Commit 551dd3c0a6d4d82a85797936edfe9147ca08af35
2008-05-04T13:37:38
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.
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diff --git a/ChangeLog b/ChangeLog
index b1e69f4..f1a9783 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -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
diff --git a/src/cff/cffparse.c b/src/cff/cffparse.c
index af276f7..0d20ab5 100644
--- a/src/cff/cffparse.c
+++ b/src/cff/cffparse.c
@@ -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;
+ if ( scaling )
+ *scaling = 0;
+
+ result = 0;
- /* first of all, read the integer part */
+ 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 )
- {
- power_ten--;
- num = num * 10 + nib;
- }
- else
+ /* Skip leading zeros if possible. */
+ if ( !nib && !number )
+ exponent_add--;
+ /* Only add digit if we don't overflow. */
+ else if ( number < 0xCCCCCCCL )
{
- 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;
-
- /* Place the decimal part into the lower 16 bits. */
- if ( num )
- result |= FT_DivFix( num, divider );
+ /* We don't check `power_ten' and `exponent_add'. */
+ exponent += power_ten + exponent_add;
- /* 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;
+
+ 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;
+
- result = FT_MulFix( divider << 16, result );
+ /* 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;
+
+ /* Check for overflow and underflow. */
+ if ( FT_ABS( integer_length ) > 5 )
+ goto Exit;
- result = FT_DivFix( result, divider << 16 );
+ /* 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 )