GskRenderNode: Use C99 flexible arrays to avoid extra allocation

Instead of a separate allocation for any arrays in the render node
we allocate these as part of the render node itself, using C99
flexible arrays.

This leads to less allocations, which is nice, but the major reason
for this is that it allows us to change the allocation scheme further
in the future. For instance, we want to do stack-like allocation so
that all the render-nodes for an entire frame are allocated in one
(or a few) chunks.

docs/reference/gsk/gsk4.types

@@ -1,3 +1,2 @@
 gsk_render_node_get_type
-gsk_render_node_iter_get_type
 gsk_renderer_get_type

gsk/gskglrenderer.c

@@ -604,7 +604,6 @@ gsk_gl_renderer_add_render_item (GskGLRenderer           *self,
                                  RenderItem              *parent)
 {
   graphene_rect_t viewport;
-  graphene_rect_t bounds;
   RenderItem item;
   RenderItem *ritem = NULL;
   int program_id;
@@ -618,24 +617,22 @@ gsk_gl_renderer_add_render_item (GskGLRenderer           *self,
   if (scale_factor < 1)
     scale_factor = 1;
 
-  gsk_render_node_get_bounds (node, &bounds);
-
   item.node = node;
   item.name = node->name != NULL ? node->name : "unnamed";
 
   /* The texture size */
-  item.size.width = bounds.size.width * scale_factor;
+  item.size.width = node->bounds.size.width * scale_factor;
-  item.size.height = bounds.size.height * scale_factor;
+  item.size.height = node->bounds.size.height * scale_factor;
 
   /* Each render item is an axis-aligned bounding box that we
    * transform using the given transformation matrix
    */
-  item.min.x = bounds.origin.x;
+  item.min.x = node->bounds.origin.x;
-  item.min.y = bounds.origin.y;
+  item.min.y = node->bounds.origin.y;
   item.min.z = 0.f;
 
-  item.max.x = item.min.x + bounds.size.width;
+  item.max.x = item.min.x + node->bounds.size.width;
-  item.max.y = item.min.y + bounds.size.height;
+  item.max.y = item.min.y + node->bounds.size.height;
   item.max.z = 0.f;
 
   /* The location of the item, in normalized world coordinates */
@@ -763,17 +760,14 @@ gsk_gl_renderer_add_render_item (GskGLRenderer           *self,
 
     default:
       {
-        graphene_rect_t bounds;
         cairo_surface_t *surface;
         cairo_t *cr;
 
-        gsk_render_node_get_bounds (node, &bounds);
-
         surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
-                                              ceil (bounds.size.width),
+                                              ceil (node->bounds.size.width),
-                                              ceil (bounds.size.height));
+                                              ceil (node->bounds.size.height));
         cr = cairo_create (surface);
-        cairo_translate (cr, -bounds.origin.x, -bounds.origin.y);
+        cairo_translate (cr, -node->bounds.origin.x, -node->bounds.origin.y);
 
         gsk_render_node_draw (node, cr);
         

gsk/gskrenderer.c

@@ -616,7 +616,7 @@ gsk_renderer_unrealize (GskRenderer *renderer)
  * using the given #GdkDrawingContext.
  *
  * The @renderer will acquire a reference on the #GskRenderNode tree while
- * the rendering is in progress, and will make the tree immutable.
+ * the rendering is in progress.
  *
  * Since: 3.90
  */
@@ -635,7 +635,6 @@ gsk_renderer_render (GskRenderer       *renderer,
   g_return_if_fail (context == priv->drawing_context);
 
   priv->root_node = gsk_render_node_ref (root);
-  gsk_render_node_make_immutable (priv->root_node);
 
 #ifdef G_ENABLE_DEBUG
   gsk_profiler_reset (priv->profiler);

gsk/gskrendernode.c

@@ -35,8 +35,8 @@
  *
  * Render nodes are meant to be transient; once they have been associated
  * to a #GskRenderer it's safe to release any reference you have on them.
- * Once a #GskRenderNode has been rendered, it is marked as immutable, and
+ * All #GskRenderNodes are immutable, you can only specify their properties
- * cannot be modified.
+ * during construction.
  */
 
 #include "config.h"
@@ -68,13 +68,11 @@ G_DEFINE_BOXED_TYPE (GskRenderNode, gsk_render_node,
 static void
 gsk_render_node_finalize (GskRenderNode *self)
 {
-  self->is_mutable = TRUE;
-
   self->node_class->finalize (self);
 
   g_clear_pointer (&self->name, g_free);
 
-  g_slice_free1 (self->node_class->struct_size, self);
+  g_free (self);
 }
 
 /*< private >
@@ -84,14 +82,14 @@ gsk_render_node_finalize (GskRenderNode *self)
  * Returns: (transfer full): the newly created #GskRenderNode
  */
 GskRenderNode *
-gsk_render_node_new (const GskRenderNodeClass *node_class)
+gsk_render_node_new (const GskRenderNodeClass *node_class, gsize extra_size)
 {
   GskRenderNode *self;
-  
+
   g_return_val_if_fail (node_class != NULL, NULL);
   g_return_val_if_fail (node_class->node_type != GSK_NOT_A_RENDER_NODE, NULL);
 
-  self = g_slice_alloc0 (node_class->struct_size);
+  self = g_malloc0 (node_class->struct_size + extra_size);
 
   self->node_class = node_class;
 
@@ -100,8 +98,6 @@ gsk_render_node_new (const GskRenderNodeClass *node_class)
   self->min_filter = GSK_SCALING_FILTER_NEAREST;
   self->mag_filter = GSK_SCALING_FILTER_NEAREST;
 
-  self->is_mutable = TRUE;
-
   return self;
 }
 
@@ -180,7 +176,7 @@ gsk_render_node_get_bounds (GskRenderNode   *node,
   g_return_if_fail (GSK_IS_RENDER_NODE (node));
   g_return_if_fail (bounds != NULL);
 
-  node->node_class->get_bounds (node, bounds);
+  graphene_rect_init_from_rect (bounds, &node->bounds);
 }
 
 void
@@ -237,23 +233,6 @@ gsk_render_node_get_name (GskRenderNode *node)
   return node->name;
 }
 
-/*< private >
- * gsk_render_node_make_immutable:
- * @node: a #GskRenderNode
- *
- * Marks @node, and all its children, as immutable.
- */
-void
-gsk_render_node_make_immutable (GskRenderNode *node)
-{
-  if (!node->is_mutable)
-    return;
-
-  node->node_class->make_immutable (node);
-
-  node->is_mutable = FALSE;
-}
-
 /**
  * gsk_render_node_draw:
  * @node: a #GskRenderNode
@@ -279,14 +258,11 @@ gsk_render_node_draw (GskRenderNode *node,
 
   if (!GSK_RENDER_MODE_CHECK (GEOMETRY))
     {
-      graphene_rect_t frame;
-
-      gsk_render_node_get_bounds (node, &frame);
       GSK_NOTE (CAIRO, g_print ("CLIP = { .x = %g, .y = %g, .width = %g, .height = %g }\n",
-                                frame.origin.x, frame.origin.y,
+                                node->bounds.origin.x, node->bounds.origin.y,
-                                frame.size.width, frame.size.height));
+                                node->bounds.size.width, node->bounds.size.height));
 
-      cairo_rectangle (cr, frame.origin.x, frame.origin.y, frame.size.width, frame.size.height);
+      cairo_rectangle (cr, node->bounds.origin.x, node->bounds.origin.y, node->bounds.size.width, node->bounds.size.height);
       cairo_clip (cr);
     }
 
@@ -298,12 +274,9 @@ gsk_render_node_draw (GskRenderNode *node,
 
   if (GSK_RENDER_MODE_CHECK (GEOMETRY))
     {
-      graphene_rect_t frame;
-
-      gsk_render_node_get_bounds (node, &frame);
-
       cairo_set_operator (cr, CAIRO_OPERATOR_OVER);
-      cairo_rectangle (cr, frame.origin.x - 1, frame.origin.y - 1, frame.size.width + 2, frame.size.height + 2);
+      cairo_rectangle (cr, node->bounds.origin.x - 1, node->bounds.origin.y - 1,
+                       node->bounds.size.width + 2, node->bounds.size.height + 2);
       cairo_set_line_width (cr, 2);
       cairo_set_source_rgba (cr, 0, 0, 0, 0.5);
       cairo_stroke (cr);

gsk/gskrendernodeprivate.h

@@ -23,8 +23,7 @@ struct _GskRenderNode
   GskScalingFilter min_filter;
   GskScalingFilter mag_filter;
 
-  /* Bit fields; leave at the end */
+  graphene_rect_t bounds;
-  gboolean is_mutable : 1;
 };
 
 struct _GskRenderNodeClass
@@ -33,16 +32,11 @@ struct _GskRenderNodeClass
   gsize struct_size;
   const char *type_name;
   void (* finalize) (GskRenderNode *node);
-  void (* make_immutable) (GskRenderNode *node);
   void (* draw) (GskRenderNode *node,
                  cairo_t       *cr);
-  void (* get_bounds) (GskRenderNode   *node,
-                       graphene_rect_t *bounds);
 };
 
-GskRenderNode *gsk_render_node_new (const GskRenderNodeClass *node_class);
+GskRenderNode *gsk_render_node_new (const GskRenderNodeClass *node_class, gsize extra_size);
-
-void gsk_render_node_make_immutable (GskRenderNode *node);
 
 void gsk_render_node_get_bounds (GskRenderNode   *node,
                                  graphene_rect_t *frame);

gsk/gskvulkanrenderpass.c

@@ -171,20 +171,20 @@ gsk_vulkan_render_pass_upload_fallback (GskVulkanRenderPass  *self,
                                         GskVulkanRender      *render,
                                         GskVulkanUploader    *uploader)
 {
-  graphene_rect_t bounds;
+  GskRenderNode *node;
   cairo_surface_t *surface;
   cairo_t *cr;
 
-  gsk_render_node_get_bounds (op->node, &bounds);
+  node = op->node;
 
   surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
-                                        ceil (bounds.size.width),
+                                        ceil (node->bounds.size.width),
-                                        ceil (bounds.size.height));
+                                        ceil (node->bounds.size.height));
   cr = cairo_create (surface);
-  cairo_translate (cr, -bounds.origin.x, -bounds.origin.y);
+  cairo_translate (cr, -node->bounds.origin.x, -node->bounds.origin.y);
+
+  gsk_render_node_draw (node, cr);
 
-  gsk_render_node_draw (op->node, cr);
-  
   cairo_destroy (cr);
 
   op->source = gsk_vulkan_image_new_from_data (uploader,
@@ -303,26 +303,20 @@ gsk_vulkan_render_pass_collect_vertex_data (GskVulkanRenderPass *self,
         case GSK_VULKAN_OP_SURFACE:
         case GSK_VULKAN_OP_TEXTURE:
           {
-            graphene_rect_t bounds;
-
-            gsk_render_node_get_bounds (op->render.node, &bounds);
             op->render.vertex_offset = offset + n_bytes;
             gsk_vulkan_blend_pipeline_collect_vertex_data (GSK_VULKAN_BLEND_PIPELINE (op->render.pipeline),
                                                            data + n_bytes + offset,
-                                                           &bounds);
+                                                           &op->render.node.bounds);
             n_bytes += op->render.vertex_count;
           }
           break;
 
         case GSK_VULKAN_OP_COLOR:
           {
-            graphene_rect_t bounds;
-
-            gsk_render_node_get_bounds (op->render.node, &bounds);
             op->render.vertex_offset = offset + n_bytes;
             gsk_vulkan_color_pipeline_collect_vertex_data (GSK_VULKAN_COLOR_PIPELINE (op->render.pipeline),
                                                            data + n_bytes + offset,
-                                                           &bounds,
+                                                           &op->render.node.bounds,
                                                            gsk_color_node_peek_color (op->render.node));
             n_bytes += op->render.vertex_count;
           }