From 23461b75020164252d6af018fa08e6e3e3907b8b Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 19 Aug 2022 09:48:12 -0600
Subject: [PATCH] [hb-ft] Only apply FT_Face's transform if we created FT_Face

Fixes https://github.com/harfbuzz/harfbuzz/issues/3788

https://github.com/harfbuzz/harfbuzz/issues/3790
---
 src/hb-ft.cc | 95 +++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 65 insertions(+), 30 deletions(-)

diff --git a/src/hb-ft.cc b/src/hb-ft.cc
index b9edcdc14..bcc1dd080 100644
--- a/src/hb-ft.cc
+++ b/src/hb-ft.cc
@@ -87,6 +87,7 @@ struct hb_ft_font_t
   int load_flags;
   bool symbol; /* Whether selected cmap is symbol cmap. */
   bool unref; /* Whether to destroy ft_face when done. */
+  bool transform; /* Whether to apply FT_Face's transform. */
 
   mutable hb_mutex_t lock;
   FT_Face ft_face;
@@ -138,6 +139,8 @@ _hb_ft_font_destroy (void *data)
 /* hb_font changed, update FT_Face. */
 static void _hb_ft_hb_font_changed (hb_font_t *font, FT_Face ft_face)
 {
+  hb_ft_font_t *ft_font = (hb_ft_font_t *) font->user_data;
+
   float x_mult = 1.f, y_mult = 1.f;
 
   if (font->x_scale < 0) x_mult = -x_mult;
@@ -175,6 +178,7 @@ static void _hb_ft_hb_font_changed (hb_font_t *font, FT_Face ft_face)
     FT_Matrix matrix = { (int) roundf (x_mult * (1<<16)), 0,
 			  0, (int) roundf (y_mult * (1<<16))};
     FT_Set_Transform (ft_face, &matrix, nullptr);
+    ft_font->transform = true;
   }
 
 #if defined(HAVE_FT_GET_VAR_BLEND_COORDINATES) && !defined(HB_NO_VAR)
@@ -430,13 +434,19 @@ hb_ft_get_glyph_h_advances (hb_font_t* font, void* font_data,
   hb_lock_t lock (ft_font->lock);
   FT_Face ft_face = ft_font->ft_face;
   int load_flags = ft_font->load_flags;
+  float x_mult;
 #ifdef HAVE_FT_GET_TRANSFORM
-  FT_Matrix matrix;
-  FT_Get_Transform (ft_face, &matrix, nullptr);
-  float x_mult = sqrtf ((float)matrix.xx * matrix.xx + (float)matrix.xy * matrix.xy) / 65536.f;
-#else
-  float x_mult = font->x_scale < 0 ? -1 : +1;
+  if (ft_font->transform)
+  {
+    FT_Matrix matrix;
+    FT_Get_Transform (ft_face, &matrix, nullptr);
+    x_mult = sqrtf ((float)matrix.xx * matrix.xx + (float)matrix.xy * matrix.xy) / 65536.f;
+  }
+  else
 #endif
+  {
+    x_mult = font->x_scale < 0 ? -1 : +1;
+  }
 
   for (unsigned int i = 0; i < count; i++)
   {
@@ -468,13 +478,19 @@ hb_ft_get_glyph_v_advance (hb_font_t *font,
   const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
   hb_lock_t lock (ft_font->lock);
   FT_Fixed v;
+  float y_mult;
 #ifdef HAVE_FT_GET_TRANSFORM
-  FT_Matrix matrix;
-  FT_Get_Transform (ft_font->ft_face, &matrix, nullptr);
-  float y_mult = sqrtf ((float)matrix.yx * matrix.yx + (float)matrix.yy * matrix.yy) / 65536.f;
-#else
-  float y_mult = font->y_scale < 0 ? -1 : +1;
+  if (ft_font->transform)
+  {
+    FT_Matrix matrix;
+    FT_Get_Transform (ft_font->ft_face, &matrix, nullptr);
+    y_mult = sqrtf ((float)matrix.yx * matrix.yx + (float)matrix.yy * matrix.yy) / 65536.f;
+  }
+  else
 #endif
+  {
+    y_mult = font->y_scale < 0 ? -1 : +1;
+  }
 
   if (unlikely (FT_Get_Advance (ft_font->ft_face, glyph, ft_font->load_flags | FT_LOAD_VERTICAL_LAYOUT, &v)))
     return 0;
@@ -500,15 +516,21 @@ hb_ft_get_glyph_v_origin (hb_font_t *font,
   const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
   hb_lock_t lock (ft_font->lock);
   FT_Face ft_face = ft_font->ft_face;
+  float x_mult, y_mult;
 #ifdef HAVE_FT_GET_TRANSFORM
-  FT_Matrix matrix;
-  FT_Get_Transform (ft_face, &matrix, nullptr);
-  float x_mult = sqrtf ((float)matrix.xx * matrix.xx + (float)matrix.xy * matrix.xy) / 65536.f;
-  float y_mult = sqrtf ((float)matrix.yx * matrix.yx + (float)matrix.yy * matrix.yy) / 65536.f;
-#else
-  float x_mult = font->x_scale < 0 ? -1 : +1;
-  float y_mult = font->y_scale < 0 ? -1 : +1;
+  if (ft_font->transform)
+  {
+    FT_Matrix matrix;
+    FT_Get_Transform (ft_face, &matrix, nullptr);
+    x_mult = sqrtf ((float)matrix.xx * matrix.xx + (float)matrix.xy * matrix.xy) / 65536.f;
+    y_mult = sqrtf ((float)matrix.yx * matrix.yx + (float)matrix.yy * matrix.yy) / 65536.f;
+  }
+  else
 #endif
+  {
+    x_mult = font->x_scale < 0 ? -1 : +1;
+    y_mult = font->y_scale < 0 ? -1 : +1;
+  }
 
   if (unlikely (FT_Load_Glyph (ft_face, glyph, ft_font->load_flags)))
     return false;
@@ -555,15 +577,21 @@ hb_ft_get_glyph_extents (hb_font_t *font,
   const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
   hb_lock_t lock (ft_font->lock);
   FT_Face ft_face = ft_font->ft_face;
+  float x_mult, y_mult;
 #ifdef HAVE_FT_GET_TRANSFORM
-  FT_Matrix matrix;
-  FT_Get_Transform (ft_face, &matrix, nullptr);
-  float x_mult = sqrtf ((float)matrix.xx * matrix.xx + (float)matrix.xy * matrix.xy) / 65536.f;
-  float y_mult = sqrtf ((float)matrix.yx * matrix.yx + (float)matrix.yy * matrix.yy) / 65536.f;
-#else
-  float x_mult = font->x_scale < 0 ? -1 : +1;
-  float y_mult = font->y_scale < 0 ? -1 : +1;
+  if (ft_font->transform)
+  {
+    FT_Matrix matrix;
+    FT_Get_Transform (ft_face, &matrix, nullptr);
+    x_mult = sqrtf ((float)matrix.xx * matrix.xx + (float)matrix.xy * matrix.xy) / 65536.f;
+    y_mult = sqrtf ((float)matrix.yx * matrix.yx + (float)matrix.yy * matrix.yy) / 65536.f;
+  }
+  else
 #endif
+  {
+    x_mult = font->x_scale < 0 ? -1 : +1;
+    y_mult = font->y_scale < 0 ? -1 : +1;
+  }
 
   if (unlikely (FT_Load_Glyph (ft_face, glyph, ft_font->load_flags)))
     return false;
@@ -665,13 +693,19 @@ hb_ft_get_font_h_extents (hb_font_t *font HB_UNUSED,
   const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
   hb_lock_t lock (ft_font->lock);
   FT_Face ft_face = ft_font->ft_face;
+  float y_mult;
 #ifdef HAVE_FT_GET_TRANSFORM
-  FT_Matrix matrix;
-  FT_Get_Transform (ft_face, &matrix, nullptr);
-  float y_mult = sqrtf ((float)matrix.yx * matrix.yx + (float)matrix.yy * matrix.yy) / 65536.f;
-#else
-  float y_mult = font->y_scale < 0 ? -1 : +1;
+  if (ft_font->transform)
+  {
+    FT_Matrix matrix;
+    FT_Get_Transform (ft_face, &matrix, nullptr);
+    y_mult = sqrtf ((float)matrix.yx * matrix.yx + (float)matrix.yy * matrix.yy) / 65536.f;
+  }
+  else
 #endif
+  {
+    y_mult = font->y_scale < 0 ? -1 : +1;
+  }
 
   if (ft_face->units_per_EM != 0)
   {
@@ -1235,13 +1269,14 @@ hb_ft_font_set_funcs (hb_font_t *font)
   if (FT_Select_Charmap (ft_face, FT_ENCODING_MS_SYMBOL))
     FT_Select_Charmap (ft_face, FT_ENCODING_UNICODE);
 
-  _hb_ft_hb_font_changed (font, ft_face);
 
   ft_face->generic.data = blob;
   ft_face->generic.finalizer = (FT_Generic_Finalizer) _release_blob;
 
   _hb_ft_font_set_funcs (font, ft_face, true);
   hb_ft_font_set_load_flags (font, FT_LOAD_DEFAULT | FT_LOAD_NO_HINTING);
+
+  _hb_ft_hb_font_changed (font, ft_face);
 }