Added in API level 28

Summary: Nested Classes | Inherited Constants | Methods | Inherited Methods

PrecomputedText

Kotlin |Java

public class PrecomputedText
extends Object implements Spannable

java.lang.Object
↳	android.text.PrecomputedText

A text which has the character metrics data. A text object that contains the character metrics data and can be used to improve the performance of text layout operations. When a PrecomputedText is created with a given CharSequence, it will measure the text metrics during the creation. This PrecomputedText instance can be set on TextView or StaticLayout. Since the text layout information will be included in this instance, TextView or StaticLayout will not have to recalculate this information. Note that the PrecomputedText created from different parameters of the target TextView will be rejected internally and compute the text layout again with the current TextView parameters.

 An example usage is:
 
  static void asyncSetText(TextView textView, final String longString, Executor bgExecutor) {
      // construct precompute related parameters using the TextView that we will set the text on.
      final PrecomputedText.Params params = textView.getTextMetricsParams();
      final Reference textViewRef = new WeakReference<>(textView);
      bgExecutor.submit(() -> {
          TextView textView = textViewRef.get();
          if (textView == null) return;
          final PrecomputedText precomputedText = PrecomputedText.create(longString, params);
          textView.post(() -> {
              TextView textView = textViewRef.get();
              if (textView == null) return;
              textView.setText(precomputedText);
          });
      });
  }

Note that the PrecomputedText created from different parameters of the target TextView will be rejected. Note that any NoCopySpan attached to the original text won't be passed to PrecomputedText.

Summary

Nested classes
`class`	`PrecomputedText.Params` The information required for building `PrecomputedText`.

Inherited constants

From interface android.text.Spanned

`int`	`SPAN_COMPOSING` This flag is set on spans that are being used to apply temporary styling information on the composing text of an input method, so that they can be found and removed when the composing text is being replaced.
`int`	`SPAN_EXCLUSIVE_EXCLUSIVE` Spans of type SPAN_EXCLUSIVE_EXCLUSIVE do not expand to include text inserted at either their starting or ending point.
`int`	`SPAN_EXCLUSIVE_INCLUSIVE` Non-0-length spans of type SPAN_EXCLUSIVE_INCLUSIVE expand to include text inserted at their ending point but not at their starting point.
`int`	`SPAN_INCLUSIVE_EXCLUSIVE` Non-0-length spans of type SPAN_INCLUSIVE_EXCLUSIVE expand to include text inserted at their starting point but not at their ending point.
`int`	`SPAN_INCLUSIVE_INCLUSIVE` Spans of type SPAN_INCLUSIVE_INCLUSIVE expand to include text inserted at either their starting or ending point.
`int`	`SPAN_INTERMEDIATE` This flag will be set for intermediate span changes, meaning there is guaranteed to be another change following it.
`int`	`SPAN_MARK_MARK` 0-length spans with type SPAN_MARK_MARK behave like text marks: they remain at their original offset when text is inserted at that offset.
`int`	`SPAN_MARK_POINT` SPAN_MARK_POINT is a synonym for `SPAN_INCLUSIVE_INCLUSIVE`.
`int`	`SPAN_PARAGRAPH` SPAN_PARAGRAPH behaves like SPAN_INCLUSIVE_EXCLUSIVE (SPAN_MARK_MARK), except that if either end of the span is at the end of the buffer, that end behaves like _POINT instead (so SPAN_INCLUSIVE_INCLUSIVE if it starts in the middle and ends at the end, or SPAN_EXCLUSIVE_INCLUSIVE if it both starts and ends at the end).
`int`	`SPAN_POINT_MARK` SPAN_POINT_MARK is a synonym for `SPAN_EXCLUSIVE_EXCLUSIVE`.
`int`	`SPAN_POINT_MARK_MASK` Bitmask of bits that are relevent for controlling point/mark behavior of spans.
`int`	`SPAN_POINT_POINT` 0-length spans with type SPAN_POINT_POINT behave like cursors: they are pushed forward by the length of the insertion when text is inserted at their offset.
`int`	`SPAN_PRIORITY` The bits specified by the SPAN_PRIORITY bitmap determine the order of change notifications -- higher numbers go first.
`int`	`SPAN_PRIORITY_SHIFT` The bits numbered just above SPAN_PRIORITY_SHIFT determine the order of change notifications -- higher numbers go first.
`int`	`SPAN_USER` The bits specified by the SPAN_USER bitfield are available for callers to use to store scalar data associated with their span object.
`int`	`SPAN_USER_SHIFT` The bits numbered SPAN_USER_SHIFT and above are available for callers to use to store scalar data associated with their span object.

Public methods
`char`	`charAt(int index)` Returns the `char` value at the specified index.
`static PrecomputedText`	`create(CharSequence text, PrecomputedText.Params params)` Create a new `PrecomputedText` which will pre-compute text measurement and glyph positioning information.
`void`	`getBounds(int start, int end, Rect bounds)` Retrieves the text bounding box for the given range.
`void`	`getFontMetricsInt(int start, int end, Paint.FontMetricsInt outMetrics)` Retrieves the text font metrics for the given range.
`int`	`getParagraphCount()` Returns the count of paragraphs.
`int`	`getParagraphEnd(int paraIndex)` Returns the paragraph end offset of the text.
`int`	`getParagraphStart(int paraIndex)` Returns the paragraph start offset of the text.
`PrecomputedText.Params`	`getParams()` Returns the layout parameters used to measure this text.
`int`	`getSpanEnd(Object tag)` Return the end of the range of text to which the specified markup object is attached, or -1 if the object is not attached.
`int`	`getSpanFlags(Object tag)` Return the flags that were specified when `Spannable.setSpan` was used to attach the specified markup object, or 0 if the specified object has not been attached.
`int`	`getSpanStart(Object tag)` Return the beginning of the range of text to which the specified markup object is attached, or -1 if the object is not attached.
`<T> T[]`	`getSpans(int start, int end, Class<T> type)` Return an array of the markup objects attached to the specified slice of this CharSequence and whose type is the specified type or a subclass of it.
`float`	`getWidth(int start, int end)` Returns text width for the given range.
`int`	`length()` Returns the length of this character sequence.
`int`	`nextSpanTransition(int start, int limit, Class<T> type)` Return the first offset greater than `start` where a markup object of class `type` begins or ends, or `limit` if there are no starts or ends greater than `start` but less than `limit`.
`void`	`removeSpan(Object what)` Remove the specified object from the range of text to which it was attached, if any.
`void`	`setSpan(Object what, int start, int end, int flags)` Attach the specified markup object to the range `start…end` of the text, or move the object to that range if it was already attached elsewhere.
`CharSequence`	`subSequence(int start, int end)` Returns a `CharSequence` that is a subsequence of this sequence.
`String`	`toString()` Returns a string representation of the object.

Inherited methods

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

From interface


        
          android.text.Spannable

`abstract void`	`removeSpan(Object what)` Remove the specified object from the range of text to which it was attached, if any.
`abstract void`	`setSpan(Object what, int start, int end, int flags)` Attach the specified markup object to the range `start…end` of the text, or move the object to that range if it was already attached elsewhere.

From interface


        
          android.text.Spanned

`abstract int`	`getSpanEnd(Object tag)` Return the end of the range of text to which the specified markup object is attached, or -1 if the object is not attached.
`abstract int`	`getSpanFlags(Object tag)` Return the flags that were specified when `Spannable.setSpan` was used to attach the specified markup object, or 0 if the specified object has not been attached.
`abstract int`	`getSpanStart(Object tag)` Return the beginning of the range of text to which the specified markup object is attached, or -1 if the object is not attached.
`abstract <T> T[]`	`getSpans(int start, int end, Class<T> type)` Return an array of the markup objects attached to the specified slice of this CharSequence and whose type is the specified type or a subclass of it.
`abstract int`	`nextSpanTransition(int start, int limit, Class<T> type)` Return the first offset greater than `start` where a markup object of class `type` begins or ends, or `limit` if there are no starts or ends greater than `start` but less than `limit`.

From interface


        
          java.lang.CharSequence

`abstract char`	`charAt(int index)` Returns the `char` value at the specified index.
`default IntStream`	`chars()` Returns a stream of `int` zero-extending the `char` values from this sequence.
`default IntStream`	`codePoints()` Returns a stream of code point values from this sequence.
`static int`	`compare(CharSequence cs1, CharSequence cs2)` Compares two `CharSequence` instances lexicographically.
`default boolean`	`isEmpty()` Returns `true` if this character sequence is empty.
`abstract int`	`length()` Returns the length of this character sequence.
`abstract CharSequence`	`subSequence(int start, int end)` Returns a `CharSequence` that is a subsequence of this sequence.
`abstract String`	`toString()` Returns a string containing the characters in this sequence in the same order as this sequence.

Public methods

charAt

Added in API level 28

public char charAt (int index)

Returns the char value at the specified index. An index ranges from zero to length() - 1. The first char value of the sequence is at index zero, the next at index one, and so on, as for array indexing.

If the char value specified by the index is a surrogate, the surrogate value is returned.

Parameters
`index`	`int`: the index of the `char` value to be returned

Returns
`char`	the specified `char` value

create

Added in API level 28

public static PrecomputedText create (CharSequence text, 
                PrecomputedText.Params params)

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.

Note that any NoCopySpan attached to the text won't be passed to the created PrecomputedText.

Parameters
`text`	`CharSequence`: the text to be measured This value cannot be `null`.
`params`	`PrecomputedText.Params`: parameters that define how text will be precomputed This value cannot be `null`.

Returns
`PrecomputedText`	A `PrecomputedText`

getBounds

Added in API level 28

public void getBounds (int start, 
                int end, 
                Rect bounds)

Retrieves the text bounding box for the given range. Both start and end offset need to be in the same paragraph, otherwise IllegalArgumentException will be thrown.

Parameters
`start`	`int`: the inclusive start offset in the text Value is 0 or greater
`end`	`int`: the exclusive end offset in the text Value is 0 or greater
`bounds`	`Rect`: the output rectangle This value cannot be `null`.

Throws
`IllegalArgumentException`	if start and end offset are in the different paragraph.

getFontMetricsInt

Added in API level 33

public void getFontMetricsInt (int start, 
                int end, 
                Paint.FontMetricsInt outMetrics)

Retrieves the text font metrics for the given range. Both start and end offset need to be in the same paragraph, otherwise IllegalArgumentException will be thrown.

Parameters
`start`	`int`: the inclusive start offset in the text Value is 0 or greater
`end`	`int`: the exclusive end offset in the text Value is 0 or greater
`outMetrics`	`Paint.FontMetricsInt`: the output font metrics This value cannot be `null`.

Throws
`IllegalArgumentException`	if start and end offset are in the different paragraph.

getParagraphCount

Added in API level 28

public int getParagraphCount ()

Returns the count of paragraphs.

Returns
`int`	Value is 0 or greater

getParagraphEnd

Added in API level 28

public int getParagraphEnd (int paraIndex)

Returns the paragraph end offset of the text.

Parameters
`paraIndex`	`int`: Value is 0 or greater

Returns
`int`	Value is 0 or greater

getParagraphStart

Added in API level 28

public int getParagraphStart (int paraIndex)

Returns the paragraph start offset of the text.

Parameters
`paraIndex`	`int`: Value is 0 or greater

Returns
`int`	Value is 0 or greater

getParams

Added in API level 28

public PrecomputedText.Params getParams ()

Returns the layout parameters used to measure this text.

Returns
`PrecomputedText.Params`	This value cannot be `null`.

getSpanEnd

Added in API level 28

public int getSpanEnd (Object tag)

Return the end of the range of text to which the specified markup object is attached, or -1 if the object is not attached.

Parameters
`tag`	`Object`

Returns
`int`

getSpanFlags

Added in API level 28

public int getSpanFlags (Object tag)

Return the flags that were specified when Spannable.setSpan was used to attach the specified markup object, or 0 if the specified object has not been attached.

Parameters
`tag`	`Object`

Returns
`int`

getSpanStart

Added in API level 28

public int getSpanStart (Object tag)

Return the beginning of the range of text to which the specified markup object is attached, or -1 if the object is not attached.

Parameters
`tag`	`Object`

Returns
`int`

getSpans

Added in API level 28

public T[] getSpans (int start, 
                int end, 
                Class<T> type)

Return an array of the markup objects attached to the specified slice of this CharSequence and whose type is the specified type or a subclass of it. Specify Object.class for the type if you want all the objects regardless of type.

Parameters
`start`	`int`
`end`	`int`
`type`	`Class`

Returns
`T[]`

getWidth

Added in API level 28

public float getWidth (int start, 
                int end)

Returns text width for the given range. Both start and end offset need to be in the same paragraph, otherwise IllegalArgumentException will be thrown.

Parameters
`start`	`int`: the inclusive start offset in the text Value is 0 or greater
`end`	`int`: the exclusive end offset in the text Value is 0 or greater

Returns
`float`	the text width Value is 0.0f or greater

Throws
`IllegalArgumentException`	if start and end offset are in the different paragraph.

length

Added in API level 28

public int length ()

Returns the length of this character sequence. The length is the number of 16-bit chars in the sequence.

Returns
`int`	the number of `char`s in this sequence

nextSpanTransition

Added in API level 28

public int nextSpanTransition (int start, 
                int limit, 
                Class<T> type)

Return the first offset greater than start where a markup object of class type begins or ends, or limit if there are no starts or ends greater than start but less than limit. Specify null or Object.class for the type if you want every transition regardless of type.

Parameters
`start`	`int`
`limit`	`int`
`type`	`Class`

Returns
`int`

removeSpan

Added in API level 28

public void removeSpan (Object what)

Remove the specified object from the range of text to which it was attached, if any. It is OK to remove an object that was never attached in the first place.

Parameters
`what`	`Object`

Throws
`IllegalArgumentException`	if `MetricAffectingSpan` is specified.

setSpan

Added in API level 28

public void setSpan (Object what, 
                int start, 
                int end, 
                int flags)

Attach the specified markup object to the range start…end of the text, or move the object to that range if it was already attached elsewhere. See Spanned for an explanation of what the flags mean. The object can be one that has meaning only within your application, or it can be one that the text system will use to affect text display or behavior. Some noteworthy ones are the subclasses of CharacterStyle and ParagraphStyle, and TextWatcher and SpanWatcher.

Parameters
`what`	`Object`
`start`	`int`
`end`	`int`
`flags`	`int`

Throws
`IllegalArgumentException`	if `MetricAffectingSpan` is specified.

subSequence

Added in API level 28

public CharSequence subSequence (int start, 
                int end)

Returns a CharSequence that is a subsequence of this sequence. The subsequence starts with the char value at the specified index and ends with the char value at index end - 1. The length (in chars) of the returned sequence is end - start, so if start == end then an empty sequence is returned.

Parameters
`start`	`int`: the start index, inclusive
`end`	`int`: the end index, exclusive

Returns
`CharSequence`	the specified subsequence

toString

Added in API level 28

public String toString ()

Returns a string representation of the object.

Returns
`String`	a string representation of the object.

PrecomputedText

Summary

Nested classes

Inherited constants

Public methods

Inherited methods

Public methods

charAt

create

getBounds

getFontMetricsInt

getParagraphCount

getParagraphEnd

getParagraphStart

getParams

getSpanEnd

getSpanFlags

getSpanStart

getSpans

getWidth

length

nextSpanTransition

removeSpan

setSpan

subSequence

toString