Using icons in Android preferences

I would like some of my preferences to have icons, like the Settings app.

I guess one way of doing this would be to copy all the relevant code and resources fro开发者_如何学编程m the Settings app, but it seems like overkill for a couple of icons.

Also I don't like the idea of having to duplicate the code and resources in each project that requires settings icons.

Has anyone solved this already with a simpler or resource-free approach?

The Settings application uses a private custom PreferenceScreen subclass to have the icon -- IconPreferenceScreen. It is 51 lines of code, including the comments, though it also requires some custom attributes. The simplest option is to clone all of that into your project, even though you do not like that.

source code

Since API level 11 you can add icon to preferences:

http://developer.android.com/reference/android/preference/Preference.html#setIcon%28int%29

http://developer.android.com/reference/android/preference/Preference.html#attr_android:icon

For older Android versions, you have to use custom layouts and bind images in code, as @roger-l suggests.

Updated.... answered and working

Use a custom layout for the icon preference

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+android:id/widget_frame"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:minHeight="?android:attr/listPreferredItemHeight"
     android:gravity="center_vertical"
     android:paddingRight="?android:attr/scrollbarSize">
     <ImageView
         android:id="@+id/icon"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginLeft="6dip"
         android:layout_marginRight="6dip"
         android:layout_gravity="center" />
     <RelativeLayout
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginLeft="2dip"
         android:layout_marginRight="6dip"
         android:layout_marginTop="6dip"
         android:layout_marginBottom="6dip"
         android:layout_weight="1">
         <TextView android:id="@+android:id/title"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:singleLine="true"
             android:textAppearance="?android:attr/textAppearanceLarge"
             android:ellipsize="marquee"
             android:fadingEdge="horizontal" />
         <TextView android:id="@+android:id/summary"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:layout_below="@android:id/title"
             android:layout_alignLeft="@android:id/title"
             android:textAppearance="?android:attr/textAppearanceSmall"
             android:maxLines="2" />
     </RelativeLayout>
</LinearLayout>

and the imported class for IconPreferenceScreen

public class IconPreferenceScreen extends Preference {
    private final Drawable mIcon;
    private static String mType;

    public IconPreferenceScreen(Context context, AttributeSet attrs, int iconRes) {
        this(context, attrs, 0, iconRes);
    }
    public IconPreferenceScreen(Context context, AttributeSet attrs,
            int defStyle, int iconRes) {
        super(context, attrs, defStyle);
        setLayoutResource(R.layout.preference_icon);
        mIcon = context.getResources().getDrawable(iconRes);
    }
    public IconPreferenceScreen(Context context, int iconRes) {
        this(context, null, iconRes);
    }
    @Override
    public void onBindView(View view) {
        super.onBindView(view);
        ImageView imageView = (ImageView) view.findViewById(R.id.icon);
        if (imageView != null && mIcon != null) {
            imageView.setImageDrawable(mIcon);
        }
    }
}

then you can just use a new IconPreferenceScreen in place of a Preference, and add an icon

Android 3.x Honeycomb shows icons defined in standard Preferences.

So probably the use of icon depends on Android OS version or screen size.