Android Question A never asked question: layouts scaling ^_^

LucaMs · Sep 5, 2015

[Just pour parle . Note that here now is 3:40 AM ! So, I'm sleeping ].

I almost abandoned the idea of using only the Designer and its scripts.

So, I was developing a small project with the intention of use code later to scale the layout.

Just out of curiosity, I wanted to look at the effect of Designer' AutoScaleAll only, on two different devices.

I had not ever done!

Let's see if I can explain the facts.

I have created a Variant which has the size and the density of my smartphone. Then: (Landscape - Full Screen without Title): 800 x 480 - 1.5.

I have a Button; Height = 50 (dips in the Designer)

a) What should be its (new, scaled) height in a device (tablet) with: 1280 x 800 - 1 ?

I think: if the Variant scale was 1, as the tablet, the Height should be: (800 / 480) x 50 = 83.
Considering the different density: (1 / 1.5) x 83 = 55.
Well, it is scaled to... 49!

Given that the result was not convincing, I have set the layout to 800 x 480 - 1, then I have changed only the Scale of the Variant.

b) What should be the scaled height now?

Height should be: (800 / 480) x 50 = 83.
It is scaled to... 62!

Finally, both 100%y and GetDeviceLayoutValues.Height returns 752, despite the full screen and no title, instead of 800.

So... Happy New Year

Cableguy · Sep 5, 2015

You left out the final question!!!!!
BTW, its exactly because of this that i prever creating my UI in code

LucaMs · Sep 5, 2015

Cableguy said:
You left out the final question!!!!!
BTW, its exactly because of this that i prever creating my UI in code

Note that also if I take in account the values of the "final question", 752 / 800 = 0.94, I can't get anyway the right height.

LucaMs · Sep 5, 2015

Attached example

Erel · Sep 6, 2015

I highly recommend you to avoid using variants with scale other than 1.0. They will only make things more complicated.

AutoScaleAll works correctly. Many developers think that it will magically scale the layout to all devices. It doesn't.

It only slightly increases or decreases the views sizes based on the ratio between the variant size and the actual screen size.

As mentioned in the tutorials the scale rate should be around 0.3. If you are setting it to 1.0 then you are not using this feature correctly.

You need to use Anchors + designer script + autoscale to implement a good layout.

In almost all cases a stretched layout (like the one you create with code) is a bad layout.

LucaMs · Sep 6, 2015

Sorry, I don't understand and I don't agree.

Erel said:
You need to use Anchors

So, before anchors could I not get a well scaled layout?

Erel said:
I highly recommend you to avoid using variants with scale other than 1.0

Why give us the possibility to create a variant with scale different to 1.0?

Erel said:
should be around 0.3

In geometry I never heard the term "around"

LucaMs said:
Finally, both 100%y and GetDeviceLayoutValues.Height returns 752, despite the full screen and no title, instead of 800.

The designer will always remain for me a mistery.

Maybe I would need to know how it works internally.

Thanks anyway for the answer (exactly what I thought I got, unfortunately).

P.S. In the example, I had only need to get the height of a simple button double in the case where the device had double height compared to variant height (same densities).
The Designer should do this very easily.

Erel · Sep 6, 2015

LucaMs said:
So, before anchors could I not get a well scaled layout?

The solution before anchors was to implement the same feature with the designer script.

LucaMs said:
Why give us the possibility to create a variant with scale different to 1.0?

It works properly with any scale. There is no advantage for using non-normalized scales and it makes it more difficult to understand. The possibility is still there mainly for historic reasons.

LucaMs said:
In geometry I never heard the term "around"

Ok.

Finally, both 100%y and GetDeviceLayoutValues.Height returns 752, despite the full screen and no title, instead of 800.

This is not really related to the designer. These values return from the device APIs. Which device are you using?

LucaMs · Sep 6, 2015

Erel said:
Which device are you using?

Asus tf103CG - Android 4.4.2

LucaMs · Sep 6, 2015

Erel said:
This is not really related to the designer. These values return from the device APIs. Which device are you using?

This is really strange:

Now I have tried using an emulator. Always 752.
So, I opened the Designer and both the Layouts have
Show Title = True
Full Screen = False

but I am absolutely certain that I have set them exactly the opposite.

The only difference is that now I have not used the rapid debugger; but I think this may not have changed the file .bal.

LucaMs · Sep 6, 2015

more strange:
reset show title to false, full screen to true... I get now... 752

Erel · Sep 6, 2015

100%y is expected to return 752 as the soft buttons are not part of the activity. The same is true for GetDeviceLayoutValues.

LucaMs · Sep 6, 2015

Something is now clearer.

The settings "Show Title" and "Full Screen" (Designer) have no effect.
Only #FullScreen and #IncludeTitle in code "have effect"

[B4A 4.30]

Erel · Sep 6, 2015

That is correct:

LucaMs · Sep 6, 2015

Tested on b4a 5.20 beta

Main - fullscreen - includetitle - layout: "same" - 752

Act2 - fullscreen - includetitle - layout: "same" - 752
Act2 - fullscreen - includetitle - layout: "inverted" - 752

[p.s. Act2 - NOT fullscreen - NOT includetitle - layout: "same" - 699]

Those settings in the Designer have not influence.

LucaMs · Sep 6, 2015

ButtonHeightAutoScaleAll

VARIANT
Device: 1280 x 800, scale = 1 (160 dpi)

Title-Full Screen:

Button1 Height:

AutoScaleRate:

Device: 1280 x 800, scale = 1 (160 dpi)
Screenshot (part):

So, I set AutoScaleRate to 1; "Value of 1 is similar to specifying all values with percentage".
Button1.Height should be = 800(device h) / 480(variant h) * 50 = 83.333
(but, wow, it is almost right, 81 )
Perhaps the problem is that "similar".

Cableguy · Sep 6, 2015

If you go the "The screen does not have half pixels" way, you must then do some rounding...

800/480 = 1.66666667 which should be rounded to 1.67 BUT the designer works with only one decimal place for the density so we get 1.6
1.6 x 50 = 80 ... closer now, hugh!?

LucaMs · Sep 6, 2015

Cableguy said:
If you go the "The screen does not have half pixels" way, you must then do some rounding...

800/480 = 1.66666667 which should be rounded to 1.67 BUT the designer works with only one decimal place for the density so we get 1.6
1.6 x 50 = 80 ... closer now, hugh!?

Yes, closer; but I suppose that Android can do same rounding and instead the result is 81.

LucaMs · Sep 6, 2015

B4X:

Log("not rounded: " & ((800/480) * 50))
Dim i As Float = Round2(800 / 480 , 2)
Log(i)
Log("    rounded: " & (i * 50))

Log:
' not rounded: 83.33333333333334
' 1.6699999570846558
'   rounded: 83.5

Android Question A never asked question: layouts scaling ^_^

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