Add additional default image sizes for srcset to accommodate wider viewports

[mor10]

Related to #6177 and #6131. Filed as separate issue because #6177 is getting too big.

Problem

Images aligned to wide will need proper size options from the srcset attribute. Currently the sizes generated for a large image (eg 4000px wide) are:

• original
• 300px
• 768px
• 1024px
• 1568px

These sizes should be closely tied to real-world data about viewport widths. Currently the only readily available data is screen sizes. One source is StatCounter's worldwide screen resolution stats. They break down as follows (October 2018):

Screen size	Usage percentage
360x640	20.04%
1366x768	11.84%
1920x1080	9.4%
375x667	5.07%
1440x900	3.26%
768x1024	2.61%

Proposal

Align automatically generated image sizes to browser stats taking into account 2x and 3x displays.

Proposed new sizing array:

• 375px (covers <=375px widths)
• 768px (covers 768px and 375x2 widths)
• 1125px (covers <=1125px and 375x3 widths)
• 1568px (covers <=1568px and 768x2 widths)
• 1920px
• 2304px (covers <=2304px and 768x3 widths)
• 3380px (covers 1568x2 widths)
• 3840px (covers 1920x2 widths)

This might seem like a lot, but for most images only the smaller sizes will be generated. For larger images, providing these additional sizes available for the srcset attribute will ensure the browser pulls down the smallest possible image for wide images displayed in wider viewports.

Note

This permanently disassociates the physical image sizes from the classic display widths defined by WordPress. Which makes sense because the old modality of pixel widths defining small/medium/large image sizes no longer applies anyway.

[mor10]

Added duplicate as Core ticket 45406: Add additional default image sizes for srcset to accommodate wider viewports.

[tomdevisser]

@mor10 I see this has issue has been stale and inactive for a long time and has other closed issues mentioning it. Is this issue still relevant or can this be closed?

[mor10]

I have no idea. I have not contributed to WP since December 2019. My educated guess based on previous history and how images are handled is no, it most likely has not been solved. Someone should check. If it has not been solved, it remains a critical issue.

[tomdevisser]

@joemcgill @paaljoachim @kevinwhoffman I see you've been active on the Trac ticket, how can we move this forward?

[paaljoachim]

Heya @tomdevisser
I do not know...