[mutter/gbsneto/graphene-matrix: 13/71] cogl/matrix: Add cogl_matrix_get_value

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit b9c2ab4b1949e31e19ff6166a8e2042eaecbe1eb
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Wed Sep 9 22:15:35 2020 -0300

    cogl/matrix: Add cogl_matrix_get_value
    
    This will allow us stop accessing members of the structure
    directly. Also mark all struct members as private.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1439

 cogl/cogl/cogl-matrix.c |  8 ++++++++
 cogl/cogl/cogl-matrix.h | 15 +++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)
---
diff --git a/cogl/cogl/cogl-matrix.c b/cogl/cogl/cogl-matrix.c
index 17ee499dde..9e4e52de9a 100644
--- a/cogl/cogl/cogl-matrix.c
+++ b/cogl/cogl/cogl-matrix.c
@@ -1941,6 +1941,14 @@ cogl_matrix_get_array (const CoglMatrix *matrix)
   return (float *)matrix;
 }
 
+float
+cogl_matrix_get_value (const CoglMatrix *matrix,
+                       unsigned int      row,
+                       unsigned int      column)
+{
+  return MAT ((float *)matrix, row, column);
+}
+
 void
 cogl_matrix_transform_point (const CoglMatrix *matrix,
                              float *x,
diff --git a/cogl/cogl/cogl-matrix.h b/cogl/cogl/cogl-matrix.h
index 4b5eef699f..03dd3e3fae 100644
--- a/cogl/cogl/cogl-matrix.h
+++ b/cogl/cogl/cogl-matrix.h
@@ -86,6 +86,8 @@ G_BEGIN_DECLS
  */
 struct _CoglMatrix
 {
+  /*< private >*/
+
   /* column 0 */
   float xx;
   float yx;
@@ -110,8 +112,6 @@ struct _CoglMatrix
   float zw;
   float ww;
 
-  /*< private >*/
-
   /* Note: we may want to extend this later with private flags
    * and a cache of the inverse transform matrix. */
   float          COGL_PRIVATE (inv)[16];
@@ -491,6 +491,17 @@ cogl_matrix_init_from_matrix (CoglMatrix       *matrix,
 COGL_EXPORT const float *
 cogl_matrix_get_array (const CoglMatrix *matrix);
 
+/**
+ * cogl_matrix_get_value:
+ * @matrix: A 4x4 transformation matrix
+ *
+ *
+ */
+COGL_EXPORT float
+cogl_matrix_get_value (const CoglMatrix *matrix,
+                       unsigned int      row,
+                       unsigned int      column);
+
 /**
  * cogl_matrix_init_from_euler:
  * @matrix: A 4x4 transformation matrix