How do I use obtainStyledAttributes(int []) with internal Themes of Android

Question

So I have looked around and found out that android.R.styleable is no longer part of the SDK eventhough it is still documented here: http://developer.android.com/reference/android/R.styleable.html
That wouldn't really be an issue if it was clearly documented what the alternative is. For example the AOSP Calendar App is still using the android.R.styleable

// Get the dim amount from the theme   
TypedArray a = obtainStyledAttributes(com.android.internal.R.styleable.Theme);
lp.dimAmount = a.getFloat(android.R.styleable.Theme_backgroundDimAmount, 0.5f);
a.recycle();

So how would one get the backgroundDimAmount without getting the int[] from android.R.styleable.Theme? What do I have to stick into obtainStyledAttributes(int []) in order to make it work with the SDK?

Answer 1

This appears to be a bug in the SDK. I have filed an issue on it, which you may wish to star so as to receive updates on it.

As a worksaround, you can use reflection to access the field:

Class clazz=Class.forName("android.R$styleable");
int i=clazz.getField("Theme_backgroundDimAmount").getInt(clazz);

Answer 2

The CustomView API demo shows how to retrieve styled attributes. The code for the view is here:

http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/view/LabelView.html

The styleable array used to retrieve the text, color, and size is defined in the section here:

http://developer.android.com/resources/samples/ApiDemos/res/values/attrs.html

You can use to define any list of attributes that you want to retrieve as a group, containing both your own and ones defined by the platform.

As far as these things being in the documentation, there is a lot of java doc around the styleable arrays that makes them useful to have in the documentation, so they have been left there. However as the arrays change, such as new attributes being added, the values of the constants can change, so the platform ones can not be in the SDK (and please do not use any tricks to try to access them). There should be no need to use the platform ones anyway, because they are each there just for the implementation of parts of the framework, and it is trivial to create your own as shown here.

Answer 3

In the example, they left out the reference to the Context 'c':

public ImageAdapter(Context c) {
    mContext = c;
    TypedArray a = c.obtainStyledAttributes(R.styleable.GalleryPrototype);
    mGalleryItemBackground = a.getResourceId(
            R.styleable.GalleryPrototype_android_galleryItemBackground, 0);
    a.recycle();
}

Changing obtainStyledAttributes to c.obtainStyledAttributes should work