[gimp] Issue #3142 - Filters on-canvas preview doesn't work ...

[Ell <ell src gnome org>]

commit 106df3b794cfb52e3ac5e716e462427a4fae5507
Author: Ell <ell_se yahoo com>
Date:   Sun Mar 24 03:06:19 2019 -0400

    Issue #3142 - Filters on-canvas preview doesn't work ...
    
    ... immediately after an image precision change
    
    When flushing a projection, make sure it has a buffer, instead of
    bailing if it doesn't.  We rely on the image projection's "update"
    signal to update the display after certain operations that free the
    buffer, which would previously fail to happen, and cause subsequent
    flushes to be ignored until the buffer is explicitly accessed.
    
    This fixes commit b07f8102738d8225c1e77e6b4f68ae12468d8a2b.

 app/core/gimpprojection.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/app/core/gimpprojection.c b/app/core/gimpprojection.c
index 103f9adb02..873393ede7 100644
--- a/app/core/gimpprojection.c
+++ b/app/core/gimpprojection.c
@@ -662,11 +662,11 @@ gimp_projection_flush_whenever (GimpProjection *proj,
                                 gboolean        now,
                                 gboolean        direct)
 {
-  if (! proj->priv->buffer)
-    return;
-
   if (proj->priv->update_region)
     {
+      /* Make sure we have a buffer */
+      gimp_projection_allocate_buffer (proj);
+
       if (now)  /* Synchronous */
         {
           gint n_rects = cairo_region_num_rectangles (proj->priv->update_region);