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

Same text size but it larger on other devices

I have a TextView in which I programmatically setup the text size in 'SP'.
tv.setTextSize(spToPx(5, context));
public static int spToPx(float sp, Context context) {
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, sp, context.getResources().getDisplayMetrics());
}
First screenshot shows how it should look (and how it looks on my Xiaomi Redmi and Doogee HT7
Second screenshot shows how it looks on other devices with higher or the same dpi.
Normally, if I understand correct, text with the same size in 'dp' or 'sp' should looks the same on other devices (with the same screen size) because it automatically converts 'dp' or 'sp' to the needed amount of pixels depending on dpi.
After reading Android Developer Guideline about devices with different density I was expecting that text would be smaller if I use the same text size on devices with higher dpi. But now I have a situation that I really don't understand.

If you are using values in sp and the user changes the default text size for his device from Settings--->Display---->TextSize, your TextViews will be affected. If on the other hand you use dp values, then no matter what text size the user sets as default, the TextViews in your app will remain the same. This is ofcourse discouraged by Google as bad practice, since the user should be able to change text sizes but it would be what you are looking for.
So, use (TypedValue.COMPLEX_UNIT_DIP,number of your choosing) instead of (TypedValue.COMPLEX_UNIT_SP, sp)

You can add dimens file to your resources . thats how I do it
heres the link where I got the answer

Try this, Add this property in your xml. It will change textsize based on all phone.
style="#android:style/TextAppearance.DeviceDefault.Medium" /*for normal text */
style="#android:style/TextAppearance.DeviceDefault.Small" /*for small text */
style="#android:style/TextAppearance.DeviceDefault.Large" /*for large text */
Hope your problem will solve.

The primary difference between an sp and a dp is that sp’s preserve a
user's font settings. Users who have larger text settings for
accessibility will see font sizes match their text size preferences.
so you could check the settings of two devices and see if there is a difference between them.

I still didn't find right explanation to this issue. The only theory I have is next:
There are density buckets (120 dpi, 160 dpi, 240 dpi, 320 dpi, 480 dpi, 640 dpi). Screen density of your device will be determinated as the closest bucket. For example, if your device has 401 dpi it will be counted as 480 dpi. So, when I create and add view with size of 20 dp it will convert into more pixels than needed. It the hardest for devices that have density right between two buckets. I also checked density of all devices that had wrong image display (like on image 2) and it was almost right between two buckets...
I still don't know why this happens only when I create and add view dynamycally, but the only way to solve this problem was the creating of separate layout with all presetted views instead of adding these views dynamically.

Android: text cropped in some devices

In my android app, there is a certain layout with a fixed height. In this layout, there are some TextView s arranged vertically. I have set the font size of text fields to be somewhat larger (18sp).
In almost all the devices I checked, The text fits inside the fixed sized layout. But in few devices, The bottom TextView gets cropped out of the layout.
If the proportion between text unit size (sp) and the layout unit height (dp) is the same in all devices, I wouldn't expect this to happen.
So, is this due to something wrong with the devices? Is there any way I can fix this?

Screen density is different than screen dimensions. dp normalizes densities across devices, but they can still have varying screen heights and widths. The obvious example is tablet vs phones, tablets have the same screen densities as phones but much larger screen dimensions. Just like that, some phones have smaller screens than others, so you need to take that into account when using fixed height layouts.
To get around this problem, you can take advantage of the width and smallest-width resource buckets and provide different layouts for smaller devices.

As it seems, the proportion between a unit sp and a unit dp depends on the font size setting (Settings->Display->Font size).
I could recreate the issue on other devices when I set the font size to be Huge.
So, it is not a good idea to set fixed sizes to layouts containing text.

Best way to set text size?

What is the best way to set the text size so it looks the same on all devices? The biggest problem I am having is setting the text size on the buttons so everything fits or isn't too small. I have tried setting the size in the xml, and I have just tried setting it dynamically by getting the screen size and messing with the screen width and height to set the size. I had tested different things on different devices and thought all was well, until I just tried my app on the Galaxy Nexus and half of my words were getting chopped off inside of the button. I made some adjustments and the font is now way too small on tablets.
Using the xml has worked fine for me before, but most of these new 7" tablets use the large layout, so my images and text are really small if I set the height, width, and text size with the xml. Setting the widths and hights dynamically have helped with the buttons and image sizes, but the font still doesn't look quite right.
Is my best bet just to find a happy medium via xml(large, x-large, etc.) or are there other ways?

Have you seen this article: Supporting Multiple Screens ?
It says:
you should prefer the sp (scale-independent pixel) to define text
sizes. The sp scale factor depends on a user setting and the system
scales the size the same as it does for dp.
The same issue is explained here, Different text size for different hardware

TextView in android

I am developing an application in which the layout is independent of screen resolution.
Now my problem is that in TextView the textview layout does change itself when the resolution of screen changes but the size of text remain same.
I want that when the resolution is high, according to that the text size should also adjust itself(i.e. text size should be changed).
And simillarly when resolution is low the text size sholud also shrink.
But here when i reduce Y-AXIS to an extent the text vanishes.
I will really appriciate any answer.
Thank you.

You should be using sp for your android:textSize.

Make a values folder for each of the four densities and make a common dimension value for each density.
So at low density it is a certain value, medium density it is a certain value and so on.