@Mithgol this passes lint (and should be fine unless tileSize / 2 isn't adequate):

// detecting retina displays, adjusting tileSize and zoom levels
if (this.options.detectRetina && window.devicePixelRatio > 1 && options.maxZoom > 0) {
    this.options.tileSize = this.options.tileSize / 2;
    options.zoomOffset++;
    if (options.minZoom > 0) {
        options.minZoom--;
    }
    options.maxZoom--;
}

basically if you can avoid bitwise operators in JS it is better since they are a) obscure and b) inefficient

@Mithgol also when testing this (I merged it into leaflet's current master, here is the leaflet-src.js I compiled) I believe it is generating incorrect tile urls.

using:

var tiles ="http://tile.stamen.com/terrain/{z}/{x}/{y}.jpg"
var layer = new L.TileLayer(tiles, {maxZoom: 16, minZoom: 3, detectRetina: true})

leaflet generates requests for tiles at URLs such as:

http://tile.stamen.com/terrain/12/1310/3165.jpg

which isn't a valid tile URL, though up one zoom level is:

http://tile.stamen.com/terrain/13/1310/3165.jpg

any ideas on why this is happening?

figured it out - you were using options instead of this.options. I tested this on a retina device and can confirm it works (and lints)

// detecting retina displays, adjusting tileSize and zoom levels
if (this.options.detectRetina && window.devicePixelRatio > 1 && options.maxZoom > 0) {
    this.options.tileSize = this.options.tileSize / 2;
    this.options.zoomOffset++;
    if (this.options.minZoom > 0) {
        this.options.minZoom--;
    }
    this.options.maxZoom--;
}

additionally we might want to check for window.devicePixelRatio === 2 specifically since certain devices have pixel ratios that aren't even integers

certain devices have pixel ratios that aren't even integers

Are there any devices with non-integer window.devicePixelRatio values? (I haven't yet heard of any.)

And if there are, what are their window.devicePixelRatio values? (I currently believe that any window.devicePixelRatio values above 1 are worthy of retina mode, but I'd consider switching to window.devicePixelRatio >= 1.5 approach if there are devices with window.devicePixelRatio values between 1 and 1.5).

I believe android devices come in flavors of 0.75px, 1.0px, 1.5px and 2.0px (ratio 3:4:6:8) and iOS comes in 1.0px or 2.0px (ratio 1:2) so since tiles aren't available in 192px or 384px how would you support non integer pixel ratios?

how would you support non integer pixel ratios?

I'd just double tile pixel ratio for window.devicePixelRatio == 2 (that one is obvious) and for window.devicePixelRatio == 1.5 also (because downscaled tiles look better than upscaled), but won't do anything for the other two ratios — window.devicePixelRatio == 1 (that one is obvious) and window.devicePixelRatio == 0.75 (that won't benefit from high quality tiles anyway).

And my pull request already does all that (it activates only when window.devicePixelRatio > 1).

@Mithgol that makes sense -- I think I was overthinking the problem :D

@mourner +1'ing this pull req

Sorry for such a delay, I'll certainly merge this into master in the next couple of days.

While you are at it, please check whether I should have taken zoomReverse into account better. I am not 100% sure that I was right to ignore it entirely.

That's not a couple of days — more like a couple of dozens. Please provide a new estimated date of landing.

Hi there,
There was an indentation error in this code - I've raised pull request #678 to sort it out. It was just a single character though, so you could just commit the same change if you like.

Thanks! I'll do a proper build with all the recently merged pulls today (needed to sort out some things in the code before).

Updated the build.

@Mithgol thanks again!

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