/* Font backend for the Microsoft W32 Uniscribe API.
- Copyright (C) 2008-2011 Free Software Foundation, Inc.
+ Copyright (C) 2008-2012 Free Software Foundation, Inc.
This file is part of GNU Emacs.
/* First we need to break up the glyph string into runs of glyphs that
can be treated together. First try a single run. */
max_items = 2;
- items = (SCRIPT_ITEM *) xmalloc (sizeof (SCRIPT_ITEM) * max_items + 1);
+ items = xmalloc (sizeof (SCRIPT_ITEM) * max_items + 1);
while ((result = ScriptItemize (chars, nchars, max_items, NULL, NULL,
items, &nitems)) == E_OUTOFMEMORY)
}
if (SUCCEEDED (result))
{
- int j, from, to;
+ int j, from, to, adj_offset = 0;
+
+ /* For RTL text, the Uniscribe shaper prepares the
+ values in ADVANCES array for layout in reverse order,
+ whereby "advance width" is applied to move the pen in
+ reverse direction and _before_ drawing the glyph.
+ Since we draw glyphs in their normal left-to-right
+ order, we need to adjust the coordinates of each
+ non-base glyph in a grapheme cluster via X-OFF
+ component of the gstring's ADJUSTMENT sub-vector.
+ This loop computes the initial value of the
+ adjustment for the base character, which is then
+ updated for each successive glyph in the grapheme
+ cluster. */
+ if (items[i].a.fRTL)
+ for (j = 1; j < nglyphs; j++)
+ adj_offset += advances[j];
from = 0;
to = from;
if (SUCCEEDED (result))
{
- LGLYPH_SET_LBEARING (lglyph, char_metric.abcA);
- LGLYPH_SET_RBEARING (lglyph, (char_metric.abcA
- + char_metric.abcB));
+ int lbearing = char_metric.abcA;
+ int rbearing = char_metric.abcA + char_metric.abcB;
+
+ LGLYPH_SET_LBEARING (lglyph, lbearing);
+ LGLYPH_SET_RBEARING (lglyph, rbearing);
}
else
{
LGLYPH_SET_RBEARING (lglyph, advances[j]);
}
- if (offsets[j].du || offsets[j].dv)
+ if (offsets[j].du || offsets[j].dv
+ /* For non-base glyphs of RTL grapheme clusters,
+ adjust the X offset even if both DU and DV
+ are zero. */
+ || (!attributes[j].fClusterStart && items[i].a.fRTL))
{
Lisp_Object vec;
vec = Fmake_vector (make_number (3), Qnil);
- ASET (vec, 0, make_number (offsets[j].du));
+ if (items[i].a.fRTL)
+ {
+ /* Empirically, it looks like Uniscribe
+ interprets DU in reverse direction for
+ RTL clusters. E.g., if we don't reverse
+ the direction, the Hebrew point HOLAM is
+ drawn above the right edge of the base
+ consonant, instead of above the left edge. */
+ ASET (vec, 0, make_number (-offsets[j].du
+ + adj_offset));
+ /* Update the adjustment value for the width
+ advance of the glyph we just emitted. */
+ adj_offset -= 2 * advances[j];
+ }
+ else
+ ASET (vec, 0, make_number (offsets[j].du + adj_offset));
ASET (vec, 1, make_number (offsets[j].dv));
/* Based on what ftfont.c does... */
ASET (vec, 2, make_number (advances[j]));
LGLYPH_SET_ADJUSTMENT (lglyph, vec);
}
else
- LGLYPH_SET_ADJUSTMENT (lglyph, Qnil);
+ {
+ LGLYPH_SET_ADJUSTMENT (lglyph, Qnil);
+ /* Update the adjustment value to compensate for
+ the width of the base character. */
+ if (items[i].a.fRTL)
+ adj_offset -= advances[j];
+ }
}
}
}