Android and setting width and height programmatically in dp units

Question

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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    lt dimen name  dimen entry in dp  gt 72dp lt  dimen gt    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

User · Answer

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

[android] Android and setting width and height programmatically in dp units

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