From c4fe95cc313bab3eac480425f822a0eeebf9b686 Mon Sep 17 00:00:00 2001
From: Matthias Clasen <mclasen@redhat.com>
Date: Wed, 24 Nov 2021 12:19:42 -0500
Subject: Add a way to get the font matrix

Add some private api for the serializer to get
the font matrix. This is needed to let the serializer
write a unique fingerprint for the font.
---
 pango/fonts.c              | 17 +++++++++++++++++
 pango/pango-font-private.h |  5 +++++
 pango/pangofc-font.c       | 22 ++++++++++++++++++++++
 3 files changed, 44 insertions(+)

diff --git a/pango/fonts.c b/pango/fonts.c
index 9d3c1bf3..d94feaf8 100644
--- a/pango/fonts.c
+++ b/pango/fonts.c
@@ -1751,6 +1751,13 @@ pango_font_default_get_face (PangoFont *font)
   return PANGO_FONT_MAP_GET_CLASS (map)->get_face (map,font);
 }
 
+static void
+pango_font_default_get_matrix (PangoFont   *font,
+                               PangoMatrix *matrix)
+{
+  *matrix = (PangoMatrix) PANGO_MATRIX_INIT;
+}
+
 static void
 pango_font_class_init (PangoFontClass *class G_GNUC_UNUSED)
 {
@@ -1766,6 +1773,7 @@ pango_font_class_init (PangoFontClass *class G_GNUC_UNUSED)
   pclass->get_scale_factors = pango_font_default_get_scale_factors;
   pclass->has_char = pango_font_default_has_char;
   pclass->get_face = pango_font_default_get_face;
+  pclass->get_matrix = pango_font_default_get_matrix;
 }
 
 static void
@@ -2717,6 +2725,15 @@ pango_font_get_languages (PangoFont *font)
   return pclass->get_languages (font);
 }
 
+void
+pango_font_get_matrix (PangoFont   *font,
+                       PangoMatrix *matrix)
+{
+  PangoFontClassPrivate *pclass = PANGO_FONT_GET_CLASS_PRIVATE (font);
+
+  pclass->get_matrix (font, matrix);
+}
+
 gboolean
 pango_font_is_hinted (PangoFont *font)
 {
diff --git a/pango/pango-font-private.h b/pango/pango-font-private.h
index 93ce27aa..1e38371d 100644
--- a/pango/pango-font-private.h
+++ b/pango/pango-font-private.h
@@ -45,12 +45,17 @@ typedef struct {
   gboolean         (* has_char) (PangoFont *font,
                                  gunichar   wc);
   PangoFontFace *  (* get_face) (PangoFont *font);
+  void             (* get_matrix) (PangoFont   *font,
+                                   PangoMatrix *matrix);
 } PangoFontClassPrivate;
 
 gboolean pango_font_is_hinted         (PangoFont *font);
 void     pango_font_get_scale_factors (PangoFont *font,
                                        double    *x_scale,
                                        double    *y_scale);
+void     pango_font_get_matrix        (PangoFont   *font,
+                                       PangoMatrix *matrix);
+
 
 G_END_DECLS
 
diff --git a/pango/pangofc-font.c b/pango/pangofc-font.c
index 74503b91..5635e0be 100644
--- a/pango/pangofc-font.c
+++ b/pango/pangofc-font.c
@@ -75,6 +75,8 @@ static gboolean             _pango_fc_font_is_hinted      (PangoFont        *fon
 static void                 _pango_fc_font_get_scale_factors (PangoFont     *font,
                                                               double        *x_scale,
                                                               double        *y_scale);
+static void                 pango_fc_font_get_matrix      (PangoFont        *font,
+                                                           PangoMatrix      *matrix);
 
 #define PANGO_FC_FONT_LOCK_FACE(font)	(PANGO_FC_FONT_GET_CLASS (font)->lock_face (font))
 #define PANGO_FC_FONT_UNLOCK_FACE(font)	(PANGO_FC_FONT_GET_CLASS (font)->unlock_face (font))
@@ -109,6 +111,7 @@ pango_fc_font_class_init (PangoFcFontClass *class)
   pclass->get_languages = _pango_fc_font_get_languages;
   pclass->is_hinted = _pango_fc_font_is_hinted;
   pclass->get_scale_factors = _pango_fc_font_get_scale_factors;
+  pclass->get_matrix = pango_fc_font_get_matrix;
 
   /**
    * PangoFcFont:pattern:
@@ -1110,3 +1113,22 @@ _pango_fc_font_get_scale_factors (PangoFont *font,
 
   pango_matrix_get_font_scale_factors (&fcfont->matrix, x_scale, y_scale);
 }
+
+static void
+pango_fc_font_get_matrix (PangoFont   *font,
+                          PangoMatrix *matrix)
+{
+  PangoFcFont *fcfont = PANGO_FC_FONT (font);
+  FcMatrix fc_matrix, *fc_matrix_val;
+
+  FcMatrixInit (&fc_matrix);
+  for (int i = 0; FcPatternGetMatrix (fcfont->font_pattern, FC_MATRIX, i, &fc_matrix_val) == FcResultMatch; i++)
+    FcMatrixMultiply (&fc_matrix, &fc_matrix, fc_matrix_val);
+
+  matrix->xx = fc_matrix.xx;
+  matrix->xy = - fc_matrix.xy;
+  matrix->yx = - fc_matrix.yx;
+  matrix->yy = fc_matrix.yy;
+  matrix->x0 = 0.;
+  matrix->y0 = 0.;
+}
-- 
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