On Tue, 2008-02-26 at 17:28 +0000, Matthew Allum wrote:
> So clutter has 2 painting modes - the regular one you see and the
> picking one - which essentially just renders offscreen per reactive
> actor color coded silhouettes (usually just quads) of actors so it can
> quickly figure out what actor a pointer event relates to. Thats
> basically what the above is doing though Im not sure why we are checking
> the mapped flag - that probably isn't needed - pippin, ebassi ?
Thanks. I'd really like some more clues about this because I hate to
write about something I don't understand. I understand that all
containers must call clutter_actor_pick() on all their children(),
but I don't understand what regular actors should do in their
ClutterActor::pick(): implementation.
Most of the pick() implementations in core clutter just use the default
implementation in ClutterActor, which draws a rectangle. I can't find
any non-container pick() implementation in clutter or tidy that doesn't
use that.
Below are some more that I found in Tidy, but I don't see a pattern yet,
so I don't see what they are actually trying to achieve. If this is just
for some kind of cursor-is-inside-the-shape detection then why is the
color significant? Why do some just call their paint() function instead
of drawing an outline?
static void
tidy_frame_pick (ClutterActor *actor,
const ClutterColor *pick_color)
{
/* chain up, so we get a box with our coordinates */
CLUTTER_ACTOR_CLASS (tidy_frame_parent_class)->pick (actor,
pick_color);
/* paint our child, if any */
if (CLUTTER_ACTOR_IS_MAPPED (actor))
{
TidyFramePrivate *priv = TIDY_FRAME (actor)->priv;
if (priv->child && CLUTTER_ACTOR_IS_MAPPED (priv->child))
clutter_actor_paint (priv->child);
}
}
static void
tidy_scroll_view_pick (ClutterActor *actor, const ClutterColor *color)
{
gint x, y, width, height;
TidyScrollViewPrivate *priv = TIDY_SCROLL_VIEW (actor)->priv;
/* Paint a background */
cogl_color (color);
x = CLUTTER_UNITS_TO_INT (priv->box.x1);
y = CLUTTER_UNITS_TO_INT (priv->box.y1);
width = CLUTTER_UNITS_TO_INT (priv->box.x2) - x;
height = CLUTTER_UNITS_TO_INT (priv->box.y2) - y;
cogl_rectangle (x, y, width, height);
tidy_scroll_view_paint (actor);
}
static void
tidy_notebook_pick (ClutterActor *self,
const ClutterColor *color)
{
tidy_notebook_paint (self);
}
static void
tidy_viewport_pick (ClutterActor *self,
const ClutterColor *color)
{
tidy_viewport_paint (self);
}
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