debug: Split debugging notes from behavioural modifiers

Some of the ClutterDebugFlags are not meant as a logging facility: they
actually change Clutter's behaviour at run-time.

It would be useful to have this distinction ratified, and thus split
ClutterDebugFlags into two: one DebugFlags for logging facilities and
another set of flags for behavioural changes.

This split is warranted because:

  • it should be possible to do "CLUTTER_DEBUG=all" and only have
    log messages on the output

  • it should be possible to use behavioural modifiers even on a
    Clutter that has been compiled without debugging messages
    support

The commit adds two new debugging flags:

  ClutterPickDebugFlags - controlled by the CLUTTER_PICK environment
                          variable

  ClutterPaintDebugFlags - controlled by the CLUTTER_PAINT environment
                           variable

The PickDebugFlags are:

  nop-picking
  dump-pick-buffers

While the PaintDebugFlags is:

  disable-swap-events

The mechanism is equivalent to the CLUTTER_DEBUG environment variable,
but it does not depend on the debug level selected when configuring and
compiling Clutter. The picking and painting debugging flags are
initialized at clutter_init() time.

http://bugzilla.openedhand.com/show_bug.cgi?id=1991

clutter/clutter-debug.h

@@ -23,11 +23,17 @@ typedef enum {
   CLUTTER_DEBUG_MULTISTAGE          = 1 << 13,
   CLUTTER_DEBUG_ANIMATION           = 1 << 14,
   CLUTTER_DEBUG_LAYOUT              = 1 << 15,
-  CLUTTER_DEBUG_NOP_PICKING         = 1 << 16,
-  CLUTTER_DEBUG_DUMP_PICK_BUFFERS   = 1 << 17,
-  CLUTTER_DEBUG_DISABLE_SWAP_EVENTS = 1 << 18,
 } ClutterDebugFlag;
 
+typedef enum {
+  CLUTTER_DEBUG_NOP_PICKING         = 1 << 0,
+  CLUTTER_DEBUG_DUMP_PICK_BUFFERS   = 1 << 1
+} ClutterPickDebugFlag;
+
+typedef enum {
+  CLUTTER_DEBUG_DISABLE_SWAP_EVENTS = 1 << 0
+} ClutterDrawDebugFlag;
+
 #ifdef CLUTTER_ENABLE_DEBUG
 
 #ifdef __GNUC__
@@ -88,6 +94,8 @@ typedef enum {
 #endif /* CLUTTER_ENABLE_DEBUG */
 
 extern guint clutter_debug_flags;
+extern guint clutter_pick_debug_flags;
+extern guint clutter_paint_debug_flags;
 
 G_END_DECLS