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[bdf] Speed up bitmap parsing.

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A dedicated parser of bitmap data with minimal error checking and
no string comparisons helps to improve performance.

* src/bdf/bdflib.c (bdf_parse_bitmap_): New dedicated bitmap parser.
(bdf_parse_glyphs_): Pass to `bdf_parse_bitmap_` on BITMAP.
This commit is contained in:
Alexei Podtelezhnikov
2025-01-11 23:11:07 -05:00
parent 4433c7b7ba
commit bbc445e165
2 changed files with 72 additions and 71 deletions
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7
docs/CHANGES
View File

@@ -5,10 +5,15 @@ CHANGES BETWEEN 2.13.3 and 2.13.4 (2025-Mmm-DD)
- Bitmap-only TrueType fonts now ignore FT_LOAD_NO_BITMAP flag and
proceed loading bitmaps instead of giving an error. This behavior
is documented and implemented for other bitmap-only fonts. The
flag has always meant to suppress the bitmap strikes in favor of
flag was always meant to suppress the bitmap strikes in favor of
outlines, not to ban them completely.
III. MISCELLANEOUS
- The BDF driver now loads fonts noticeably faster.
======================================================================
CHANGES BETWEEN 2.13.2 and 2.13.3 (2024-Aug-11)

136
src/bdf/bdflib.c
View File

@@ -268,6 +268,7 @@
char* glyph_name;
long glyph_enc;
bdf_glyph_t* glyph;
bdf_font_t* font;
bdf_options_t* opts;
@@ -940,9 +941,6 @@
BDF_BBX_ | \
BDF_BITMAP_ )
#define BDF_GLYPH_WIDTH_CHECK_ 0x40000000UL
#define BDF_GLYPH_HEIGHT_CHECK_ 0x80000000UL
static FT_Error
bdf_add_comment_( bdf_font_t* font,
@@ -1280,7 +1278,67 @@
}
/* Actually parse the glyph info and bitmaps. */
/* Line function prototype. */
static FT_Error
bdf_parse_glyphs_( char* line,
unsigned long linelen,
unsigned long lineno,
void* call_data,
void* client_data );
/* Aggressively parse the glyph bitmaps. */
static FT_Error
bdf_parse_bitmap_( char* line,
unsigned long linelen,
unsigned long lineno,
void* call_data,
void* client_data )
{
bdf_line_func_t_* next = (bdf_line_func_t_ *)call_data;
bdf_parse_t_* p = (bdf_parse_t_ *) client_data;
bdf_glyph_t* glyph = p->glyph;
unsigned char* bp;
unsigned long i, nibbles;
int x;
FT_UNUSED( lineno ); /* only used in debug mode */
nibbles = glyph->bpr << 1;
bp = glyph->bitmap + p->row * glyph->bpr;
if ( nibbles > linelen )
{
FT_TRACE2(( "bdf_parse_bitmap_: " ACMSG16, glyph->encoding ));
nibbles = linelen;
}
for ( i = 0; i < nibbles; i++ )
{
/* char to hex without checks */
x = line[i];
x += ( x & 0x40 ) * 9 >> 6; /* for [A-Fa-f] */
x &= 0x0F;
if ( i & 1 )
*bp++ |= x;
else
*bp = x << 4;
}
p->row++;
/* When done, go back to parsing glyphs */
if ( p->row >= (unsigned long)glyph->bbx.height )
*next = bdf_parse_glyphs_;
return FT_Err_Ok;
}
/* Actually parse the glyph info. */
static FT_Error
bdf_parse_glyphs_( char* line,
unsigned long linelen,
@@ -1296,10 +1354,8 @@
FT_Memory memory = font->memory;
FT_Error error = FT_Err_Ok;
int c, mask_index;
char* s;
unsigned char* bp;
unsigned long i, slen, nibbles;
unsigned long slen;
FT_UNUSED( lineno ); /* only used in debug mode */
@@ -1528,10 +1584,6 @@
}
}
/* Clear the flags that might be added when width and height are */
/* checked for consistency. */
p->flags &= ~( BDF_GLYPH_WIDTH_CHECK_ | BDF_GLYPH_HEIGHT_CHECK_ );
p->flags |= BDF_ENCODING_;
goto Exit;
@@ -1546,64 +1598,6 @@
else
glyph = font->glyphs + ( font->glyphs_used - 1 );
/* Check whether a bitmap is being constructed. */
if ( p->flags & BDF_BITMAP_ )
{
/* If there are more rows than are specified in the glyph metrics, */
/* ignore the remaining lines. */
if ( p->row >= (unsigned long)glyph->bbx.height )
{
if ( !( p->flags & BDF_GLYPH_HEIGHT_CHECK_ ) )
{
FT_TRACE2(( "bdf_parse_glyphs_: " ACMSG13, glyph->encoding ));
p->flags |= BDF_GLYPH_HEIGHT_CHECK_;
}
goto Exit;
}
/* Only collect the number of nibbles indicated by the glyph */
/* metrics. If there are more columns, they are simply ignored. */
nibbles = glyph->bpr << 1;
bp = glyph->bitmap + p->row * glyph->bpr;
for ( i = 0; i < nibbles; i++ )
{
c = line[i];
if ( !sbitset( hdigits, c ) )
break;
*bp = (FT_Byte)( ( *bp << 4 ) + a2i[c] );
if ( i + 1 < nibbles && ( i & 1 ) )
*++bp = 0;
}
/* If any line has not enough columns, */
/* indicate they have been padded with zero bits. */
if ( i < nibbles &&
!( p->flags & BDF_GLYPH_WIDTH_CHECK_ ) )
{
FT_TRACE2(( "bdf_parse_glyphs_: " ACMSG16, glyph->encoding ));
p->flags |= BDF_GLYPH_WIDTH_CHECK_;
}
/* Remove possible garbage at the right. */
mask_index = ( glyph->bbx.width * p->font->bpp ) & 7;
if ( glyph->bbx.width )
*bp &= nibble_mask[mask_index];
/* If any line has extra columns, indicate they have been removed. */
if ( i == nibbles &&
sbitset( hdigits, line[nibbles] ) &&
!( p->flags & BDF_GLYPH_WIDTH_CHECK_ ) )
{
FT_TRACE2(( "bdf_parse_glyphs_: " ACMSG14, glyph->encoding ));
p->flags |= BDF_GLYPH_WIDTH_CHECK_;
}
p->row++;
goto Exit;
}
/* Expect the SWIDTH (scalable width) field next. */
if ( _bdf_strncmp( line, "SWIDTH", 6 ) == 0 )
{
@@ -1727,11 +1721,13 @@
else
glyph->bytes = (unsigned short)bitmap_size;
if ( FT_ALLOC( glyph->bitmap, glyph->bytes ) )
if ( !bitmap_size || FT_ALLOC( glyph->bitmap, glyph->bytes ) )
goto Exit;
p->glyph = glyph;
p->row = 0;
p->flags |= BDF_BITMAP_;
*next = bdf_parse_bitmap_;
goto Exit;
}