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Asked: 2026-05-22T02:07:48+00:00

I want to put a toolbar in my application. The toolbar will use ImageViews

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I want to put a toolbar in my application. The toolbar will use ImageViews as application buttons. I would like the ImageViews to be the exact same size regardless device; by “same size” I mean that, when rendered to the screen, if I measure them with a ruler, the dimensions will be the same. I would like this size to be ~10mm (the width of my index finger).

I have been completely unsuccessful in accomplishing this.

I am testing on a MDPI, large screen Acer Iconia Tab and a HDPI medium screen Samsung Galaxy Tab. If I set layout_width="50dip" and layout_height="50dip", the buttons render as ~10mm on the Samsung, and ~8mm on the Acer. If I set the buttons as layout_width="12mm" and layout_height="12mm", they render as 12mm on the Acer and ~9mm on the Galaxy (confusing that 50dip renders bigger on the Galaxy than the Acer, but 12 mm renders smaller on the Galaxy than on the Acer).

If I place a 32pix x 32pix icon in my drawable-mdpi folder (and no equivalent in the drawable-hdpi folder), and set layout_width="wrap_content" and layout_height="wrap_content"; the results are similar to if set to 50dip, the Samsung is about 10mm, the Acer about 8mm. If I add a 48pix x 48pix icon to my drawable-hdpi folder, there is no change; presumably because the Acer still uses the mdpi icon and the Samsung uses the bigger one, but scales it down by 50% because it knows its hdpi (if am confident that this surprising scaling occurs because if I move the 48pix icon to the mdpi folder, and have nothing in the hdpi folder, the icon shows very large on the Samsung).

I am confused and could really use advice. How do I make my button fingertip sized regardless of dpi and screen size?

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1 Answer

  1. Editorial Team

    Ok, I finally figured out what is going on:

    The problem is that a image button who’s width is specified as 10mm,
    shows as about 7mm on my Galaxy tab, and about 9mm on my Iconia Tab.
    There are 2 reasons for this rather significant difference:

    1. The Iconia Tab reports its xdpi as ~160, when its actual xdpi
      is ~150.
    2. Honeycomb uses a new drawable for its button background, with
      significantly smaller margin than the drawable in Froyo.

    Issue 1 accounts for about .6mm of the difference, Issue 2 accounts
    for the remainder. Issue 2 can be solved by choosing one of the two
    backgrounds, packaging it with the application, and specifying it as
    the background for the ImageButton. Issue 1 cannot be resolved, but the difference it creates is relatively minor once issue 2 is dealt
    with.

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