.. include:: /include/substitutions.txt .. _xml_preview:

======= Preview

Overview

In <component> and <widget>, it is possible to define <preview> tags. These are not exported to code and are not loaded from XML.

They are used only by the UI |nbsp| Editor to describe the context of the Component. For example, you might want to:

change the background of the Editor's preview to dark,
center the Component,
set margins,
change the size of the preview.

style_radius can be used to make the preview rounded.

Usage

You can think of a <preview> tag as an lv_obj where the following properties can be used:

width, height
Any local style properties, for example, style_bg_color="0x333"
flex and flex_flow

It is also possible to define multiple previews, and in the UI |nbsp| Editor, you can select one of them.

For Screens

Screens don't support the :ref:<preview> <xml_preview> tag because it doesn't make sense to preview each screen in different resolutions.

As Screens are related to the target hardware in the project.xml file, multiple <display> elements can be defined. In the UI |nbsp| Editor, when a Screen is being developed, the user can select from all the defined displays in the Preview, and the Screen will be shown with the given resolution and color depth.

This is useful for verifying responsive designs.

Example

.. code-block:: xml

<component>
    <previews>

        <preview name="small_dark_round"
                 width="240" height="240"
                 style_bg_color="0x333" style_pad_all="32"
                 style_radius="32"/>

        <preview name="large_light"
                 width="1980" height="1080"
                 style_bg_color="0xeeeeee"/>

    </previews>

    <view>
        ...
    </view>

</component>