How to implement TextView line spacing methods for older Android API?

Question

Previously, I asked a question titled: "How to paginate text in Android" on stackoverflow, which lead to a great answer that helped me so much. Now I need to port the code on the older Android API, and in case, Android API version 8, so I can run my application on mostly all Android devices, starting from Android 2.2.

The problem I come across is that some methods used in the answer are only available in Android API 16+.

        mPagination = new Pagination(mText,
                mTextView.getWidth(),
                mTextView.getHeight(),
                mTextView.getPaint(),
                mTextView.getLineSpacingMultiplier(),
                mTextView.getLineSpacingExtra(),
                mTextView.getIncludeFontPadding());

So, I have to implement at least these methods:

                TextView.getLineSpacingMultiplier()
                TextView.getLineSpacingExtra()
                TextView.getIncludeFontPadding()

The second one seems to be already described here as:

mTextView.getPaint().getFontSpacing()
* mTextView.getLineSpacingMultiplier() + mTextView.getLineSpacingExtra()

But I don't know if the other two are relevant in 2.2, and if they are, how to implement them in Android API version 8. There is some hint here, using the source code of Android TextView which I could not fully understand.

Answer 1

If we look at the TextView's sources we can see the following.

In Android 5.0:

private float mSpacingMult = 1.0f;
private float mSpacingAdd = 0.0f;
...
private boolean mIncludePad = true;

In Android 2.0:

private float mSpacingMult = 1;
private float mSpacingAdd = 0;
...
private boolean mIncludePad = true;

So the default values are equal.

With that said, you can use the Pagination's constructor with the default values which would work for API 8+:

new Pagination(mText,
            mTextView.getWidth(),
            mTextView.getHeight(),
            mTextView.getPaint(),
            1.0f, 0.0f, true);

In case you let a user change/set (via a settings menu) these parameters, again, no need to use the getters. You simply set a new value(s) of parameter(s) utilizing one of the TextView's setters and pass the same value(s) to the Pagination's constructor. For instance,

new Pagination(mText,
            mTextView.getWidth(),
            mTextView.getHeight(),
            mTextView.getPaint(),
            newValueOfSpacingMultiplier,
            newValueOfSpacingExtra,
            newValueOfIncludeFontPadding);

EDIT

What I'm trying to say is that there is no need "to implement them in Android API version 8". Once set the parameters never change within TextView's lifecycle. You can check it with a simple test. Just look at their values before setting any text (for example, in onCreate() of the sample code) and after (in onGlobalLayout() right after mPagination initialization or in the update() method).

The idea of passing all the parameters of TextView to the Pagination's constructor is to use identically configured instances of the Layout class under the hood of both TextView and Pagination. So instead of passing the parameters to Pagination's constructor previously retrieved from TextView with getters, you could achieve the identically configured Layout by passing whatever values you'd like to Pagination and setting the same values to TextView with proper setters that are already met in API version 8.