Converting pixels to dpi for mdpi and hdpi screens

Question

I am using this code that I have found on another thread which is working fine on mdpi screens:

public static float convertDpToPixel(float dp,Context context){
        Resources resources = context.getResources();
        DisplayMetrics metrics = resources.getDisplayMetrics();
        float px = dp * (metrics.densityDpi/160f);
        return px;
    }

public static float convertPixelsToDp(float px,Context context){
        Resources resources = context.getResources();
        DisplayMetrics metrics = resources.getDisplayMetrics();
        float dp = px / (metrics.densityDpi /160f);
        return dp;

    }

When using it on hdpi screens the text size jumps when trying to increase the text size. I am assuming its because it is using the hardcoded 160f when dividing the densityDpi? Is there any dynamic way to determine whether it is 160dpi or 240dpi?

score 2 · Accepted Answer · answered Dec 06 '12 at 23:11

2

Try this method:

public float dpToPx(float dp, Context context) {
    float density = context.getResources().getDisplayMetrics().density;
    return dp * density;
}

answered Dec 06 '12 at 23:11

Michał Kisiel

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12

score 1 · Answer 2 · answered Dec 06 '12 at 19:50

From the doc:

metrics.density

is the scaling factor you are looking for.

This is a scaling factor for the Density Independent Pixel unit, where one DIP is one pixel on an approximately 160 dpi screen (for example a 240x320, 1.5"x2" screen), providing the baseline of the system's display. Thus on a 160dpi screen this density value will be 1; on a 120 dpi screen it would be .75; etc.

Converting pixels to dpi for mdpi and hdpi screens

2 Answers2

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