /* allocate table of springs */ if ( FT_NEW_ARRAY( springs, num_springs ) ) goto Exit; /* fill the springs table */ spring = springs; for ( stem = stems; stem+1 < stem_limit; stem++ ) { AH_Stem* stem2; FT_Pos area; for ( stem2 = stem + 1; stem2 < stem_limit; stem2++ ) { area = stem_spring_area( stem, stem2 ); if ( area ) { /* add a new spring here */ spring->stem1 = stem; spring->stem2 = stem2; spring->owidth = stem2->opos - ( stem->opos + stem->owidth ); spring->tension = 0; spring++; } } } } *p_num_springs = num_springs; *p_springs = springs; stems = optimizer->vert_stems; stem_limit = stems + optimizer->num_vstems; p_springs = &optimizer->vert_springs; p_num_springs = &optimizer->num_vsprings; } Exit: #ifdef AH_DEBUG_OPTIM AH_Dump_Springs( optimizer ); #endif return error; } /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /**** ****/ /**** OPTIMIZE THROUGH MY STRANGE SIMULATED ANNEALING ALGO ;-) ****/ /**** ****/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ #ifndef AH_BRUTE_FORCE /* compute all spring tensions */ static void optim_compute_tensions( AH_Optimizer* optimizer ) { AH_Spring* spring = optimizer->springs; AH_Spring* limit = spring + optimizer->num_springs; for ( ; spring < limit; spring++ ) { AH_Stem* stem1 = spring->stem1; AH_Stem* stem2 = spring->stem2; FT_Int status; FT_Pos width; FT_Pos tension; FT_Pos sign; /* compute the tension; it simply is -K*(new_width-old_width) */ width = stem2->pos - ( stem1->pos + stem1->width ); tension = width - spring->owidth; sign = 1; if ( tension < 0 ) { sign = -1; tension = -tension; } if ( width <= 0 ) tension = 32000; else tension = ( tension << 10 ) / width; tension = -sign * FT_MulFix( tension, optimizer->tension_scale ); spring->tension = tension; /* now, distribute tension among the englobing stems, if they */ /* are able to move */ status = 0; if ( stem1->pos <= stem1->min_pos ) status |= 1; if ( stem2->pos >= stem2->max_pos ) status |= 2; if ( !status ) tension /= 2; if ( ( status & 1 ) == 0 ) stem1->force -= tension; if ( ( status & 2 ) == 0 ) stem2->force += tension; } } /* compute all stem movements -- returns 0 if nothing moved */ static int optim_compute_stem_movements( AH_Optimizer* optimizer ) { AH_Stem* stems = optimizer->stems; AH_Stem* limit = stems + optimizer->num_stems; AH_Stem* stem = stems; int moved = 0; /* set initial forces to velocity */ for ( stem = stems; stem < limit; stem++ ) { stem->force = stem->velocity; stem->velocity /= 2; /* XXX: Heuristics */ } /* compute the sum of forces applied on each stem */ optim_compute_tensions( optimizer ); #ifdef AH_DEBUG_OPTIM AH_Dump_Springs( optimizer ); AH_Dump_Stems2( optimizer ); #endif /* now, see whether something can move */ for ( stem = stems; stem < limit; stem++ ) { if ( stem->force > optimizer->tension_threshold ) { /* there is enough tension to move the stem to the right */ if ( stem->pos < stem->max_pos ) { stem->pos += 64; stem->velocity = stem->force / 2; moved = 1; } else stem->velocity = 0; } else if ( stem->force < optimizer->tension_threshold ) { /* there is enough tension to move the stem to the left */ if ( stem->pos > stem->min_pos ) { stem->pos -= 64; stem->velocity = stem->force / 2; moved = 1; } else stem->velocity = 0; } } /* return 0 if nothing moved */ return moved; } #endif /* AH_BRUTE_FORCE */ /* compute current global distortion from springs */ static FT_Pos optim_compute_distortion( AH_Optimizer* optimizer ) { AH_Spring* spring = optimizer->springs; AH_Spring* limit = spring + optimizer->num_springs; FT_Pos distortion = 0; for ( ; spring < limit; spring++ ) { AH_Stem* stem1 = spring->stem1; AH_Stem* stem2 = spring->stem2; FT_Pos width; width = stem2->pos - ( stem1->pos + stem1->width ); width -= spring->owidth; if ( width < 0 ) width = -width; distortion += width; } return distortion; } /* record stems configuration in `best of' history */ static void optim_record_configuration( AH_Optimizer* optimizer ) { FT_Pos distortion; AH_Configuration* configs = optimizer->configs; AH_Configuration* limit = configs + optimizer->num_configs; AH_Configuration* config; distortion = optim_compute_distortion( optimizer ); LOG(( "config distortion = %.1f ", FLOAT( distortion * 64 ) )); /* check that we really need to add this configuration to our */ /* sorted history */ if ( limit > configs && limit[-1].distortion < distortion ) { LOG(( "ejected\n" )); return; } /* add new configuration at the end of the table */ { int n; config = limit; if ( optimizer->num_configs < AH_MAX_CONFIGS ) optimizer->num_configs++; else config--; config->distortion = distortion; for ( n = 0; n < optimizer->num_stems; n++ ) config->positions[n] = optimizer->stems[n].pos; } /* move the current configuration towards the front of the list */ /* when necessary -- yes this is slow bubble sort ;-) */ while ( config > configs && config[0].distortion < config[-1].distortion ) { AH_Configuration temp; config--; temp = config[0]; config[0] = config[1]; config[1] = temp; } LOG(( "recorded!\n" )); } #ifdef AH_BRUTE_FORCE /* optimize outline in a single direction */ static void optim_compute( AH_Optimizer* optimizer ) { int n; FT_Bool moved; AH_Stem* stem = optimizer->stems; AH_Stem* limit = stem + optimizer->num_stems; /* empty, exit */ if ( stem >= limit ) return; optimizer->num_configs = 0; stem = optimizer->stems; for ( ; stem < limit; stem++ ) stem->pos = stem->min_pos; do { /* record current configuration */ optim_record_configuration( optimizer ); /* now change configuration */ moved = 0; for ( stem = optimizer->stems; stem < limit; stem++ ) { if ( stem->pos < stem->max_pos ) { stem->pos += 64; moved = 1; break; } stem->pos = stem->min_pos; } } while ( moved ); /* now, set the best stem positions */ for ( n = 0; n < optimizer->num_stems; n++ ) { AH_Stem* stem = optimizer->stems + n; FT_Pos pos = optimizer->configs[0].positions[n]; stem->edge1->pos = pos; stem->edge2->pos = pos + stem->width; stem->edge1->flags |= ah_edge_done; stem->edge2->flags |= ah_edge_done; } } #else /* AH_BRUTE_FORCE */ /* optimize outline in a single direction */ static void optim_compute( AH_Optimizer* optimizer ) { int n, counter, counter2; optimizer->num_configs = 0; optimizer->tension_scale = 0x80000L; optimizer->tension_threshold = 64; /* record initial configuration threshold */ optim_record_configuration( optimizer ); counter = 0; for ( counter2 = optimizer->num_stems*8; counter2 >= 0; counter2-- ) { if ( counter == 0 ) counter = 2 * optimizer->num_stems; if ( !optim_compute_stem_movements( optimizer ) ) break; optim_record_configuration( optimizer ); counter--; if ( counter == 0 ) optimizer->tension_scale /= 2; } /* now, set the best stem positions */ for ( n = 0; n < optimizer->num_stems; n++ ) { AH_Stem* stem = optimizer->stems + n; FT_Pos pos = optimizer->configs[0].positions[n]; stem->edge1->pos = pos; stem->edge2->pos = pos + stem->width; stem->edge1->flags |= ah_edge_done; stem->edge2->flags |= ah_edge_done; } } #endif /* AH_BRUTE_FORCE */ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /**** ****/ /**** HIGH-LEVEL OPTIMIZER API ****/ /**** ****/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /* releases the optimization data */ void AH_Optimizer_Done( AH_Optimizer* optimizer ) { if ( optimizer ) { FT_Memory memory = optimizer->memory; FT_FREE( optimizer->horz_stems ); FT_FREE( optimizer->vert_stems ); FT_FREE( optimizer->horz_springs ); FT_FREE( optimizer->vert_springs ); FT_FREE( optimizer->positions ); } } /* loads the outline into the optimizer */ int AH_Optimizer_Init( AH_Optimizer* optimizer, AH_Outline* outline, FT_Memory memory ) { FT_Error error; FT_MEM_ZERO( optimizer, sizeof ( *optimizer ) ); optimizer->outline = outline; optimizer->memory = memory; LOG(( "initializing new optimizer\n" )); /* compute stems and springs */ error = optim_compute_stems ( optimizer ) || optim_compute_springs( optimizer ); if ( error ) goto Fail; /* allocate stem positions history and configurations */ { int n, max_stems; max_stems = optimizer->num_hstems; if ( max_stems < optimizer->num_vstems ) max_stems = optimizer->num_vstems; if ( FT_NEW_ARRAY( optimizer->positions, max_stems * AH_MAX_CONFIGS ) ) goto Fail; optimizer->num_configs = 0; for ( n = 0; n < AH_MAX_CONFIGS; n++ ) optimizer->configs[n].positions = optimizer->positions + n * max_stems; } return error; Fail: AH_Optimizer_Done( optimizer ); return error; } /* compute optimal outline */ void AH_Optimizer_Compute( AH_Optimizer* optimizer ) { optimizer->num_stems = optimizer->num_hstems; optimizer->stems = optimizer->horz_stems; optimizer->num_springs = optimizer->num_hsprings; optimizer->springs = optimizer->horz_springs; if ( optimizer->num_springs > 0 ) { LOG(( "horizontal optimization ------------------------\n" )); optim_compute( optimizer ); } optimizer->num_stems = optimizer->num_vstems; optimizer->stems = optimizer->vert_stems; optimizer->num_springs = optimizer->num_vsprings; optimizer->springs = optimizer->vert_springs; if ( optimizer->num_springs ) { LOG(( "vertical optimization --------------------------\n" )); optim_compute( optimizer ); } } /* END */