Which unit of measurement does the Paint.setTextSize(float) use?

Question

I want to draw text with an specific height(in pixels) on a view using Canvas. Can you simply use Paint.setTextSize(float) with the number of pixels or is this using dp or sp?

Answer 1

It uses pixels, but you can convert it to dp using this code:

double getDPFromPixels(double pixels) {
    DisplayMetrics metrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(metrics);
    switch(metrics.densityDpi){
     case DisplayMetrics.DENSITY_LOW:
                pixels = pixels * 0.75;
                break;
     case DisplayMetrics.DENSITY_MEDIUM:
                 //pixels = pixels * 1;
                 break;
     case DisplayMetrics.DENSITY_HIGH:
                 pixels = pixels * 1.5;
                 break;
    }
    return pixels;
}

Answer 2

The easiest way to get a px value for such methods is to simply define the appropriate dp or sp value in the dimens.xml file and retrieve it like this:

int sizeInPx = context.getResources().getDimensionPixelSize(R.dimen.sizeInSp);

You actually have 3 methods available to use depending on your needs:

• getDimension() Returns a float in pixels.

• getDimensionPixelSize() Returns an int in pixels. This is the same as getDimension(), except the returned value is ROUNDED to the nearest integer value and it ensures that a non-zero input value results in a non zero output value (eg 0.1 is returned as 1, not 0).

• getDimensionPixelOffset() Returns an int in pixels. This is the same as getDimension(), except the returned value is TRUNCATED (ie. rounded down). The result may be zero.

Answer 3

These methods include DisplayMetrics that can be added into future Android SDK.

Pixels to dip:

public static float getDipFromPixels(float px) {
        return TypedValue.applyDimension(
                TypedValue.COMPLEX_UNIT_PX,
                px,
                Resources.getSystem().getDisplayMetrics()
        );
}

Dip to pixels:

public static float getPixelsFromDip(float dip) {
        return TypedValue.applyDimension(
                TypedValue.COMPLEX_UNIT_DIP, 
                dip,
                Resources.getSystem().getDisplayMetrics()
        );
}