Windows Onscreen display areas in the target window system 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. Composited Windows 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 composited window it is the responsibility of the application to render the window contents at the right spot. Composited windows /* 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; } ]]> In the 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. 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. 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. Offscreen Windows 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. 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. 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(). 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. @gdkwindow: the object which received the signal. @arg1: @arg2: @arg3: @arg4: @gdkwindow: the object which received the signal. @arg1: @arg2: @Returns: @gdkwindow: the object which received the signal. @arg1: @arg2: @arg3: @arg4: Describes the kind of window. @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 ). Since 2.18 @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. @GDK_INPUT_OUTPUT: window for graphics and events @GDK_INPUT_ONLY: window for events only 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. @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 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. 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. 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. Here's an example of how the terminal example would be implemented, assuming a terminal area widget called "terminal" and a toplevel window "toplevel": 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), &hints, GDK_HINT_RESIZE_INC | GDK_HINT_MIN_SIZE | GDK_HINT_BASE_SIZE); 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. @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() 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 Extended Window Manager Hints specification for more details. @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. Determines a window edge or corner. @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. 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. See the Extended Window Manager Hints specification for more details about window types. @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. Attributes to use for a newly-created window. @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 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. @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 @parent: @attributes: @attributes_mask: @Returns: @window: Deprecated equivalent of g_object_ref() @Returns: the window Deprecated equivalent of g_object_unref() @window: @Returns: @win_x: @win_y: @Returns: @window: @window: @window: @window: @Returns: @window: @Returns: @window: @Returns: @window: @Returns: @window: @window: @window: @window: @window: @window: @window: @window: @window: @window: @setting: @window: @setting: @window: @opacity: @window: @composited: @window: @x: @y: @window: @width: @height: @window: @x: @y: @width: @height: @window: @dx: @dy: @window: @region: @dx: @dy: @window: @window: @Returns: @window: @new_parent: @x: @y: @window: @window: @x: @y: @width: @height: @window: @x: @y: @width: @height: Deprecated equivalent to gdk_draw_drawable(), see that function for docs @drawable: a #GdkDrawable @gc: a #GdkGC sharing the drawable's visual and colormap @x: X position in @drawable where the rectangle should be drawn @y: Y position in @drawable where the rectangle should be drawn @source_drawable: the source #GdkDrawable, which may be the same as @drawable @source_x: X position in @src of rectangle to draw @source_y: Y position in @src of rectangle to draw @width: width of rectangle to draw, or -1 for entire @src width @height: height of rectangle to draw, or -1 for entire @src height @drawable: a #GdkDrawable @xdest: X position in @drawable where the rectangle should be drawn @ydest: Y position in @drawable where the rectangle should be drawn @window: @window: @window: @sibling: @above: @window: @timestamp: Registers a window as a potential drop destination. @window: a #GdkWindow. @window: @edge: @button: @root_x: @root_y: @timestamp: @window: @button: @root_x: @root_y: @timestamp: @geometry: @flags: @width: @height: @new_width: @new_height: @window: @window: @rectangle: @window: @region: @window: @window: @rect: @invalidate_children: @window: @region: @invalidate_children: @window: @region: @GdkWindow *, gpointer: @GdkWindow *, gpointer: @user_data: @window: @Returns: @window: @window: @void: @window: @update_children: @setting: @window: @real_drawable: @x_offset: @y_offset: @window: @window: @window: @user_data: @window: @override_redirect: @window: @accept_focus: @window: @focus_on_map: @window: @function: @data: @window: @function: @data: Specifies the type of function used to filter native events before they are converted to GDK events. When a filter is called, @event is unpopulated, except for event->window. The filter may translate the native event to a GDK event and store the result in @event, or handle it without translation. If the filter translates the event and processing should continue, it should return GDK_FILTER_TRANSLATE. @xevent: the native event to filter. @event: the GDK event to which the X event will be translated. @data: user data set when the filter was installed. @Returns: a #GdkFilterReturn value. Specifies the result of applying a #GdkFilterFunc to a native event. @GDK_FILTER_CONTINUE: event not handled, continue processing. @GDK_FILTER_TRANSLATE: native event translated into a GDK event and stored in the event structure that was passed in. @GDK_FILTER_REMOVE: event handled, terminate processing. Used to represent native events (XEvents for the X11 backend, MSGs for Win32). @window: @mask: @x: @y: @window: @shape_region: @offset_x: @offset_y: @window: @window: @window: @mask: @x: @y: @window: @shape_region: @offset_x: @offset_y: @window: @window: @window: @use_static: @Returns: @window: @x: @y: @min_width: @min_height: @max_width: @max_height: @flags: @window: @title: @window: @color: @window: @pixmap: @parent_relative: A special value for GdkPixmap* variables, indicating that the background pixmap for a window should be inherited from the parent window. @window: @cursor: @window: @Returns: Deprecated equivalent to gdk_drawable_set_colormap() @window: @data: @window: @x: @y: @width: @height: @depth: @window: @geometry: @geom_mask: @window: @pixbufs: @window: @modal: @window: @hint: @window: @Returns: @window: @skips_taskbar: @window: @skips_pager: @window: @urgent: @window: @x: @y: @window: @x: @y: @window: @rect: Deprecated equivalent of gdk_drawable_get_size(). Deprecated equivalent of gdk_drawable_get_visual(). @Returns: the #GdkVisual of the window Deprecated equivalent of gdk_drawable_get_colormap(). @Returns: colormap for the window Deprecated equivalent of gdk_drawable_get_type(). @Returns: type of drawable @window: @x: @y: @Returns: @window: @x: @y: @Returns: @window: @x: @y: @root_x: @root_y: @window: @x: @y: @mask: @Returns: A set of bit-flags to indicate the state of modifier keys and mouse buttons in various event types. Typical modifier keys are Shift, Control, Meta, Super, Hyper, Alt, Compose, Apple, CapsLock or ShiftLock. Like the X Window System, GDK supports 8 modifier keys and 5 mouse buttons. Since 2.10, GDK recognizes which of the Meta, Super or Hyper keys are mapped to Mod2 - Mod5, and indicates this by setting %GDK_SUPER_MASK, %GDK_HYPER_MASK or %GDK_META_MASK in the state field of key events. @GDK_SHIFT_MASK: the Shift key. @GDK_LOCK_MASK: a Lock key (depending on the modifier mapping of the X server this may either be CapsLock or ShiftLock). @GDK_CONTROL_MASK: the Control key. @GDK_MOD1_MASK: the fourth modifier key (it depends on the modifier mapping of the X server which key is interpreted as this modifier, but normally it is the Alt key). @GDK_MOD2_MASK: the fifth modifier key (it depends on the modifier mapping of the X server which key is interpreted as this modifier). @GDK_MOD3_MASK: the sixth modifier key (it depends on the modifier mapping of the X server which key is interpreted as this modifier). @GDK_MOD4_MASK: the seventh modifier key (it depends on the modifier mapping of the X server which key is interpreted as this modifier). @GDK_MOD5_MASK: the eighth modifier key (it depends on the modifier mapping of the X server which key is interpreted as this modifier). @GDK_BUTTON1_MASK: the first mouse button. @GDK_BUTTON2_MASK: the second mouse button. @GDK_BUTTON3_MASK: the third mouse button. @GDK_BUTTON4_MASK: the fourth mouse button. @GDK_BUTTON5_MASK: the fifth mouse button. @GDK_SUPER_MASK: the Super modifier. Since 2.10 @GDK_HYPER_MASK: the Hyper modifier. Since 2.10 @GDK_META_MASK: the Meta modifier. Since 2.10 @GDK_RELEASE_MASK: not used in GDK itself. GTK+ uses it to differentiate between (keyval, modifiers) pairs from key press and release events. @GDK_MODIFIER_MASK: a mask covering all modifier types. @window: @Returns: @window: @Returns: @window: @Returns: @window: @Returns: @window: @Returns: @window: @event_mask: @window: @icon_window: @pixmap: @mask: @window: @name: @window: @parent: @window: @role: @window: @startup_id: @window: @leader: @window: @Returns: @window: @decorations: @window: The window to get the decorations from @decorations: The window decorations will be written here @Returns: %TRUE if the window has decorations set, %FALSE otherwise. These are hints originally defined by the Motif toolkit. The window manager can use them when determining how to decorate the window. The hint must be set before mapping the window. @GDK_DECOR_ALL: all decorations should be applied. @GDK_DECOR_BORDER: a frame should be drawn around the window. @GDK_DECOR_RESIZEH: the frame should have resize handles. @GDK_DECOR_TITLE: a titlebar should be placed above the window. @GDK_DECOR_MENU: a button for opening a menu should be included. @GDK_DECOR_MINIMIZE: a minimize button should be included. @GDK_DECOR_MAXIMIZE: a maximize button should be included. @window: @functions: These are hints originally defined by the Motif toolkit. The window manager can use them when determining the functions to offer for the window. The hint must be set before mapping the window. @GDK_FUNC_ALL: all functions should be offered. @GDK_FUNC_RESIZE: the window should be resizable. @GDK_FUNC_MOVE: the window should be movable. @GDK_FUNC_MINIMIZE: the window should be minimizable. @GDK_FUNC_MAXIMIZE: the window should be maximizable. @GDK_FUNC_CLOSE: the window should be closable. @void: @Returns: @void: @Returns: A table of pointers to functions for getting quantities related to the current pointer position. GDK has one global table of this type, which can be set using gdk_set_pointer_hooks(). This is only useful for such low-level tools as an event recorder. Applications should never have any reason to use this facility @get_pointer: Obtains the current pointer position and modifier state. The position is given in coordinates relative to the window containing the pointer, which is returned in @window. @window_at_pointer: Obtains the window underneath the mouse pointer, returning the location of that window in @win_x, @win_y. Returns %NULL if the window under the mouse pointer is not known to GDK (for example, belongs to another application). @new_hooks: @Returns: @window: @Returns: @window: @embedder: @window: @Returns: @window: @window: @drawable: @src_x: @src_y: @dest_x: @dest_y: @width: @height: @window: