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[OTLayout] More 'size' feature sanity checking 

We still don't look for the old incorrect place of the featureParams.
I'll wait till someone actually complains about it...
This commit is contained in:
Behdad Esfahbod 2012-12-12 11:38:49 -05:00
parent 0bae50a36f
commit 85bc44b90a
1 changed files with 81 additions and 22 deletions
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103
src/hb-ot-layout.cc
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@ -658,33 +658,92 @@ hb_ot_layout_get_size_params (hb_face_t *face,
const OT::Feature &f = gpos.get_feature (i);
const OT::FeatureParamsSize &params = f.get_feature_params ().u.size;
#define PARAM(a, A) if (a) *a = params.A
if (!params.designSize)
goto zero_all;
PARAM (design_size, designSize);
if (!params.subfamilyID)
{
ret = true;
goto zero_most;
};
PARAM (subfamily_id, subfamilyID);
PARAM (subfamily_name_id, subfamilyNameID);
PARAM (range_start, rangeStart);
PARAM (range_end, rangeEnd);
#undef PARAM
/* This subtable has some "history", if you will. Some earlier versions of
* Adobe tools calculated the offset of the FeatureParams sutable from the
* beginning of the FeatureList table! Now, we don't check for that possibility,
* but we want to at least detect junk data and reject it.
*
* Read Roberts wrote on 9/15/06 on opentype-list@indx.co.uk :
*
* Yes, it is correct that a new version of the AFDKO (version 2.0) will be
* coming out soon, and that the makeotf program will build a font with a
* 'size' feature that is correct by the specification.
*
* The specification for this feature tag is in the "OpenType Layout Tag
* Registry". You can see a copy of this at:
* http://partners.adobe.com/public/developer/opentype/index_tag8.html#size
*
* Here is one set of rules to determine if the 'size' feature is built
* correctly, or as by the older versions of MakeOTF. You may be able to do
* better.
*
* Assume that the offset to the size feature is according to specification,
* and make the following value checks. If it fails, assume the the size
* feature is calculated as versions of MakeOTF before the AFDKO 2.0 built it.
* If this fails, reject the 'size' feature. The older makeOTF's calculated the
* offset from the beginning of the FeatureList table, rather than from the
* beginning of the 'size' Feature table.
*
* If "design size" == 0:
* fails check
*
* Else if ("subfamily identifier" == 0 and
* "range start" == 0 and
* "range end" == 0 and
* "range start" == 0 and
* "menu name ID" == 0)
* passes check: this is the format used when there is a design size
* specified, but there is no recommended size range.
*
* Else if ("design size" < "range start" or
* "design size" > "range end" or
* "range end" <= "range start" or
* "menu name ID" < 256 or
* "menu name ID" > 32767 or
* menu name ID is not a name ID which is actually in the name table)
* fails test
* Else
* passes test.
*/
return true;
if (!params.designSize)
ret = false;
else if (params.subfamilyID == 0 &&
params.subfamilyNameID == 0 &&
params.rangeStart == 0 &&
params.rangeEnd == 0)
ret = true;
else if (params.designSize < params.rangeStart ||
params.designSize > params.rangeEnd ||
params.subfamilyNameID < 256 ||
params.subfamilyNameID > 32767)
ret = false;
else
ret = true;
#define PARAM(a, A) if (a) *a = params.A
if (ret)
{
PARAM (design_size, designSize);
PARAM (subfamily_id, subfamilyID);
PARAM (subfamily_name_id, subfamilyNameID);
PARAM (range_start, rangeStart);
PARAM (range_end, rangeEnd);
break;
}
#undef PARAM
}
}
#define PARAM(a, A) if (a) *a = 0
zero_all:
PARAM (design_size, designSize);
zero_most:
PARAM (subfamily_id, subfamilyID);
PARAM (subfamily_name_id, subfamilyNameID);
PARAM (range_start, rangeStart);
PARAM (range_end, rangeEnd);
if (!ret)
{
PARAM (design_size, designSize);
PARAM (subfamily_id, subfamilyID);
PARAM (subfamily_name_id, subfamilyNameID);
PARAM (range_start, rangeStart);
PARAM (range_end, rangeEnd);
}
#undef PARAM
return ret;