From 865564b32f2e3ff951d6634984dbb3185d416f26 Mon Sep 17 00:00:00 2001
From: Matthias Clasen <mclasen@redhat.com>
Date: Sun, 11 Feb 2024 19:28:43 -0500
Subject: [PATCH] gsk: Make matrix transforms roundtrip better

When we parse a 2D matrix, we produce a 2D transform, and we
can easily regenerate a 2D matrix from it.

Tests included.
---
 gsk/gsktransform.c        | 34 +++++++++++++++++++++++++++-------
 testsuite/gsk/transform.c | 28 ++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 7 deletions(-)

diff --git a/gsk/gsktransform.c b/gsk/gsktransform.c
index ada7164e37..4ab9e9dc79 100644
--- a/gsk/gsktransform.c
+++ b/gsk/gsktransform.c
@@ -382,15 +382,35 @@ gsk_matrix_transform_print (GskTransform *transform,
   guint i;
   float f[16];
 
-  g_string_append (string, "matrix3d(");
-  graphene_matrix_to_float (&self->matrix, f);
-  for (i = 0; i < 16; i++)
+  if (transform->category >= GSK_TRANSFORM_CATEGORY_2D)
     {
-      if (i > 0)
-        g_string_append (string, ", ");
-      string_append_double (string, f[i]);
+      g_string_append (string, "matrix(");
+      graphene_matrix_to_float (&self->matrix, f);
+      string_append_double (string, f[0]);
+      g_string_append (string, ", ");
+      string_append_double (string, f[1]);
+      g_string_append (string, ", ");
+      string_append_double (string, f[4]);
+      g_string_append (string, ", ");
+      string_append_double (string, f[5]);
+      g_string_append (string, ", ");
+      string_append_double (string, f[12]);
+      g_string_append (string, ", ");
+      string_append_double (string, f[13]);
+      g_string_append (string, ")");
+    }
+  else
+    {
+      g_string_append (string, "matrix3d(");
+      graphene_matrix_to_float (&self->matrix, f);
+      for (i = 0; i < 16; i++)
+        {
+          if (i > 0)
+            g_string_append (string, ", ");
+          string_append_double (string, f[i]);
+        }
+      g_string_append (string, ")");
     }
-  g_string_append (string, ")");
 }
 
 static GskTransform *
diff --git a/testsuite/gsk/transform.c b/testsuite/gsk/transform.c
index 01220a2b2f..7075ce9533 100644
--- a/testsuite/gsk/transform.c
+++ b/testsuite/gsk/transform.c
@@ -967,6 +967,33 @@ test_matrix_transform (void)
   gsk_transform_unref (t2);
 }
 
+static void
+test_matrix_roundtrip (void)
+{
+  GskTransform *transform;
+  gboolean res;
+  const char *input;
+  char *str;
+
+  input = "matrix(2, 3, 4, 5, 6, 7)";
+  res = gsk_transform_parse (input, &transform);
+  g_assert_true (res);
+  g_assert_true (gsk_transform_get_category (transform) >= GSK_TRANSFORM_CATEGORY_2D);
+
+  str = gsk_transform_to_string (transform);
+  g_assert_cmpstr (str, ==, input);
+  g_free (str);
+
+  input = "matrix3d(2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)";
+  res = gsk_transform_parse (input, &transform);
+  g_assert_true (res);
+  g_assert_true (gsk_transform_get_category (transform) < GSK_TRANSFORM_CATEGORY_2D);
+
+  str = gsk_transform_to_string (transform);
+  g_assert_cmpstr (str, ==, input);
+  g_free (str);
+}
+
 int
 main (int   argc,
       char *argv[])
@@ -991,6 +1018,7 @@ main (int   argc,
   g_test_add_func ("/transform/rotate", test_rotate_transform);
   g_test_add_func ("/transform/rotate3d", test_rotate3d_transform);
   g_test_add_func ("/transform/matrix", test_matrix_transform);
+  g_test_add_func ("/transform/matrix/roundtrip", test_matrix_roundtrip);
 
   return g_test_run ();
 }