tdf#103403: Wrong glyph advances with Graphite

Patch sent upstream:
https://github.com/behdad/harfbuzz/pull/357

Change-Id: I245509d386e83970e4b08bd2a4b20a590303025a

2 files changed, 131 insertions, 0 deletions

diff --git a/external/harfbuzz/0001-graphite-Fix-shaping-with-varying-font-size.patch b/external/harfbuzz/0001-graphite-Fix-shaping-with-varying-font-size.patch
new file mode 100644
index 000000000000..f9e6afc1a37b
--- /dev/null
+++ b/external/harfbuzz/0001-graphite-Fix-shaping-with-varying-font-size.patch
@@ -0,0 +1,130 @@
+From 82f7be388090f19333876877366907fec09f0312 Mon Sep 17 00:00:00 2001
+From: Khaled Hosny <khaledhosny@eglug.org>
+Date: Sun, 30 Oct 2016 20:16:41 +0200
+Subject: [PATCH] [graphite] Fix shaping with varying font size
+
+See https://bugs.documentfoundation.org/show_bug.cgi?id=103403#c7
+---
+ src/hb-graphite2.cc | 40 ++++++++++++++++++++++++++++------------
+ 1 file changed, 28 insertions(+), 12 deletions(-)
+
+diff --git a/src/hb-graphite2.cc b/src/hb-graphite2.cc
+index c32318d..138a5ae 100644
+--- src/hb-graphite2.cc
++++ src/hb-graphite2.cc
+@@ -27,7 +27,6 @@
+  */
+ 
+ #define HB_SHAPER graphite2
+-#define hb_graphite2_shaper_font_data_t gr_font
+ #include "hb-shaper-impl-private.hh"
+ 
+ #include "hb-graphite2.h"
+@@ -55,6 +54,12 @@ struct hb_graphite2_shaper_face_data_t {
+   hb_graphite2_tablelist_t *tlist;
+ };
+ 
++struct hb_graphite2_shaper_font_data_t {
++  gr_font   *grfont;
++  int        xscale;
++  int        yscale;
++};
++
+ static const void *hb_graphite2_get_table (const void *data, unsigned int tag, size_t *len)
+ {
+   hb_graphite2_shaper_face_data_t *face_data = (hb_graphite2_shaper_face_data_t *) data;
+@@ -166,13 +171,20 @@ _hb_graphite2_shaper_font_data_create (hb_font_t *font)
+   hb_face_t *face = font->face;
+   hb_graphite2_shaper_face_data_t *face_data = HB_SHAPER_DATA_GET (face);
+ 
+-  return gr_make_font_with_advance_fn (font->x_scale, font, &hb_graphite2_get_advance, face_data->grface);
++  hb_graphite2_shaper_font_data_t *data = (hb_graphite2_shaper_font_data_t *) calloc (1, sizeof (hb_graphite2_shaper_font_data_t));
++  data->grfont = gr_make_font_with_advance_fn (font->x_scale, font, &hb_graphite2_get_advance, face_data->grface);
++  data->xscale = font->x_scale;
++  data->yscale = font->y_scale;
++
++  return data;
+ }
+ 
+ void
+ _hb_graphite2_shaper_font_data_destroy (hb_graphite2_shaper_font_data_t *data)
+ {
+-  gr_font_destroy (data);
++  gr_font_destroy (data->grfont);
++
++  free (data);
+ }
+ 
+ /*
+@@ -182,7 +194,7 @@ gr_font *
+ hb_graphite2_font_get_gr_font (hb_font_t *font)
+ {
+   if (unlikely (!hb_graphite2_shaper_font_data_ensure (font))) return NULL;
+-  return HB_SHAPER_DATA_GET (font);
++  return HB_SHAPER_DATA_GET (font)->grfont;
+ }
+ 
+ 
+@@ -228,7 +240,7 @@ _hb_graphite2_shape (hb_shape_plan_t    *shape_plan,
+ {
+   hb_face_t *face = font->face;
+   gr_face *grface = HB_SHAPER_DATA_GET (face)->grface;
+-  gr_font *grfont = HB_SHAPER_DATA_GET (font);
++  gr_font *grfont = HB_SHAPER_DATA_GET (font)->grfont;
+ 
+   const char *lang = hb_language_to_string (hb_buffer_get_language (buffer));
+   const char *lang_end = lang ? strchr (lang, '-') : NULL;
+@@ -371,7 +383,11 @@ _hb_graphite2_shape (hb_shape_plan_t    *shape_plan,
+   }
+   buffer->len = glyph_count;
+ 
+-  float yscale = font->y_scale / font->x_scale;
++  hb_graphite2_shaper_font_data_t* font_data = HB_SHAPER_DATA_GET (font);
++
++  float xscale = (float) font->x_scale / (float) font_data->xscale;
++  float yscale = (float) font->y_scale / (float) font_data->yscale;
++  yscale *= yscale / xscale;
+   /* Positioning. */
+   if (!HB_DIRECTION_IS_BACKWARD(buffer->props.direction))
+   {
+@@ -381,10 +397,10 @@ _hb_graphite2_shape (hb_shape_plan_t    *shape_plan,
+     curradvx = 0;
+     for (is = gr_seg_first_slot (seg); is; pPos++, ++info, is = gr_slot_next_in_segment (is))
+     {
+-      pPos->x_offset = gr_slot_origin_X (is) - curradvx;
++      pPos->x_offset = gr_slot_origin_X (is) * xscale - curradvx;
+       pPos->y_offset = gr_slot_origin_Y (is) * yscale - curradvy;
+       if (info->cluster != currclus) {
+-        pPos->x_advance = info->var1.i32;
++        pPos->x_advance = info->var1.i32 * xscale;
+         curradvx += pPos->x_advance;
+         currclus = info->cluster;
+       } else
+@@ -399,20 +415,20 @@ _hb_graphite2_shape (hb_shape_plan_t    *shape_plan,
+     int currclus = -1;
+     const hb_glyph_info_t *info = buffer->info;
+     hb_glyph_position_t *pPos = hb_buffer_get_glyph_positions (buffer, NULL);
+-    curradvx = gr_seg_advance_X(seg);
++    curradvx = gr_seg_advance_X(seg) * xscale;
+     for (is = gr_seg_first_slot (seg); is; pPos++, info++, is = gr_slot_next_in_segment (is))
+     {
+       if (info->cluster != currclus)
+       {
+-        pPos->x_advance = info->var1.i32;
+-        if (currclus != -1) curradvx -= info[-1].var1.i32;
++        pPos->x_advance = info->var1.i32 * xscale;
++        if (currclus != -1) curradvx -= info[-1].var1.i32 * xscale;
+         currclus = info->cluster;
+       } else
+       pPos->x_advance = 0.;
+ 
+       pPos->y_advance = gr_slot_advance_Y (is, grface, grfont) * yscale;
+       curradvy -= pPos->y_advance;
+-      pPos->x_offset = gr_slot_origin_X (is) - curradvx + pPos->x_advance;
++      pPos->x_offset = gr_slot_origin_X (is) * xscale - curradvx + pPos->x_advance;
+       pPos->y_offset = gr_slot_origin_Y (is) * yscale - curradvy;
+     }
+     hb_buffer_reverse_clusters (buffer);
+-- 
+2.10.1
+
diff --git a/external/harfbuzz/UnpackedTarball_harfbuzz.mk b/external/harfbuzz/UnpackedTarball_harfbuzz.mk
index 7d408d2a2348..ed4a12c8be46 100644
--- a/external/harfbuzz/UnpackedTarball_harfbuzz.mk
+++ b/external/harfbuzz/UnpackedTarball_harfbuzz.mk
@@ -16,6 +16,7 @@ $(eval $(call gb_UnpackedTarball_set_patchlevel,harfbuzz,0))
 $(eval $(call gb_UnpackedTarball_add_patches,harfbuzz, \
     external/harfbuzz/ubsan.patch \
     external/harfbuzz/clang-cl.patch \
+    external/harfbuzz/0001-graphite-Fix-shaping-with-varying-font-size.patch \
 ))
 
 ifneq ($(ENABLE_RUNTIME_OPTIMIZATIONS),TRUE)