debug: Add GTK_DEBUG=no-css-cache

See inline comments for what it does. Its main use is figuring out if
something has been caused by GTK's caching of CSS properties or if it's
a different problem.

4 files changed, 27 insertions, 1 deletions

diff --git a/docs/reference/gtk/running.sgml b/docs/reference/gtk/running.sgml
index fe91aead74..3e4966af0e 100644
--- a/docs/reference/gtk/running.sgml
+++ b/docs/reference/gtk/running.sgml
@@ -186,6 +186,14 @@ additional environment variables.
       <term>builder</term>
       <listitem><para>GtkBuilder support</para></listitem>
     </varlistentry>
+    <varlistentry>
+      <term>size-request</term>
+      <listitem><para>Size requests</para></listitem>
+    </varlistentry>
+    <varlistentry>
+      <term>no-css-cache</term>
+      <listitem><para>Bypass caching for CSS style properties.</para></listitem>
+    </varlistentry>
 
   </variablelist>
   The special value <literal>all</literal> can be used to turn on all
diff --git a/gtk/gtkdebug.h b/gtk/gtkdebug.h
index b1eb70a020..1eed41a2b9 100644
--- a/gtk/gtkdebug.h
+++ b/gtk/gtkdebug.h
@@ -46,7 +46,8 @@ typedef enum {
   GTK_DEBUG_ICONTHEME       = 1 << 9,
   GTK_DEBUG_PRINTING        = 1 << 10,
   GTK_DEBUG_BUILDER         = 1 << 11,
-  GTK_DEBUG_SIZE_REQUEST    = 1 << 12
+  GTK_DEBUG_SIZE_REQUEST    = 1 << 12,
+  GTK_DEBUG_NO_CSS_CACHE    = 1 << 13
 } GtkDebugFlag;
 
 #ifdef G_ENABLE_DEBUG
diff --git a/gtk/gtkmain.c b/gtk/gtkmain.c
index 65df934ccb..c9f91736b7 100644
--- a/gtk/gtkmain.c
+++ b/gtk/gtkmain.c
@@ -172,6 +172,7 @@ static const GDebugKey gtk_debug_keys[] = {
   {"printing", GTK_DEBUG_PRINTING},
   {"builder", GTK_DEBUG_BUILDER},
   {"size-request", GTK_DEBUG_SIZE_REQUEST},
+  {"no-css-cache", GTK_DEBUG_NO_CSS_CACHE}
 };
 #endif /* G_ENABLE_DEBUG */
 
diff --git a/gtk/gtkstylecontext.c b/gtk/gtkstylecontext.c
index 5fd398eaa9..ece1b8db0a 100644
--- a/gtk/gtkstylecontext.c
+++ b/gtk/gtkstylecontext.c
@@ -28,6 +28,7 @@
 #include "gtkcssenginevalueprivate.h"
 #include "gtkcssnumbervalueprivate.h"
 #include "gtkcssrgbavalueprivate.h"
+#include "gtkdebug.h"
 #include "gtkstylepropertiesprivate.h"
 #include "gtktypebuiltins.h"
 #include "gtkthemingengineprivate.h"
@@ -3041,6 +3042,21 @@ _gtk_style_context_validate (GtkStyleContext *context,
   priv = context->priv;
 
   change |= priv->pending_changes;
+  
+  /* If you run your application with
+   *   GTK_DEBUG=no-css-cache
+   * every invalidation will purge the cache and completely query
+   * everything anew form the cache. This is slow (in particular
+   * when animating), but useful for figuring out bugs.
+   *
+   * We achieve that by pretending that everything that could have
+   * changed has and so we of course totally need to redo everything.
+   *
+   * Note that this also completely revalidates child widgets all
+   * the time.
+   */
+  if (G_UNLIKELY (gtk_get_debug_flags () & GTK_DEBUG_NO_CSS_CACHE))
+    change = GTK_CSS_CHANGE_ANY;
 
   if (!priv->invalid && change == 0)
     return;