[gtk+] snapshot: Fix graphene misunderstandings

[Benjamin Otte <otte src gnome org>]

commit 5dfe788e9e0ce5ba56d595aad45bc57193c08ec9
Author: Benjamin Otte <otte redhat com>
Date:   Thu Nov 17 01:05:15 2016 +0100

    snapshot: Fix graphene misunderstandings
    
    The equivalent to cairo_matrix_multiply (a, b, c) is
    graphene_matrix_multiply (c, b, a).
    
    graphene_matrix_multiply (a, b, c) may not be called with b and c being
    the same matrix.

 gtk/gtkrendericon.c |   36 ++++++++++++++++++------------------
 gtk/gtksnapshot.c   |    2 +-
 2 files changed, 19 insertions(+), 19 deletions(-)
---
diff --git a/gtk/gtkrendericon.c b/gtk/gtkrendericon.c
index 8ed65e0..a9dc20e 100644
--- a/gtk/gtkrendericon.c
+++ b/gtk/gtkrendericon.c
@@ -91,7 +91,7 @@ gtk_css_style_snapshot_icon (GtkCssStyle            *style,
 {
   const GtkCssValue *shadows, *transform;
   cairo_matrix_t transform_matrix;
-  graphene_matrix_t matrix, other, saved_matrix;
+  graphene_matrix_t m1, m2, m3, saved_matrix;
   GtkCssImage *image;
 
   g_return_if_fail (GTK_IS_CSS_STYLE (style));
@@ -110,14 +110,14 @@ gtk_css_style_snapshot_icon (GtkCssStyle            *style,
   graphene_matrix_init_from_matrix (&saved_matrix, gtk_snapshot_get_transform (snapshot));
 
   /* XXX: Implement -gtk-icon-transform-origin instead of hardcoding "50% 50%" here */
-  graphene_matrix_init_translate (&matrix, &(graphene_point3d_t)GRAPHENE_POINT3D_INIT(width / 2.0, height / 
2.0, 0));
-  graphene_matrix_init_from_2d (&other, transform_matrix.xx, transform_matrix.yx,
-                                        transform_matrix.xy, transform_matrix.yy,
-                                        transform_matrix.x0, transform_matrix.y0);
-  graphene_matrix_multiply (&other, &matrix, &matrix);
-  graphene_matrix_init_translate (&other, &(graphene_point3d_t)GRAPHENE_POINT3D_INIT(- width / 2.0, - height 
/ 2.0, 0));
-  graphene_matrix_multiply (&matrix, &other, &matrix);
-  gtk_snapshot_transform (snapshot, &matrix);
+  graphene_matrix_init_translate (&m1, &(graphene_point3d_t)GRAPHENE_POINT3D_INIT(width / 2.0, height / 2.0, 
0));
+  graphene_matrix_init_from_2d (&m2, transform_matrix.xx, transform_matrix.yx,
+                                     transform_matrix.xy, transform_matrix.yy,
+                                     transform_matrix.x0, transform_matrix.y0);
+  graphene_matrix_multiply (&m2, &m1, &m3);
+  graphene_matrix_init_translate (&m2, &(graphene_point3d_t)GRAPHENE_POINT3D_INIT(- width / 2.0, - height / 
2.0, 0));
+  graphene_matrix_multiply (&m2, &m3, &m1);
+  gtk_snapshot_transform (snapshot, &m1);
 
   if (!_gtk_css_shadows_value_is_none (shadows))
     {
@@ -276,7 +276,7 @@ gtk_css_style_snapshot_icon_texture (GtkCssStyle *style,
 {
   const GtkCssValue *shadows, *transform;
   cairo_matrix_t transform_matrix;
-  graphene_matrix_t matrix, other, saved_matrix;
+  graphene_matrix_t m1, m2, m3, saved_matrix;
   graphene_rect_t bounds;
   GskRenderNode *node;
   int width, height;
@@ -296,14 +296,14 @@ gtk_css_style_snapshot_icon_texture (GtkCssStyle *style,
   graphene_matrix_init_from_matrix (&saved_matrix, gtk_snapshot_get_transform (snapshot));
 
   /* XXX: Implement -gtk-icon-transform-origin instead of hardcoding "50% 50%" here */
-  graphene_matrix_init_translate (&matrix, &(graphene_point3d_t)GRAPHENE_POINT3D_INIT(width / 2.0, height / 
2.0, 0));
-  graphene_matrix_init_from_2d (&other, transform_matrix.xx, transform_matrix.yx,
-                                        transform_matrix.xy, transform_matrix.yy,
-                                        transform_matrix.x0, transform_matrix.y0);
-  graphene_matrix_multiply (&other, &matrix, &matrix);
-  graphene_matrix_init_translate (&other, &(graphene_point3d_t)GRAPHENE_POINT3D_INIT(- width / 2.0, - height 
/ 2.0, 0));
-  graphene_matrix_multiply (&matrix, &other, &matrix);
-  gtk_snapshot_transform (snapshot, &matrix);
+  graphene_matrix_init_translate (&m1, &(graphene_point3d_t)GRAPHENE_POINT3D_INIT(width / 2.0, height / 2.0, 
0));
+  graphene_matrix_init_from_2d (&m2, transform_matrix.xx, transform_matrix.yx,
+                                     transform_matrix.xy, transform_matrix.yy,
+                                     transform_matrix.x0, transform_matrix.y0);
+  graphene_matrix_multiply (&m2, &m1, &m3);
+  graphene_matrix_init_translate (&m2, &(graphene_point3d_t)GRAPHENE_POINT3D_INIT(- width / 2.0, - height / 
2.0, 0));
+  graphene_matrix_multiply (&m2, &m3, &m1);
+  gtk_snapshot_transform (snapshot, &m1);
 
   graphene_rect_init (&bounds, 0, 0, width, height);
 
diff --git a/gtk/gtksnapshot.c b/gtk/gtksnapshot.c
index 3f2fd4b..fe3500c 100644
--- a/gtk/gtksnapshot.c
+++ b/gtk/gtksnapshot.c
@@ -151,7 +151,7 @@ gtk_snapshot_transform (GtkSnapshot             *state,
 {
   graphene_matrix_t result;
 
-  graphene_matrix_multiply (&state->transform, transform, &result);
+  graphene_matrix_multiply (transform, &state->transform, &result);
   graphene_matrix_init_from_matrix (&state->transform, &result);
 }