vaadin-framework/documentation/layout/layout-orderedlayout.asciidoc

---
title: VerticalLayout and HorizontalLayout
order: 3
layout: page
---

[[layout.orderedlayout]]
= [classname]#VerticalLayout# and [classname]#HorizontalLayout#

[classname]#VerticalLayout# and [classname]#HorizontalLayout# are ordered
layouts for laying components out either vertically or horizontally,
respectively. They both extend from [classname]#AbstractOrderedLayout#, together
with the [classname]#FormLayout#. These are the two most important layout
components in Vaadin, and typically you have a [classname]#VerticalLayout# as
the root content of a UI.

[classname]#VerticalLayout# has 100% default width and undefined height, so it
fills the containing layout (or UI) horizontally, and fits its content
vertically. [classname]#HorizontalLayout# has undefined size in both dimensions.

Typical use of the layouts goes as follows:

[source, java]
----
VerticalLayout vertical = new VerticalLayout ();
vertical.addComponent(new TextField("Name"));
vertical.addComponent(new TextField("Street address"));
vertical.addComponent(new TextField("Postal code"));
layout.addComponent(vertical);
----
See the http://demo.vaadin.com/book-examples-vaadin7/book#layout.orderedlayout.basic[on-line example, window="_blank"].

In [classname]#VerticalLayout#, the captions of child components are placed above each component, so the layout would look as follows:

image::img/orderedlayout_vertical.png[width=30%, scaledwidth=65%]

[classname]#HorizontalLayout# gives the following layout:

image::img/orderedlayout_horizontal.png[width=80%, scaledwidth=100%]

ifdef::web[]
[[layout.orderedlayout.declarative]]
== Declarative Format

Ordered layouts have the following declarative elements:

|===============
|Component|Element Name
|[classname]#VerticalLayout#|[elementname]#v-verticallayout#
|[classname]#HorizontalLayout#|[elementname]#v-horizontallayout#
|[classname]#FormLayout#|[elementname]#v-formlayout#
|===============

The have the following declarative attributes:

[[layout.orderedlayout.properties.table]]
.Properties and Declarative Attributes

[cols="1,2"]
|===============
|Property|Declarative Attribute
|[parameter]#componentAlignment#|Alignment of a child component is specified in the child with: [literal]#++:left++# (default), [literal]#++:center++#, [literal]#++:right++#, [literal]#++:top++# (default), [literal]##++:middle++##, [literal]##++:bottom++##
|[parameter]#spacing#|[parameter]##spacing##++[=++[replaceable]##<boolean>##++]++
|[parameter]#margin#|[parameter]##margin##++[=++[replaceable]##<boolean>##++]++
|[parameter]#expandRatio#|Expand ratio of a child component is specified in the child with: [parameter]#:expand#++[=++[replaceable]##<integer>##++]++ or [parameter]#:expand# (implies ratio 1)
|===============

They can also have any attributes applicable to super classes.

For example:

[source, html]
----
<!-- Use margin and spacing -->
<v-vertical-layout size-full margin spacing>
  <v-label><b>Hello!</b> - How are you?</v-label>

  <!-- Use expand ratio -->
  <v-horizontal-layout size-full :expand>
    ...

    <!-- Use expand ratio -->
    <v-table _id="mytable" caption="My Table"
             size-full :expand/>
  </v-horizontal-layout>

  <v-horizontal-layout width-full>
    ...

    <!-- Use alignment -->
    <v-button :right><b>OK</b></v-button>
  </v-horizontal-layout>
</v-vertical-layout>
----
endif::web[]

[[layout.orderedlayout.spacing]]
== Spacing in Ordered Layouts

The ordered layouts can have spacing between the horizontal or vertical cells.
The spacing can be enabled with [methodname]#setSpacing(true)# or declaratively
with the [literal]#++spacing++# attribute.

The spacing as a default height or width, which can be customized in CSS. You
need to set the height or width for spacing elements with
[literal]#++v-spacing++# style. You also need to specify an enclosing rule
element in a CSS selector, such as [literal]#++v-verticallayout++# for a
[classname]#VerticalLayout# or [literal]#++v-horizontallayout++# for a
[classname]#HorizontalLayout#. You can also use [literal]#++v-vertical++# and
[literal]#++v-horizontal++# for all vertically or horizontally ordered layouts,
such as [classname]#FormLayout#.

For example, the following sets the amount of spacing for all [classname]##VerticalLayout##s (as well as [classname]##FormLayout##s) in the UI:

[source, css]
----
.v-vertical > .v-spacing {
    height: 30px;
}
----

Or for [classname]#HorizontalLayout#:

[source, css]
----
.v-horizontal > .v-spacing {
    width: 50px;
}
----

[[layout.orderedlayout.sizing]]
== Sizing Contained Components

The components contained within an ordered layout can be laid out in a number of
different ways depending on how you specify their height or width in the primary
direction of the layout component.

[[figure.layout.orderedlayout.size.summary]]
.Component widths in [classname]#HorizontalLayout#
image::img/horizontallayout_sizing.png[width=75%, scaledwidth=100%]

<<figure.layout.orderedlayout.size.summary>> gives a summary of the sizing
options for a [classname]#HorizontalLayout#. The figure is broken down in the
following subsections.

[[layout.orderedlayout.sizing.undefined]]
=== Layout with Undefined Size

If a [classname]#VerticalLayout# has undefined height or
[classname]#HorizontalLayout# undefined width, the layout will shrink to fit the
contained components so that there is no extra space between them.


[source, java]
----
HorizontalLayout fittingLayout = new HorizontalLayout();
fittingLayout.setWidth(Sizeable.SIZE_UNDEFINED, 0); // Default
fittingLayout.addComponent(new Button("Small"));
fittingLayout.addComponent(new Button("Medium-sized"));
fittingLayout.addComponent(new Button("Quite a big component"));
parentLayout.addComponent(fittingLayout);
----

The both layouts actually have undefined height by default and
[classname]#HorizontalLayout# has also undefined width, while
[classname]#VerticalLayout# has 100% relative width.

If such a vertical layout with undefined height continues below the bottom of a
window (a [classname]#Window# object), the window will pop up a vertical scroll
bar on the right side of the window area. This way, you get a "web page". The
same applies to [classname]#Panel#.


[WARNING]
.A layout that contains components with percentual size must have a defined size!
====
If a layout has undefined size and a contained component has, say, 100% size,
the component would fill the space given by the layout, while the layout would
shrink to fit the space taken by the component, which would be a paradox. This
requirement holds for height and width separately. The debug window allows
detecting such invalid cases; see
<<dummy/../../../framework/advanced/advanced-debug#advanced.debug.hierarchy,"Inspecting
Component Hierarchy">>.

====

An exception to the above rule is a case where you have a layout with undefined
size that contains a component with a fixed or undefined size together with one
or more components with relative size. In this case, the contained component
with fixed (or undefined) size in a sense defines the size of the containing
layout, removing the paradox. That size is then used for the relatively sized
components.

ifdef::web[]
The technique can be used to define the width of a [classname]#VerticalLayout#
or the height of a [classname]#HorizontalLayout#.


[source, java]
----
// Vertical layout would normally have 100% width
VerticalLayout vertical = new VerticalLayout();

// Shrink to fit the width of contained components
vertical.setWidth(Sizeable.SIZE_UNDEFINED, 0);

// Label has normally 100% width, but we set it as
// undefined so that it will take only the needed space
Label label =
    new Label("\u2190 The VerticalLayout shrinks to fit "+
              "the width of this Label \u2192");
label.setWidth(Sizeable.SIZE_UNDEFINED, 0);
vertical.addComponent(label);

// Button has undefined width by default
Button butt = new Button("\u2190 This Button takes 100% "+
                         "of the width \u2192");
butt.setWidth("100%");
vertical.addComponent(butt);
----
See the http://demo.vaadin.com/book-examples-vaadin7/book#layout.orderedlayout.sizing.sizing-undefined-defining[on-line example, window="_blank"].

[[figure.layout.orderedlayout.sizing.undefined.defining]]
.Defining the Size with a Component
image::img/orderedlayout-sizing-undefined.png[width=50%, scaledwidth=75%]

endif::web[]

=== Layout with Defined Size

If you set a [classname]#HorizontalLayout# to a defined size horizontally or a
[classname]#VerticalLayout# vertically, and there is space left over from the
contained components, the extra space is distributed equally between the
component cells. The components are aligned within these cells according to
their alignment setting, top left by default, as in the example below.


[source, java]
----
fixedLayout.setWidth("400px");
----

Using percentual sizes for components contained in a layout requires answering
the question, "Percentage of what?" There is no sensible default answer for this
question in the current implementation of the layouts, so in practice, you may
not define "100%" size alone.


=== Expanding Components

Often, you want to have one component that takes all the available space left
over from other components. You need to set its size as 100% and set it as
__expanding__ with [methodname]#setExpandRatio()#. The second parameter for the
method is an expansion ratio, which is relevant if there are more than one
expanding component, but its value is irrelevant for a single expanding
component.


[source, java]
----
HorizontalLayout layout = new HorizontalLayout();
layout.setWidth("400px");

// These buttons take the minimum size.
layout.addComponent(new Button("Small"));
layout.addComponent(new Button("Medium-sized"));

// This button will expand.
Button expandButton = new Button("Expanding component");

// Use 100% of the expansion cell's width.
expandButton.setWidth("100%");

// The component must be added to layout before setting the ratio.
layout.addComponent(expandButton);

// Set the component's cell to expand.
layout.setExpandRatio(expandButton, 1.0f);

parentLayout.addComponent(layout);
----

In the declarative format, you need to specify the [literal]#++:expand++#
attribute in the child components. The attribute defaults to expand ratio 1.

Notice that you can not call [methodname]#setExpandRatio()# before you have
added the component to the layout, because it can not operate on an component
that it doesn't yet have.


=== Expand Ratios

If you specify an expand ratio for multiple components, they will all try to use
the available space according to the ratio.


[source, java]
----
HorizontalLayout layout = new HorizontalLayout();
layout.setWidth("400px");

// Create three equally expanding components.
String[] captions = { "Small", "Medium-sized",
                      "Quite a big component" };
for (int i = 1; i <= 3; i++) {
    Button button = new Button(captions[i-1]);
    button.setWidth("100%");
    layout.addComponent(button);

    // Have uniform 1:1:1 expand ratio.
    layout.setExpandRatio(button, 1.0f);
}
----

As the example used the same ratio for all components, the ones with more
content may have the content cut. Below, we use differing ratios:


[source, java]
----
// Expand ratios for the components are 1:2:3.
layout.setExpandRatio(button, i * 1.0f);
----

If the size of the expanding components is defined as a percentage (typically
"100%"), the ratio is calculated from the __overall__ space available for the
relatively sized components. For example, if you have a 100 pixels wide layout
with two cells with 1.0 and 4.0 respective expansion ratios, and both the
components in the layout are set as [methodname]#setWidth("100%")#, the cells
will have respective widths of 20 and 80 pixels, regardless of the minimum size
of the components.

However, if the size of the contained components is undefined or fixed, the
expansion ratio is of the __excess__ available space. In this case, it is the
excess space that expands, not the components.


[source, java]
----
for (int i = 1; i <= 3; i++) {
    // Button with undefined size.
    Button button = new Button(captions[i - 1]);

    layout4.addComponent(button);

    // Expand ratios are 1:2:3.
    layout4.setExpandRatio(button, i * 1.0f);
}
----

It is not meaningful to combine expanding components with percentually defined
size and components with fixed or undefined size. Such combination can lead to a
very unexpected size for the percentually sized components.


=== Percentage of Cells

A percentual size of a component defines the size of the component __within its
cell__. Usually, you use "100%", but a smaller percentage or a fixed size
(smaller than the cell size) will leave an empty space in the cell and align the
component within the cell according to its alignment setting, top left by
default.


[source, java]
----
HorizontalLayout layout50 = new HorizontalLayout();
layout50.setWidth("400px");

String[] captions1 = { "Small 50%", "Medium 50%",
                       "Quite a big 50%" };
for (int i = 1; i <= 3; i++) {
    Button button = new Button(captions1[i-1]);
    button.setWidth("50%");
    layout50.addComponent(button);

    // Expand ratios for the components are 1:2:3.
    layout50.setExpandRatio(button, i * 1.0f);
}
parentLayout.addComponent(layout50);
----