- Qt 6.9
- Qt GUI
- C++ Classes
- QTextBlockFormat
- Qt 6.9.1 Reference Documentation

# QTextBlockFormat Class

The QTextBlockFormat class provides formatting information for blocks of text in a QTextDocument. More...

Header: | `#include <QTextBlockFormat>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Gui)` `target_link_libraries(mytarget PRIVATE Qt6::Gui)`
qmake: | `QT += gui`
Inherits: | QTextFormat

- List of all members, including inherited members
- QTextBlockFormat is part of Rich Text Processing APIs and Implicitly Shared Classes.

Note: All functions in this class are reentrant.

## Public Types

enum | LineHeightTypes { SingleHeight, ProportionalHeight, FixedHeight, MinimumHeight, LineDistanceHeight }
enum class | MarkerType { NoMarker, Unchecked, Checked }

## Public Functions

| QTextBlockFormat()
Qt::Alignment | alignment() const
qreal | bottomMargin() const
int | headingLevel() const
int | indent() const
bool | isValid() const
qreal | leftMargin() const
qreal | lineHeight() const
qreal | lineHeight(qreal scriptLineHeight, qreal scaling = 1.0) const
int | lineHeightType() const
QTextBlockFormat::MarkerType | marker() const
bool | nonBreakableLines() const
QTextFormat::PageBreakFlags | pageBreakPolicy() const
qreal | rightMargin() const
void | setAlignment(Qt::Alignment alignment)
void | setBottomMargin(qreal margin)
void | setHeadingLevel(int level)
void | setIndent(int indentation)
void | setLeftMargin(qreal margin)
void | setLineHeight(qreal height, int heightType)
void | setMarker(QTextBlockFormat::MarkerType marker)
void | setNonBreakableLines(bool b)
void | setPageBreakPolicy(QTextFormat::PageBreakFlags policy)
void | setRightMargin(qreal margin)
void | setTabPositions(const QList<QTextOption::Tab> &tabs)
void | setTextIndent(qreal indent)
void | setTopMargin(qreal margin)
QList<QTextOption::Tab> | tabPositions() const
qreal | textIndent() const
qreal | topMargin() const

## Detailed Description

A document is composed of a list of blocks, represented by QTextBlock objects. Each block can contain an item of some kind, such as a paragraph of text, a table, a list, or an image. Every block has an associated QTextBlockFormat that specifies its characteristics.

To cater for left-to-right and right-to-left languages you can set a block's direction with setLayoutDirection(). Paragraph alignment is set with setAlignment(). Margins are controlled by setTopMargin(), setBottomMargin(), setLeftMargin(), setRightMargin(). Overall indentation is set with setIndent(), the indentation of the first line with setTextIndent().

Line spacing is set with setLineHeight() and retrieved via lineHeight() and lineHeightType(). The types of line spacing available are in the LineHeightTypes enum.

Line breaking can be enabled and disabled with setNonBreakableLines().

The brush used to paint the paragraph's background is set with setBackground(), and other aspects of the text's appearance can be customized by using the setProperty() function with the `OutlinePen`, `ForegroundBrush`, and `BackgroundBrush` QTextFormat::Property values.

If a text block is part of a list, it can also have a list format that is accessible with the listFormat() function.

See also QTextBlock and QTextCharFormat.

## Member Type Documentation

### enum QTextBlockFormat::LineHeightTypes

This enum describes the various types of line spacing support paragraphs can have.

Constant | Value | Description
--- | --- | ---
`QTextBlockFormat::SingleHeight` | `0` | This is the default line height: single spacing.
`QTextBlockFormat::ProportionalHeight` | `1` | This sets the spacing proportional to the line (in percentage). For example, set to 200 for double spacing.
`QTextBlockFormat::FixedHeight` | `2` | This sets the line height to a fixed line height (in pixels).
`QTextBlockFormat::MinimumHeight` | `3` | This sets the minimum line height (in pixels).
`QTextBlockFormat::LineDistanceHeight` | `4` | This adds the specified height between lines (in pixels).

See also lineHeight(), lineHeightType(), and setLineHeight().

### enum class QTextBlockFormat::MarkerType

This enum describes the types of markers a list item can have. If a list item (a paragraph for which QTextBlock::textList() returns the list) has a marker, it is rendered instead of the normal bullet. In this way, checkable list items can be mixed with plain list items in the same list, overriding the type of bullet specified by the QTextListFormat::style() for the entire list.

Constant | Value | Description
--- | --- | ---
`QTextBlockFormat::MarkerType::NoMarker` | `0` | This is the default: the list item's bullet will be shown.
`QTextBlockFormat::MarkerType::Unchecked` | `1` | Instead of the list item's bullet, an unchecked checkbox will be shown.
`QTextBlockFormat::MarkerType::Checked` | `2` | Instead of the list item's bullet, a checked checkbox will be shown.

In the future, this may be extended to specify other types of paragraph decorations.

See also QTextListFormat::style().

## Member Function Documentation

### QTextBlockFormat::QTextBlockFormat()

Constructs a new QTextBlockFormat.

### Qt::Alignment QTextBlockFormat::alignment() const

Returns the paragraph's alignment.

See also setAlignment().

### qreal QTextBlockFormat::bottomMargin() const

Returns the paragraph's bottom margin.

See also setBottomMargin() and topMargin().

### int QTextBlockFormat::headingLevel() const

Returns the paragraph's heading level if it is a heading, or 0 if not.

See also setHeadingLevel().

### int QTextBlockFormat::indent() const

Returns the paragraph's indent.

See also setIndent().

### bool QTextBlockFormat::isValid() const

Returns `true` if this block format is valid; otherwise returns false.

### qreal QTextBlockFormat::leftMargin() const

Returns the paragraph's left margin.

See also setLeftMargin(), rightMargin(), and indent().

### qreal QTextBlockFormat::lineHeight() const

This returns the LineHeight property for the paragraph.

See also LineHeightTypes, setLineHeight(), and lineHeightType().

### qreal QTextBlockFormat::lineHeight(qreal scriptLineHeight, qreal scaling = 1.0) const

Returns the height of the lines in the paragraph based on the height of the script line given by scriptLineHeight and the specified scaling factor.

The value that is returned is also dependent on the given LineHeightType of the paragraph as well as the LineHeight setting that has been set for the paragraph.

The scaling is needed for heights that include a fixed number of pixels, to scale them appropriately for printing.

See also LineHeightTypes, setLineHeight(), and lineHeightType().

### int QTextBlockFormat::lineHeightType() const

This returns the LineHeightType property of the paragraph.

See also LineHeightTypes, setLineHeight(), and lineHeight().

### QTextBlockFormat::MarkerType QTextBlockFormat::marker() const

Returns the paragraph's marker if one has been set, or `NoMarker` if not.

See also setMarker().

### bool QTextBlockFormat::nonBreakableLines() const

Returns `true` if the lines in the paragraph are non-breakable; otherwise returns `false`.

See also setNonBreakableLines().

### QTextFormat::PageBreakFlags QTextBlockFormat::pageBreakPolicy() const

Returns the currently set page break policy for the paragraph. The default is QTextFormat::PageBreak_Auto.

See also setPageBreakPolicy().

### qreal QTextBlockFormat::rightMargin() const

Returns the paragraph's right margin.

See also setRightMargin() and leftMargin().

### void QTextBlockFormat::setAlignment(Qt::Alignment alignment)

Sets the paragraph's alignment.

See also alignment().

### void QTextBlockFormat::setBottomMargin(qreal margin)

Sets the paragraph's bottom margin.

See also bottomMargin(), setTopMargin(), setLeftMargin(), and setRightMargin().

### void QTextBlockFormat::setHeadingLevel(int level)

Sets the paragraph's heading level, where 1 is the highest-level heading type (usually with the largest possible heading font size), and increasing values are progressively deeper into the document (and usually with smaller font sizes). For example when reading an HTML H1 tag, the heading level is set to 1. Setting the heading level does not automatically change the font size; however QTextDocumentFragment::fromHtml() sets both the heading level and the font size simultaneously.

If the paragraph is not a heading, the level should be set to 0 (the default).

See also headingLevel().

### void QTextBlockFormat::setIndent(int indentation)

Sets the paragraph's indentation. Margins are set independently of indentation with setLeftMargin() and setTextIndent(). The indentation is an integer that is multiplied with the document-wide standard indent, resulting in the actual indent of the paragraph.

See also indent() and QTextDocument::indentWidth().

### void QTextBlockFormat::setLeftMargin(qreal margin)

Sets the paragraph's left margin. Indentation can be applied separately with setIndent().

See also leftMargin(), setRightMargin(), setTopMargin(), and setBottomMargin().

### void QTextBlockFormat::setLineHeight(qreal height, int heightType)

Sets the line height for the paragraph to the value given by height which is dependent on heightType in the way described by the LineHeightTypes enum.

See also LineHeightTypes, lineHeight(), and lineHeightType().

### void QTextBlockFormat::setMarker(QTextBlockFormat::MarkerType marker)

Sets the type of adornment that should be rendered alongside the paragraph to marker. For example, a list item can be adorned with a checkbox, either checked or unchecked, as a replacement for its bullet. The default is `NoMarker`.

See also marker().

### void QTextBlockFormat::setNonBreakableLines(bool b)

If b is true, the lines in the paragraph are treated as non-breakable; otherwise they are breakable.

See also nonBreakableLines().

### void QTextBlockFormat::setPageBreakPolicy(QTextFormat::PageBreakFlags policy)

Sets the page break policy for the paragraph to policy.

See also pageBreakPolicy().

### void QTextBlockFormat::setRightMargin(qreal margin)

Sets the paragraph's right margin.

See also rightMargin(), setLeftMargin(), setTopMargin(), and setBottomMargin().

### void QTextBlockFormat::setTabPositions(const QList<QTextOption::Tab> &tabs)

Sets the tab positions for the text block to those specified by tabs.

See also tabPositions().

### void QTextBlockFormat::setTextIndent(qreal indent)

Sets the indent for the first line in the block. This allows the first line of a paragraph to be indented differently to the other lines, enhancing the readability of the text.

See also textIndent(), setLeftMargin(), setRightMargin(), setTopMargin(), and setBottomMargin().

### void QTextBlockFormat::setTopMargin(qreal margin)

Sets the paragraph's top margin.

See also topMargin(), setBottomMargin(), setLeftMargin(), and setRightMargin().

### QList<QTextOption::Tab> QTextBlockFormat::tabPositions() const

Returns a list of tab positions defined for the text block.

See also setTabPositions().

### qreal QTextBlockFormat::textIndent() const

Returns the paragraph's text indent.

See also setTextIndent().

### qreal QTextBlockFormat::topMargin() const

Returns the paragraph's top margin.

See also setTopMargin() and bottomMargin().