[gtk+] snapshot: Fix blend mode handling

[Matthias Clasen <matthiasc src gnome org>]

commit f597de817ead93c78a7ea110a7a22493fa13c067
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Oct 7 23:31:47 2017 -0400

    snapshot: Fix blend mode handling
    
    We were getting out states confused and were always creating
    a blend mode node with mode NORMAL.

 gtk/gtksnapshot.c |   27 +++++++++++++--------------
 1 files changed, 13 insertions(+), 14 deletions(-)
---
diff --git a/gtk/gtksnapshot.c b/gtk/gtksnapshot.c
index d846d7b..a9a428d 100644
--- a/gtk/gtksnapshot.c
+++ b/gtk/gtksnapshot.c
@@ -772,7 +772,7 @@ gtk_snapshot_collect_blend_bottom (GtkSnapshot      *snapshot,
                                    guint             n_nodes,
                                    const char       *name)
 {
-  GtkSnapshotState *prev_state = gtk_snapshot_get_current_state (snapshot);
+  GtkSnapshotState *prev_state = gtk_snapshot_get_previous_state (snapshot);
 
   g_assert (prev_state->collect_func == gtk_snapshot_collect_blend_top);
 
@@ -803,7 +803,6 @@ gtk_snapshot_push_blend (GtkSnapshot  *snapshot,
                          ...)
 {
   GtkSnapshotState *current_state = gtk_snapshot_get_current_state (snapshot);
-  GtkSnapshotState *bottom_state;
   GtkSnapshotState *top_state;
   char *str;
 
@@ -818,19 +817,19 @@ gtk_snapshot_push_blend (GtkSnapshot  *snapshot,
   else
     str = NULL;
 
-  bottom_state = gtk_snapshot_push_state (snapshot,
-                                          str,
-                                          current_state->clip_region,
-                                          current_state->translate_x,
-                                          current_state->translate_y,
-                                          gtk_snapshot_collect_blend_top);
-
   top_state = gtk_snapshot_push_state (snapshot,
-                                       g_strdup (str),
-                                       bottom_state->clip_region,
-                                       bottom_state->translate_x,
-                                       bottom_state->translate_y,
-                                       gtk_snapshot_collect_blend_bottom);
+                                       str,
+                                       current_state->clip_region,
+                                       current_state->translate_x,
+                                       current_state->translate_y,
+                                       gtk_snapshot_collect_blend_top);
+
+  gtk_snapshot_push_state (snapshot,
+                           g_strdup (str),
+                           top_state->clip_region,
+                           top_state->translate_x,
+                           top_state->translate_y,
+                           gtk_snapshot_collect_blend_bottom);
   top_state->data.blend.blend_mode = blend_mode;
 }