devicePixelRatio in Opera Mobile
I've been enjoying PPK's recent look at devicePixelRatio and More about devicePixelRatio, but one detail in the latter post caught my eye: discussing the
devicePixelRatio on the Galaxy Nexus, he notes that Opera Mobile goes for a ratio of
2.25, while other browser use a ratio of
By default, the
devicePixelRatio in Opera Mobile is determined by the device's reported resolution:
Now, the Galaxy Nexus has a nominal resolution of 316dpi, so it should actually end up with a
2...but perhaps the OS is reporting it as 320dpi, triggering the slightly higher ratio.
One aspect that seems to be unique to Opera Mobile, however, is that users can change the
devicePixelRatio through the Zoom preference in the browser's Settings.
On regular (non-mobile-optimised) sites, this setting affects how closely the browser zooms into the page when double-tapping. At the same time, though, changing this setting also changes the
devicePixelRatio, to make this preference more effective on mobile-optimised sites. For instance, setting the preference to 175% globally sets the
devicePixelRatio to 1.75. This will obviously have an effect on sites that use viewport
meta to set things like
width=device-width and sites that use pixel-ratio-specific Media Queries, as the reported values will now be different.
Note that this global Zoom setting is different from a user's normal zoom/pinch-zoom action – in those situations,
devicePixelRatio doesn't change.