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android – Programmatically set height on LayoutParams as density-independent pixels

Posted by: admin March 11, 2020 Leave a comment

Questions:

Is there any way to set the height/width of a LayoutParams as density-independent pixels (dp)? It looks like the height/width, when set programmatically, are in pixels and not dp.

How to&Answers:

You need to convert your dip value into pixels:

int height = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, <HEIGHT>, getResources().getDisplayMetrics());

For me this does the trick.

Answer:

 public static int getDPI(int size, DisplayMetrics metrics){
     return (size * metrics.densityDpi) / DisplayMetrics.DENSITY_DEFAULT;        
 }

Call the function like this,

DisplayMetrics metrics;
metrics = new DisplayMetrics();         
getWindowManager().getDefaultDisplay().getMetrics(metrics);

int heigh = getDPI(height or width, metrics);

Answer:

Since it may be used multiple times:

public static int convDpToPx(Context context, float dp) {
    DisplayMetrics metrics = context.getResources().getDisplayMetrics();
    return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, metrics);
}

I found it more practical to use the conversion rate, as usally more than one value has to be converted. Since the conversion rate does not change, it saves a bit of processing time.

/**
 * Get conversion rate from dp into px.<br>
 * E.g. to convert 100dp: px = (int) (100 * convRate);
 * @param context e.g. activity
 * @return conversion rate
 */
public static float convRateDpToPx(Context context) {
    return context.getResources().getDisplayMetrics().densityDpi / 160f;
}

Answer:

Here is my snippet:

public class DpiUtils {

    public static int toPixels(int dp, DisplayMetrics metrics) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, metrics);
    }

}

where DisplayMetrics metrics = getResources().getDisplayMetrics()

Answer:

The answered solution didn’t work for me, the height of the view was still off. I ended up with this, which works well:

protected int dp2px(int dp){
    final float scale = getResources().getDisplayMetrics().density;
    return (int) (dp * scale + 0.5f);
}

And if you want the other way round, pixels to dp …

protected float px2dp(float px){
    DisplayMetrics metrics = Resources.getSystem().getDisplayMetrics();
    float dp = px / (metrics.densityDpi / 160f);
    return Math.round(dp);
}