Commit a4c2a31138221165db524ca02f28f0b54698b305
2016-08-22T19:32:34
[truetype] Fix `MPS' instruction. According to Greg Hitchcock, MPS in DWrite really returns the point size. * src/truetype/ttobjs.h (TT_SizeRec): Add `point_size' member. * src/truetype/ttdriver.c (tt_size_request): Set `point_size'. * src/truetype/ttinterp.h (TT_ExecContextRec): Add `pointSize' member. * src/truetype/ttinterp.c (TT_Load_Context): Updated. (Ins_MPS): Fix instruction.
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diff --git a/ChangeLog b/ChangeLog
index 8aaa78e..cfb9ae5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,22 @@
2016-08-16 Werner Lemberg <wl@gnu.org>
+ [truetype] Fix `MPS' instruction.
+
+ According to Greg Hitchcock, MPS in DWrite really returns the point
+ size.
+
+ * src/truetype/ttobjs.h (TT_SizeRec): Add `point_size' member.
+
+ * src/truetype/ttdriver.c (tt_size_request): Set `point_size'.
+
+ * src/truetype/ttinterp.h (TT_ExecContextRec): Add `pointSize'
+ member.
+
+ * src/truetype/ttinterp.c (TT_Load_Context): Updated.
+ (Ins_MPS): Fix instruction.
+
+2016-08-16 Werner Lemberg <wl@gnu.org>
+
[lzw] Optimize last commit.
* src/lzw/ftzopen.c (ft_lzwstate_get_code): Move check into
diff --git a/src/truetype/ttdriver.c b/src/truetype/ttdriver.c
index 2659b9c..6520c93 100644
--- a/src/truetype/ttdriver.c
+++ b/src/truetype/ttdriver.c
@@ -339,6 +339,25 @@
{
error = tt_size_reset( ttsize );
ttsize->root.metrics = ttsize->metrics;
+
+#ifdef TT_USE_BYTECODE_INTERPRETER
+ /* for the `MPS' bytecode instruction we need the point size */
+ {
+ FT_UInt resolution = ttsize->metrics.x_ppem > ttsize->metrics.y_ppem
+ ? req->horiResolution
+ : req->vertResolution;
+
+
+ /* if we don't have a resolution value, assume 72dpi */
+ if ( req->type == FT_SIZE_REQUEST_TYPE_SCALES ||
+ !resolution )
+ resolution = 72;
+
+ ttsize->point_size = FT_MulDiv( ttsize->ttmetrics.ppem,
+ 64 * 72,
+ resolution );
+ }
+#endif
}
return error;
diff --git a/src/truetype/ttinterp.c b/src/truetype/ttinterp.c
index f23a3dd..caeb6ca 100644
--- a/src/truetype/ttinterp.c
+++ b/src/truetype/ttinterp.c
@@ -397,6 +397,7 @@
exec->maxIDefs = size->max_instruction_defs;
exec->FDefs = size->function_defs;
exec->IDefs = size->instruction_defs;
+ exec->pointSize = size->point_size;
exec->tt_metrics = size->ttmetrics;
exec->metrics = size->metrics;
@@ -2580,13 +2581,20 @@
Ins_MPS( TT_ExecContext exc,
FT_Long* args )
{
- /* Note: The point size should be irrelevant in a given font program; */
- /* we thus decide to return only the PPEM value. */
-#if 0
- args[0] = exc->metrics.pointSize;
-#else
- args[0] = exc->func_cur_ppem( exc );
-#endif
+ if ( NO_SUBPIXEL_HINTING )
+ {
+ /* Microsoft's GDI bytecode interpreter always returns value 12; */
+ /* we return the current PPEM value instead. */
+ args[0] = exc->func_cur_ppem( exc );
+ }
+ else
+ {
+ /* A possible practical application of the MPS instruction is to */
+ /* implement optical scaling and similar features, which should be */
+ /* based on perceptual attributes, thus independent of the */
+ /* resolution. */
+ args[0] = exc->pointSize;
+ }
}
diff --git a/src/truetype/ttinterp.h b/src/truetype/ttinterp.h
index df7ce51..53f0944 100644
--- a/src/truetype/ttinterp.h
+++ b/src/truetype/ttinterp.h
@@ -170,6 +170,7 @@ FT_BEGIN_HEADER
pts,
twilight;
+ FT_Long pointSize; /* in 26.6 format */
FT_Size_Metrics metrics;
TT_Size_Metrics tt_metrics; /* size metrics */
diff --git a/src/truetype/ttobjs.h b/src/truetype/ttobjs.h
index ed61a7d..98ad383 100644
--- a/src/truetype/ttobjs.h
+++ b/src/truetype/ttobjs.h
@@ -286,6 +286,8 @@ FT_BEGIN_HEADER
#ifdef TT_USE_BYTECODE_INTERPRETER
+ FT_Long point_size; /* for the `MPS' bytecode instruction */
+
FT_UInt num_function_defs; /* number of function definitions */
FT_UInt max_function_defs;
TT_DefArray function_defs; /* table of function definitions */