[mutter/gbsneto/paint-nodes] Port ClutterText to ClutterPaintNode

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 5a4ade857a505fc1a8948b178d26a0a96eb7f86c
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Wed Sep 26 02:05:28 2018 -0300

    Port ClutterText to ClutterPaintNode
    
    The port to use ClutterPaintNodes basically mirrors what
    it currently does, with the major benefit of not depending
    on cogl_get_draw_framebuffer() anymore.
    
    There are various factors that influence the number of
    subnodes:
    
     * The background color adds a color subnode;
     * The selection adds a clip subnode, and a color subnode,
       or a color and a text subnode;
    
    The simplest case is when the text does not overflow and
    has no background color nor selection. In that case, the
    render tree is simply:
    
        [ Dummy ]
            ↓
        [ Text ]
    
    In contrast, the most complex case is when drawing the text
    with selection, in which case the render tree looks like:
    
        [ Dummy ]
            ↓
        [ Clip ]
            ↓
        [ Text ] → [ Clip ]
                      ↓
                   [ Color ] → [ Text ]
    
    Since the selection may have another text color, the selected
    text must be rendered again, but clipped to only cover the
    selection rectangle. This is suboptimal, but it's what the
    current code already does anyway.

 clutter/clutter/clutter-text.c | 179 ++++++++++++++++++++++++++---------------
 1 file changed, 116 insertions(+), 63 deletions(-)
---
diff --git a/clutter/clutter/clutter-text.c b/clutter/clutter/clutter-text.c
index d8c7f2875..4e480fecf 100644
--- a/clutter/clutter/clutter-text.c
+++ b/clutter/clutter/clutter-text.c
@@ -1746,7 +1746,8 @@ add_selection_rectangle_to_path (ClutterText           *text,
 
 /* Draws the selected text, its background, and the cursor */
 static void
-selection_paint (ClutterText *self)
+paint_selection (ClutterText      *self,
+                 ClutterPaintNode *node)
 {
   ClutterTextPrivate *priv = self->priv;
   ClutterActor *actor = CLUTTER_ACTOR (self);
@@ -1758,33 +1759,59 @@ selection_paint (ClutterText *self)
 
   if (priv->position == priv->selection_bound)
     {
+      g_autoptr(ClutterPaintNode) cursor_node = NULL;
+
       /* No selection, just draw the cursor */
       if (priv->cursor_color_set)
         color = &priv->cursor_color;
       else
         color = &priv->text_color;
 
-      cogl_set_source_color4ub (color->red,
-                                color->green,
-                                color->blue,
-                                paint_opacity * color->alpha / 255);
-
-      cogl_rectangle (priv->cursor_rect.origin.x,
-                      priv->cursor_rect.origin.y,
-                      priv->cursor_rect.origin.x + priv->cursor_rect.size.width,
-                      priv->cursor_rect.origin.y + priv->cursor_rect.size.height);
+      cursor_node = clutter_color_node_new (&(ClutterColor) {
+                                              color->red,
+                                              color->green,
+                                              color->blue,
+                                              paint_opacity * color->alpha / 255,
+                                            });
+      clutter_paint_node_set_name (cursor_node, "ClutterText.selection-background");
+      clutter_paint_node_add_child (node, cursor_node);
+
+      clutter_paint_node_add_rectangle (cursor_node,
+                                        &(ClutterActorBox) {
+                                          priv->cursor_rect.origin.x,
+                                          priv->cursor_rect.origin.y,
+                                          priv->cursor_rect.origin.x + priv->cursor_rect.size.width,
+                                          priv->cursor_rect.origin.y + priv->cursor_rect.size.height
+                                        });
     }
   else
     {
       /* Paint selection background first */
+      g_autoptr(ClutterPaintNode) selection_background_node = NULL;
+      g_autoptr(ClutterPaintNode) selection_text_node = NULL;
+      g_autoptr(ClutterPaintNode) selection_clip_node = NULL;
       PangoLayout *layout = clutter_text_get_layout (self);
+      ClutterActorBox alloc = { 0, };
       CoglPath *selection_path = cogl_path_new ();
-      CoglColor cogl_color = { 0, };
-      CoglFramebuffer *fb;
 
-      fb = cogl_get_draw_framebuffer ();
-      if (G_UNLIKELY (fb == NULL))
-        return;
+      clutter_text_foreach_selection_rectangle (self,
+                                                add_selection_rectangle_to_path,
+                                                selection_path);
+
+      /* Clip against both the actor allocation - we don't want to draw
+       * the selection rectangle outside the actor - and the selection
+       * path - we don't want to render the text over the unselected
+       * text either.
+       */
+      selection_clip_node = clutter_clip_node_new ();
+      clutter_paint_node_set_name (selection_clip_node, "ClutterText.clip-selection");
+      clutter_paint_node_add_child (node, selection_clip_node);
+
+      clutter_actor_get_allocation_box (CLUTTER_ACTOR (self), &alloc);
+      clutter_actor_box_set_origin (&alloc, 0, 0);
+
+      clutter_paint_node_add_rectangle (selection_clip_node, &alloc);
+      clutter_paint_node_add_path (selection_clip_node, selection_path);
 
       /* Paint selection background */
       if (priv->selection_color_set)
@@ -1794,35 +1821,40 @@ selection_paint (ClutterText *self)
       else
         color = &priv->text_color;
 
-      cogl_set_source_color4ub (color->red,
-                                color->green,
-                                color->blue,
-                                paint_opacity * color->alpha / 255);
+      selection_background_node = clutter_color_node_new (&(ClutterColor) {
+                                                            color->red,
+                                                            color->green,
+                                                            color->blue,
+                                                            paint_opacity * color->alpha / 255,
+                                                          });
+      clutter_paint_node_set_name (selection_background_node, "ClutterText.selection-background");
+      clutter_paint_node_add_child (selection_clip_node, selection_background_node);
 
-      clutter_text_foreach_selection_rectangle (self,
-                                                add_selection_rectangle_to_path,
-                                                selection_path);
-
-      cogl_path_fill (selection_path);
+      clutter_paint_node_add_path (selection_background_node, selection_path);
 
       /* Paint selected text */
-      cogl_framebuffer_push_path_clip (fb, selection_path);
-      cogl_object_unref (selection_path);
-
       if (priv->selected_text_color_set)
         color = &priv->selected_text_color;
       else
         color = &priv->text_color;
 
-      cogl_color_init_from_4ub (&cogl_color,
-                                color->red,
-                                color->green,
-                                color->blue,
-                                paint_opacity * color->alpha / 255);
+      selection_text_node = clutter_text_node_new (layout,
+                                                   &(ClutterColor) {
+                                                     color->red,
+                                                     color->green,
+                                                     color->blue,
+                                                     paint_opacity * color->alpha / 255,
+                                                   });
+
+      clutter_paint_node_set_name (selection_text_node, "ClutterText.selection-text");
+      clutter_paint_node_add_child (selection_clip_node, selection_text_node);
 
-      cogl_pango_render_layout (layout, priv->text_x, 0, &cogl_color, 0);
+      clutter_paint_node_add_texture_rectangle (selection_text_node,
+                                                &alloc,
+                                                priv->text_x, priv->text_y,
+                                                1, 1);
 
-      cogl_framebuffer_pop_clip (fb);
+      cogl_object_unref (selection_path);
     }
 }
 
@@ -2373,26 +2405,43 @@ clutter_text_compute_layout_offsets (ClutterText           *self,
 
 #define TEXT_PADDING    2
 
+static inline ClutterPaintNode *
+create_clip_node (ClutterPaintNode *node,
+                  float             width,
+                  float             height)
+{
+  g_autoptr(ClutterPaintNode) clip_node = NULL;
+
+  clip_node = clutter_clip_node_new ();
+  clutter_paint_node_set_name (clip_node, "ClutterText.clip");
+  clutter_paint_node_add_child (node, clip_node);
+
+  clutter_paint_node_add_rectangle (clip_node,
+                                    &(ClutterActorBox) {
+                                      0, 0,
+                                      width, height,
+                                    });
+
+  return g_steal_pointer (&clip_node);
+}
+
 static void
-clutter_text_paint (ClutterActor *self)
+clutter_text_paint_node (ClutterActor     *self,
+                         ClutterPaintNode *node)
 {
+  g_autoptr(ClutterPaintNode) text_node = NULL;
   ClutterText *text = CLUTTER_TEXT (self);
   ClutterTextPrivate *priv = text->priv;
-  CoglFramebuffer *fb;
   PangoLayout *layout;
   ClutterActorBox alloc = { 0, };
-  CoglColor color = { 0, };
   guint8 real_opacity;
   gint text_x = priv->text_x;
   gint text_y = priv->text_y;
-  gboolean clip_set = FALSE;
   gboolean bg_color_set = FALSE;
   guint n_chars;
   float alloc_width;
   float alloc_height;
 
-  fb = cogl_get_draw_framebuffer ();
-
   /* Note that if anything in this paint method changes it needs to be
      reflected in the get_paint_volume implementation which is tightly
      tied to the workings of this function */
@@ -2405,6 +2454,7 @@ clutter_text_paint (ClutterActor *self)
   g_object_get (self, "background-color-set", &bg_color_set, NULL);
   if (bg_color_set)
     {
+      g_autoptr(ClutterPaintNode) background_color_node = NULL;
       ClutterColor bg_color;
 
       clutter_actor_get_background_color (self, &bg_color);
@@ -2412,11 +2462,11 @@ clutter_text_paint (ClutterActor *self)
                      * bg_color.alpha
                      / 255;
 
-      cogl_set_source_color4ub (bg_color.red,
-                                bg_color.green,
-                                bg_color.blue,
-                                bg_color.alpha);
-      cogl_rectangle (0, 0, alloc_width, alloc_height);
+      background_color_node = clutter_color_node_new (&bg_color);
+      clutter_paint_node_set_name (background_color_node, "ClutterText.background-color");
+      clutter_paint_node_add_child (node, background_color_node);
+
+      clutter_paint_node_add_rectangle (background_color_node, &alloc);
     }
 
   /* don't bother painting an empty text actor, unless it's
@@ -2469,8 +2519,7 @@ clutter_text_paint (ClutterActor *self)
 
       pango_layout_get_extents (layout, NULL, &logical_rect);
 
-      cogl_framebuffer_push_rectangle_clip (fb, 0, 0, alloc_width, alloc_height);
-      clip_set = TRUE;
+      node = create_clip_node (node, alloc_width, alloc_height);
 
       actor_width = alloc_width - 2 * TEXT_PADDING;
       text_width  = logical_rect.width / PANGO_SCALE;
@@ -2513,12 +2562,8 @@ clutter_text_paint (ClutterActor *self)
       pango_layout_get_pixel_extents (layout, NULL, &logical_rect);
 
       /* don't clip if the layout managed to fit inside our allocation */
-      if (logical_rect.width > alloc_width ||
-          logical_rect.height > alloc_height)
-        {
-          cogl_framebuffer_push_rectangle_clip (fb, 0, 0, alloc_width, alloc_height);
-          clip_set = TRUE;
-        }
+      if (logical_rect.width > alloc_width || logical_rect.height > alloc_height)
+        node = create_clip_node (node, alloc_width, alloc_height);
 
       clutter_text_compute_layout_offsets (text, layout, &alloc, &text_x, &text_y);
     }
@@ -2541,17 +2586,25 @@ clutter_text_paint (ClutterActor *self)
   CLUTTER_NOTE (PAINT, "painting text (text: '%s')",
                 clutter_text_buffer_get_text (get_buffer (text)));
 
-  cogl_color_init_from_4ub (&color,
-                            priv->text_color.red,
-                            priv->text_color.green,
-                            priv->text_color.blue,
-                            real_opacity);
-  cogl_pango_render_layout (layout, priv->text_x, priv->text_y, &color, 0);
+  text_node = clutter_text_node_new (layout,
+                                     &(ClutterColor) {
+                                        priv->text_color.red,
+                                        priv->text_color.green,
+                                        priv->text_color.blue,
+                                        real_opacity
+                                      });
+
+  clutter_paint_node_set_name (text_node, "ClutterText.text");
+  clutter_paint_node_add_child (node, text_node);
 
-  selection_paint (text);
+  clutter_actor_box_set_origin (&alloc, 0, 0);
+  clutter_paint_node_add_texture_rectangle (text_node,
+                                            &alloc,
+                                            priv->text_x,
+                                            priv->text_y,
+                                            1, 1);
 
-  if (clip_set)
-    cogl_framebuffer_pop_clip (fb);
+  paint_selection (text, node);
 }
 
 static void
@@ -3548,7 +3601,7 @@ clutter_text_class_init (ClutterTextClass *klass)
   gobject_class->dispose = clutter_text_dispose;
   gobject_class->finalize = clutter_text_finalize;
 
-  actor_class->paint = clutter_text_paint;
+  actor_class->paint_node = clutter_text_paint_node;
   actor_class->get_paint_volume = clutter_text_get_paint_volume;
   actor_class->get_preferred_width = clutter_text_get_preferred_width;
   actor_class->get_preferred_height = clutter_text_get_preferred_height;