TextDelegate
class TextDelegate
| kotlin.Any | |
| ↳ | androidx.ui.text.TextDelegate |
An object that paints text onto a Canvas.
To use a TextDelegate, follow these steps:
- Create an AnnotatedString and pass it to the TextDelegate constructor.
- Call layout to prepare the paragraph.
- Call paint as often as desired to paint the paragraph.
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.
Summary
Public constructors |
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|---|---|
<init>(text: AnnotatedString, style: TextStyle? = null, paragraphStyle: ParagraphStyle? = null, maxLines: Int? = null, softWrap: Boolean = true, overflow: TextOverflow = TextOverflow.Clip, density: Density, layoutDirection: LayoutDirection, resourceLoader: Font.ResourceLoader)An object that paints text onto a Canvas. |
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Public methods |
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|---|---|
| TextDirection |
getBidiRunDirection(offset: Int)Get the text direction of the character at the given offset. |
| Rect |
getBoundingBox(offset: Int)Returns the bounding box as Rect of the character for given character offset. |
| Float |
getHorizontalPosition(offset: Int, usePrimaryDirection: Boolean)Get the horizontal position for the specified text offset. |
| Float |
getLineBottom(lineIndex: Int)Returns the bottom y coordinate of the given line. |
| Int |
getLineForOffset(offset: Int)Returns the line number on which the specified text offset appears. |
| Int |
getOffsetForPosition(position: PxPosition)Returns the character offset closest to the given graphical position. |
| TextDirection |
getParagraphDirection(offset: Int)Get the text direction of the paragraph containing the given offset. |
| TextRange |
getWordBoundary(offset: Int)Returns the text range of the word at the given character offset. |
| Unit |
layout(constraints: Constraints) |
| Unit | |
| Unit |
Paints the text onto the given canvas. |
| Unit |
paintBackground(start: Int, end: Int, color: Color, canvas: Canvas)Draws text background of the given range. |
| Unit |
paintCursor(offset: Int, canvas: Canvas)Draws the cursor at the given character offset. |
Properties |
|
|---|---|
| Density | |
| IntPx |
The vertical space from the top of text box to the baseline of the first line. |
| IntPx |
The vertical space required to paint this text. |
| IntPx |
The vertical space from the top of text box to the baseline of the last line. |
| LayoutDirection |
The composable layout direction. |
| IntPx |
The width at which increasing the width of the text no longer decreases the height. |
| Int? |
An optional maximum number of lines for the text to span, wrapping if necessary. |
| IntPx |
The width for text if all soft wrap opportunities were taken. |
| TextOverflow |
How visual overflow should be handled. |
| ParagraphStyle |
The paragraph style. |
| Font.ResourceLoader | |
| Boolean |
Whether the text should break at soft line breaks. |
| AnnotatedString |
the text to paint. |
| TextStyle |
The resolved text style. |
| IntPx |
The horizontal space required to paint this text. |
Public constructors
<init>
TextDelegate(
text: AnnotatedString,
style: TextStyle? = null,
paragraphStyle: ParagraphStyle? = null,
maxLines: Int? = null,
softWrap: Boolean = true,
overflow: TextOverflow = TextOverflow.Clip,
density: Density,
layoutDirection: LayoutDirection,
resourceLoader: Font.ResourceLoader)
An object that paints text onto a Canvas.
To use a TextDelegate, follow these steps:
- Create an AnnotatedString and pass it to the TextDelegate constructor.
- Call layout to prepare the paragraph.
- Call paint as often as desired to paint the paragraph.
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.
| Parameters | |
|---|---|
| text: AnnotatedString | the text to paint. |
| style: TextStyle? = null | The text style specified to render the text. Notice that you can also set text style on the given AnnotatedString, and the style set on text always has higher priority than this setting. But if only one global text style is needed, passing it to TextDelegate is always preferred. |
| paragraphStyle: ParagraphStyle? = null | style configuration that applies only to paragraphs such as text alignment, or text direction. |
| maxLines: Int? = null | An optional maximum number of lines for the text to span, wrapping if necessary. If the text exceeds the given number of lines, it is truncated such that subsequent lines are dropped. |
| softWrap: Boolean = true | Whether the text should break at soft line breaks. If false, the glyphs in the text will be positioned as if there was unlimited horizontal space. If softWrap is false, overflow and TextAlign may have unexpected effects. |
| overflow: TextOverflow = TextOverflow.Clip | How visual overflow should be handled. Specifically, the ellipsis is applied to the last line before the line truncated by maxLines, if maxLines is non-null and that line overflows the width constraint. |
| layoutDirection: LayoutDirection | The composable layout direction. |
Public methods
getBidiRunDirection
fun getBidiRunDirection(offset: Int): TextDirection
Get the text direction of the character at the given offset.
getBoundingBox
fun getBoundingBox(offset: Int): Rect
Returns the bounding box as Rect of the character for given character offset. Rect includes the top, bottom, left and right of a character.
Valid only after layout has been called.
getHorizontalPosition
fun getHorizontalPosition(
offset: Int,
usePrimaryDirection: Boolean
): Float
Get the horizontal position for the specified text offset.
See Also
getLineBottom
fun getLineBottom(lineIndex: Int): Float
Returns the bottom y coordinate of the given line.
getLineForOffset
fun getLineForOffset(offset: Int): Int
Returns the line number on which the specified text offset appears. If you ask for a position before 0, you get 0; if you ask for a position beyond the end of the text, you get the last line.
getOffsetForPosition
fun getOffsetForPosition(position: PxPosition): Int
Returns the character offset closest to the given graphical position.
getParagraphDirection
fun getParagraphDirection(offset: Int): TextDirection
Get the text direction of the paragraph containing the given offset.
getWordBoundary
fun getWordBoundary(offset: Int): TextRange
Returns the text range of the word at the given character 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 character offset.
Word boundaries are defined more precisely in Unicode Standard Annex #29 <_>.
layout
fun layout(constraints: Constraints): Unit
layoutIntrinsics
fun layoutIntrinsics(): Unit
paint
fun paint(canvas: Canvas): Unit
Paints the text onto the given canvas.
Valid only after layout has been called.
If you cannot see the text being painted, check that your text color does not conflict with the background on which you are drawing. The default text color is white (to contrast with the default black background color), so if you are writing an application with a white background, the text will not be visible by default.
To set the text style, specify a TextStyle when creating the TextSpan that you pass to the TextDelegate constructor or to the text property.
paintBackground
fun paintBackground(
start: Int,
end: Int,
color: Color,
canvas: Canvas
): Unit
Draws text background of the given range.
If the given range is empty, do nothing.
| Parameters | |
|---|---|
| start: Int | inclusive start character offset of the drawing range. |
| end: Int | exclusive end character offset of the drawing range. |
| color: Color | a color to be used for drawing background. |
| canvas: Canvas | the target canvas. |
paintCursor
fun paintCursor(
offset: Int,
canvas: Canvas
): Unit
Draws the cursor at the given character offset.
| Parameters | |
|---|---|
| offset: Int | the cursor offset in the text. |
| canvas: Canvas | the target canvas. |
Properties
density
val density: Density
firstBaseline
val firstBaseline: IntPx
The vertical space from the top of text box to the baseline of the first line.
Valid only after layout has been called.
height
val height: IntPx
The vertical space required to paint this text.
Valid only after layout has been called.
lastBaseline
val lastBaseline: IntPx
The vertical space from the top of text box to the baseline of the last line.
Valid only after layout has been called.
maxIntrinsicWidth
val maxIntrinsicWidth: IntPx
The width at which increasing the width of the text no longer decreases the height.
Valid only after layout has been called.
maxLines
val maxLines: Int?
An optional maximum number of lines for the text to span, wrapping if necessary. If the text exceeds the given number of lines, it is truncated such that subsequent lines are dropped.
minIntrinsicWidth
val minIntrinsicWidth: IntPx
The width for text if all soft wrap opportunities were taken.
Valid only after layout has been called.
overflow
val overflow: TextOverflow
How visual overflow should be handled. Specifically, the ellipsis is applied to the last line before the line truncated by maxLines, if maxLines is non-null and that line overflows the width constraint.
paragraphStyle
val paragraphStyle: ParagraphStyle
The paragraph style.
If null is passed to constructor, use default paragraph style.
resourceLoader
val resourceLoader: Font.ResourceLoader
softWrap
val softWrap: Boolean
Whether the text should break at soft line breaks. If false, the glyphs in the text will be positioned as if there was unlimited horizontal space. If softWrap is false, overflow and TextAlign may have unexpected effects.