[mutter/gbsneto/paint-nodes: 2/2] Port ClutterText to ClutterPaintNode

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

commit bfa4a1b09b51b150b0fd0c3a3a211675b3066d1a
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 ]
            ↓
        [ 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 | 187 ++++++++++++++++++++++++-----------------
 1 file changed, 111 insertions(+), 76 deletions(-)
---
diff --git a/clutter/clutter/clutter-text.c b/clutter/clutter/clutter-text.c
index d8c7f2875..c8cf3f351 100644
--- a/clutter/clutter/clutter-text.c
+++ b/clutter/clutter/clutter-text.c
@@ -1737,54 +1737,65 @@ clutter_text_foreach_selection_rectangle (ClutterText              *self,
 }
 
 static void
-add_selection_rectangle_to_path (ClutterText           *text,
-                                 const ClutterActorBox *box,
-                                 gpointer               user_data)
+add_selection_rectangle_to_box (ClutterText           *text,
+                                const ClutterActorBox *box,
+                                gpointer               user_data)
 {
-  cogl_path_rectangle (user_data, box->x1, box->y1, box->x2, box->y2);
+  ClutterActorBox *selection_box = user_data;
+
+  if (selection_box->x1 == 0 &&
+      selection_box->y1 == 0 &&
+      selection_box->x2 == 0 &&
+      selection_box->x2 == 0)
+    clutter_actor_box_init (selection_box, box->x1, box->y1, box->x2, box->y2);
+  else
+    clutter_actor_box_union (selection_box, box, selection_box);
 }
 
 /* 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);
   guint8 paint_opacity = clutter_actor_get_paint_opacity (actor);
   const ClutterColor *color;
 
-  if (!clutter_text_should_draw_cursor (self))
-    return;
-
   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;
       PangoLayout *layout = clutter_text_get_layout (self);
-      CoglPath *selection_path = cogl_path_new ();
-      CoglColor cogl_color = { 0, };
-      CoglFramebuffer *fb;
-
-      fb = cogl_get_draw_framebuffer ();
-      if (G_UNLIKELY (fb == NULL))
-        return;
+      ClutterActorBox box = { 0, };
 
       /* Paint selection background */
       if (priv->selection_color_set)
@@ -1794,35 +1805,42 @@ selection_paint (ClutterText *self)
       else
         color = &priv->text_color;
 
-      cogl_set_source_color4ub (color->red,
-                                color->green,
-                                color->blue,
-                                paint_opacity * color->alpha / 255);
-
       clutter_text_foreach_selection_rectangle (self,
-                                                add_selection_rectangle_to_path,
-                                                selection_path);
+                                                add_selection_rectangle_to_box,
+                                                &box);
 
-      cogl_path_fill (selection_path);
+      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 (node, selection_background_node);
 
-      /* Paint selected text */
-      cogl_framebuffer_push_path_clip (fb, selection_path);
-      cogl_object_unref (selection_path);
+      clutter_paint_node_add_rectangle (selection_background_node, &box);
 
+      /* Paint selected text */
       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);
-
-      cogl_pango_render_layout (layout, priv->text_x, 0, &cogl_color, 0);
-
-      cogl_framebuffer_pop_clip (fb);
+      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 (node, selection_text_node);
+
+      clutter_paint_node_add_texture_rectangle (selection_text_node,
+                                                &box,
+                                                priv->text_x, priv->text_y,
+                                                1, 1);
     }
 }
 
@@ -2374,25 +2392,22 @@ clutter_text_compute_layout_offsets (ClutterText           *self,
 #define TEXT_PADDING    2
 
 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 +2420,7 @@ 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 +2428,11 @@ 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
@@ -2469,9 +2485,6 @@ 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;
-
       actor_width = alloc_width - 2 * TEXT_PADDING;
       text_width  = logical_rect.width / PANGO_SCALE;
 
@@ -2512,14 +2525,6 @@ 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;
-        }
-
       clutter_text_compute_layout_offsets (text, layout, &alloc, &text_x, &text_y);
     }
   else
@@ -2541,17 +2546,47 @@ 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);
+
+  clutter_paint_node_add_texture_rectangle (text_node,
+                                            &(ClutterActorBox) {
+                                              0, 0,
+                                              alloc_width,
+                                              alloc_height,
+                                            },
+                                            priv->text_x,
+                                            priv->text_y,
+                                            1, 1);
+
+  /* Clip the selection to the allocated size, otherwise the selected
+   * contents overflow the actor boundaries.
+   */
+  if (clutter_text_should_draw_cursor (text))
+    {
+      g_autoptr(ClutterPaintNode) clip_node = NULL;
+
+      clip_node = clutter_clip_node_new ();
+      clutter_paint_node_set_name (clip_node, "ClutterText.clip-selection");
+      clutter_paint_node_add_child (node, clip_node);
 
-  selection_paint (text);
+      clutter_paint_node_add_rectangle (clip_node,
+                                        &(ClutterActorBox) {
+                                          0, 0,
+                                          alloc_width,
+                                          alloc_height,
+                                        });
 
-  if (clip_set)
-    cogl_framebuffer_pop_clip (fb);
+      paint_selection (text, clip_node);
+    }
 }
 
 static void
@@ -3548,7 +3583,7 @@ 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;