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