Scrolling to a specific item in a list can be triggered via behaviors. The scroll action can be used in <list> and <section-list>. It is paired with a target attribute, that defines where the scroll position should be set to, and it accepts a couple optional attributes that help configuring the behavior.

Here's an example of a button that will cause a list to scroll back to the top, with an animation:

<list>
  <item id="top"><text>Item 1</text></item>
  <item><text>Item 1</text></item>
  <item><text>Item 1</text></item>
  ...
  <item>
    <text>Item 100</text>
    <view style="Button">
      <behavior
        xmlns:scroll="https://hyperview.org/hyperview-scroll"
        action="scroll"
        trigger="press"
        target="top"
        scroll:animated="true"
      />
      <text style="Button__Label">Scroll to top</text>
    </view>
  </item>
</list>

Structure

Scroll behaviors are created using the standard <behavior> element. To trigger a scroll behavior, just set the action attribute to "scroll", and set a target to an element that exists and is nested under the list you're targetting.

NOTES:

The behavior should also be defined as a nested child of the list.
The target element can either be set with the id attribute value of an <item> element of the list, or a child element of an <item>. When the target is a child of an <item>, Hyperview will perform the scroll to the parent <item>. You can further refine the scroll position by using one of the configuring attributes (see below).

Attributes that configure the scroll behavior require their own namespace:

https://hyperview.org/hyperview-scroll

It's usually convenient to define the XML namespace on the <behavior> element too:

<behavior
  xmlns:scroll="https://hyperview.org/hyperview-scroll"
  trigger="longPress"
  action="scroll"
  target="some-id"
/>

Note that any standard trigger can be used, as long as it's supported by the element containing the <behavior>.

The shared message and url are defined as namespaced attributes on the <behavior> element:

<behavior
  xmlns:scroll="https://hyperview.org/hyperview-scroll"
  trigger="longPress"
  action="scroll"
  target="some-id"
  scroll:animated="true"
  scroll:offset="100"
  scroll:position="0.5"
/>

Scroll attributes

The following attributes are part of the https://hyperview.org/hyperview-scroll namespace.

animated

Type	Required
false (default), true	No

This will condition whether the scrolling should be animated or not.

offset

Type	Required
integer	No

A fixed number of pixels to offset the final target position.

position

Type	Required
float between 0 (default) and 1	No

A value of 0 places the item specified by index at the top, 1 at the bottom, and 0.5 centered in the middle.