[forms-devel] Scaling sizes (Fonts/Width/Height) of across devices

Fri Jun 17 05:32:56 UTC 2016

Hi,

First I want to apologize if I am sending an email to a list which was
intended to be Xamarin internal. I mainly subscribed out of interest of
seeing what was worked on.

---

I have been following this thread now and I think one first needs to clearly
define what exactly it is that one wants to achieve.

In the given example you are comparing a 6” device with a 10” device but
what is the end goal here? Should the label font be scaled so they appear
the same height physically on all devices or the same height based on a
percentage of the screen size (or height I guess)?

The former is what I would expect from such a system, but the latter is what
would make the GUI “look the same” across devices of different screen sizes
and resolutions, disregarding aspect ratios.

Coming from iOS side I am already used to never talk about pixels but
instead points which the system then maps internally to screen pixels.
However, iOS is blessed with devices with roughly the same points (not
pixels!) per inch which makes it a lot easier.

To me a useful system would be a reliable way to get a scale-factor for
manually mapping sizes in Xamarin-Forms to cm or inches, that way I could
make sure the UI is readable/usable in all cases no matter the device. This
could then be applied to all GUI elements, not just fonts.

Cheers,

Christoffer Årstrand
Development Lead

Yooba Head Office +46 11 - 12 20 90
Visit: Västgötegatan 7, 602 21 Norrköping

Yooba Stockholm +46 8 - 410 035 40
Visit: Engelbrektsgatan 7, 114 32 Stockholm
www.yooba.se <http://www.yooba.se/>  | christoffer.arstrand at yooba.com
se.linkedin.com/in/arstrand <http://se.linkedin.com/in/arstrand>

From:  <forms-devel-bounces at lists.xamarin.com> on behalf of Michael Ridland
<rid00z at gmail.com>
Date:  Friday 17 June 2016 at 06:29
To:  Jason Smith <jason.smith at xamarin.com>
Cc:  Forms devel <forms-devel at lists.xamarin.com>
Subject:  Re: [forms-devel] Scaling sizes (Fonts/Width/Height) of across
devices

This is the same Forms code, on iPhone 6 and Nexus 10. I would expect if I
used a dynamic/scaled size they would match more evenly, just a idea, not
sure if it's bad or good.

<StackLayout>
        <BoxView HeightRequest="20"  ></BoxView>
        <BoxView HeightRequest="20" BackgroundColor="Blue" ></BoxView>
        <Label FontSize="16" Text="Welcome to Xamarin Forms!"
VerticalOptions="Center" HorizontalOptions="Center" />
</StackLayout>  

Thanks

Michael Ridland | Technical Director | Xamarin MVP

XAM Consulting - Mobile Technology Specialists

www.xam-consulting.com <http://www.xam-consulting.com/>

Blog: www.michaelridland.com <http://www.michaelridland.com>

On Fri, Jun 17, 2016 at 2:14 PM, Jason Smith <jason.smith at xamarin.com>
wrote:
> So what would <Label DynamicFontSize="8" FontSize="20" /> produce?
> 
> On Thu, Jun 16, 2016 at 8:40 PM, Michael Ridland <rid00z at gmail.com> wrote:
>> 
>> I'm wondering if something like this would work, as a user I would like to be
>> able to set a width/height/font that dynamically changes to look the same on
>> all devices. 
>> 
>> <Label DynamicFontSize="8"  DynamicPadding="16" DynamicHeightRequest="20"
>> 
>> Does that make sense at all? There might be a better word than dynamic..
>> scaled.. 
>> 
>> Thanks
>> 
>> Michael Ridland | Technical Director | Xamarin MVP
>> 
>> XAM Consulting - Mobile Technology Specialists
>> 
>> www.xam-consulting.com <http://www.xam-consulting.com/>
>> 
>> Blog: www.michaelridland.com <http://www.michaelridland.com>
>> 
>> 
>> 
>> On Thu, Jun 16, 2016 at 3:22 AM, Jason Smith <jason.smith at xamarin.com> wrote:
>>> As a side note, a better API would probably be
>>> 
>>> double fontSize = Device.GetUnitFontSize (double size, MeasurementUnit
>>> unit); where MeasurementUnit is some enum that contains something like:
>>> 
>>> ScaledPixels,
>>> ScreenPixels,
>>> Point
>>> 
>>> On Wed, Jun 15, 2016 at 10:20 AM, Jason Smith <jason.smith at xamarin.com>
>>> wrote:
>>>> The best idea we have come up with is as follows:
>>>> 
>>>> double fontSize = Device.GetPixelFontSize (double pixelSize);
>>>> 
>>>> However this has some implementation issues around the fact that point size
>>>> doesn't always perfectly map to pixel size due to a bunch of tiny factors.
>>>> So a good solution would be do change FontSize from a double to a FontSize
>>>> struct which could be a double + unit combination, however this would
>>>> represent a breaking change we cannot take, so the above is the best we got
>>>> which appears to be quite misleading in some edge cases. This is the reason
>>>> we haven't done it so far.
>>>> 
>>>> On Tue, Jun 14, 2016 at 6:25 PM, Michael Ridland <rid00z at gmail.com> wrote:
>>>>> Hi
>>>>> 
>>>>> One limitation of Forms that I come up with in all projects is the limited
>>>>> ability to set sizes which scale based on platform density etc. I've been
>>>>> pondering some solutions I can put onto nuget, but that's the old way now
>>>>> Forms is open source.
>>>>> 
>>>>> What idea's does the Forms team have for this and would you like any help
>>>>> to build this into core?
>>>>> 
>>>>> Thanks
>>>>> 
>>>>> Michael Ridland | Technical Director | Xamarin MVP
>>>>> 
>>>>> XAM Consulting - Mobile Technology Specialists
>>>>> 
>>>>> www.xam-consulting.com <http://www.xam-consulting.com/>
>>>>> 
>>>>> Blog: www.michaelridland.com <http://www.michaelridland.com>
>>>>> 
>>>>> 
>>>>> 
>>>>> _______________________________________________
>>>>> forms-devel mailing list
>>>>> forms-devel at lists.xamarin.com
>>>>> http://lists.ximian.com/mailman/listinfo/forms-devel
>>>>> 
>>>> 
>>> 
>> 
> 

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