Thanks for the explanation, that part about high-dpi is now clear, and
was worth the question :)
I am porting a (=my) QWidget application (with tiled maps) to QML Map,
many things are better with qml but of course I am sure I will need in
the end to build my own plugin. For instance in some cases I have
encrypted tiles that I cannot just serve un-encrypted through an
internal tcpserver that will reply to anyone, obviously. Ideally the
plugin itself should do the decryption, from disk cache or not. There
are some other tricky cases.
Thanks again
Philippe.
Le 20-02-2019 18:29, Paolo Angelelli a écrit :
The way this works is that the logical tile size (in osm case fixed at
256x256) is
independent of the physical tile size (in your case 512x512).
QtLocation/Qt/OpenGL will basically push the pixels through the tiles
either by enabling mipmapping
if the tile on-screen size is < tile physical size, or bilinear
interpolation if the opposite is true.
in case of x1 screens, with 512x512 tiles (lets call them @2x), this
is enough to give you a sharp map all the way through zooming.
with a high-dpi screen it's different. at x2, you will get sharp maps
at integer zoom levels only, but in between you won't have enough
pixels and will get tiles bilinearly interpolated because of that.
To get a map that is sharp all the way through zooming on an x2
screen, you would need @4x rasters, which however become overkill
(1024x1024 tiles would probably kill most desktop HW).
So it's a matter of tradeoff there
On Wed, 20 Feb 2019 17:33:05 +0100
maitai <[email protected]> wrote:
Hi Paolo,
My initial question was concerning a custom map type, not a derived
plugin. So basically you are saying that on a retina x2 screen I can
send back 512x512 tiles and the plugin will mark the tile with
pixelRatio = 2 (i.e not just rescale it) ?
But in fact I would prefer to be able to create my own plugin, because
the charts I am using are just local (some of them drawn on the fly,
some of them stored in mbtiles, some of them encrypted, and
potentially
I also need vector tiles). For the time being I create a thread for
each
type of map which is also a QTcpServer, but I would prefer to be able
to
communicate directly and control more things at the plugin level. I
will
investigate all this once more.
Thanks again for you replies
Philippe.
Le 20-02-2019 09:59, Paolo Angelelli a écrit :
> I may have misunderstood what you meant with "custom osm plugin".
> What does that mean?
> If you meant "a modified osm plugin", then you would be already using
> this class anyway.
> If you meant "custom map type", then just feeding 512x512 tiles should
> work.
>
> On Wed, 20 Feb 2019 08:38:44 +0100
> maitai <[email protected]> wrote:
>
>> Hi,
>>
>> Seems to me that QGeoCameraCapabilities is a private qt API?
>>
>> From what I found on the net seems it would help a lot for customizing
>> own map plugin or tile server, but it's not clear how I can access it.
>>
>> Philippe
>>
>> Le 19-02-2019 19:40, maitai a écrit :
>>
>> > Thanks I'll give it a try
>> >
>> > -------- Message d'origine --------
>> > De : Paolo Angelelli <[email protected]>
>> > Date : 19/02/2019 7:21 PM (GMT+01:00)
>> > À : [email protected]
>> > Objet : Re: [Interest] Qt Location custom osm plugin and high res tiles
>> >
>> > Hi, yes it's easy.
>> > All you have to do is setting the appropriate QGeoCameraCapabilities for
the map types you have high dpi tiles for.
>> > So in your case, set the tilesize to 256x256, so that you will have more
data per logical pixel.
>> >
>> > hope it's clear enough. Or just check how it's done in either osm or here
or mapbox plugins
>> >
>> > On Tue, 19 Feb 2019 09:51:30 +0100
>> > maitai <[email protected]> wrote:
>> >
>> >> Hello,
>> >>
>> >> Is it possible to use high res tiles with a custom osm plugin?
>> >> In fact I created my own local server and would like to know if I can
>> >> send high res tiles, for instance if devicePixelRatio is 2 I would send
>> >> 512x512 tiles, expecting Qt Location to set the tile pixel ratio to 2.
>> >>
>> >> Thanks
>> >> Philippe.
>> >> _______________________________________________
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>> >
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