ICU 78.2: icu::ParagraphLayout Class Reference

ICU 78.2 78.2

Data Structures | Public Member Functions | Static Public Member Functions
icu::ParagraphLayout Class Reference

ParagraphLayout. More...

`#include <ParagraphLayout.h>`

Inheritance diagram for icu::ParagraphLayout:

## Data Structures
class | Line
| This class represents a single line of text in a `ParagraphLayout`. More...
class | VisualRun
| This object represents a single visual run in a line of text in a paragraph. More...

## Public Member Functions
| ParagraphLayout (const LEUnicode chars[], le_int32 count, const FontRuns *fontRuns, const ValueRuns *levelRuns, const ValueRuns *scriptRuns, const LocaleRuns *localeRuns, UBiDiLevel paragraphLevel, le_bool vertical, LEErrorCode &status)
| Construct a `ParagraphLayout` object for a styled paragraph. More...
| ~ParagraphLayout ()
| The destructor. More...
UBiDiLevel | getParagraphLevel ()
| Return the resolved paragraph level. More...
UBiDiDirection | getTextDirection ()
| Return the directionality of the text in the paragraph. More...
virtual le_int32 | getAscent () const
| Return the max ascent value for all the fonts in the paragraph. More...
virtual le_int32 | getDescent () const
| Return the max descent value for all the fonts in the paragraph. More...
virtual le_int32 | getLeading () const
| Return the max leading value for all the fonts in the paragraph. More...
void | reflow ()
| Reset line breaking to start from the beginning of the paragraph. More...
le_bool | isDone () const
| Convenience method for determining if paragraph layout processing is complete ( i.e. More...
Line * | nextLine (float width)
| Return a `ParagraphLayout::Line` object which represents next line in the paragraph. More...
UClassID | getDynamicClassID () const override
| ICU "poor man's RTTI", returns a UClassID for the actual class. More...
Public Member Functions inherited from icu::UObject
virtual | ~UObject ()
| Destructor. More...

## Static Public Member Functions
static le_bool | isComplex (const LEUnicode chars[], le_int32 count)
| Examine the given text and determine if it contains characters in any script which requires complex processing to be rendered correctly. More...
static UClassID | getStaticClassID ()
| ICU "poor man's RTTI", returns a UClassID for this class. More...

## Detailed Description

ParagraphLayout.

The `ParagraphLayout` object will analyze the text into runs of text in the same font, script and direction, and will create a `LayoutEngine` object for each run. The `LayoutEngine` will transform the characters into glyph codes in visual order.

Clients can use this to break a paragraph into lines, and to display the glyphs in each line.

Note that the ICU layout engine has been deprecated and removed. You may use this class with the HarfBuzz icu-le-hb wrapper, see http://www.freedesktop.org/wiki/Software/HarfBuzz/

See https://unicode-org.github.io/icu/userguide/layoutengine for special build instructions.

Definition at line 51 of file ParagraphLayout.h.

## Constructor & Destructor Documentation

## ◆ ParagraphLayout()

icu::ParagraphLayout::ParagraphLayout | ( | const LEUnicode | chars[],
|  | le_int32 | count,
|  | const FontRuns * | fontRuns,
|  | const ValueRuns * | levelRuns,
|  | const ValueRuns * | scriptRuns,
|  | const LocaleRuns * | localeRuns,
|  | UBiDiLevel | paragraphLevel,
|  | le_bool | vertical,
|  | LEErrorCode & | status
| ) |  |

Construct a `ParagraphLayout` object for a styled paragraph.

The paragraph is specified as runs of text all in the same font. An `LEFontInstance` object and a limit offset are specified for each font run. The limit offset is the offset of the character immediately after the font run.

Clients can optionally specify directional runs and / or script runs. If these aren't specified they will be computed.

If any errors are encountered during construction, `status` will be set, and the object will be set to be empty.

Parameters

  chars | is an array of the characters in the paragraph
  count | is the number of characters in the paragraph.
  fontRuns | a pointer to a `FontRuns` object representing the font runs.
  levelRuns | is a pointer to a `ValueRuns` object representing the directional levels. If this pointer in `nullptr` the levels will be determined by running the Unicode Bidi algorithm.
  scriptRuns | is a pointer to a `ValueRuns` object representing script runs. If this pointer in `nullptr` the script runs will be determined using the Unicode code points.
  localeRuns | is a pointer to a `LocaleRuns` object representing locale runs. The `Locale` objects are used to determine the language of the text. If this pointer is `nullptr` the default locale will be used for all of the text.
  paragraphLevel | is the directionality of the paragraph, as in the UBiDi object.
  vertical | is `true` if the paragraph should be set vertically.
  status | will be set to any error code encountered during construction.

See also
  ubidi.h
  LEFontInstance.h
  LayoutEngine.h
  RunArrays.h

Stable:
  ICU 2.8

## ◆ ~ParagraphLayout()

icu::ParagraphLayout::~ParagraphLayout | ( |  | ) |

The destructor.

Virtual so that it works correctly with subclasses.

Stable:
  ICU 3.2

## Member Function Documentation

## ◆ getAscent()

virtual le_int32 icu::ParagraphLayout::getAscent | ( |  | ) | const
| virtual

Return the max ascent value for all the fonts in the paragraph.

Returns
  the ascent value.

Stable:
  ICU 3.2

## ◆ getDescent()

virtual le_int32 icu::ParagraphLayout::getDescent | ( |  | ) | const
| virtual

Return the max descent value for all the fonts in the paragraph.

Returns
  the decent value.

Stable:
  ICU 3.2

## ◆ getDynamicClassID()

UClassID icu::ParagraphLayout::getDynamicClassID | ( |  | ) | const
| inlineoverridevirtual

ICU "poor man's RTTI", returns a UClassID for the actual class.

Stable:
  ICU 3.2

Reimplemented from icu::UObject.

Definition at line 553 of file ParagraphLayout.h.

## ◆ getLeading()

virtual le_int32 icu::ParagraphLayout::getLeading | ( |  | ) | const
| virtual

Return the max leading value for all the fonts in the paragraph.

Returns
  the leading value.

Stable:
  ICU 3.2

## ◆ getParagraphLevel()

UBiDiLevel icu::ParagraphLayout::getParagraphLevel | ( |  | ) |
| inline

Return the resolved paragraph level.

This is useful for those cases where the bidi analysis has determined the level based on the first strong character in the paragraph.

Returns
  the resolved paragraph level.

Stable:
  ICU 3.2

Definition at line 648 of file ParagraphLayout.h.

References ubidi_getParaLevel().

## ◆ getStaticClassID()

static UClassID icu::ParagraphLayout::getStaticClassID | ( |  | ) |
| inlinestatic

ICU "poor man's RTTI", returns a UClassID for this class.

Stable:
  ICU 3.2

Definition at line 546 of file ParagraphLayout.h.

## ◆ getTextDirection()

UBiDiDirection icu::ParagraphLayout::getTextDirection | ( |  | ) |
| inline

Return the directionality of the text in the paragraph.

Returns
  `UBIDI_LTR` if the text is all left to right, `UBIDI_RTL` if the text is all right to left, or `UBIDI_MIXED` if the text has mixed direction.

Stable:
  ICU 3.2

Definition at line 653 of file ParagraphLayout.h.

References ubidi_getDirection().

## ◆ isComplex()

static le_bool icu::ParagraphLayout::isComplex | ( | const LEUnicode | chars[],
|  | le_int32 | count
| ) |  |
| static

Examine the given text and determine if it contains characters in any script which requires complex processing to be rendered correctly.

Parameters

  chars | is an array of the characters in the paragraph
  count | is the number of characters in the paragraph.

Returns
  `true` if any of the text requires complex processing.

Stable:
  ICU 3.2

## ◆ isDone()

le_bool icu::ParagraphLayout::isDone | ( |  | ) | const
| inline

Convenience method for determining if paragraph layout processing is complete ( i.e.

there are no more lines left to process. )

Returns
  true if there are no more lines to be processed

Internal:
  Do not use. This API is for internal use only.

## ◆ nextLine()

Line* icu::ParagraphLayout::nextLine | ( | float | width | ) |

Return a `ParagraphLayout::Line` object which represents next line in the paragraph.

The width of the line is specified each time so that it can be varied to support arbitrary paragraph shapes.

Parameters

  width | is the width of the line. If `width` is less than or equal to zero, a `ParagraphLayout::Line` object representing the rest of the paragraph will be returned.

Returns
  a `ParagraphLayout::Line` object which represents the line. The caller is responsible for deleting the object. Returns `nullptr` if there are no more lines in the paragraph.

See also
  ParagraphLayout::Line

Stable:
  ICU 3.2

## ◆ reflow()

void icu::ParagraphLayout::reflow | ( |  | ) |
| inline

Reset line breaking to start from the beginning of the paragraph.

Stable:
  ICU 3.2

Definition at line 658 of file ParagraphLayout.h.

The documentation for this class was generated from the following file:

- layoutex/layout/ParagraphLayout.h