Commit ff61948d authored by Tadej Borovšak's avatar Tadej Borovšak Committed by Javier Jardon
Browse files

Move documentation to inline comments: GdkWindow

Use examples/gdk to store documentation code examples.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=618498

Signed-off-by: Javier Jardon's avatarJavier Jardón <jjardon@gnome.org>
parent 47dd78a7
<!-- ##### SECTION Title ##### -->
Windows
<!-- ##### SECTION Short_Description ##### -->
Onscreen display areas in the target window system
<!-- ##### SECTION Long_Description ##### -->
<para>
A #GdkWindow is a rectangular region on the screen. It's a low-level object,
used to implement high-level objects such as #GtkWidget and #GtkWindow on the
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>
<refsect2 id="COMPOSITED-WINDOWS"><title>Composited Windows</title>
<para>
Normally, the windowing system takes care of rendering the contents of a child
window onto its parent window. This mechanism can be intercepted by calling
gdk_window_set_composited() on the child window. For a
<firstterm>composited</firstterm> window it is the responsibility of the
application to render the window contents at the right spot.
</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_connect_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 1.6
* 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>
</refsect2>
<refsect2 id="OFFSCREEN-WINDOWS"><title>Offscreen Windows</title>
<para>
Offscreen windows are more general than composited windows, since they
allow not only to modify the rendering of the child window onto its parent,
but also to apply coordinate transformations.
</para>
<para>
To integrate an offscreen window into a window hierarchy, one has to call
gdk_offscreen_window_set_embedder() and handle a number of signals. The
#GdkWindow::pick-embedded-child signal on the embedder window is used to
select an offscreen child at given coordinates, and the #GdkWindow::to-embedder
and #GdkWindow::from-embedder signals on the offscreen window are used to
translate coordinates between the embedder and the offscreen window.
</para>
<para>
For rendering an offscreen window onto its embedder, the contents of the
offscreen window are available as a pixmap, via
gdk_offscreen_window_get_pixmap().
</para>
</refsect2>
<!-- ##### SECTION See_Also ##### -->
<para>
</para>
<!-- ##### SECTION Stability_Level ##### -->
<!-- ##### SECTION Image ##### -->
<!-- ##### TYPEDEF GdkWindow ##### -->
<para>
An opaque structure representing an onscreen drawable.
Pointers to structures of type #GdkPixmap, #GdkBitmap,
and #GdkWindow, can often be used interchangeably.
The type #GdkDrawable refers generically to any of
these types.
</para>
<!-- ##### SIGNAL GdkWindow::from-embedder ##### -->
<para>
</para>
@gdkwindow: the object which received the signal.
@arg1:
@arg2:
@arg3:
@arg4:
<!-- ##### SIGNAL GdkWindow::pick-embedded-child ##### -->
<para>
</para>
@gdkwindow: the object which received the signal.
@arg1:
@arg2:
@Returns:
<!-- ##### SIGNAL GdkWindow::to-embedder ##### -->
<para>
</para>
@gdkwindow: the object which received the signal.
@arg1:
@arg2:
@arg3:
@arg4:
<!-- ##### ARG GdkWindow:cursor ##### -->
<para>
</para>
<!-- ##### ENUM GdkWindowType ##### -->
<para>
Describes the kind of window.
</para>
@GDK_WINDOW_ROOT: root window; this window has no parent, covers the entire screen, and is created by the window system
@GDK_WINDOW_TOPLEVEL: toplevel window (used to implement #GtkWindow)
@GDK_WINDOW_CHILD: child window (used to implement e.g. #GtkEntry)
@GDK_WINDOW_DIALOG: useless/deprecated compatibility type
@GDK_WINDOW_TEMP: override redirect temporary window (used to implement #GtkMenu)
@GDK_WINDOW_FOREIGN: foreign window (see gdk_window_foreign_new())
@GDK_WINDOW_OFFSCREEN: offscreen window (see <xref linkend="OFFSCREEN-WINDOWS"/>). Since 2.18
<!-- ##### ENUM GdkWindowClass ##### -->
<para>
@GDK_INPUT_OUTPUT windows are the standard kind of window you might expect.
@GDK_INPUT_ONLY windows are invisible; they are used to trap events, but
you can't draw on them.
</para>
@GDK_INPUT_OUTPUT: window for graphics and events
@GDK_INPUT_ONLY: window for events only
<!-- ##### ENUM GdkWindowHints ##### -->
<para>
Used to indicate which fields of a #GdkGeometry struct should be paid attention
to. Also, the presence/absence of @GDK_HINT_POS, @GDK_HINT_USER_POS, and
@GDK_HINT_USER_SIZE is significant, though they don't directly refer to
#GdkGeometry fields. @GDK_HINT_USER_POS will be set automatically by #GtkWindow
if you call gtk_window_move(). @GDK_HINT_USER_POS and @GDK_HINT_USER_SIZE
should be set if the user specified a size/position using a --geometry
command-line argument; gtk_window_parse_geometry() automatically sets these
flags.
</para>
@GDK_HINT_POS: indicates that the program has positioned the window
@GDK_HINT_MIN_SIZE: min size fields are set
@GDK_HINT_MAX_SIZE: max size fields are set
@GDK_HINT_BASE_SIZE: base size fields are set
@GDK_HINT_ASPECT: aspect ratio fields are set
@GDK_HINT_RESIZE_INC: resize increment fields are set
@GDK_HINT_WIN_GRAVITY: window gravity field is set
@GDK_HINT_USER_POS: indicates that the window's position was explicitly set by the user
@GDK_HINT_USER_SIZE: indicates that the window's size was explicitly set by the user
<!-- ##### STRUCT GdkGeometry ##### -->
<para>
The #GdkGeometry struct gives the window manager information about
a window's geometry constraints. Normally you would set these on
the GTK+ level using gtk_window_set_geometry_hints(). #GtkWindow
then sets the hints on the #GdkWindow it creates.
</para>
<para>
gdk_window_set_geometry_hints() expects the hints to be fully valid already and
simply passes them to the window manager; in contrast,
gtk_window_set_geometry_hints() performs some interpretation. For example,
#GtkWindow will apply the hints to the geometry widget instead of the toplevel
window, if you set a geometry widget. Also, the
@min_width/@min_height/@max_width/@max_height fields may be set to -1, and
#GtkWindow will substitute the size request of the window or geometry widget. If
the minimum size hint is not provided, #GtkWindow will use its requisition as
the minimum size. If the minimum size is provided and a geometry widget is set,
#GtkWindow will take the minimum size as the minimum size of the geometry widget
rather than the entire window. The base size is treated similarly.
</para>
<para>
The canonical use-case for gtk_window_set_geometry_hints() is to get a terminal
widget to resize properly. Here, the terminal text area should be the geometry
widget; #GtkWindow will then automatically set the base size to the size of
other widgets in the terminal window, such as the menubar and scrollbar. Then,
the @width_inc and @height_inc fields should be set to the size of one character
in the terminal. Finally, the base size should be set to the size of one
character. The net effect is that the minimum size of the terminal
will have a 1x1 character terminal area, and only terminal sizes on
the "character grid" will be allowed.
</para>
<para>
Here's an example of how the terminal example would be implemented, assuming
a terminal area widget called "terminal" and a toplevel window "toplevel":
<informalexample><programlisting>
GdkGeometry hints;
hints.base_width = terminal->char_width;
hints.base_height = terminal->char_height;
hints.min_width = terminal->char_width;
hints.min_height = terminal->char_height;
hints.width_inc = terminal->char_width;
hints.height_inc = terminal->char_height;
gtk_window_set_geometry_hints (GTK_WINDOW (toplevel),
GTK_WIDGET (terminal),
&amp;hints,
GDK_HINT_RESIZE_INC |
GDK_HINT_MIN_SIZE |
GDK_HINT_BASE_SIZE);
</programlisting></informalexample>
</para>
<para>
The other useful fields are the @min_aspect and @max_aspect fields; these
contain a width/height ratio as a floating point number. If a geometry widget is
set, the aspect applies to the geometry widget rather than the entire window.
The most common use of these hints is probably to set @min_aspect and
@max_aspect to the same value, thus forcing the window to keep a constant aspect
ratio.
</para>
@min_width: minimum width of window (or -1 to use requisition, with #GtkWindow only)
@min_height: minimum height of window (or -1 to use requisition, with #GtkWindow only)
@max_width: maximum width of window (or -1 to use requisition, with #GtkWindow only)
@max_height: maximum height of window (or -1 to use requisition, with #GtkWindow only)
@base_width: allowed window widths are @base_width + @width_inc * N where N is any integer (-1 allowed with #GtkWindow)
@base_height: allowed window widths are @base_height + @height_inc * N where N is any integer (-1 allowed with #GtkWindow)
@width_inc: width resize increment
@height_inc: height resize increment
@min_aspect: minimum width/height ratio
@max_aspect: maximum width/height ratio
@win_gravity: window gravity, see gtk_window_set_gravity()
<!-- ##### ENUM GdkGravity ##### -->
<para>
Defines the reference point of a window and the meaning of coordinates
passed to gtk_window_move(). See gtk_window_move() and the "implementation
notes" section of the
<ulink url="http://www.freedesktop.org/Standards/wm-spec">Extended
Window Manager Hints</ulink> specification for more details.
</para>
@GDK_GRAVITY_NORTH_WEST: the reference point is at the top left corner.
@GDK_GRAVITY_NORTH: the reference point is in the middle of the top edge.
@GDK_GRAVITY_NORTH_EAST: the reference point is at the top right corner.
@GDK_GRAVITY_WEST: the reference point is at the middle of the left edge.
@GDK_GRAVITY_CENTER: the reference point is at the center of the window.
@GDK_GRAVITY_EAST: the reference point is at the middle of the right edge.
@GDK_GRAVITY_SOUTH_WEST: the reference point is at the lower left corner.
@GDK_GRAVITY_SOUTH: the reference point is at the middle of the lower edge.
@GDK_GRAVITY_SOUTH_EAST: the reference point is at the lower right corner.
@GDK_GRAVITY_STATIC: the reference point is at the top left corner of the
window itself, ignoring window manager decorations.
<!-- ##### ENUM GdkWindowEdge ##### -->
<para>
Determines a window edge or corner.
</para>
@GDK_WINDOW_EDGE_NORTH_WEST: the top left corner.
@GDK_WINDOW_EDGE_NORTH: the top edge.
@GDK_WINDOW_EDGE_NORTH_EAST: the top right corner.
@GDK_WINDOW_EDGE_WEST: the left edge.
@GDK_WINDOW_EDGE_EAST: the right edge.
@GDK_WINDOW_EDGE_SOUTH_WEST: the lower left corner.
@GDK_WINDOW_EDGE_SOUTH: the lower edge.
@GDK_WINDOW_EDGE_SOUTH_EAST: the lower right corner.
<!-- ##### ENUM GdkWindowTypeHint ##### -->
<para>
These are hints for the window manager that indicate what type of function
the window has. The window manager can use this when determining decoration
and behaviour of the window. The hint must be set before mapping the window.
</para>
<para>
See the
<ulink url="http://www.freedesktop.org/Standards/wm-spec">Extended
Window Manager Hints</ulink> specification for more details about
window types.
</para>
@GDK_WINDOW_TYPE_HINT_NORMAL: Normal toplevel window.
@GDK_WINDOW_TYPE_HINT_DIALOG: Dialog window.
@GDK_WINDOW_TYPE_HINT_MENU: Window used to implement a menu; GTK+ uses
this hint only for torn-off menus, see #GtkTearoffMenuItem.
@GDK_WINDOW_TYPE_HINT_TOOLBAR: Window used to implement toolbars.
@GDK_WINDOW_TYPE_HINT_SPLASHSCREEN: Window used to display a splash
screen during application startup.
@GDK_WINDOW_TYPE_HINT_UTILITY: Utility windows which are not detached
toolbars or dialogs.
@GDK_WINDOW_TYPE_HINT_DOCK: Used for creating dock or panel windows.
@GDK_WINDOW_TYPE_HINT_DESKTOP: Used for creating the desktop background
window.
@GDK_WINDOW_TYPE_HINT_DROPDOWN_MENU: A menu that belongs to a menubar.
@GDK_WINDOW_TYPE_HINT_POPUP_MENU: A menu that does not belong to a menubar,
e.g. a context menu.
@GDK_WINDOW_TYPE_HINT_TOOLTIP: A tooltip.
@GDK_WINDOW_TYPE_HINT_NOTIFICATION: A notification - typically a "bubble"
that belongs to a status icon.
@GDK_WINDOW_TYPE_HINT_COMBO: A popup from a combo box.
@GDK_WINDOW_TYPE_HINT_DND: A window that is used to implement a DND cursor.
<!-- ##### STRUCT GdkWindowAttr ##### -->
<para>
Attributes to use for a newly-created window.
</para>
@title: title of the window (for toplevel windows)
@event_mask: event mask (see gdk_window_set_events())
@x: X coordinate relative to parent window (see gdk_window_move())
@y: Y coordinate relative to parent window (see gdk_window_move())
@width: width of window
@height: height of window
@wclass: #GDK_INPUT_OUTPUT (normal window) or #GDK_INPUT_ONLY (invisible window that receives events)
@visual: #GdkVisual for window
@colormap: #GdkColormap for window
@window_type: type of window
@cursor: cursor for the window (see gdk_window_set_cursor())
@wmclass_name: don't use (see gtk_window_set_wmclass())
@wmclass_class: don't use (see gtk_window_set_wmclass())
@override_redirect: %TRUE to bypass the window manager
@type_hint: a hint of the function of the window
<!-- ##### ENUM GdkWindowAttributesType ##### -->
<para>
Used to indicate which fields in the #GdkWindowAttr struct should be
honored. For example, if you filled in the "cursor" and "x" fields of
#GdkWindowAttr, pass "@GDK_WA_X | @GDK_WA_CURSOR" to gdk_window_new(). Fields
in #GdkWindowAttr not covered by a bit in this enum are required; for example,
the @width/@height, @wclass, and @window_type fields are required, they have no
corresponding flag in #GdkWindowAttributesType.
</para>
@GDK_WA_TITLE: Honor the title field
@GDK_WA_X: Honor the X coordinate field
@GDK_WA_Y: Honor the Y coordinate field
@GDK_WA_CURSOR: Honor the cursor field
@GDK_WA_COLORMAP: Honor the colormap field
@GDK_WA_VISUAL: Honor the visual field
@GDK_WA_WMCLASS: Honor the wmclass_class and wmclass_name fields
@GDK_WA_NOREDIR: Honor the override_redirect field
@GDK_WA_TYPE_HINT: Honor the type_hint field
<!-- ##### FUNCTION gdk_window_new ##### -->
<para>
</para>
@parent:
@attributes:
@attributes_mask:
@Returns:
<!-- ##### FUNCTION gdk_window_destroy ##### -->
<para>
</para>
@window:
<!-- ##### FUNCTION gdk_window_get_window_type ##### -->
<para>
</para>
@window:
@Returns:
<!-- ##### FUNCTION gdk_window_at_pointer ##### -->
<para>
</para>
@win_x:
@win_y:
@Returns:
<!-- ##### FUNCTION gdk_window_show ##### -->
<para>
</para>
@window:
<!-- ##### FUNCTION gdk_window_show_unraised ##### -->
<para>
</para>
@window:
<!-- ##### FUNCTION gdk_window_hide ##### -->
<para>
</para>
@window:
<!-- ##### FUNCTION gdk_window_is_destroyed ##### -->
<para>
</para>
@window:
@Returns:
<!-- ##### FUNCTION gdk_window_is_visible ##### -->
<para>
</para>
@window:
@Returns:
<!-- ##### FUNCTION gdk_window_is_viewable ##### -->
<para>
</para>
@window:
@Returns:
<!-- ##### FUNCTION gdk_window_get_state ##### -->
<para>
</para>
@window:
@Returns:
<!-- ##### FUNCTION gdk_window_withdraw ##### -->
<para>
</para>
@window:
<!-- ##### FUNCTION gdk_window_iconify ##### -->
<para>
</para>
@window:
<!-- ##### FUNCTION gdk_window_deiconify ##### -->
<para>
</para>
@window:
<!-- ##### FUNCTION gdk_window_stick ##### -->
<para>
</para>
@window:
<!-- ##### FUNCTION gdk_window_unstick ##### -->
<para>
</para>
@window:
<!-- ##### FUNCTION gdk_window_maximize ##### -->
<para>
</para>
@window:
<!-- ##### FUNCTION gdk_window_unmaximize ##### -->
<para>