TextPainter class

An object that paints a TextSpan tree into a Canvas.

To use a TextPainter, follow these steps:

Create a TextSpan tree and pass it to the TextPainter constructor.
Call layout to prepare the paragraph.
Call paint as often as desired to paint the paragraph.
Call dispose when the object will no longer be accessed to release native resources. For TextPainter objects that are used repeatedly and stored on a State or RenderObject, call dispose from State.dispose or RenderObject.dispose or similar. For TextPainter objects that are only used ephemerally, it is safe to immediately dispose them after the last call to methods or properties on the object.

If the width of the area into which the text is being painted changes, return to step 2. If the text to be painted changes, return to step 1.

The default text style is white. To change the color of the text, pass a TextStyle object to the TextSpan in text.

Constructors

TextPainter({InlineSpan? text, TextAlign textAlign = TextAlign.start, TextDirection? textDirection, @Deprecated('Use textScaler instead. ' 'Use of textScaleFactor was deprecated in preparation for the upcoming nonlinear text scaling support. ' 'This feature was deprecated after v3.12.0-2.0.pre.') double textScaleFactor = 1.0, TextScaler textScaler = TextScaler.noScaling, int? maxLines, String? ellipsis, Locale? locale, StrutStyle? strutStyle, TextWidthBasis textWidthBasis = TextWidthBasis.parent, TextHeightBehavior? textHeightBehavior}): Creates a text painter that paints the given text.

Properties

debugDisposed → bool: Whether this object has been disposed or not.
no setter
didExceedMaxLines → bool: Whether any text was truncated or ellipsized.
no setter
ellipsis ↔ String?: The string used to ellipsize overflowing text. Setting this to a non-empty string will cause this string to be substituted for the remaining text if the text can not fit within the specified maximum width.
getter/setter pair
hashCode → int: The hash code for this object.
no setterinherited
height → double: The vertical space required to paint this text.
no setter
inlinePlaceholderBoxes → List<TextBox>?: An ordered list of TextBoxes that bound the positions of the placeholders in the paragraph.
no setter
locale ↔ Locale?: The locale used to select region-specific glyphs.
getter/setter pair
maxIntrinsicWidth → double: The width at which increasing the width of the text no longer decreases the height.
no setter
maxLines ↔ int?: An optional maximum number of lines for the text to span, wrapping if necessary.
getter/setter pair
minIntrinsicWidth → double: The width at which decreasing the width of the text would prevent it from painting itself completely within its bounds.
no setter
plainText → String: Returns a plain text version of the text to paint.
no setter
preferredLineHeight → double: The height of a space in text in logical pixels.
no setter
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
size → Size: The amount of space required to paint this text.
no setter
strutStyle ↔ StrutStyle?: The strut style to use. Strut style defines the strut, which sets minimum vertical layout metrics.
getter/setter pair
text ↔ InlineSpan?: The (potentially styled) text to paint.
getter/setter pair
textAlign ↔ TextAlign: How the text should be aligned horizontally.
getter/setter pair
textDirection ↔ TextDirection?: The default directionality of the text.
getter/setter pair
textHeightBehavior ↔ TextHeightBehavior?: Defines how to apply TextStyle.height over and under text.
getter/setter pair
textScaleFactor ↔ double: Deprecated. Will be removed in a future version of Flutter. Use textScaler instead.
getter/setter pair
textScaler ↔ TextScaler: The font scaling strategy to use when laying out and rendering the text.
getter/setter pair
textWidthBasis ↔ TextWidthBasis: Defines how to measure the width of the rendered text.
getter/setter pair
width → double: The horizontal space required to paint this text.
no setter
wordBoundaries → WordBoundary: Returns a TextBoundary that can be used to perform word boundary analysis on the current text.
no setter

Methods

computeDistanceToActualBaseline(TextBaseline baseline) → double: Returns the distance from the top of the text to the first baseline of the given type.
computeLineMetrics() → List<LineMetrics>: Returns the full list of LineMetrics that describe in detail the various metrics of each laid out line.
dispose() → void: Releases the resources associated with this painter.
getBoxesForSelection(TextSelection selection, {BoxHeightStyle boxHeightStyle = ui.BoxHeightStyle.tight, BoxWidthStyle boxWidthStyle = ui.BoxWidthStyle.tight}) → List<TextBox>: Returns a list of rects that bound the given selection.
getClosestGlyphForOffset(Offset offset) → GlyphInfo?: Returns the GlyphInfo of the glyph closest to the given offset in the paragraph coordinate system, or null if the text is empty, or is entirely clipped or ellipsized away.
getFullHeightForCaret(TextPosition position, Rect caretPrototype) → double: Returns the strut bounded height of the glyph at the given position.
getLineBoundary(TextPosition position) → TextRange: Returns the text range of the line at the given offset.
getOffsetAfter(int offset) → int?: Returns the closest offset after offset at which the input cursor can be positioned.
getOffsetBefore(int offset) → int?: Returns the closest offset before offset at which the input cursor can be positioned.
getOffsetForCaret(TextPosition position, Rect caretPrototype) → Offset: Returns the offset at which to paint the caret.
getPositionForOffset(Offset offset) → TextPosition: Returns the closest position within the text for the given pixel offset.
getWordBoundary(TextPosition position) → TextRange: Returns the text range of the word at the given offset. Characters not part of a word, such as spaces, symbols, and punctuation, have word breaks on both sides. In such cases, this method will return a text range that contains the given text position.
layout({double minWidth = 0.0, double maxWidth = double.infinity}) → void: Computes the visual position of the glyphs for painting the text.
markNeedsLayout() → void: Marks this text painter's layout information as dirty and removes cached information.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
paint(Canvas canvas, Offset offset) → void: Paints the text onto the given canvas at the given offset.
setPlaceholderDimensions(List<PlaceholderDimensions>? value) → void: Sets the dimensions of each placeholder in text.
toString() → String: A string representation of this object.
inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited

Static Methods

computeMaxIntrinsicWidth({required InlineSpan text, required TextDirection textDirection, TextAlign textAlign = TextAlign.start, double textScaleFactor = 1.0, TextScaler textScaler = TextScaler.noScaling, int? maxLines, String? ellipsis, Locale? locale, StrutStyle? strutStyle, TextWidthBasis textWidthBasis = TextWidthBasis.parent, TextHeightBehavior? textHeightBehavior, double minWidth = 0.0, double maxWidth = double.infinity}) → double: Computes the max intrinsic width of a configured TextPainter.
computeWidth({required InlineSpan text, required TextDirection textDirection, TextAlign textAlign = TextAlign.start, double textScaleFactor = 1.0, TextScaler textScaler = TextScaler.noScaling, int? maxLines, String? ellipsis, Locale? locale, StrutStyle? strutStyle, TextWidthBasis textWidthBasis = TextWidthBasis.parent, TextHeightBehavior? textHeightBehavior, double minWidth = 0.0, double maxWidth = double.infinity}) → double: Computes the width of a configured TextPainter.
isHighSurrogate(int value) → bool: Returns true iff the given value is a valid UTF-16 high (first) surrogate. The value must be a UTF-16 code unit, meaning it must be in the range 0x0000-0xFFFF.
isLowSurrogate(int value) → bool: Returns true iff the given value is a valid UTF-16 low (second) surrogate. The value must be a UTF-16 code unit, meaning it must be in the range 0x0000-0xFFFF.