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First steps to fix the scaling bug of CID-keyed CFF subfonts, 

reported by Ding Li on 2008/03/28 on freetype-devel.

* src/base/cff/cffparse.c (power_tens): New array.
(cff_parse_real): Rewritten to introduce a fourth parameter which
returns the `scaling' of the real number so that we have no
precision loss.  This is not used yet.
Update all callers.
(cff_parse_fixed_thousand): Replace with...
(cff_parse_fixed_scaled): This function.  Update all callers.
This commit is contained in:
Werner Lemberg 2008-05-04 13:37:38 +00:00
parent 6d29f0f1e8
commit 551dd3c0a6
2 changed files with 173 additions and 72 deletions
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13
ChangeLog
View File

@ -1,3 +1,16 @@
2008-05-04 Werner Lemberg <wl@gnu.org>
First steps to fix the scaling bug of CID-keyed CFF subfonts,
reported by Ding Li on 2008/03/28 on freetype-devel.
* src/base/cff/cffparse.c (power_tens): New array.
(cff_parse_real): Rewritten to introduce a fourth parameter which
returns the `scaling' of the real number so that we have no
precision loss. This is not used yet.
Update all callers.
(cff_parse_fixed_thousand): Replace with...
(cff_parse_fixed_scaled): This function. Update all callers.
2008-05-03 Werner Lemberg <wl@gnu.org>
* src/base/ftobjs.c (FT_Load_Glyph): Call the auto-hinter without

232
src/cff/cffparse.c
View File

@ -136,24 +136,51 @@
}
static const FT_Long power_tens[] =
{
1L,
10L,
100L,
1000L,
10000L,
100000L,
1000000L,
10000000L,
100000000L,
1000000000L
};
/* read a real */
static FT_Fixed
cff_parse_real( FT_Byte* start,
FT_Byte* limit,
FT_Int power_ten )
FT_Int power_ten,
FT_Int* scaling )
{
FT_Byte* p = start;
FT_Long num, divider, result, exponent;
FT_Int sign = 0, exponent_sign = 0;
FT_Byte* p = start;
FT_UInt nib;
FT_UInt phase;
FT_Long result, number, rest, exponent;
FT_Int sign = 0, exponent_sign = 0;
FT_Int exponent_add, integer_length, fraction_length;
result = 0;
num = 0;
divider = 1;
/* first of all, read the integer part */
if ( scaling )
*scaling = 0;
result = 0;
number = 0;
rest = 0;
exponent = 0;
exponent_add = 0;
integer_length = 0;
fraction_length = 0;
/* First of all, read the integer part. */
phase = 4;
for (;;)
@ -166,7 +193,7 @@
/* Make sure we don't read past the end. */
if ( p >= limit )
goto Bad;
goto Exit;
}
/* Get the nibble. */
@ -178,10 +205,20 @@
else if ( nib > 9 )
break;
else
result = result * 10 + nib;
{
/* Increase exponent if we can't add the digit. */
if ( number >= 0xCCCCCCCL )
exponent_add++;
/* Skip leading zeros. */
else if ( nib || number )
{
integer_length++;
number = number * 10 + nib;
}
}
}
/* read decimal part, if any */
/* Read fraction part, if any. */
if ( nib == 0xa )
for (;;)
{
@ -193,7 +230,7 @@
/* Make sure we don't read past the end. */
if ( p >= limit )
goto Bad;
goto Exit;
}
/* Get the nibble. */
@ -202,24 +239,18 @@
if ( nib >= 10 )
break;
/* Increase precision if the integer part is zero */
/* and we have to scale the real number. */
if ( !result && power_ten )
/* Skip leading zeros if possible. */
if ( !nib && !number )
exponent_add--;
/* Only add digit if we don't overflow. */
else if ( number < 0xCCCCCCCL )
{
power_ten--;
num = num * 10 + nib;
}
else
{
if ( divider < 10000000L )
{
num = num * 10 + nib;
divider *= 10;
}
fraction_length++;
number = number * 10 + nib;
}
}
/* read exponent, if any */
/* Read exponent, if any. */
if ( nib == 12 )
{
exponent_sign = 1;
@ -228,19 +259,17 @@
if ( nib == 11 )
{
exponent = 0;
for (;;)
{
/* If we entered this iteration with phase == 4, we need */
/* to read a new byte. */
/* If we entered this iteration with phase == 4, */
/* we need to read a new byte. */
if ( phase )
{
p++;
/* Make sure we don't read past the end. */
if ( p >= limit )
goto Bad;
goto Exit;
}
/* Get the nibble. */
@ -250,37 +279,98 @@
break;
exponent = exponent * 10 + nib;
/* Arbitrarily limit exponent. */
if ( exponent > 1000 )
goto Exit;
}
if ( exponent_sign )
exponent = -exponent;
power_ten += (FT_Int)exponent;
}
/* Move the integer part into the higher 16 bits. */
result <<= 16;
/* We don't check `power_ten' and `exponent_add'. */
exponent += power_ten + exponent_add;
/* Place the decimal part into the lower 16 bits. */
if ( num )
result |= FT_DivFix( num, divider );
/* apply power of 10 if needed */
if ( power_ten > 0 )
if ( scaling )
{
divider = 10; /* actually, this will be used as multiplier here */
while ( --power_ten > 0 )
divider = divider * 10;
/* Only use `fraction_length'. */
fraction_length += integer_length;
exponent += integer_length;
result = FT_MulFix( divider << 16, result );
if ( fraction_length <= 5 )
{
if ( number > 0x7FFFL )
{
result = FT_DivFix( number, 10 );
*scaling = exponent - fraction_length + 1;
}
else
{
if ( exponent > 0 )
{
FT_Int new_fraction_length, shift;
/* Make `scaling' as small as possible. */
new_fraction_length = FT_MIN( exponent, 5 );
exponent -= new_fraction_length;
shift = new_fraction_length - fraction_length;
number *= power_tens[shift];
if ( number > 0x7FFFL )
{
number /= 10;
exponent += 1;
}
}
else
exponent -= fraction_length;
result = number << 16;
*scaling = exponent;
}
}
else
{
if ( ( number / power_tens[fraction_length - 5] ) > 0x7FFFL )
{
result = FT_DivFix( number, power_tens[fraction_length - 4] );
*scaling = exponent - 4;
}
else
{
result = FT_DivFix( number, power_tens[fraction_length - 5] );
*scaling = exponent - 5;
}
}
}
else if ( power_ten < 0 )
else
{
divider = 10;
while ( ++power_ten < 0 )
divider = divider * 10;
integer_length += exponent;
fraction_length -= exponent;
result = FT_DivFix( result, divider << 16 );
/* Check for overflow and underflow. */
if ( FT_ABS( integer_length ) > 5 )
goto Exit;
/* Convert into 16.16 format. */
if ( fraction_length > 0 )
{
if ( ( number / power_tens[fraction_length] ) > 0x7FFFL )
goto Exit;
result = FT_DivFix( number, power_tens[fraction_length] );
}
else
{
number *= power_tens[-fraction_length];
if ( number > 0x7FFFL )
goto Exit;
result = number << 16;
}
}
if ( sign )
@ -288,10 +378,6 @@
Exit:
return result;
Bad:
result = 0;
goto Exit;
}
@ -299,8 +385,8 @@
static FT_Long
cff_parse_num( FT_Byte** d )
{
return ( **d == 30 ? ( cff_parse_real ( d[0], d[1], 0 ) >> 16 )
: cff_parse_integer( d[0], d[1] ) );
return **d == 30 ? ( cff_parse_real( d[0], d[1], 0, NULL ) >> 16 )
: cff_parse_integer( d[0], d[1] );
}
@ -308,20 +394,24 @@
static FT_Fixed
cff_parse_fixed( FT_Byte** d )
{
return ( **d == 30 ? cff_parse_real ( d[0], d[1], 0 )
: cff_parse_integer( d[0], d[1] ) << 16 );
return **d == 30 ? cff_parse_real( d[0], d[1], 0, NULL )
: cff_parse_integer( d[0], d[1] ) << 16;
}
/* read a floating point number, either integer or real, */
/* but return 1000 times the number read in. */
/* but return `10^scaling' times the number read in */
static FT_Fixed
cff_parse_fixed_thousand( FT_Byte** d )
cff_parse_fixed_scaled( FT_Byte** d,
FT_Int scaling )
{
return **d ==
30 ? cff_parse_real ( d[0], d[1], 3 )
: (FT_Fixed)FT_MulFix( cff_parse_integer( d[0], d[1] ) << 16, 1000 );
30 ? cff_parse_real( d[0], d[1], scaling, NULL )
: (FT_Fixed)FT_MulFix( cff_parse_integer( d[0], d[1] ) << 16,
power_tens[scaling] );
}
static FT_Error
cff_parse_font_matrix( CFF_Parser parser )
{
@ -330,20 +420,18 @@
FT_Vector* offset = &dict->font_offset;
FT_UShort* upm = &dict->units_per_em;
FT_Byte** data = parser->stack;
FT_Error error;
FT_Error error = CFF_Err_Stack_Underflow;
FT_Fixed temp;
error = CFF_Err_Stack_Underflow;
if ( parser->top >= parser->stack + 6 )
{
matrix->xx = cff_parse_fixed_thousand( data++ );
matrix->yx = cff_parse_fixed_thousand( data++ );
matrix->xy = cff_parse_fixed_thousand( data++ );
matrix->yy = cff_parse_fixed_thousand( data++ );
offset->x = cff_parse_fixed_thousand( data++ );
offset->y = cff_parse_fixed_thousand( data );
matrix->xx = cff_parse_fixed_scaled( data++, 3 );
matrix->yx = cff_parse_fixed_scaled( data++, 3 );
matrix->xy = cff_parse_fixed_scaled( data++, 3 );
matrix->yy = cff_parse_fixed_scaled( data++, 3 );
offset->x = cff_parse_fixed_scaled( data++, 3 );
offset->y = cff_parse_fixed_scaled( data, 3 );
temp = FT_ABS( matrix->yy );
@ -599,7 +687,7 @@
goto Store_Number;
case cff_kind_fixed_thousand:
val = cff_parse_fixed_thousand( parser->stack );
val = cff_parse_fixed_scaled( parser->stack, 3 );
Store_Number:
switch ( field->size )