LayoutManager

Layout managers are delegate classes that handle the preferred size and the allocation of a widget.

You typically subclass gtk.layout_manager.LayoutManager if you want to implement a layout policy for the children of a widget, or if you want to determine the size of a widget depending on its contents.

Each gtk.widget.Widget can only have a gtk.layout_manager.LayoutManager instance associated to it at any given time; it is possible, though, to replace the layout manager instance using gtk.widget.Widget.setLayoutManager.

Layout properties

A layout manager can expose properties for controlling the layout of each child, by creating an object type derived from gtk.layout_child.LayoutChild and installing the properties on it as normal gobject.object.ObjectG properties.

Each gtk.layout_child.LayoutChild instance storing the layout properties for a specific child is created through the gtk.layout_manager.LayoutManager.getLayoutChild method; a gtk.layout_manager.LayoutManager controls the creation of its gtk.layout_child.LayoutChild instances by overriding the GtkLayoutManagerClass.create_layout_child() virtual function. The typical implementation should look like:

static GtkLayoutChild *
create_layout_child (GtkLayoutManager *manager,
                     GtkWidget        *container,
                     GtkWidget        *child)
{
  return g_object_new (your_layout_child_get_type (),
                       "layout-manager", manager,
                       "child-widget", child,
                       NULL);
}

The property@Gtk.LayoutChild:layout-manager and property@Gtk.LayoutChild:child-widget properties on the newly created gtk.layout_child.LayoutChild instance are mandatory. The gtk.layout_manager.LayoutManager will cache the newly created gtk.layout_child.LayoutChild instance until the widget is removed from its parent, or the parent removes the layout manager.

Each gtk.layout_manager.LayoutManager instance creating a gtk.layout_child.LayoutChild should use gtk.layout_manager.LayoutManager.getLayoutChild every time it needs to query the layout properties; each gtk.layout_child.LayoutChild instance should call gtk.layout_manager.LayoutManager.layoutChanged every time a property is updated, in order to queue a new size measuring and allocation.

class LayoutManager : ObjectG {

void allocate(gtk.widget.Widget widget, int width, int height, int baseline);

gtk.layout_child.LayoutChild getLayoutChild(gtk.widget.Widget child);

gtk.types.SizeRequestMode getRequestMode();

gtk.widget.Widget getWidget();

void layoutChanged();

void measure(gtk.widget.Widget widget, gtk.types.Orientation orientation, int forSize, int minimum, int natural, int minimumBaseline, int naturalBaseline);

}

Members

Functions

allocate void allocate(gtk.widget.Widget widget, int width, int height, int baseline): Assigns the given width, height, and baseline to a widget, and computes the position and sizes of the children of the widget using the layout management policy of manager.
getLayoutChild gtk.layout_child.LayoutChild getLayoutChild(gtk.widget.Widget child): Retrieves a gtk.layout_child.LayoutChild instance for the gtk.layout_manager.LayoutManager, creating one if necessary.
getRequestMode gtk.types.SizeRequestMode getRequestMode(): Retrieves the request mode of manager.
getWidget gtk.widget.Widget getWidget(): Retrieves the gtk.widget.Widget using the given gtk.layout_manager.LayoutManager.
layoutChanged void layoutChanged(): Queues a resize on the gtk.widget.Widget using manager, if any.
measure void measure(gtk.widget.Widget widget, gtk.types.Orientation orientation, int forSize, int minimum, int natural, int minimumBaseline, int naturalBaseline): Measures the size of the widget using manager, for the given orientation and size.

Inherited Members

From ObjectG

setGObject void setGObject(void* cObj, Flag!"Take" take): Set the GObject of a D ObjectG wrapper.
cPtr void* cPtr(Flag!"Dup" dup): Get a pointer to the underlying C object.
ref_ void* ref_(void* gObj): Calls g_object_ref() on a GObject.
unref unref(void* gObj): Calls g_object_unref() on a GObject.
getType GType getType(): Get the GType of an object.
gType GType gType [@property getter]: GObject GType property.
self ObjectG self(): Convenience method to return this cast to a type. For use in D with statements.
getDObject T getDObject(void* cptr, Flag!"Take" take): Template to get the D object from a C GObject and cast it to the given D object type.
connectSignalClosure ulong connectSignalClosure(string signalDetail, DClosure closure, Flag!"After" after): Connect a D closure to an object signal.
setProperty void setProperty(string propertyName, T val): Template for setting a GObject property.
getProperty T getProperty(string propertyName): Template for getting a GObject property.
compatControl size_t compatControl(size_t what, void* data)
bindProperty gobject.binding.Binding bindProperty(string sourceProperty, gobject.object.ObjectG target, string targetProperty, gobject.types.BindingFlags flags): Creates a binding between source_property on source and target_property on target.
bindPropertyFull gobject.binding.Binding bindPropertyFull(string sourceProperty, gobject.object.ObjectG target, string targetProperty, gobject.types.BindingFlags flags, gobject.closure.Closure transformTo, gobject.closure.Closure transformFrom): Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.
forceFloating void forceFloating(): This function is intended for #GObject implementations to re-enforce a floating[floating-ref] object reference. Doing this is seldom required: all #GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling gobject.object.ObjectG.refSink.
freezeNotify void freezeNotify(): Increases the freeze count on object. If the freeze count is non-zero, the emission of "notify" signals on object is stopped. The signals are queued until the freeze count is decreased to zero. Duplicate notifications are squashed so that at most one #GObject::notify signal is emitted for each property modified while the object is frozen.
getData void* getData(string key): Gets a named field from the objects table of associations (see gobject.object.ObjectG.setData).
getProperty void getProperty(string propertyName, gobject.value.Value value): Gets a property of an object.
getQdata void* getQdata(glib.types.Quark quark): This function gets back user data pointers stored via gobject.object.ObjectG.setQdata.
getv void getv(string[] names, gobject.value.Value[] values): Gets n_properties properties for an object. Obtained properties will be set to values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.
isFloating bool isFloating(): Checks whether object has a floating[floating-ref] reference.
notify void notify(string propertyName): Emits a "notify" signal for the property property_name on object.
notifyByPspec void notifyByPspec(gobject.param_spec.ParamSpec pspec): Emits a "notify" signal for the property specified by pspec on object.
refSink gobject.object.ObjectG refSink(): Increase the reference count of object, and possibly remove the floating[floating-ref] reference, if object has a floating reference.
runDispose void runDispose(): Releases all references to other objects. This can be used to break reference cycles.
setData void setData(string key, void* data): Each object carries around a table of associations from strings to pointers. This function lets you set an association.
setProperty void setProperty(string propertyName, gobject.value.Value value): Sets a property on an object.
stealData void* stealData(string key): Remove a specified datum from the object's data associations, without invoking the association's destroy handler.
stealQdata void* stealQdata(glib.types.Quark quark): This function gets back user data pointers stored via gobject.object.ObjectG.setQdata and removes the data from object without invoking its destroy() function (if any was set). Usually, calling this function is only required to update user data pointers with a destroy notifier, for example:
thawNotify void thawNotify(): Reverts the effect of a previous call to gobject.object.ObjectG.freezeNotify. The freeze count is decreased on object and when it reaches zero, queued "notify" signals are emitted.
watchClosure void watchClosure(gobject.closure.Closure closure): This function essentially limits the life time of the closure to the life time of the object. That is, when the object is finalized, the closure is invalidated by calling gobject.closure.Closure.invalidate on it, in order to prevent invocations of the closure with a finalized (nonexisting) object. Also, gobject.object.ObjectG.ref_ and gobject.object.ObjectG.unref are added as marshal guards to the closure, to ensure that an extra reference count is held on object during invocation of the closure. Usually, this function will be called on closures that use this object as closure data.
connectNotify ulong connectNotify(string detail, T callback, Flag!"After" after): Connect to Notify signal.

gtk layout_manager classes

LayoutManager