Develop Reference

Text sizes, different density devices and material design

I'm trying my best to follow the material design guidelines when it comes to fonts as I can, but I'm struggling to fix an issue I'm having without using dimens dependant on density. My issue is;
I'm using styles for my fonts so an example of this;
<style name="Text.MyApp.Heading3" parent="TextAppearance.MaterialComponents.Headline3">
<item name="android:fontFamily">?attr/RegularFont</item>
<item name="fontFamily">?attr/RegularFont</item>
<item name="android:textSize">?attr/TextSizeHeadingThree</item>
</style>
And applying this as the style of the text, my font size comes from the material guidelines so for Heading 4 I have
<dimen name="text_size_heading_three">48sp</dimen>
My problem is, I've got a view where there's two numbers using Heading3 in a row on the screen, This may look like +£100.00 | -£200.00, these are constrained to a separator view in the middle.
Where my issue lies is on a Pixel 4 XL (xx-hdpi) this looks fine, but bringing this down onto a Nexus S (hdpi) the text squashes together, overlaps the separator in the centre and comes off the end of the screen slightly.
It was to my understanding of the use of SP is that it would scale this text size which doesn't appear to be happening, a worry also arises that SP takes from the users text size preferences so increasing the text size of the device will likely also break this.
Just short of changing the font size for hdpi to a smaller text size for this text view, is there a way I can make this style scale with the screen?

sp actually scales in regard to the screen pixel density and the selected font size of the system.
The issue you are facing is related to the screen's actual width instead.
To achieve what you want, you can try either of the following two:
Have different sp values for your dimen for each screen width. You can do this by creating additional resource files that would contain your dimen values and will be screen width dependant. You can read more about this here:
https://developer.android.com/training/multiscreen/screensizes#TaskUseSWQuali
Use an autosizing TextView. You can find more information here:
https://developer.android.com/guide/topics/ui/look-and-feel/autosizing-textview

sp units are literally about the user's choice of text size:
Scale-independent Pixels - This is like the dp unit, but it is also scaled by the user's font size preference. It is recommend you use this unit when specifying font sizes, so they will be adjusted for both the screen density and the user's preference.
Basically users can choose the general size of text on their device, and that multiplies dp values by a specific factor (Normal is * 1.0, I think Huge is * 2.0) and that's what the sp value is. When you specify sizes in sp, you're allowing the system to scale that text up so it's readable for everyone.
So you need to be mindful of that when designing - it's always worth having an emulator with a small screen (limited space) and the text size set to the largest setting, just to make sure everything still fits in those extreme cases.
You have four options I think:
reduce your font's sp size in the layout, so it always fits
make different layouts for different configs, and tweak that (more work for you)
use autosizing TextViews like #kandrit mentions - set the space you want to fill, and it will scale the text size to fit it (this sounds like what you were expecting, and you can tweak things like having a fixed set of possible sizes)
don't use sp, use dp instead (won't scale according to the user's preference - but above a certain size, it doesn't need to because it will be readable)
You'll get a warning about the last one, but in my opinion it's completely fine and the right thing to do in some cases. Think about an app with a clock in the middle of the screen - it's a fixed size, designed and laid out a certain way, and it's large enough to be easily read. It's meant to look a specific way, take up a specific area of the screen, and there's no need for it to change size - so it makes sense to define it in dp like any other visual element. Maybe that works for what you're doing!

Problem is not with your text size, it is with your layout design
I also had the similar problem I solved it by giving a margin to views which was placed inside constraint layout so in a case of large screen it will use constraints and ignore the value of margin and in case of small screen it use the value of margin to keep views separate
If you are using a Linear Layout then set layout_weight to 1 and give margins to views then it will work same as with constraint layout

Android add a padding with size that looks equal on all devices

I have a view that is the same size as my screen / fragment. However, I want to add a padding on the left and right edges such that on all devices, this padding looks like its the same size. when I use:
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:paddingStart="20dp"
android:paddingEnd="20dp">
....
The padding is not equal on all devices. On a tablet, it is much smaller than on a small phone. Is there a way maybe programmatically to set the padding as equal on all devices?
and is dp supposed to be density-independent? Then how come, on different density devices the padding set to dp is not always the same size visually?

Notice that what you want is not scalable and not recommended. The reason is that the sizes of devices vary a lot in Android, as well as their pixel densities.
Furthermore, I include a more general article that might help you.
However:
A. Try with other units like mm or in, which are "based on the physical size of the screen" (see documentation).
B. Maybe set it programmatically. That is, calculate how many px/etc. you need on each device so that it looks the same (mm) on all of them.
float px = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_MM, 1, getResources().getDisplayMetrics());
Finally, I am not sure if this is the case, but as other users sugest, maybe this could help. Once again, however, I am not entirely sure if this is what you need. On the same line, you can also define sizes depending on the details of the device with qualificators (refer here).

You need manage different dimens file for different resolutions , please check this link , You just need to put your padings parameter in dimens and then use from dimens.
How to define dimens.xml for every different screen size in android?

Like the answer said in here
on API 21 padding doesn't work via XML, you can define programmatically like the link i share above
but you can try create style="#style/RootLayoutWithPadding" use this in your view
and inside styles.xml add this
<style name="RootLayoutWithPadding">
<item name="android:paddingLeft">#dimen/activity_horizontal_margin</item>
<item name="android:paddingTop">#dimen/activity_vertical_margin</item>
<item name="android:paddingRight">#dimen/activity_horizontal_margin</item>
<item name="android:paddingBottom">#dimen/activity_vertical_margin</item>
</style>
for every padding you can fill the sizes you want inside values.xml
i hope it help you :)

Supporting multiple screen sizes and rotations in android

Firstly I wanna say that I red probably all there is on internet on this topic.
I kinda get the picture about it but still I am not sure, and my brain is boiling trying to think about how it should go properly so I need somebody to clarify me these things maybe better than I found at other tutorials and topics.
Also a lot of questions and answers are kinda old and I know that these qualifiers for layouts like small, large and xlarge are kinda deprecated so refreshing would be nice.
So the thing that bothers me is how to support multiple screen sizes and orientations in android?
I understand that I need to support different drawable resources for different screen density's and that I need to use smallest width available qualifier for different screen sizes.
The thing that is the problem and I don't understand is how to accompany both of that together.
For instance for first example I have like logo sign which should draw over the whole screen of the mobile.
Can I actually provide all possible solutions and all possible sizes of that logo in all orientations or the android will size them as needed from the closest ones I give him?
How does the smallest width qualifier go in hand with different density drawable resources?
They just change the size of the picture depending on the screen dpi but they don't change the layout appearance.
Should I change layouts depending on screen sizes, and the pictures will change according to the density by itself what is actually a second example, because like buttons are different story, if they are 50 x 50 px in mdpi they will be 100 x 100 px in xhdpi.
And that's what I kinda get.
The bigger problem is how to put in the picture all alone that is filling the screen by itself and also to take screen rotations and changing of width and height with it in account.
So it was a long question, hope I told you what you need to know, the similar questions have already been asked but they are kinda old and outdated in some parts, and even there I still didn't find all the answers I was looking for so I hope I will find them here.
Looking forward for your help and thank you in advance !

I would say you're over complicating the topic, to support all sizes/layouts, you just have to keep them in mind while designing your layout. A vast majority of your layouts should only need to be built once and if they're built in a way that scales well it'll work out.
For example, if you're trying to draw a splash screen with a logo in the center, you can do something like this.
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_gravity="center"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/my_logo" />
</FrameLayout>
This would work on all devices/sizes/orientations as it is just putting the logo in the center.
When building a layout, just focus on an average size of a current modern phone but keep in mind people have smaller devices. Use that as your base for assets, and try to include smaller ones, or use vector images.
And if you're building a View that is long, wrap it in a ScrollView so it can scroll on smaller devices.
I would only ever use the other layout directories ( for sizing or orientation ) for very specific cases, like when you want to completely change how your layout looks.
Hopefully that helps.

How do I edit my fontsize programmatically?

This problem is more complicated than the title.
I have a java class which maps on the values from the server. Now I am setting the textsize programmatically, as follows:
headerButton.setTextSize(Application.getAppResources().getDimensionPixelSize(R.dimen.manage_markets_text));
and setting manage_markets_text in dimensions as 15sp for layout, for values-xlarge: 20sp and for values-large dimension 18sp. Now, For the xlarge tablet it is getting 20sp as desired, However for htcone phone it is mapping on some large font size which I don't even know where it gets from (appears to be like 40-50sp). Now I changed the code, to accept getDimension instead of Pizelsize and I still have the same issue. if I set settextsize(r.dimen.manage_market_text) ,it displays blank page. How do I go about fixing this issue? Any clue?

I would think that you would want to set this in your XML.
<Button
...
android:textSize="#dimen/manage_market_text"
...
/>
Also, using values-xlarge is a bit old fashioned. According to
http://developer.android.com/guide/practices/screens_support.html
You should format your files such more like values-sw600dp.
To answer your original question simply write
Resources res = this.getResources();
headerButton.setTextSize(res.getDimension(R.dimen.manage_market_text))
That should do the trick

trouble with font size for different screen size/resolution

I know this has been answered in other questions, but nothing is working for me. I have a text view where I want the text to appear the same size in a variety of density/screen size combinations. I have tried specifying
android:textSize="30dp"
and
android:textSize="30sp"
and have also used
TextView text = (TextView) findViewById(R.id.text);
text.setTextSize(30 * (getResources().getDisplayMetrics().density));
30 is my font size *****
the text doesn't scale properly. It becomes way too small at lower densities and as screen size increases. Are there additional techniques I can use to scale my font?

create layout-large, layout-small, layout-xlarge etc.. versions of your layout xml file.
You can set the size differently in each so that the font will look right across a variety of screen sizes.

After years of constantly having everything slightly off on different devices, I recently discovered that the inches and cm measurements for dimensions are literally that.
So even on devices where 160dp isn't quite an inch, specifying 1inch will give exactly that, on everything, even if they have a custom scaled ROM.
I now specify anything I want very tight control over with these.

If you just want to have separate font sizes for separate screens, you can create dimens in your value.xml for sw600dp and sw720dp folder too and put different values there. You don't need to create separate xml layout for each, if you just need to change font sizes.