gtk.texi

gtk是linux一款强大的夸平台的图形化开发工具

widget should expand and position itself to fill the area it is
allocated.

@subsection Options

@defopt xscale
@defoptx yscale
The @var{xscale} and @var{yscale} options specify how to scale the child
widget. If the scale value is 0.0, the child widget is allocated exactly
the size it requested in that dimension. If the scale value is 1.0, the
child widget is allocated all of the space in a dimension. A scale value
of 1.0 for both x and y is equivalent to not using an alignment widget.
@end defopt

@defopt xalign
@defoptx yalign
The @var{xalign} and @var{yalign} options specify how to position the
child widget when it is not allocated all the space available to it
(because the @var{xscale} and/or @var{yscale} options are less than
1.0). If an alignment value is 0.0 the widget is positioned to the left
(or top) of its allocated space. An alignment value of 1.0 positions the
widget to the right (or bottom) of its allocated space. A common usage
is to specify @var{xalign} and @var{yalign} to be 0.5 which causes the
widget to be centered within its allocated area.
@end defopt

@subsection Signals

@subsection Functions

@deftypefun guint gtk_alignment_get_type (void)
Returns the @code{GtkAlignment} type identifier.
@end deftypefun

@deftypefun GtkWidget* gtk_alignment_new (gfloat @var{xalign}, gfloat @var{yalign}, gfloat @var{xscale}, gfloat @var{yscale})
Create a new @code{GtkAlignment} object and initialize it with the
values @var{xalign}, @var{yalign}, @var{xscale} and @var{yscale}. The
new widget is returned as a pointer to a @code{GtkWidget}
object. @code{NULL} is returned on failure.
@end deftypefun

@deftypefun void gtk_alignment_set (GtkAlignment *@var{alignment}, gfloat @var{xalign}, gfloat @var{yalign}, gfloat @var{xscale}, gfloat @var{yscale})
Set the @var{xalign}, @var{yalign}, @var{xscale} and @var{yscale} options
of an alignment widget. It is important to not set the fields of the
@code{GtkAlignment} structure directly (or, for that matter, any type
derived from @code{GtkObject}).
@end deftypefun

@gtkstdmacros{Alignment, ALIGNMENT}

@page
@node GtkArrow, GtkAspectFrame, GtkAlignment, Widgets
@comment node-name, next, previous, up
@section The arrow widget

@subsection Description

The arrow widget is derived from the misc widget (@pxref{GtkMisc}) and
is intended for use where a directional arrow (in one of the four
cardinal directions) is desired. As such, it has very limited
functionality and basically only draws itself in a particular direction
and with a particular shadow type. The arrow widget will expand to fill
all the space it is allocated.

@subsection Options

@defopt arrow_type
The @var{arrow_type} option specifies which direction the arrow will
point. It can be one of @code{GTK_ARROW_UP}, @code{GTK_ARROW_DOWN},
@code{GTK_ARROW_LEFT} or @code{GTK_ARROW_RIGHT}. This will set the arrow
pointing in the direction specified.
@end defopt

@defopt shadow_type
The @var{shadow_type} option specifies how to draw the shadow for the
arrow. Currently, only the @code{GTK_SHADOW_IN} and
@code{GTK_SHADOW_OUT} shadow types are supported for drawing
arrows. Other shadow types will cause nothing to be drawn.
@end defopt

@subsection Signals

@subsection Functions

@deftypefun guint gtk_arrow_get_type (void)
Returns the @code{GtkArrow} type identifier.
@end deftypefun

@deftypefun GtkWidget* gtk_arrow_new (GtkArrowType @var{arrow_type}, GtkShadowType @var{shadow_type})
Create a new @code{GtkArrow} object and initialize it with the values
@var{arrow_type} and @var{shadow_type}. The new widget is returned as a
pointer to a @code{GtkWidget} object. @code{NULL} is returned on
failure.
@end deftypefun

@deftypefun void gtk_arrow_set (GtkArrow *@var{arrow}, GtkArrowType @var{arrow_type}, GtkShadowType @var{shadow_type})
Set the @var{arrow_type} and @var{shadow_type} options of an arrow
widget. It is important to not set the fields of the @code{GtkArrow}
structure directly (or, for that matter, any type derived from
@code{GtkObject}).
@end deftypefun

@gtkstdmacros{Arrow, ARROW}


@page
@node GtkAspectFrame, GtkBin, GtkArrow, Widgets
@comment node-name, next, previous, upa
@section The aspect frame widget

@subsection Description

Ensure that the child window has a specified aspect ratio or, if
obey_child, has the same aspect ratio as its requested size.  Derived
from @pxref{GtkFrame}).

@subsection Options

@defopt label
@end defopt

@defopt xalign
@end defopt

@defopt yalign
@end defopt

@defopt ratio
@end defopt

@defopt obey_child
@end defopt

@subsection Signals

@subsection Functions

@deftypefun guint gtk_aspect_frame_get_type (void)
Returns the @code{GtkAspectFrame} type identifier.
@end deftypefun

@deftypefun GtkWidget* gtk_aspect_frame_new (gchar *@var{label}, gfloat @var{xalign}, gfloat @var{yalign}, gfloat @var{ratio}, gint @var{obey_child})
Create a new @code{GtkAspectFrame} object and initialize it with the values 
@var{label}, @var{xalign}, @var{yalign}, @var{ratio} and @var{obey_child}.
The new widget is returned as a pointer to a @code{GtkWidget} object. 
@code{NULL} is returned on failure.
@end deftypefun

@deftypefun void gtk_aspect_frame_set (GtkAspectFrame *@var{aspect_frame}, gfloat @var{xalign}, gfloat @var{yalign}, gfloat @var{ratio}, gint @var{obey_child})
@end deftypefun


@gtkstdmacros{AspectFrame, ASPECT_FRAME}

@page
@node GtkBin, GtkBox, GtkAspectFrame, Widgets
@comment node-name, next, previous, up
@section The bin widget

@subsection Description

The bin widget is a container (@pxref{GtkContainer}) derived from the
container widget. It is an abstract base class. That is, it is not
possible to create an actual bin widget. It exists only to provide a
base of functionality for other widgets. Specifically, the bin widget
provides a base for several other widgets that contain only a single
child. These widgets include alignments (@pxref{GtkAlignment}), frames
(@pxref{GtkFrame}), items (@pxref{GtkItem}), viewports
(@pxref{GtkViewport}) and windows (@pxref{GtkWindow})

@subsection Options

@subsection Signals

@subsection Functions

@deftypefun guint gtk_bin_get_type (void)
Returns the @code{GtkBin} type identifier.
@end deftypefun

@gtkstdmacros{Bin, BIN}


@page
@node GtkBox, GtkButtonBox, GtkBin, Widgets
@comment node-name, next, previous, up
@section The box widget


@subsection Description

The box widget is a container (@pxref{GtkContainer}) derived from the
container widget. It is an abstract base class used by the horizontal
box (@pxref{GtkHBox}), the vertical box (@pxref{GtkVBox}) and the 
(@pxref{GtkButtonBox}) widgets to provide a base of common functionality.

A box provides an abstraction for organizing the position and size of
widgets. Widgets in a box are laid out horizontally or vertically. By
using a box widget appropriately, a programmer can control how widgets
are positioned and how they will be allocated space when a window gets
resized.

The key attribute of boxes is that they position their children in a
single row (horizontal boxes) or column (vertical boxes). In the case of
horizontal boxes, all children are stretched vertically. The vertical
size of the box is determined by the largest vertical requisition of all
of its children. Similarly, a vertical box stretches all of its children
horizontally. The horizontal size (of the vertical box) is determined by
the largest horizontal requisition of all of its children. An alignment
widget (@pxref{GtkAlignment}) can be used to control child allocation
more precisely on a per child basis.

The second attribute of boxes is how they expand children. In the case
of a horizontal box, the main control is over how children are expanded
horizontally to fill the allocated area. (The rest of this discussion
will focus on horizontal boxes but it applies to vertical boxes as
well).

There are two flags which can be set controlling how a widget is
expanded horizontally in a horizontal box. These are the @code{expand}
and @code{fill}. There operation is fairly simple. If @code{expand} is
set, the child's potentially allocated area will expand to fill available
space. If @code{fill} is set, the child's actual allocated area will be
its potentially allocated area. There is a difference between
the potentially area (which is the area the box widget sets aside for
the child) and the actual allocated area (which is the area the box
widget actual allocates for the widget via
@code{gtk_widget_size_allocate}).

The allocation of space to children occurs as follows (for horizontal
boxes):
@enumerate
@item
All children are allocated at least their requested size horizontally
and the maximum requested child size vertically.

@item
Any child with the @code{expand} flag set is allocated @code{extra_width
/ nexpand_children} extra pixels horizontally. If the @code{homogeneous}
flag was set, all children are considered to have the @code{expand} flag
set. That is, all children will be allocated the same area.The
horizontal box is a fair widget and, as such, divides up any extra
allocated space evenly among the ``expand'' children. (Those children
which have the @code{expand} flag set). The exception occurs when
@code{extra_width / nexpand_children} does not divide cleanly. The extra
space is given to the last widget.

@item
@code{spacing} number of pixels separate each child. Note: The
separation is between the potentially allocated area for each child and
not the actual allocated area. The @code{padding} value associated with
each child causes that many pixels to be left empty to each side of the
child.

@item
If a child has the @code{fill} flag set it is allocated its potentially
allocated area. If it does not, it is allocated its requested size
horizontally and centered within its potentially allocated area. Its
vertical allocation is still the maximum requested size of any child.

@item
Children placed at the start of the box are placed in order of addition
to the box from left to right in the boxes allocated area.. Children
placed at the end of the box are placed in order of addition from right
to left in the boxes allocated area.
@end enumerate

@xref{GtkHBox}, and @ref{GtkVBox}, for code examples of using horizontal
and vertical boxes.

@subsection Options

@defopt expand
@end defopt

@defopt fill
@end defopt

@defopt padding
@end defopt

@defopt expand
@end defopt

@c FIXME: options for GtkBox

@subsection Signals

@subsection Functions

@deftypefun guint gtk_box_get_type (void)
Returns the @code{GtkBox} type identifier.
@end deftypefun

@deftypefun void gtk_box_pack_start (GtkBox *@var{box}, GtkWidget *@var{child}, gint @var{expand}, gint @var{fill}, gint @var{padding})
Add @var{child} to the front of @var{box}. The flags @var{expand} and
@var{fill} and the padding value of @var{padding} are associated with
@var{child}.
@end deftypefun

@deftypefun void gtk_box_pack_en