How can I shrink the drawable on a button?

Use a ScaleDrawable as Abhinav suggested.

The problem is that the drawable doesn't show then - it's some sort of bug in ScaleDrawables. you'll need to change the "level" programmatically. This should work for every button:

// Fix level of existing drawables
Drawable[] drawables = myButton.getCompoundDrawables();
for (Drawable d : drawables) if (d != null && d instanceof ScaleDrawable) d.setLevel(1);
myButton.setCompoundDrawables(drawables[0], drawables[1], drawables[2], drawables[3]);

You should use a ImageButton and specify the image in android:src, and set android:scaletype to fitXY

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Setting scaled drawable in code

Drawable drawable = getResources().getDrawable(R.drawable.s_vit);
drawable.setBounds(0, 0, (int)(drawable.getIntrinsicWidth()*0.5), 
                         (int)(drawable.getIntrinsicHeight()*0.5));
ScaleDrawable sd = new ScaleDrawable(drawable, 0, scaleWidth, scaleHeight);
Button btn = findViewbyId(R.id.yourbtnID);
btn.setCompoundDrawables(sd.getDrawable(), null, null, null); //set drawableLeft for example

Buttons do not resize their inner images.

My solution does not require code manipulation.

It uses a layout with TextView and ImageView.

The background of the layout should have the red 3d drawable.

You may need to define the android:scaleType xml attribute.

Example:

<LinearLayout
    android:id="@+id/list_item"
    android:layout_width="fill_parent"
    android:layout_height="50dp"
    android:padding="2dp" >

    <ImageView
        android:layout_width="50dp"
        android:layout_height="fill_parent"
        android:src="@drawable/camera" />

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_weight="1"
        android:lines="1"
        android:gravity="center_vertical"
        android:text="Hello - primary" />

</LinearLayout>

BTW:

1. Counting on different resolution icons may result in a non predictable UI (icon too big or too small)
2. Text in textview (including in buttons) does not fill the component. This is an Android problem and I don't know how to solve it.
3. You can use it as an include.

Good luck

I have found a very simple and effective XML solution that doesn't require ImageButton

Make a drawable file for your image as below and use it for android:drawableLeft

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <item
    android:id="@+id/half_overlay"
    android:drawable="@drawable/myDrawable"
    android:width="40dp"
    android:height="40dp"
    />

</layer-list>

You can set the image size with android:width and android:height properties.

This way you could at least get the same size for different screens.

The drawback is that it is not exactly like fitXY which would scale image width to fit X and scale image height accordingly.