What does the text-rendering css property do?

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Post Posted April 26th, 2015, 12:51 am

I have some questions about this MDN page: ... -rendering

The text-rendering property is supposed to affect how texts look on the screen, specifically how kerning pairs look and whether letter pairs can be substituted by ligatures. It has 4 values: auto, optimizeSpeed, optimizeLegibility and geometricPrecision.

So far, so good, but I can't see any differences when I test those values. And if you read the MDN page carefully, auto means the same as either optimizeSpeed or optimizeLegibility depending on font size, geometricPrecision means the same as optimizeLegibility, and as a throwaway remark at the very end of the page, optimizeSpeed has no effect.

In other words, the property doesn't actually do anything! Then why doesn't the page simply say so, instead of stating that the property is supported in Gecko 1.9 and up? Or am I missing something?
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Post Posted April 26th, 2015, 6:25 pm

It looks like there is no distinction between optimizeSpeed and optimizeLegibility in Firefox 4 and higher: ... ecko_Notes


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Post Posted April 26th, 2015, 6:38 pm

Doesn't do anything for me in Fx or SM. Neither does the somewhat-related font-feature-settings: ... e-settings

But since fonts are rendered based on what's installed on the OS via the graphics card, this stuff might work on some systems and not others.
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Post Posted April 18th, 2016, 5:57 am

The text-rendering property in CSS allows you to choose quality of text over speed (or vice versa) allowing you to fine tune optimization by suggesting to the browser as to how it should render text on the screen.
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