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+/*
+ * Copyright © 2017 Google, Inc.
+ *
+ * This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_KERN_HH
+#define HB_KERN_HH
+
+#include "hb-open-type.hh"
+#include "hb-aat-layout-common.hh"
+#include "hb-ot-layout-gpos-table.hh"
+
+
+namespace OT {
+
+
+template <typename Driver>
+struct hb_kern_machine_t
+{
+ hb_kern_machine_t (const Driver &driver_,
+ bool crossStream_ = false) :
+ driver (driver_),
+ crossStream (crossStream_) {}
+
+ HB_NO_SANITIZE_SIGNED_INTEGER_OVERFLOW
+ void kern (hb_font_t *font,
+ hb_buffer_t *buffer,
+ hb_mask_t kern_mask,
+ bool scale = true) const
+ {
+ if (!buffer->message (font, "start kern"))
+ return;
+
+ buffer->unsafe_to_concat ();
+ OT::hb_ot_apply_context_t c (1, font, buffer);
+ c.set_lookup_mask (kern_mask);
+ c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
+ auto &skippy_iter = c.iter_input;
+
+ bool horizontal = HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction);
+ unsigned int count = buffer->len;
+ hb_glyph_info_t *info = buffer->info;
+ hb_glyph_position_t *pos = buffer->pos;
+ for (unsigned int idx = 0; idx < count;)
+ {
+ if (!(info[idx].mask & kern_mask))
+ {
+ idx++;
+ continue;
+ }
+
+ skippy_iter.reset (idx, 1);
+ unsigned unsafe_to;
+ if (!skippy_iter.next (&unsafe_to))
+ {
+ idx++;
+ continue;
+ }
+
+ unsigned int i = idx;
+ unsigned int j = skippy_iter.idx;
+
+ hb_position_t kern = driver.get_kerning (info[i].codepoint,
+ info[j].codepoint);
+
+
+ if (likely (!kern))
+ goto skip;
+
+ if (horizontal)
+ {
+ if (scale)
+ kern = font->em_scale_x (kern);
+ if (crossStream)
+ {
+ pos[j].y_offset = kern;
+ buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT;
+ }
+ else
+ {
+ hb_position_t kern1 = kern >> 1;
+ hb_position_t kern2 = kern - kern1;
+ pos[i].x_advance += kern1;
+ pos[j].x_advance += kern2;
+ pos[j].x_offset += kern2;
+ }
+ }
+ else
+ {
+ if (scale)
+ kern = font->em_scale_y (kern);
+ if (crossStream)
+ {
+ pos[j].x_offset = kern;
+ buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT;
+ }
+ else
+ {
+ hb_position_t kern1 = kern >> 1;
+ hb_position_t kern2 = kern - kern1;
+ pos[i].y_advance += kern1;
+ pos[j].y_advance += kern2;
+ pos[j].y_offset += kern2;
+ }
+ }
+
+ buffer->unsafe_to_break (i, j + 1);
+
+ skip:
+ idx = skippy_iter.idx;
+ }
+
+ (void) buffer->message (font, "end kern");
+ }
+
+ const Driver &driver;
+ bool crossStream;
+};
+
+
+} /* namespace OT */
+
+
+#endif /* HB_KERN_HH */