[Dashboards] give embeddable a say in panel dimensions

[drewdaemon]

Describe the feature:
Giving embeddables power to inform the containing panel's dimensions. The embeddable could supply

• hard constraints such as an aspect ratio
• softer suggestions such as initial panel dimensions that can be overridden by the user

This could improve both appearance and accessibility. For example, if the Lens metric is created with the default panel size today, there is a great deal of distance between the label and the data. This is not true to the intent of the design and makes comprehension harder, especially for visually-impaired users.

#136567 adds a new API for embeddables to inform the panel of display preferences. This could be extended to panel dimensions.

Describe a specific use case for the feature:
Lens visualizations can look very wonky if they are at the wrong aspect ratio. This feature would

• allow the Lens embeddable to guide dashboard users toward the optimal visual appearance of a chart
• allow us to introduce dimensional parity between what users see in the Lens editor and on a dashboard

Related to #136993

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[drewdaemon]

Related to #136993

[ninoslavmiskovic]

I could not agree more on this issue. 👍🏻

We should guide the users.

Skaermoptagelse.2023-08-08.kl.15.56.37.mov

[cqliu1]

Closing because embeddables can set their initial dimensions, but we don't want to set hard restrictions on panel size so our authors have the freedom to make any layout they choose.

RE: 1x1 panels, we want to increase the minimum dimensions allowed for a panel to avoid this situation: #144753 and we will address this as part of our new layout engine work.

[drewdaemon]

because embeddables can set their initial dimensions

@cqliu1 could you please provide specifics on this existing capability?

[ThomThomson]

@drewdaemon embeddable factories can add a getPanelPlacementSettings function which takes an input and returns initial panel placement settings. You can see an implementation of this in src/plugins/links/public/embeddable/links_embeddable_factory.ts.

The API may change in the new Embeddable system, but the base concept / capability will remain.