CODEWITHSUNDEEP
androidscaling
Ken
Ken

Reputation: 31171

Android and setting width and height programmatically in dp units

I'm doing:

button.setLayoutParams(new GridView.LayoutParams(65, 65));

According to the docs the units for the width and height (both 65 in the above) are "pixels". How do you force this to be device independent pixels, or "dp"?

Upvotes: 346

Views: 230333

Answers (7)

Mohamed Slama
Mohamed Slama

Reputation: 197

Simply you can use androidx.annotation

@Dimension(unit = Dimension.DP)
private static final int strokeWidth = 1;

Upvotes: 0

Quick learner
Quick learner

Reputation: 11477

Kotlin Version

val scale: Float = resources.displayMetrics.density
val resizedInDp = (stream.videoWidth * scale + 0.5f).toInt()

Usage:-

val params: ViewGroup.LayoutParams = yourLayout!!.layoutParams
            val scale: Float = resources.displayMetrics.density
            params.width = (widthDp * scale + 0.5f).toInt() // dp to px
            params.height =
                (heightDp * scale + 0.5f).toInt() // setting height according to aspect ratio
            yourLayout!!.layoutParams = params

Upvotes: 0

RickSanchez725
RickSanchez725

Reputation: 329

Based on drspaceboo's solution, with Kotlin you can use an extension to convert Float to dips more easily.

fun Float.toDips() =
        TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, this, resources.displayMetrics);

Usage:

(65f).toDips()

Upvotes: 7

Cassie
Cassie

Reputation: 5244

I know this is an old question however I've found a much neater way of doing this conversion.

Java

TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 65, getResources().getDisplayMetrics());

Kotlin

TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 65f, resources.displayMetrics)

Upvotes: 277

David
David

Reputation: 2179

simplest way(and even works from api 1) that tested is:

getResources().getDimensionPixelSize(R.dimen.example_dimen);

From documentations:

Retrieve a dimensional for a particular resource ID for use as a size in raw pixels. This is the same as getDimension(int), except the returned value is converted to integer pixels for use as a size. A size conversion involves rounding the base value, and ensuring that a non-zero base value is at least one pixel in size.

Yes it rounding the value but it's not very bad(just in odd values on hdpi and ldpi devices need to add a little value when ldpi is not very common) I tested in a xxhdpi device that converts 4dp to 16(pixels) and that is true.

Upvotes: 47

vine'th
vine'th

Reputation: 5030

Looking at your requirement, there is alternate solution as well. It seems you know the dimensions in dp at compile time, so you can add a dimen entry in the resources. Then you can query the dimen entry and it will be automatically converted to pixels in this call:

final float inPixels= mActivity.getResources().getDimension(R.dimen.dimen_entry_in_dp);

And your dimens.xml will have:

<dimen name="dimen_entry_in_dp">72dp</dimen>

Extending this idea, you can simply store the value of 1dp or 1sp as a dimen entry and query the value and use it as a multiplier. Using this approach you will insulate the code from the math stuff and rely on the library to perform the calculations.

Upvotes: 45

Robby Pond
Robby Pond

Reputation: 73494

You'll have to convert it from dps to pixels using the display scale factor.

final float scale = getContext().getResources().getDisplayMetrics().density;
int pixels = (int) (dps * scale + 0.5f);

Upvotes: 585

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