Elements outside the viewport are not drawn on entering about litho

[astreet]

Hey @asier2, sorry about the trouble. Litho has 'incremental mount' on by default - this is a performance optimization which only mounts things within the viewport. The downside here is that when Litho is integrated into normal Android Views which can change the viewport (like a ScrollView), the change in viewport must be manually dispatched.

You can do this by extending ScrollView and overriding these methods:

  @Override
  protected void onScrollChanged(int l, int t, int oldl, int oldt) {
    super.onScrollChanged(l, t, oldl, oldt);

    IncrementalMountUtils.incrementallyMountLithoViews(this);
  }

  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    super.onLayout(changed, l, t, r, b);

    IncrementalMountUtils.incrementallyMountLithoViews(this);
  }

Alternately, if you don't care about 'incremental mount', you can turn it off by setting .incrementalMount(false) when you create your ComponentTree.

ComponentTree ct = ComponentTree.create(c, Text.create(c).text("test").build())
    .incrementalMount(false)
    .build();
LithoView lithoView = new LithoView(this);
lithoView.setComponentTree(ct);

We're investing in trying to make viewport updates automatic but this isn't something ready to release yet.

[asier2]

It works as expected, thank you!