mutter/src/compositor/mutter-window-group.h

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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
#ifndef MUTTER_WINDOW_GROUP_H
#define MUTTER_WINDOW_GROUP_H
#include <clutter/clutter.h>
#include "screen.h"
/**
* MutterWindowGroup:
*
* This class is a subclass of ClutterGroup with special handling for
* MutterWindow when painting the group. When we are painting a stack
* of 5-10 maximized windows, the standard bottom-to-top method of
* drawing every actor results in a tremendous amount of overdraw
* and can easily max out the available memory bandwidth on a low-end
* graphics chipset. It's even worse if window textures are being accessed
* over the AGP bus.
*
* The basic technique applied here is to do a pre-pass before painting
* where we walk window from top to bottom and compute the visible area
* at each step by subtracting out the windows above it. The visible
* area is passed to MutterWindow which uses it to clip the portion of
* the window which drawn and avoid redrawing the shadow if it is completely
* obscured.
*
* A caveat is that this is ineffective if applications are using ARGB
* visuals, since we have no way of knowing whether a window obscures
* the windows behind it or not. Alternate approaches using the depth
* or stencil buffer rather than client side regions might be able to
* handle alpha windows, but the combination of glAlphaFunc and stenciling
* tends not to be efficient except on newer cards. (And on newer cards
* we have lots of memory and bandwidth.)
*/
#define MUTTER_TYPE_WINDOW_GROUP (mutter_window_group_get_type ())
#define MUTTER_WINDOW_GROUP(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), MUTTER_TYPE_WINDOW_GROUP, MutterWindowGroup))
#define MUTTER_WINDOW_GROUP_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), MUTTER_TYPE_WINDOW_GROUP, MutterWindowGroupClass))
#define MUTTER_IS_WINDOW_GROUP(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), MUTTER_TYPE_WINDOW_GROUP))
#define MUTTER_IS_WINDOW_GROU_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), MUTTER_TYPE_WINDOW_GROUP))
#define MUTTER_WINDOW_GROUP_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), MUTTER_TYPE_WINDOW_GROUP, MutterWindowGroupClass))
typedef struct _MutterWindowGroup MutterWindowGroup;
typedef struct _MutterWindowGroupClass MutterWindowGroupClass;
typedef struct _MutterWindowGroupPrivate MutterWindowGroupPrivate;
GType mutter_window_group_get_type (void);
ClutterActor *mutter_window_group_new (MetaScreen *screen);
#endif /* MUTTER_WINDOW_GROUP_H */