PrecomputedTextCompat

java-static fun create(text: CharSequence, params: PrecomputedTextCompat.Params): PrecomputedTextCompat!

Create a new PrecomputedText which will pre-compute text measurement and glyph positioning information.

This can be expensive, so computing this on a background thread before your text will be presented can save work on the UI thread.

fun getParagraphCount(): @IntRange(from = 0) Int

Returns the count of paragraphs.

fun getParagraphEnd(paraIndex: @IntRange(from = 0) Int): @IntRange(from = 0) Int

Returns the paragraph end offset of the text.

fun getParagraphStart(paraIndex: @IntRange(from = 0) Int): @IntRange(from = 0) Int

Returns the paragraph start offset of the text.

fun getParams(): PrecomputedTextCompat.Params

Returns the parameters used to measure this text.

@UiThread
java-static fun getTextFuture(
    charSequence: CharSequence,
    params: PrecomputedTextCompat.Params,
    executor: Executor?
): Future<PrecomputedTextCompat!>!

Helper for PrecomputedText that returns a future to be used with setTextFuture. PrecomputedText is suited to compute on a background thread, but when TextView properties are dynamic, it's common to configure text properties and text at the same time, when binding a View. For example, in a RecyclerView Adapter:

    void onBindViewHolder(ViewHolder vh, int position) {
        ItemData data = getData(position);

        vh.textView.setTextSize(...);
        vh.textView.setFontVariationSettings(...);
        vh.textView.setText(data.text);
    }

With getTextFuture(), you can block on the result of the precomputation safely before the result is needed. AppCompatTextView provides setTextFuture for exactly this use case. With the following code, the app's layout work is largely done on a background thread:

    void onBindViewHolder(ViewHolder vh, int position) {
        ItemData data = getData(position);

        vh.textView.setTextSize(...);
        vh.textView.setFontVariationSettings(...);

        // start precompute
        Futurefuture = PrecomputedTextCompat.getTextFuture(
                data.text, vh.textView.getTextMetricsParamsCompat(), myExecutor);

        // and pass future to TextView, which awaits result before measuring
        vh.textView.setTextFuture(future);
    }

Note: all TextView layout properties must be set before creating the Params object. If they are changed during the precomputation, this can cause a IllegalArgumentException when the precomputed value is consumed during measure, and doesn't reflect the TextView's current state.