Load dimension value from res/values/dimension.xml from source code

Question

I'd like to load the value as it is. I have two dimension.xml files, one in /res/values/dimension.xml and the other one in /res/values-sw360dp/dimension.xml.

From source code I'd like to do something like

getResources().getDimension(R.dimen.tutorial_cross_marginTop);

This works but the value I get is multiplied times the screen density factor (1.5 for hdpi, 2.0 for xhdpi, etc).

I also tried to do

getResources().getString(R.dimen.tutorial_cross_marginTop);

This would work in principle but I get a string that ends in "dip"...

• Paul Verest: I wonder if it is bug in Android as Resources has method getDimensionPixelSize(int id) that exactly states that it returns in Pixel, so getDimension(int id) should return in dp (dependency independent units), that would be ready for use, e.g. with View setPadding
• mdelolmo: @PaulVerest I was also puzzled by that redundancy in the API but since it's 2022 and the API documentation states that all methods return "pixels", I imagine it's expected behaviour.

Answer 1

In my dimens.xml I have

<dimen name="test">48dp</dimen>

In code If I do

int valueInPixels = (int) getResources().getDimension(R.dimen.test)

this will return 72 which as docs state is multiplied by density of current phone (48dp x 1.5 in my case)

exactly as docs state :

Retrieve a dimensional for a particular resource ID. Unit conversions are based on the current DisplayMetrics associated with the resources.

so if you want exact dp value just as in xml just divide it with DisplayMetrics density

int dp = (int) (getResources().getDimension(R.dimen.test) / getResources().getDisplayMetrics().density);

dp will be 48 now

• NoDataDumpNoContribution: I think the documentation is particularly unclear here. "Unit conversions are based on the current DisplayMetrics associated with the resources." when all they want to say is that they convert to pixels.
• Michael Peterson: If you are essentially going to be discarding the display metrics multiplier, you may as well just define your dimension in px. <dimen name="test">48px</dimen>. getDimension(R.dimen.test) will return 48.
• Alex: Not work for me: stackoverflow.com/questions/55972518/…
• Abandoned Cart: @Trilarion They do not simply convert to pixels, though. They are saying that dp will give the scaled pixel value relative to the scale of the resource object used to retrieve it. Once you get into various ways to obtain resources, this will be more relevant. For simplicity, you can think of it as being relative to screen scale. There is also sp, or pixels relative to the system text size, and px, or pixels directly. Each is different and has a different purpose.
• Seven: If you want sp value from dimens.xml, then you'll need int sp = (int) (getResources().getDimension(R.dimen.test) / getResources().getDisplayMetrics().scaledDensity)

Answer 2

Context.getResources().getDimension(int id);

Answer 3

For those who just need to save some int value in the resources, you can do the following.

integers.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <integer name="default_value">100</integer>
</resources> 

Code

int defaultValue = getResources().getInteger(R.integer.default_value);

• JamisonMan111: Thank you for this, was more of what I was looking for even though maybe not for others, but this solution provided actually provided me with some insight into other areas of my code
• Acauã Pitta: works like a charm for magic numbers

Answer 4

The Resource class also has a method getDimensionPixelSize() which I think will fit your needs.

• Muhammad Babar: This is wrong! the metrics conversion also does occurs in getDimensionPixelSize() if you can refer the docs it clearly states Returns Resource dimension value multiplied by the appropriate metric and truncated to integer pixels.
• Michael Peterson: This is wrong. The metrics conversion occurs using this method as well.

Answer 5

You can use getDimensionPixelOffset() instead of getDimension, so you didn't have to cast to int.

int valueInPixels = getResources().getDimensionPixelOffset(R.dimen.test)

Answer 6

Use a Kotlin Extension

You can add an extension to simplify this process. It enables you to just call context.dp(R.dimen. tutorial_cross_marginTop) to get the Float value

fun Context.px(@DimenRes dimen: Int): Int = resources.getDimension(dimen).toInt()
fun Context.dp(@DimenRes dimen: Int): Float = px(dimen) / resources.displayMetrics.density

If you want to handle it without context, you can use Resources.getSystem():

val Int.dp get() = this / Resources.getSystem().displayMetrics.density // Float
val Int.px get() = (this * Resources.getSystem().displayMetrics.density).toInt()

For example, on an xhdpi device, use 24.dp to get 12.0 or 12.px to get 24

Answer 7

Here is a better solution, not involving double conversion from dp to px then px to dp:

In Kotlin

fun Resources.getRawDimensionInDp(@DimenRes dimenResId: Int): Float {
 val value = TypedValue()
 getValue(dimenResId, value, true)
 return TypedValue.complexToFloat(value.data)
}
// Usage: 
resources.getRawDimensionInDp(R.dimen.my_dimen_id)

In Java

public class ResourcesUtil {
 static Float getRawDimensionInDp(Resources resources, @DimenRes int dimenResId) {
 TypedValue value = new TypedValue();
 resources.getValue(dimenResId, value, true);
 return TypedValue.complexToFloat(value.data);
 }
}
// Usage: 
ResourcesUtil.getRawDimensionInDp(resources, R.dimen.my_dimen_id);

Answer 8

You can write integer in xml file also..
have you seen [this] http://developer.android.com/guide/topics/resources/more-resources.html#Integer ? use as .

 context.getResources().getInteger(R.integer.height_pop);

Answer 9

Two helper functions I wrote in kotlin for this

/**
 * Gets the float value defined in dimens
 * Define float value as following
 * Example:
 * <item name="example" format="float" type="dimen">1.0</item>
 */
fun Resources.getFloatDimension(dimensResourceId: Int): Float {
 val outValue = TypedValue()
 this.getValue(dimensResourceId, outValue, true)
 return outValue.float
}
/**
 * Gets the dp value defined in dimens
 * Example:
 * <dimen name="example">12dp</dimen>
 *
 * Will return 12
 */
fun Resources.getDimensionInDp(dimensResourceId: Int): Int {
 return (getDimension(dimensResourceId) / displayMetrics.density).toInt()
}

Answer 10

If you just want to change the size font dynamically then you can:

textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, resources.getDimension(R.dimen.tutorial_cross_marginTop))

As @achie's answer, you can get the dp from dimens.xml like this:

val dpValue = (resources.getDimension(R.dimen.tutorial_cross_marginTop)/ resources.displayMetrics.density).toInt()

or get sp like this

val spValue = (resources.getDimension(R.dimen.font_size)/ resources.displayMetrics.scaledDensity).toInt()

About Resources.java #{getDimension}

 /**
 * Retrieve a dimensional for a particular resource ID. Unit 
 * conversions are based on the current {@link DisplayMetrics} associated
 * with the resources.
 * 
 * @param id The desired resource identifier, as generated by the aapt
 * tool. This integer encodes the package, type, and resource
 * entry. The value 0 is an invalid identifier.
 * 
 * @return Resource dimension value multiplied by the appropriate 
 * metric.
 * 
 * @throws NotFoundException Throws NotFoundException if the given ID does not exist.
 *
 * @see #getDimensionPixelOffset
 * @see #getDimensionPixelSize
 */

Resource dimension value multiplied by the appropriate

Answer 11

Kotlin:

// Activity
val pixels: Float = resources.getDimension(R.dimen.your_dimen_id)
// Fragment
val pixels: Float = (activity as? MainActivity)?.resources?.getDimension(R.dimen.your_dimen_id) ?: return

Afterwards, if you need to convert Pixels to DP:

fun convertPixelsToDp(px: Float, context: Context): Float {
 return px / (context.resources.displayMetrics.densityDpi.toFloat() / DisplayMetrics.DENSITY_DEFAULT)
}