cogl/snippet: Add way to add an opaque capability

A snippet is assigned a capability, which is then transferred to the
pipeline it gets added to. Managers of pipelines can then check whether
a pipeline it got handed whether it has a certain capability, and if
not, handle the situation where it is not.

The intention is to allow Clutter to tag color state transformation
snippets with a capability, allowing generic paint nodes to handle color
transformations when needed.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3433>

cogl/cogl/cogl-pipeline-layer-state.c

@@ -623,6 +623,8 @@ _cogl_pipeline_layer_add_vertex_snippet (CoglPipeline *pipeline,
   _cogl_pipeline_snippet_list_add (&layer->big_state->vertex_snippets,
                                    snippet);
 
+  cogl_pipeline_add_capability_from_snippet (pipeline, snippet);
+
   /* If we weren't previously the authority on this state then we need
    * to extended our differences mask and so it's possible that some
    * of our ancestry will now become redundant, so we aim to reparent
@@ -659,6 +661,8 @@ _cogl_pipeline_layer_add_fragment_snippet (CoglPipeline *pipeline,
   _cogl_pipeline_snippet_list_add (&layer->big_state->fragment_snippets,
                                    snippet);
 
+  cogl_pipeline_add_capability_from_snippet (pipeline, snippet);
+
   /* If we weren't previously the authority on this state then we need
    * to extended our differences mask and so it's possible that some
    * of our ancestry will now become redundant, so we aim to reparent

cogl/cogl/cogl-pipeline-private.h

@@ -323,6 +323,10 @@ struct _CoglPipeline
    * and corresponding authorities_cache_dirty:1 bitfield
    */
 
+  /* Array of opaque capabilities tagged by owners of pipelines.
+   */
+  GArray *capabilities;
+
   /* bitfields */
 
   /* Weak pipelines don't count as dependants on their parents which
@@ -783,3 +787,7 @@ _cogl_pipeline_get_layer_state_for_fragment_codegen (CoglContext *context);
 
 CoglPipelineState
 _cogl_pipeline_get_state_for_fragment_codegen (CoglContext *context);
+
+void
+cogl_pipeline_add_capability_from_snippet (CoglPipeline *pipeline,
+                                           CoglSnippet  *snippet);

cogl/cogl/cogl-pipeline-state.c

@@ -1146,6 +1146,8 @@ _cogl_pipeline_add_vertex_snippet (CoglPipeline *pipeline,
 
   _cogl_pipeline_snippet_list_add (&pipeline->big_state->vertex_snippets,
                                    snippet);
+
+  cogl_pipeline_add_capability_from_snippet (pipeline, snippet);
 }
 
 static void
@@ -1163,6 +1165,8 @@ _cogl_pipeline_add_fragment_snippet (CoglPipeline *pipeline,
 
   _cogl_pipeline_snippet_list_add (&pipeline->big_state->fragment_snippets,
                                    snippet);
+
+  cogl_pipeline_add_capability_from_snippet (pipeline, snippet);
 }
 
 void

cogl/cogl/cogl-pipeline.c

@@ -45,6 +45,7 @@
 #include "cogl/cogl-util.h"
 #include "cogl/cogl-profile.h"
 #include "cogl/cogl-depth-state-private.h"
+#include "cogl/cogl-snippet-private.h"
 #include "cogl/cogl1-context.h"
 
 #include <glib.h>
@@ -154,6 +155,8 @@ cogl_pipeline_dispose (GObject *object)
 
   recursively_free_layer_caches (pipeline);
 
+  g_clear_pointer (&pipeline->capabilities, g_array_unref);
+
   G_OBJECT_CLASS (cogl_pipeline_parent_class)->dispose (object);
 }
 
@@ -329,6 +332,9 @@ _cogl_pipeline_copy (CoglPipeline *src, gboolean is_weak)
   pipeline->dirty_real_blend_enable = src->dirty_real_blend_enable;
   pipeline->unknown_color_alpha = src->unknown_color_alpha;
 
+  if (src->capabilities)
+    pipeline->capabilities = g_array_copy (src->capabilities);
+
   /* XXX:
    * consider generalizing the idea of "cached" properties. These
    * would still have an authority like other sparse properties but
@@ -2792,3 +2798,60 @@ cogl_pipeline_get_uniform_location (CoglPipeline *pipeline,
 
   return ctx->n_uniform_names++;
 }
+
+typedef struct
+{
+  GQuark domain;
+  unsigned int capability;
+} CapabilityEntry;
+
+static void
+cogl_pipeline_add_capability (CoglPipeline *pipeline,
+                              GQuark        domain,
+                              unsigned int  capability)
+{
+  CapabilityEntry entry = {
+    .domain = domain,
+    .capability = capability,
+  };
+
+  if (!pipeline->capabilities)
+    pipeline->capabilities = g_array_new (FALSE, FALSE, sizeof (entry));
+
+  g_array_append_val (pipeline->capabilities, entry);
+}
+
+void
+cogl_pipeline_add_capability_from_snippet (CoglPipeline *pipeline,
+                                           CoglSnippet  *snippet)
+{
+  GQuark capability_domain;
+  unsigned int capability;
+
+  if (cogl_snippet_get_capability (snippet, &capability_domain, &capability))
+    cogl_pipeline_add_capability (pipeline, capability_domain, capability);
+}
+
+gboolean
+cogl_pipeline_has_capability (CoglPipeline *pipeline,
+                              GQuark        domain,
+                              unsigned int  capability)
+{
+  int i;
+
+  if (!pipeline->capabilities)
+    return FALSE;
+
+  for (i = 0; i < pipeline->capabilities->len; i++)
+    {
+      CapabilityEntry *entry = &g_array_index (pipeline->capabilities,
+                                               CapabilityEntry,
+                                               i);
+
+      if (entry->domain == domain &&
+          entry->capability == capability)
+        return TRUE;
+    }
+
+  return FALSE;
+}

cogl/cogl/cogl-pipeline.h

@@ -155,4 +155,9 @@ COGL_EXPORT int
 cogl_pipeline_get_uniform_location (CoglPipeline *pipeline,
                                     const char *uniform_name);
 
+COGL_EXPORT gboolean
+cogl_pipeline_has_capability (CoglPipeline *pipeline,
+                              GQuark        domain,
+                              unsigned int  capability);
+
 G_END_DECLS

cogl/cogl/cogl-snippet-private.h

@@ -66,7 +66,15 @@ struct _CoglSnippet
   char *pre;
   char *replace;
   char *post;
+
+  GQuark capability_domain;
+  unsigned int capability;
 };
 
 void
 _cogl_snippet_make_immutable (CoglSnippet *snippet);
+
+gboolean
+cogl_snippet_get_capability (CoglSnippet  *snippet,
+                             GQuark       *domain,
+                             unsigned int *capability);

cogl/cogl/cogl-snippet.c

@@ -194,3 +194,31 @@ _cogl_snippet_make_immutable (CoglSnippet *snippet)
 {
   snippet->immutable = TRUE;
 }
+
+void
+cogl_snippet_set_capability (CoglSnippet  *snippet,
+                             GQuark        domain,
+                             unsigned int  capability)
+{
+  g_return_if_fail (!snippet->capability_domain);
+
+  snippet->capability_domain = domain;
+  snippet->capability = capability;
+}
+
+gboolean
+cogl_snippet_get_capability (CoglSnippet  *snippet,
+                             GQuark       *domain,
+                             unsigned int *capability)
+{
+  if (snippet->capability_domain)
+    {
+      *domain = snippet->capability_domain;
+      *capability = snippet->capability;
+      return TRUE;
+    }
+  else
+    {
+      return FALSE;
+    }
+}

cogl/cogl/cogl-snippet.h

@@ -622,4 +622,9 @@ cogl_snippet_set_post (CoglSnippet *snippet,
 COGL_EXPORT const char *
 cogl_snippet_get_post (CoglSnippet *snippet);
 
+COGL_EXPORT void
+cogl_snippet_set_capability (CoglSnippet  *snippet,
+                             GQuark        domain,
+                             unsigned int  capability);
+
 G_END_DECLS