[Lens] Improve reporting image size for each visualization type

[dej611]

Describe the feature:

With the new reporting feature merged in Lens users can now print in PDF/PNG formats visualizations.
The reporting tool is using a default size ratio for all visualizations at the moment as shown in #153429 .

It would be nice to have a per-visualization tailored size to better fit each report format.

[elasticmachine]

Pinging @elastic/kibana-visualizations @elastic/kibana-visualizations-external (Team:Visualizations)

[drewdaemon]

Semi-related to other dimension-by-vis-type issues

• [Lens] workspace panel dimensions by chart type #136993
• [Dashboards] give embeddable a say in panel dimensions #136995

[dej611]

Did some quick investigation on this topic and found some interesting behaviour.
It is possible to force layout dimensions for the final PNG screenshot (i.e. dimensions: { height: 999, width: 1793 } ), this information is forwarded as job params, but a 2x zoom is applied to that ( { height: 999, width: 1793, zoom: 2 } ).
On the server side a headless chrome instance is launched with the following params: Launching with viewport: width=1793 height=1200 scaleFactor=2 - can you spot the subtle difference here? The height magically 🪄 changed from 999 to 1200px 🤔 .
From that the actual viewport is about 10% vertically smaller than the given params (1200px => 1086px) but it probably depends from OS implementation of the Chromium app.
The final picture taken as screenshot will then have the following dimensions: height: 1086 x width: 1793 x zoom: 2 => ~3500 x 2170 px

Can you confirm all this is correct @tsullivan ?
If I understood the full process correctly then we might have a problem on the Lens side as some specific visualizations might require a lower height size than the fixed one used for the chromium app.
cc @gvnmagni

[elasticmachine]

Pinging @elastic/appex-sharedux (Team:SharedUX)

[dej611]

Discussed with @gvnmagni offline about this issue and made up a plan:

1. Integrate the PoC [Lens] Improve reporting size for Lens visualizations #154931 to fix most of Lens' visualizations providing a better ratio dimensions (even if upscaled)
2. Work together with the @elastic/appex-sharedux team in order to provide a better reporting experience to the user (16:9, 4:3, Preserve current screen dimensions)
3. Find together with the @elastic/appex-sharedux team a solution for those visualization types that require a custom dimensions layout (height lower than 1200px).

[gvnmagni]

Exactly, especially points 2 and 3 are worth a conversation around users expectations. I believe that could affect how we offer this functionality. Happy to talk about it when we can!