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"?
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7 Answers
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);
12 Comments
Romain Guy
The correct conversion is (int) (dps * scale + 0.5f). This is the formula we use throughout the framework.
Ken
The formula is in the docs. For further reading, go to section 3 of developer.android.com/guide/practices/…
AlikElzin-kilaka
@RomainGuy, can you please add a utility function to the API to convert from
dp to px? Thanks.
Deepak
what is dps here? im getting "dps cannot be resolved to a variable" error? what type of "dps" need to declare??
Robby Pond
The "dps" variable is the input value that you want to convert.
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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)
6 Comments
darrenp
Well done for finding out how to do this. I'm not a fan of repeating a formula in several places! Thanks.
Abdul Saleem
If not, then create function with the formula
Cassie
@Kenobi It does the conversion for you from DP to PX. The
65 above is the DP value you want converted to PX
Johny19
This should be the accepted answer, not the current one where these number (0.5) coming magically from no where
MarredCheese
@Johny19 The 0.5 is not magic. It's just how to round a floating point number to the nearest integer instead of truncating it. See my comment on Robby Pond's answer for more detail.
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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.
Comments
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.
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()
Comments
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
Comments
Simply you can use androidx.annotation
@Dimension(unit = Dimension.DP)
private static final int strokeWidth = 1;
