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Add support for composited child windows. (#412882, Ryan Lortie)

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2007-06-01  Matthias Clasen  <mclasen@redhat.com>

        Add support for composited child windows.  (#412882, Ryan Lortie)

        * gdk/gdk.symbols:
        * gdk/gdkdisplay.h:
        * gdk/gdkinternals.h:
        * gdk/gdkwindow.[hc]: Add gdk_display_supports_composite() and
        gdk_window_set_composited().

        * gdk/x11/gdkevents-x11.c:
        * gdk/x11/gdkdisplay-x11.[hc]:
        * gdk/x11/gdkwindow-x11.[hc]: X11 implementation.

        * gdk/win32/gdkdisplay-win32.c:
        * gdk/win32/gdkwindow-win32.c: Dummy win32 implementration.

        * gdk/quartz/gdkdisplay-quartz.c:
        * gdk/quartz/gdkwindow-quartz.c: Dummy Quartz implementation.

        * gdk/directfb/gdkdisplay-directfb.c:
        * gdk/directfb/gdkwindow-directfb.c: Dummy DirectFB implementation.

        * tests/testgtk.c: Add a "composited window" test.


svn path=/trunk/; revision=18004
This commit is contained in:
Matthias Clasen 2007-06-01 12:16:12 +00:00 committed by Matthias Clasen
parent 62c13f0463
commit 885ba04648
21 changed files with 635 additions and 3 deletions
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25
ChangeLog
View File

@ -1,3 +1,28 @@
2007-06-01 Matthias Clasen <mclasen@redhat.com>
Add support for composited child windows. (#412882, Ryan Lortie)
* gdk/gdk.symbols:
* gdk/gdkdisplay.h:
* gdk/gdkinternals.h:
* gdk/gdkwindow.[hc]: Add gdk_display_supports_composite() and
gdk_window_set_composited().
* gdk/x11/gdkevents-x11.c:
* gdk/x11/gdkdisplay-x11.[hc]:
* gdk/x11/gdkwindow-x11.[hc]: X11 implementation.
* gdk/win32/gdkdisplay-win32.c:
* gdk/win32/gdkwindow-win32.c: Dummy win32 implementration.
* gdk/quartz/gdkdisplay-quartz.c:
* gdk/quartz/gdkwindow-quartz.c: Dummy Quartz implementation.
* gdk/directfb/gdkdisplay-directfb.c:
* gdk/directfb/gdkwindow-directfb.c: Dummy DirectFB implementation.
* tests/testgtk.c: Add a "composited window" test.
2007-06-01 Michael Natterer <mitch@imendio.com>
* gtk/gtkmenuitem.c (gtk_menu_item_position_menu): don't switch

5
docs/reference/ChangeLog
View File

@ -1,3 +1,8 @@
2007-06-01 Matthias Clasen <mclasen@redhat.com>
* gdk/gdk-sections.txt: Add new composited window api
* gdk/tmpl/windows.sgml: Add composited window example
2007-05-26 Matthias Clasen <mclasen@redhat.com>
* gtk/migrating*.sgml: Some cleanups

2
docs/reference/gdk/gdk-sections.txt
View File

@ -155,6 +155,7 @@ gdk_display_supports_clipboard_persistence
gdk_display_store_clipboard
gdk_display_supports_shapes
gdk_display_supports_input_shapes
gdk_display_supports_composite
<SUBSECTION Standard>
GDK_DISPLAY_OBJECT
GDK_IS_DISPLAY
@ -651,6 +652,7 @@ gdk_window_unfullscreen
gdk_window_set_keep_above
gdk_window_set_keep_below
gdk_window_set_opacity
gdk_window_set_composited
gdk_window_move
gdk_window_resize
gdk_window_move_resize

167
docs/reference/gdk/tmpl/windows.sgml
View File

@ -12,6 +12,164 @@ GTK+ level. A #GtkWindow is a toplevel window, the thing a user might think of
as a "window" with a titlebar and so on; a #GtkWindow may contain many #GdkWindow.
For example, each #GtkButton has a #GdkWindow associated with it.
</para>
<example id="composited-window-example"><title>Composited windows</title>
<programlisting><![CDATA[
#include <gtk/gtk.h>
/* The expose event handler for the event box.
*
* This function simply draws a transparency onto a widget on the area
* for which it receives expose events. This is intended to give the
* event box a "transparent" background.
*
* In order for this to work properly, the widget must have an RGBA
* colourmap. The widget should also be set as app-paintable since it
* doesn't make sense for GTK+ to draw a background if we are drawing it
* (and because GTK+ might actually replace our transparency with its
* default background colour).
*/
static gboolean
transparent_expose (GtkWidget *widget,
GdkEventExpose *event)
{
cairo_t *cr;
cr = gdk_cairo_create (widget->window);
cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
gdk_cairo_region (cr, event->region);
cairo_fill (cr);
cairo_destroy (cr);
return FALSE;
}
/* The expose event handler for the window.
*
* This function performs the actual compositing of the event box onto
* the already-existing background of the window at 50% normal opacity.
*
* In this case we do not want app-paintable to be set on the widget
* since we want it to draw its own (red) background. Because of this,
* however, we must ensure that we use g_signal_register_after so that
* this handler is called after the red has been drawn. If it was
* called before then GTK would just blindly paint over our work.
*
* Note: if the child window has children, then you need a cairo 1.16
* feature to make this work correctly.
*/
static gboolean
window_expose_event (GtkWidget *widget,
GdkEventExpose *event)
{
GdkRegion *region;
GtkWidget *child;
cairo_t *cr;
/* get our child (in this case, the event box) */
child = gtk_bin_get_child (GTK_BIN (widget));
/* create a cairo context to draw to the window */
cr = gdk_cairo_create (widget->window);
/* the source data is the (composited) event box */
gdk_cairo_set_source_pixmap (cr, child->window,
child->allocation.x,
child->allocation.y);
/* draw no more than our expose event intersects our child */
region = gdk_region_rectangle (&child->allocation);
gdk_region_intersect (region, event->region);
gdk_cairo_region (cr, region);
cairo_clip (cr);
/* composite, with a 50% opacity */
cairo_set_operator (cr, CAIRO_OPERATOR_OVER);
cairo_paint_with_alpha (cr, 0.5);
/* we're done */
cairo_destroy (cr);
return FALSE;
}
int
main (int argc, char **argv)
{
GtkWidget *window, *event, *button;
GdkScreen *screen;
GdkColormap *rgba;
GdkColor red;
gtk_init (&argc, &argv);
/* Make the widgets */
button = gtk_button_new_with_label ("A Button");
event = gtk_event_box_new ();
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
/* Put a red background on the window */
gdk_color_parse ("red", &red);
gtk_widget_modify_bg (window, GTK_STATE_NORMAL, &red);
/* Set the colourmap for the event box.
* Must be done before the event box is realised.
*/
screen = gtk_widget_get_screen (event);
rgba = gdk_screen_get_rgba_colormap (screen);
gtk_widget_set_colormap (event, rgba);
/* Set our event box to have a fully-transparent background
* drawn on it. Currently there is no way to simply tell GTK+
* that "transparency" is the background colour for a widget.
*/
gtk_widget_set_app_paintable (GTK_WIDGET (event), TRUE);
g_signal_connect (event, "expose-event",
G_CALLBACK (transparent_expose), NULL);
/* Put them inside one another */
gtk_container_set_border_width (GTK_CONTAINER (window), 10);
gtk_container_add (GTK_CONTAINER (window), event);
gtk_container_add (GTK_CONTAINER (event), button);
/* Realise and show everything */
gtk_widget_show_all (window);
/* Set the event box GdkWindow to be composited.
* Obviously must be performed after event box is realised.
*/
gdk_window_set_composited (event->window, TRUE);
/* Set up the compositing handler.
* Note that we do _after_ so that the normal (red) background is drawn
* by gtk before our compositing occurs.
*/
g_signal_connect_after (window, "expose-event",
G_CALLBACK (window_expose_event), NULL);
gtk_main (<!-- -->);
return 0;
}
]]>
</programlisting></example>
<para>
In the example <xref linkend="composited-window-example"/>, a button is
placed inside of an event box inside of a window. The event box is
set as composited and therefore is no longer automatically drawn to
the screen.
</para>
<para>
When the contents of the event box change, an expose event is
generated on its parent window (which, in this case, belongs to
the toplevel #GtkWindow). The expose handler for this widget is
responsible for merging the changes back on the screen in the way
that it wishes.
</para>
<para>
In our case, we merge the contents with a 50% transparency. We
also set the background colour of the window to red. The effect is
that the background shows through the button.
</para>
<!-- ##### SECTION See_Also ##### -->
<para>
@ -465,6 +623,15 @@ Deprecated equivalent of g_object_unref()
@opacity:
<!-- ##### FUNCTION gdk_window_set_composited ##### -->
<para>
</para>
@window:
@composited:
<!-- ##### FUNCTION gdk_window_move ##### -->
<para>

7
gdk/directfb/gdkdisplay-directfb.c
View File

@ -511,6 +511,13 @@ gdk_notify_startup_complete_with_id (const gchar* startup_id)
{
}
gboolean
gdk_display_supports_composite (GdkDisplay *display)
{
return FALSE;
}
#define __GDK_DISPLAY_X11_C__
#include "gdkaliasdef.c"

8
gdk/directfb/gdkwindow-directfb.c
View File

@ -3038,6 +3038,14 @@ gdk_window_set_opacity (GdkWindow *window,
cardinal = opacity * 0xff;
gdk_directfb_window_set_opacity(window,cardinal);
}
void
_gdk_windowing_window_set_composited (GdkWindow *window,
gboolean composited)
{
}
#define __GDK_WINDOW_X11_C__
#include "gdkaliasdef.c"

2
gdk/gdk.symbols
View File

@ -466,6 +466,7 @@ gdk_display_supports_clipboard_persistence
gdk_display_supports_selection_notification
gdk_display_supports_shapes
gdk_display_supports_input_shapes
gdk_display_supports_composite
#endif
#endif
@ -673,6 +674,7 @@ gdk_window_remove_filter
gdk_window_set_debug_updates
gdk_window_set_user_data
gdk_window_thaw_updates
gdk_window_set_composited
#endif
#endif

1
gdk/gdkdisplay.h
View File

@ -181,6 +181,7 @@ void gdk_display_store_clipboard (GdkDisplay *display,
gboolean gdk_display_supports_shapes (GdkDisplay *display);
gboolean gdk_display_supports_input_shapes (GdkDisplay *display);
gboolean gdk_display_supports_composite (GdkDisplay *display);
G_END_DECLS

3
gdk/gdkinternals.h
View File

@ -337,6 +337,9 @@ void _gdk_windowing_window_destroy_foreign (GdkWindow *window);
void _gdk_windowing_display_set_sm_client_id (GdkDisplay *display,
const gchar *sm_client_id);
void _gdk_windowing_window_set_composited (GdkWindow *window,
gboolean composited);
#define GDK_TYPE_PAINTABLE (_gdk_paintable_get_type ())
#define GDK_PAINTABLE(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), GDK_TYPE_PAINTABLE, GdkPaintable))
#define GDK_IS_PAINTABLE(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GDK_TYPE_PAINTABLE))

91
gdk/gdkwindow.c
View File

@ -1042,6 +1042,7 @@ gdk_window_end_paint (GdkWindow *window)
{
#ifdef USE_BACKING_STORE
GdkWindowObject *private = (GdkWindowObject *)window;
GdkWindowObject *composited;
GdkWindowPaint *paint;
GdkGC *tmp_gc;
GdkRectangle clip_box;
@ -1094,6 +1095,34 @@ gdk_window_end_paint (GdkWindow *window)
g_object_unref (paint->pixmap);
gdk_region_destroy (paint->region);
g_free (paint);
/* find a composited window in our hierarchy to signal its
* parent to redraw, calculating the clip box as we go...
*
* stop if parent becomes NULL since then we'd have nowhere
* to draw (ie: 'composited' will always be non-NULL here).
*/
for (composited = private;
composited->parent;
composited = composited->parent)
{
int width, height;
gdk_drawable_get_size (GDK_DRAWABLE (composited->parent),
&width, &height);
clip_box.x += composited->x;
clip_box.y += composited->y;
clip_box.width = MIN (clip_box.width, width - clip_box.x);
clip_box.height = MIN (clip_box.height, height - clip_box.y);
if (composited->composited)
{
gdk_window_invalidate_rect (GDK_WINDOW (composited->parent),
&clip_box, FALSE);
break;
}
}
#endif /* USE_BACKING_STORE */
}
@ -2601,7 +2630,8 @@ gdk_window_invalidate_maybe_recurse (GdkWindow *window,
child_region = gdk_region_rectangle (&child_rect);
/* remove child area from the invalid area of the parent */
if (GDK_WINDOW_IS_MAPPED (child) && !child->shaped)
if (GDK_WINDOW_IS_MAPPED (child) && !child->shaped &&
!child->composited)
gdk_region_subtract (visible_region, child_region);
if (child_func && (*child_func) ((GdkWindow *)child, user_data))
@ -3056,5 +3086,64 @@ gdk_window_foreign_new (GdkNativeWindow anid)
return gdk_window_foreign_new_for_display (gdk_display_get_default (), anid);
}
/**
* gdk_window_set_composited:
* @window: a #GdkWindow
*
* Sets a #GdkWindow as composited. Composited windows do
* not automatically have their contents drawn to the screen.
* Drawing is redirected to an offscreen buffer and an expose
* event is emitted on the parent of the composited window.
* It is the responsibility of the parent's expose handler to
* manually merge the off-screen content onto the screen in
* whatever way it sees fit. See <xref linkend="composited-window-example"/>
* for an example.
*
* It only makes sense for child windows to be composited; see
* gdk_window_set_opacity() if you need translucent toplevel
* windows.
*
* An additional effect of this call is that the area of this
* window is no longer clipped from regions marked for
* invalidation on its parent. Draws done on the parent
* window are also no longer clipped by the child.
*
* This call is only supported on some systems (currently,
* only X11 with new enough Xcomposite and Xdamage extensions).
* You must call gdk_display_supports_composite() to check if
* setting a window as composited is supported before
* attempting to do so.
*
* Since: 2.12
*/
void
gdk_window_set_composited (GdkWindow *window,
gboolean composited)
{
GdkWindowObject *private = (GdkWindowObject *)window;
GdkDisplay *display;
g_return_if_fail (window != NULL);
g_return_if_fail (GDK_IS_WINDOW (window));
composited = composited != FALSE;
if (private->composited == composited)
return;
display = gdk_drawable_get_display (GDK_DRAWABLE (window));
if (!gdk_display_supports_composite (display) && composited)
{
g_warning ("gdk_window_set_composited called but "
"compositing is not supported");
return;
}
_gdk_windowing_window_set_composited (window, composited);
private->composited = composited;
}
#define __GDK_WINDOW_C__
#include "gdkaliasdef.c"

4
gdk/gdkwindow.h
View File

@ -289,6 +289,7 @@ struct _GdkWindowObject
guint guffaw_gravity : 1;
guint input_only : 1;
guint modal_hint : 1;
guint composited : 1;
guint destroyed : 2;
@ -394,6 +395,9 @@ void gdk_window_shape_combine_region (GdkWindow *window,
*/
void gdk_window_set_child_shapes (GdkWindow *window);
void gdk_window_set_composited (GdkWindow *window,
gboolean composited);
/*
* This routine allows you to merge (ie ADD) child shapes to your
* own window's shape keeping its current shape and ADDING the child

8
gdk/quartz/gdkdisplay-quartz.c
View File

@ -169,3 +169,11 @@ gdk_display_store_clipboard (GdkDisplay *display,
{
/* FIXME: Implement */
}
gboolean
gdk_display_supports_composite (GdkDisplay *display)
{
/* FIXME: Implement */
return FALSE;
}

5
gdk/quartz/gdkwindow-quartz.c
View File

@ -2155,3 +2155,8 @@ gdk_window_set_opacity (GdkWindow *window,
[impl->toplevel setAlphaValue: opacity];
}
void
_gdk_windowing_window_set_composited (GdkWindow *window, gboolean composited)
{
}

6
gdk/win32/gdkdisplay-win32.c
View File

@ -389,3 +389,9 @@ gdk_display_supports_input_shapes (GdkDisplay *display)
return FALSE;
}
gboolean
gdk_display_supports_composite (GdkDisplay *display)
{
return FALSE;
}

5
gdk/win32/gdkwindow-win32.c
View File

@ -3571,3 +3571,8 @@ gdk_window_set_opacity (GdkWindow *window,
opacity * 0xff,
LWA_ALPHA));
}
void
_gdk_windowing_window_set_composited (GdkWindow *window, gboolean composited)
{
}

56
gdk/x11/gdkdisplay-x11.c
View File

@ -54,6 +54,14 @@
#include <X11/extensions/shape.h>
#endif
#ifdef HAVE_XCOMPOSITE
#include <X11/extensions/Xcomposite.h>
#endif
#ifdef HAVE_XDAMAGE
#include <X11/extensions/Xdamage.h>
#endif
static void gdk_display_x11_dispose (GObject *object);
static void gdk_display_x11_finalize (GObject *object);
@ -206,6 +214,29 @@ gdk_display_open (const gchar *display_name)
#endif
display_x11->have_xfixes = FALSE;
#ifdef HAVE_XCOMPOSITE
if (XCompositeQueryExtension (display_x11->xdisplay,
&ignore, &ignore))
display_x11->have_xcomposite = TRUE;
else
#endif
display_x11->have_xcomposite = FALSE;
#ifdef HAVE_XDAMAGE
if (XDamageQueryExtension (display_x11->xdisplay,
&display_x11->xdamage_event_base,
&ignore))
{
display_x11->have_xdamage = TRUE;
gdk_x11_register_standard_event_type (display,
display_x11->xdamage_event_base,
XDamageNumberEvents);
}
else
#endif
display_x11->have_xdamage = FALSE;
display_x11->have_shapes = FALSE;
display_x11->have_input_shapes = FALSE;
#ifdef HAVE_SHAPE_EXT
@ -1363,5 +1394,30 @@ gdk_x11_display_get_startup_notification_id (GdkDisplay *display)
return GDK_DISPLAY_X11 (display)->startup_notification_id;
}
/**
* gdk_display_supports_composite:
* @display: a #GdkDisplay
*
* Returns %TRUE if gdk_window_set_composited() can be used
* to redirect drawing on the window using compositing.
*
* Currently this only works on X11 with XComposite and
* XDamage extensions available.
*
* Returns: %TRUE if windows may be composited.
*
* Since: 2.12
*/
gboolean
gdk_display_supports_composite (GdkDisplay *display)
{
GdkDisplayX11 *x11_display = GDK_DISPLAY_X11 (display);
return x11_display->have_xcomposite &&
x11_display->have_xdamage &&
x11_display->have_xfixes;
}
#define __GDK_DISPLAY_X11_C__
#include "gdkaliasdef.c"

4
gdk/x11/gdkdisplay-x11.h
View File

@ -81,6 +81,10 @@ struct _GdkDisplayX11
gboolean have_xfixes;
gint xfixes_event_base;
gboolean have_xcomposite;
gboolean have_xdamage;
gint xdamage_event_base;
/* If the SECURITY extension is in place, whether this client holds
* a trusted authorization and so is allowed to make various requests
* (grabs, properties etc.) Otherwise always TRUE. */

28
gdk/x11/gdkevents-x11.c
View File

@ -2101,6 +2101,34 @@ gdk_event_translate (GdkDisplay *display,
}
else
#endif
#if defined(HAVE_XCOMPOSITE) && defined (HAVE_XDAMAGE) && defined (HAVE_XFIXES)
if (display_x11->have_xdamage && window_private->composited &&
xevent->type == display_x11->xdamage_event_base + XDamageNotify)
{
XDamageNotifyEvent *damage_event = (XDamageNotifyEvent *) xevent;
XserverRegion repair;
GdkRectangle rect;
rect.x = window_private->x + damage_event->area.x;
rect.y = window_private->y + damage_event->area.y;
rect.width = damage_event->area.width;
rect.height = damage_event->area.height;
repair = XFixesCreateRegion (display_x11->xdisplay,
&damage_event->area, 1);
XDamageSubtract (display_x11->xdisplay,
window_impl->damage,
repair, None);
XFixesDestroyRegion (display_x11->xdisplay, repair);
if (window_private->parent != NULL)
_gdk_window_process_expose (GDK_WINDOW (window_private->parent),
damage_event->serial, &rect);
return_val = TRUE;
}
else
#endif
{
/* something else - (e.g., a Xinput event) */

62
gdk/x11/gdkwindow-x11.c
View File

@ -59,6 +59,18 @@
#include <X11/extensions/shape.h>
#endif
#ifdef HAVE_XCOMPOSITE
#include <X11/extensions/Xcomposite.h>
#endif
#ifdef HAVE_XFIXES
#include <X11/extensions/Xfixes.h>
#endif
#ifdef HAVE_XDAMAGE
#include <X11/extensions/Xdamage.h>
#endif
const int _gdk_event_mask_table[21] =
{
ExposureMask,
@ -185,6 +197,14 @@ gdk_window_impl_x11_finalize (GObject *object)
_gdk_xgrab_check_destroy (GDK_WINDOW (wrapper));
#if defined(HAVE_XCOMPOSITE) && defined(HAVE_XDAMAGE) && defined (HAVE_XFIXES)
if (window_impl->damage != None)
{
XDamageDestroy (GDK_WINDOW_XDISPLAY (object), window_impl->damage);
window_impl->damage = None;
}
#endif
if (!GDK_WINDOW_DESTROYED (wrapper))
{
GdkDisplay *display = GDK_WINDOW_DISPLAY (wrapper);
@ -6413,10 +6433,14 @@ gdk_window_beep (GdkWindow *window)
*
* Request the windowing system to make @window partially transparent,
* with opacity 0 being fully transparent and 1 fully opaque. (Values
* of the opacity parameter are clamped to the [0,1] range.) On X11
* this works only on X screens with a compositing manager running.
* of the opacity parameter are clamped to the [0,1] range.)
*
* On X11, this works only on X screens with a compositing manager
* running.
*
* For setting up per-pixel alpha, see gdk_screen_get_rgba_colormap().
* For making non-toplevel windows translucent, see
* gdk_window_set_composited().
*
* Since: 2.12
*/
@ -6455,5 +6479,39 @@ gdk_window_set_opacity (GdkWindow *window,
(guchar *) cardinal, 1);
}
void
_gdk_windowing_window_set_composited (GdkWindow *window,
gboolean composited)
{
#if defined(HAVE_XCOMPOSITE) && defined(HAVE_XDAMAGE) && defined (HAVE_XFIXES)
GdkWindowObject *private = (GdkWindowObject *) window;
GdkDisplayX11 *x11_display;
GdkWindowImplX11 *impl;
GdkDisplay *display;
Display *dpy;
Window xid;
impl = GDK_WINDOW_IMPL_X11 (private->impl);
display = gdk_screen_get_display (GDK_DRAWABLE_IMPL_X11 (impl)->screen);
x11_display = GDK_DISPLAY_X11 (display);
dpy = GDK_DISPLAY_XDISPLAY (display);
xid = GDK_WINDOW_XWINDOW (private);
if (composited)
{
XCompositeRedirectWindow (dpy, xid, CompositeRedirectManual);
impl->damage = XDamageCreate (dpy, xid, XDamageReportBoundingBox);
}
else
{
XCompositeUnredirectWindow (dpy, xid, CompositeRedirectManual);
XDamageDestroy (dpy, impl->damage);
impl->damage = None;
}
#endif
}
#define __GDK_WINDOW_X11_C__
#include "gdkaliasdef.c"

8
gdk/x11/gdkwindow-x11.h
View File

@ -29,6 +29,10 @@
#include <gdk/x11/gdkdrawable-x11.h>
#ifdef HAVE_XDAMAGE
#include <X11/extensions/Xdamage.h>
#endif
#ifdef HAVE_XSYNC
#include <X11/extensions/sync.h>
#endif
@ -79,6 +83,10 @@ struct _GdkWindowImplX11
gint8 toplevel_window_type;
guint override_redirect : 1;
guint use_synchronized_configure : 1;
#if defined (HAVE_XCOMPOSITE) && defined(HAVE_XDAMAGE) && defined (HAVE_XFIXES)
Damage damage;
#endif
};
struct _GdkWindowImplX11Class

141
tests/testgtk.c
View File

@ -420,6 +420,146 @@ create_alpha_window (GtkWidget *widget)
gtk_widget_destroy (window);
}
/*
* Composited non-toplevel window
*/
/* The expose event handler for the event box.
*
* This function simply draws a transparency onto a widget on the area
* for which it receives expose events. This is intended to give the
* event box a "transparent" background.
*
* In order for this to work properly, the widget must have an RGBA
* colourmap. The widget should also be set as app-paintable since it
* doesn't make sense for GTK to draw a background if we are drawing it
* (and because GTK might actually replace our transparency with its
* default background colour).
*/
static gboolean
transparent_expose (GtkWidget *widget,
GdkEventExpose *event)
{
cairo_t *cr;
cr = gdk_cairo_create (widget->window);
cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
gdk_cairo_region (cr, event->region);
cairo_fill (cr);
cairo_destroy (cr);
return FALSE;
}
/* The expose event handler for the window.
*
* This function performs the actual compositing of the event box onto
* the already-existing background of the window at 50% normal opacity.
*
* In this case we do not want app-paintable to be set on the widget
* since we want it to draw its own (red) background. Because of this,
* however, we must ensure that we use g_signal_register_after so that
* this handler is called after the red has been drawn. If it was
* called before then GTK would just blindly paint over our work.
*/
static gboolean
window_expose_event (GtkWidget *widget,
GdkEventExpose *event)
{
GdkRegion *region;
GtkWidget *child;
cairo_t *cr;
/* get our child (in this case, the event box) */
child = gtk_bin_get_child (GTK_BIN (widget));
/* create a cairo context to draw to the window */
cr = gdk_cairo_create (widget->window);
/* the source data is the (composited) event box */
gdk_cairo_set_source_pixmap (cr, child->window,
child->allocation.x,
child->allocation.y);
/* draw no more than our expose event intersects our child */
region = gdk_region_rectangle (&child->allocation);
gdk_region_intersect (region, event->region);
gdk_cairo_region (cr, region);
cairo_clip (cr);
/* composite, with a 50% opacity */
cairo_set_operator (cr, CAIRO_OPERATOR_OVER);
cairo_paint_with_alpha (cr, 0.5);
/* we're done */
cairo_destroy (cr);
return FALSE;
}
void
create_composited_window (GtkWidget *widget)
{
static GtkWidget *window;
if (!window)
{
GtkWidget *event, *button;
GdkScreen *screen;
GdkColormap *rgba;
GdkColor red;
/* make the widgets */
button = gtk_button_new_with_label ("A Button");
event = gtk_event_box_new ();
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
/* put a red background on the window */
gdk_color_parse ("red", &red);
gtk_widget_modify_bg (window, GTK_STATE_NORMAL, &red);
/* set the colourmap for the event box.
* must be done before the event box is realised.
*/
screen = gtk_widget_get_screen (event);
rgba = gdk_screen_get_rgba_colormap (screen);
gtk_widget_set_colormap (event, rgba);
/* set our event box to have a fully-transparent background
* drawn on it. currently there is no way to simply tell gtk
* that "transparency" is the background colour for a widget.
*/
gtk_widget_set_app_paintable (GTK_WIDGET (event), TRUE);
g_signal_connect (event, "expose-event",
G_CALLBACK (transparent_expose), NULL);
/* put them inside one another */
gtk_container_set_border_width (GTK_CONTAINER (window), 10);
gtk_container_add (GTK_CONTAINER (window), event);
gtk_container_add (GTK_CONTAINER (event), button);
/* realise and show everything */
gtk_widget_realize (button);
/* set the event box GdkWindow to be composited.
* obviously must be performed after event box is realised.
*/
gdk_window_set_composited (event->window, TRUE);
/* set up the compositing handler.
* note that we do _after so that the normal (red) background is drawn
* by gtk before our compositing occurs.
*/
g_signal_connect_after (window, "expose-event",
G_CALLBACK (window_expose_event), NULL);
}
if (!GTK_WIDGET_VISIBLE (window))
gtk_widget_show_all (window);
else
gtk_widget_destroy (window);
}
/*
* Big windows and guffaw scrolling
*/
@ -13290,6 +13430,7 @@ struct {
{ "check buttons", create_check_buttons },
{ "clist", create_clist},
{ "color selection", create_color_selection },
{ "composited window", create_composited_window },
{ "ctree", create_ctree },
{ "cursors", create_cursors },
{ "dialog", create_dialog, TRUE },