Question

1. New -> Android project for testing the problem

2. Code for Test.java:

   package test.density.yeah;

   import android.app.Activity;
   import android.os.Bundle;
   
   public class TestActivity extends Activity {
       /** Called when the activity is first created. */
       @Override
       public void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.main);
       }
   }
   

3. Code for main.xml:

   <ImageButton
   android:background="@null"
   android:src="@drawable/icon"
   android:layout_width="200dp"
   android:layout_height="200dp">
   </ImageButton>
   

4. Started emulator with settings:

Resolution – 480×800

Avstracted LCD Density – 190

RESULT:

http://cs5961.userapi.com/u68152416/-3/y_ef134df2.jpg

After that I’ve started emulator with such settings:

Resolution – 480×800

Avstracted LCD Density – 240

RESULT:

http://cs5961.userapi.com/u68152416/-3/y_8b99507b.jpg

Emulator settings for the first test mathes my HTC HD2 characteristics and second is the same as the HTC Sensation XL is. When running this test app on them
it is the same problem. HD2 (480×800, 190dpi) – small image, Sensation (480×800, 240dpi) – huge image.

So why “density independent pixels” do not work?

Answer 1

It works fine, but there’s a twist you need to know about.

You’re using the src attribute on the View. If you do that, the View will be sized according to the bitmap size, and you’d normally have different versions for the various densities, mdpi, hdpi, xhdpi etc. It will ignore layout_height and layout_width.

If you want your View to ignore the bitmap size and use the layout_width and layout_height values to force the size, you need to use the background attribute, not src.

<ImageButton
    android:background="@drawable/icon"
    android:layout_width="200dp"
    android:layout_height="200dp">
</ImageButton>