GI.Pango.Objects.Layout

A PangoLayout structure represents an entire paragraph of text.

While complete access to the layout capabilities of Pango is provided using the detailed interfaces for itemization and shaping, using that functionality directly involves writing a fairly large amount of code. PangoLayout provides a high-level driver for formatting entire paragraphs of text at once. This includes paragraph-level functionality such as line breaking, justification, alignment and ellipsization.

A PangoLayout is initialized with a PangoContext, UTF-8 string and set of attributes for that string. Once that is done, the set of formatted lines can be extracted from the object, the layout can be rendered, and conversion between logical character positions within the layout's text, and the physical position of the resulting glyphs can be made.

There are a number of parameters to adjust the formatting of a PangoLayout. The following image shows adjustable parameters (on the left) and font metrics (on the right):

<picture> <source srcset="layout-dark.png" media="(prefers-color-scheme: dark)"> <img alt="Pango Layout Parameters" src="layout-light.png"> </picture>

The following images demonstrate the effect of alignment and justification on the layout of text:

| | | | --- | --- | | | | | | | | | |

It is possible, as well, to ignore the 2-D setup, and simply treat the results of a PangoLayout as a list of lines.

Exported types

newtype Layout

Memory-managed wrapper type.

Constructors

Layout (ManagedPtr Layout)

Instances

Eq Layout

Defined in GI.Pango.Objects.Layout

Methods

(==) :: Layout -> Layout -> Bool

(/=) :: Layout -> Layout -> Bool

GObject Layout

Defined in GI.Pango.Objects.Layout

ManagedPtrNewtype Layout

Defined in GI.Pango.Objects.Layout

Methods

toManagedPtr :: Layout -> ManagedPtr Layout

TypedObject Layout

Defined in GI.Pango.Objects.Layout

Methods

glibType :: IO GType

HasParentTypes Layout

Defined in GI.Pango.Objects.Layout

IsGValue (Maybe Layout)

Convert Layout to and from GValue. See toGValue and fromGValue.

Defined in GI.Pango.Objects.Layout

Methods

gvalueGType_ :: IO GType

gvalueSet_ :: Ptr GValue -> Maybe Layout -> IO ()

gvalueGet_ :: Ptr GValue -> IO (Maybe Layout)

type ParentTypes Layout

Defined in GI.Pango.Objects.Layout

type ParentTypes Layout = '[Object]

class (GObject o, IsDescendantOf Layout o) => IsLayout o

Type class for types which can be safely cast to Layout, for instance with toLayout.

Instances

(GObject o, IsDescendantOf Layout o) => IsLayout o

Defined in GI.Pango.Objects.Layout

toLayout :: (MonadIO m, IsLayout o) => o -> m Layout

Cast to Layout, for types for which this is known to be safe. For general casts, use castTo.

Methods

Click to display all available methods, including inherited ones

Methods

bindProperty, bindPropertyFull, contextChanged, copy, forceFloating, freezeNotify, getv, indexToLineX, indexToPos, isEllipsized, isFloating, isWrapped, moveCursorVisually, notify, notifyByPspec, ref, refSink, runDispose, serialize, stealData, stealQdata, thawNotify, unref, watchClosure, writeToFile, xyToIndex.

Getters

getAlignment, getAttributes, getAutoDir, getBaseline, getCaretPos, getCharacterCount, getContext, getCursorPos, getData, getDirection, getEllipsize, getExtents, getFontDescription, getHeight, getIndent, getIter, getJustify, getJustifyLastLine, getLine, getLineCount, getLineReadonly, getLineSpacing, getLines, getLinesReadonly, getLogAttrs, getLogAttrsReadonly, getPixelExtents, getPixelSize, getProperty, getQdata, getSerial, getSingleParagraphMode, getSize, getSpacing, getTabs, getText, getUnknownGlyphsCount, getWidth, getWrap.

Setters

setAlignment, setAttributes, setAutoDir, setData, setDataFull, setEllipsize, setFontDescription, setHeight, setIndent, setJustify, setJustifyLastLine, setLineSpacing, setMarkup, setMarkupWithAccel, setProperty, setSingleParagraphMode, setSpacing, setTabs, setText, setWidth, setWrap.

contextChanged

layoutContextChanged

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m ()

Forces recomputation of any state in the PangoLayout that might depend on the layout's context.

This function should be called if you make changes to the context subsequent to creating the layout.

copy

layoutCopy

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

src: a PangoLayout

-> m Layout

Returns: the newly allocated PangoLayout

Creates a deep copy-by-value of the layout.

The attribute list, tab array, and text from the original layout are all copied by value.

deserialize

layoutDeserialize

Arguments

:: (HasCallStack, MonadIO m, IsContext a)

=> a

context: a PangoContext

-> Bytes

bytes: the bytes containing the data

-> [LayoutDeserializeFlags]

flags: PangoLayoutDeserializeFlags

-> m (Maybe Layout)

Returns: a new PangoLayout (Can throw GError)

Loads data previously created via layoutSerialize.

For a discussion of the supported format, see that function.

Note: to verify that the returned layout is identical to the one that was serialized, you can compare bytes to the result of serializing the layout again.

Since: 1.50

getAlignment

layoutGetAlignment

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Alignment

Returns: the alignment

Gets the alignment for the layout: how partial lines are positioned within the horizontal space available.

getAttributes

layoutGetAttributes

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m (Maybe AttrList)

Returns: a PangoAttrList

Gets the attribute list for the layout, if any.

getAutoDir

layoutGetAutoDir

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Bool

Returns: True if the bidirectional base direction is computed from the layout's contents, False otherwise

Gets whether to calculate the base direction for the layout according to its contents.

See layoutSetAutoDir.

Since: 1.4

getBaseline

layoutGetBaseline

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Int32

Returns: baseline of first line, from top of layout

Gets the Y position of baseline of the first line in layout.

Since: 1.22

getCaretPos

layoutGetCaretPos

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Int32

index_: the byte index of the cursor

-> m (Rectangle, Rectangle)

Given an index within a layout, determines the positions that of the strong and weak cursors if the insertion point is at that index.

This is a variant of layoutGetCursorPos that applies font metric information about caret slope and offset to the positions it returns.

<picture> <source srcset="caret-metrics-dark.png" media="(prefers-color-scheme: dark)"> <img alt="Caret metrics" src="caret-metrics-light.png"> </picture>

Since: 1.50

getCharacterCount

layoutGetCharacterCount

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Int32

Returns: the number of Unicode characters in the text of layout

Returns the number of Unicode characters in the the text of layout.

Since: 1.30

getContext

layoutGetContext

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Context

Returns: the PangoContext for the layout

Retrieves the PangoContext used for this layout.

getCursorPos

layoutGetCursorPos

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Int32

index_: the byte index of the cursor

-> m (Rectangle, Rectangle)

Given an index within a layout, determines the positions that of the strong and weak cursors if the insertion point is at that index.

The position of each cursor is stored as a zero-width rectangle with the height of the run extents.

<picture> <source srcset="cursor-positions-dark.png" media="(prefers-color-scheme: dark)"> <img alt="Cursor positions" src="cursor-positions-light.png"> </picture>

The strong cursor location is the location where characters of the directionality equal to the base direction of the layout are inserted. The weak cursor location is the location where characters of the directionality opposite to the base direction of the layout are inserted.

The following example shows text with both a strong and a weak cursor.

<picture> <source srcset="split-cursor-dark.png" media="(prefers-color-scheme: dark)"> <img alt="Strong and weak cursors" src="split-cursor-light.png"> </picture>

The strong cursor has a little arrow pointing to the right, the weak cursor to the left. Typing a 'c' in this situation will insert the character after the 'b', and typing another Hebrew character, like 'ג', will insert it at the end.

getDirection

layoutGetDirection

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Int32

index: the byte index of the char

-> m Direction

Returns: the text direction at index

Gets the text direction at the given character position in layout.

Since: 1.46

getEllipsize

layoutGetEllipsize

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m EllipsizeMode

Returns: the current ellipsization mode for layout

Gets the type of ellipsization being performed for layout.

See layoutSetEllipsize.

Use layoutIsEllipsized to query whether any paragraphs were actually ellipsized.

Since: 1.6

getExtents

layoutGetExtents

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m (Rectangle, Rectangle)

Computes the logical and ink extents of layout.

Logical extents are usually what you want for positioning things. Note that both extents may have non-zero x and y. You may want to use those to offset where you render the layout. Not doing that is a very typical bug that shows up as right-to-left layouts not being correctly positioned in a layout with a set width.

The extents are given in layout coordinates and in Pango units; layout coordinates begin at the top left corner of the layout.

getFontDescription

layoutGetFontDescription

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m (Maybe FontDescription)

Returns: a pointer to the layout's font description, or Nothing if the font description from the layout's context is inherited.

Gets the font description for the layout, if any.

Since: 1.8

getHeight

layoutGetHeight

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Int32

Returns: the height, in Pango units if positive, or number of lines if negative.

Gets the height of layout used for ellipsization.

See layoutSetHeight for details.

Since: 1.20

getIndent

layoutGetIndent

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Int32

Returns: the indent in Pango units

Gets the paragraph indent width in Pango units.

A negative value indicates a hanging indentation.

getIter

layoutGetIter

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m LayoutIter

Returns: the new PangoLayoutIter

Returns an iterator to iterate over the visual extents of the layout.

getJustify

layoutGetJustify

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Bool

Returns: the justify value

Gets whether each complete line should be stretched to fill the entire width of the layout.

getJustifyLastLine

layoutGetJustifyLastLine

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Bool

Returns: the justify value

Gets whether the last line should be stretched to fill the entire width of the layout.

Since: 1.50

getLine

layoutGetLine

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Int32

line: the index of a line, which must be between 0 and pango_layout_get_line_count(layout) - 1, inclusive.

-> m (Maybe LayoutLine)

Returns: the requested PangoLayoutLine, or Nothing if the index is out of range. This layout line can be ref'ed and retained, but will become invalid if changes are made to the PangoLayout.

Retrieves a particular line from a PangoLayout.

Use the faster layoutGetLineReadonly if you do not plan to modify the contents of the line (glyphs, glyph widths, etc.).

getLineCount

layoutGetLineCount

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: PangoLayout

-> m Int32

Returns: the line count

Retrieves the count of lines for the layout.

getLineReadonly

layoutGetLineReadonly

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Int32

line: the index of a line, which must be between 0 and pango_layout_get_line_count(layout) - 1, inclusive.

-> m (Maybe LayoutLine)

Returns: the requested PangoLayoutLine, or Nothing if the index is out of range. This layout line can be ref'ed and retained, but will become invalid if changes are made to the PangoLayout. No changes should be made to the line.

Retrieves a particular line from a PangoLayout.

This is a faster alternative to layoutGetLine, but the user is not expected to modify the contents of the line (glyphs, glyph widths, etc.).

Since: 1.16

getLineSpacing

layoutGetLineSpacing

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Float

Gets the line spacing factor of layout.

See layoutSetLineSpacing.

Since: 1.44

getLines

layoutGetLines

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m [LayoutLine]

Returns: a GSList containing the lines in the layout. This points to internal data of the PangoLayout and must be used with care. It will become invalid on any change to the layout's text or properties.

Returns the lines of the layout as a list.

Use the faster layoutGetLinesReadonly if you do not plan to modify the contents of the lines (glyphs, glyph widths, etc.).

getLinesReadonly

layoutGetLinesReadonly

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m [LayoutLine]

Returns: a GSList containing the lines in the layout. This points to internal data of the PangoLayout and must be used with care. It will become invalid on any change to the layout's text or properties. No changes should be made to the lines.

Returns the lines of the layout as a list.

This is a faster alternative to layoutGetLines, but the user is not expected to modify the contents of the lines (glyphs, glyph widths, etc.).

Since: 1.16

getLogAttrs

layoutGetLogAttrs

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m [LogAttr]

Retrieves an array of logical attributes for each character in the layout.

getLogAttrsReadonly

layoutGetLogAttrsReadonly

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m [LogAttr]

Returns: an array of logical attributes

Retrieves an array of logical attributes for each character in the layout.

This is a faster alternative to layoutGetLogAttrs. The returned array is part of layout and must not be modified. Modifying the layout will invalidate the returned array.

The number of attributes returned in nAttrs will be one more than the total number of characters in the layout, since there need to be attributes corresponding to both the position before the first character and the position after the last character.

Since: 1.30

getPixelExtents

layoutGetPixelExtents

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m (Rectangle, Rectangle)

Computes the logical and ink extents of layout in device units.

This function just calls layoutGetExtents followed by two [funcextentsToPixels] calls, rounding inkRect and logicalRect such that the rounded rectangles fully contain the unrounded one (that is, passes them as first argument to extentsToPixels).

getPixelSize

layoutGetPixelSize

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m (Int32, Int32)

Determines the logical width and height of a PangoLayout in device units.

layoutGetSize returns the width and height scaled by SCALE. This is simply a convenience function around layoutGetPixelExtents.

getSerial

layoutGetSerial

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Word32

Returns: The current serial number of layout.

Returns the current serial number of layout.

The serial number is initialized to an small number larger than zero when a new layout is created and is increased whenever the layout is changed using any of the setter functions, or the PangoContext it uses has changed. The serial may wrap, but will never have the value 0. Since it can wrap, never compare it with "less than", always use "not equals".

This can be used to automatically detect changes to a PangoLayout, and is useful for example to decide whether a layout needs redrawing. To force the serial to be increased, use layoutContextChanged.

Since: 1.32.4

getSingleParagraphMode

layoutGetSingleParagraphMode

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Bool

Returns: True if the layout does not break paragraphs at paragraph separator characters, False otherwise

Obtains whether layout is in single paragraph mode.

See layoutSetSingleParagraphMode.

getSize

layoutGetSize

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m (Int32, Int32)

Determines the logical width and height of a PangoLayout in Pango units.

This is simply a convenience function around layoutGetExtents.

getSpacing

layoutGetSpacing

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Int32

Returns: the spacing in Pango units

Gets the amount of spacing between the lines of the layout.

getTabs

layoutGetTabs

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m (Maybe TabArray)

Returns: a copy of the tabs for this layout

Gets the current PangoTabArray used by this layout.

If no PangoTabArray has been set, then the default tabs are in use and Nothing is returned. Default tabs are every 8 spaces.

The return value should be freed with tabArrayFree.

getText

layoutGetText

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Text

Returns: the text in the layout

Gets the text in the layout.

The returned text should not be freed or modified.

getUnknownGlyphsCount

layoutGetUnknownGlyphsCount

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Int32

Returns: The number of unknown glyphs in layout

Counts the number of unknown glyphs in layout.

This function can be used to determine if there are any fonts available to render all characters in a certain string, or when used in combination with AttrTypeFallback, to check if a certain font supports all the characters in the string.

Since: 1.16

getWidth

layoutGetWidth

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Int32

Returns: the width in Pango units, or -1 if no width set.

Gets the width to which the lines of the PangoLayout should wrap.

getWrap

layoutGetWrap

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m WrapMode

Returns: active wrap mode.

Gets the wrap mode for the layout.

Use layoutIsWrapped to query whether any paragraphs were actually wrapped.

indexToLineX

layoutIndexToLineX

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Int32

index_: the byte index of a grapheme within the layout

-> Bool

trailing: an integer indicating the edge of the grapheme to retrieve the position of. If > 0, the trailing edge of the grapheme, if 0, the leading of the grapheme

-> m (Int32, Int32)

Converts from byte index_ within the layout to line and X position.

The X position is measured from the left edge of the line.

indexToPos

layoutIndexToPos

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Int32

index_: byte index within layout

-> m Rectangle

Converts from an index within a PangoLayout to the onscreen position corresponding to the grapheme at that index.

The return value is represented as rectangle. Note that pos->x is always the leading edge of the grapheme and pos->x + pos->width the trailing edge of the grapheme. If the directionality of the grapheme is right-to-left, then pos->width will be negative.

isEllipsized

layoutIsEllipsized

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Bool

Returns: True if any paragraphs had to be ellipsized, False otherwise

Queries whether the layout had to ellipsize any paragraphs.

This returns True if the ellipsization mode for layout is not EllipsizeModeNone, a positive width is set on layout, and there are paragraphs exceeding that width that have to be ellipsized.

Since: 1.16

isWrapped

layoutIsWrapped

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> m Bool

Returns: True if any paragraphs had to be wrapped, False otherwise

Queries whether the layout had to wrap any paragraphs.

This returns True if a positive width is set on layout, ellipsization mode of layout is set to EllipsizeModeNone, and there are paragraphs exceeding the layout width that have to be wrapped.

Since: 1.16

moveCursorVisually

layoutMoveCursorVisually

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Bool

strong: whether the moving cursor is the strong cursor or the weak cursor. The strong cursor is the cursor corresponding to text insertion in the base direction for the layout.

-> Int32

oldIndex: the byte index of the current cursor position

-> Int32

oldTrailing: if 0, the cursor was at the leading edge of the grapheme indicated by oldIndex, if > 0, the cursor was at the trailing edge.

-> Int32

direction: direction to move cursor. A negative value indicates motion to the left

-> m (Int32, Int32)

Computes a new cursor position from an old position and a direction.

If direction is positive, then the new position will cause the strong or weak cursor to be displayed one position to right of where it was with the old cursor position. If direction is negative, it will be moved to the left.

In the presence of bidirectional text, the correspondence between logical and visual order will depend on the direction of the current run, and there may be jumps when the cursor is moved off of the end of a run.

Motion here is in cursor positions, not in characters, so a single call to this function may move the cursor over multiple characters when multiple characters combine to form a single grapheme.

new

layoutNew

Arguments

:: (HasCallStack, MonadIO m, IsContext a)

=> a

context: a PangoContext

-> m Layout

Returns: the newly allocated PangoLayout

Create a new PangoLayout object with attributes initialized to default values for a particular PangoContext.

serialize

layoutSerialize

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> [LayoutSerializeFlags]

flags: PangoLayoutSerializeFlags

-> m Bytes

Returns: a GBytes containing the serialized form of layout

Serializes the layout for later deserialization via [funcpango.Layout.deserialize].

There are no guarantees about the format of the output across different versions of Pango and [funcpango.Layout.deserialize] will reject data that it cannot parse.

The intended use of this function is testing, benchmarking and debugging. The format is not meant as a permanent storage format.

Since: 1.50

setAlignment

layoutSetAlignment

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Alignment

alignment: the alignment

-> m ()

Sets the alignment for the layout: how partial lines are positioned within the horizontal space available.

The default alignment is AlignmentLeft.

setAttributes

layoutSetAttributes

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Maybe AttrList

attrs: a PangoAttrList

-> m ()

Sets the text attributes for a layout object.

References attrs, so the caller can unref its reference.

setAutoDir

layoutSetAutoDir

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Bool

autoDir: if True, compute the bidirectional base direction from the layout's contents

-> m ()

Sets whether to calculate the base direction for the layout according to its contents.

When this flag is on (the default), then paragraphs in layout that begin with strong right-to-left characters (Arabic and Hebrew principally), will have right-to-left layout, paragraphs with letters from other scripts will have left-to-right layout. Paragraphs with only neutral characters get their direction from the surrounding paragraphs.

When False, the choice between left-to-right and right-to-left layout is done according to the base direction of the layout's PangoContext. (See contextSetBaseDir).

When the auto-computed direction of a paragraph differs from the base direction of the context, the interpretation of AlignmentLeft and AlignmentRight are swapped.

Since: 1.4

setEllipsize

layoutSetEllipsize

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> EllipsizeMode

ellipsize: the new ellipsization mode for layout

-> m ()

Sets the type of ellipsization being performed for layout.

Depending on the ellipsization mode ellipsize text is removed from the start, middle, or end of text so they fit within the width and height of layout set with layoutSetWidth and layoutSetHeight.

If the layout contains characters such as newlines that force it to be layed out in multiple paragraphs, then whether each paragraph is ellipsized separately or the entire layout is ellipsized as a whole depends on the set height of the layout.

The default value is EllipsizeModeNone.

See layoutSetHeight for details.

Since: 1.6

setFontDescription

layoutSetFontDescription

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Maybe FontDescription

desc: the new PangoFontDescription to unset the current font description

-> m ()

Sets the default font description for the layout.

If no font description is set on the layout, the font description from the layout's context is used.

setHeight

layoutSetHeight

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout.

-> Int32

height: the desired height of the layout in Pango units if positive, or desired number of lines if negative.

-> m ()

Sets the height to which the PangoLayout should be ellipsized at.

There are two different behaviors, based on whether height is positive or negative.

If height is positive, it will be the maximum height of the layout. Only lines would be shown that would fit, and if there is any text omitted, an ellipsis added. At least one line is included in each paragraph regardless of how small the height value is. A value of zero will render exactly one line for the entire layout.

If height is negative, it will be the (negative of) maximum number of lines per paragraph. That is, the total number of lines shown may well be more than this value if the layout contains multiple paragraphs of text. The default value of -1 means that the first line of each paragraph is ellipsized. This behavior may be changed in the future to act per layout instead of per paragraph. File a bug against pango at https://gitlab.gnome.org/gnome/pango if your code relies on this behavior.

Height setting only has effect if a positive width is set on layout and ellipsization mode of layout is not EllipsizeModeNone. The behavior is undefined if a height other than -1 is set and ellipsization mode is set to EllipsizeModeNone, and may change in the future.

Since: 1.20

setIndent

layoutSetIndent

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Int32

indent: the amount by which to indent

-> m ()

Sets the width in Pango units to indent each paragraph.

A negative value of indent will produce a hanging indentation. That is, the first line will have the full width, and subsequent lines will be indented by the absolute value of indent.

The indent setting is ignored if layout alignment is set to AlignmentCenter.

The default value is 0.

setJustify

layoutSetJustify

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Bool

justify: whether the lines in the layout should be justified

-> m ()

Sets whether each complete line should be stretched to fill the entire width of the layout.

Stretching is typically done by adding whitespace, but for some scripts (such as Arabic), the justification may be done in more complex ways, like extending the characters.

Note that this setting is not implemented and so is ignored in Pango older than 1.18.

Note that tabs and justification conflict with each other: Justification will move content away from its tab-aligned positions.

The default value is False.

Also see layoutSetJustifyLastLine.

setJustifyLastLine

layoutSetJustifyLastLine

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Bool

justify: whether the last line in the layout should be justified

-> m ()

Sets whether the last line should be stretched to fill the entire width of the layout.

This only has an effect if layoutSetJustify has been called as well.

The default value is False.

Since: 1.50

setLineSpacing

layoutSetLineSpacing

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Float

factor: the new line spacing factor

-> m ()

Sets a factor for line spacing.

Typical values are: 0, 1, 1.5, 2. The default values is 0.

If factor is non-zero, lines are placed so that

baseline2 = baseline1 + factor * height2

where height2 is the line height of the second line (as determined by the font(s)). In this case, the spacing set with layoutSetSpacing is ignored.

If factor is zero (the default), spacing is applied as before.

Note: for semantics that are closer to the CSS line-height property, see attrLineHeightNew.

Since: 1.44

setMarkup

layoutSetMarkup

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Text

markup: marked-up text

-> Int32

length: length of marked-up text in bytes, or -1 if markup is NUL-terminated

-> m ()

Sets the layout text and attribute list from marked-up text.

See Pango Markup).

Replaces the current text and attribute list.

This is the same as layoutSetMarkupWithAccel, but the markup text isn't scanned for accelerators.

setSingleParagraphMode

layoutSetSingleParagraphMode

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Bool

setting: new setting

-> m ()

Sets the single paragraph mode of layout.

If setting is True, do not treat newlines and similar characters as paragraph separators; instead, keep all text in a single paragraph, and display a glyph for paragraph separator characters. Used when you want to allow editing of newlines on a single text line.

The default value is False.

setSpacing

layoutSetSpacing

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Int32

spacing: the amount of spacing

-> m ()

Sets the amount of spacing in Pango units between the lines of the layout.

When placing lines with spacing, Pango arranges things so that

line2.top = line1.bottom + spacing

The default value is 0.

Note: Since 1.44, Pango is using the line height (as determined by the font) for placing lines when the line spacing factor is set to a non-zero value with layoutSetLineSpacing. In that case, the spacing set with this function is ignored.

Note: for semantics that are closer to the CSS line-height property, see attrLineHeightNew.

setTabs

layoutSetTabs

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Maybe TabArray

tabs: a PangoTabArray

-> m ()

Sets the tabs to use for layout, overriding the default tabs.

PangoLayout will place content at the next tab position whenever it meets a Tab character (U+0009).

By default, tabs are every 8 spaces. If tabs is Nothing, the default tabs are reinstated. tabs is copied into the layout; you must free your copy of tabs yourself.

Note that tabs and justification conflict with each other: Justification will move content away from its tab-aligned positions. The same is true for alignments other than AlignmentLeft.

setText

layoutSetText

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Text

text: the text

-> Int32

length: maximum length of text, in bytes. -1 indicates that the string is nul-terminated and the length should be calculated. The text will also be truncated on encountering a nul-termination even when length is positive.

-> m ()

Sets the text of the layout.

This function validates text and renders invalid UTF-8 with a placeholder glyph.

Note that if you have used layoutSetMarkup or layoutSetMarkupWithAccel on layout before, you may want to call layoutSetAttributes to clear the attributes set on the layout from the markup as this function does not clear attributes.

setWidth

layoutSetWidth

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout.

-> Int32

width: the desired width in Pango units, or -1 to indicate that no wrapping or ellipsization should be performed.

-> m ()

Sets the width to which the lines of the PangoLayout should wrap or ellipsized.

The default value is -1: no width set.

setWrap

layoutSetWrap

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> WrapMode

wrap: the wrap mode

-> m ()

Sets the wrap mode.

The wrap mode only has effect if a width is set on the layout with layoutSetWidth. To turn off wrapping, set the width to -1.

The default value is WrapModeWord.

writeToFile

layoutWriteToFile

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> [LayoutSerializeFlags]

flags: PangoLayoutSerializeFlags

-> [Char]

filename: the file to save it to

-> m ()

(Can throw GError)

A convenience method to serialize a layout to a file.

It is equivalent to calling layoutSerialize followed by fileSetContents.

See those two functions for details on the arguments.

It is mostly intended for use inside a debugger to quickly dump a layout to a file for later inspection.

Since: 1.50

xyToIndex

layoutXyToIndex

Arguments

:: (HasCallStack, MonadIO m, IsLayout a)

=> a

layout: a PangoLayout

-> Int32

x: the X offset (in Pango units) from the left edge of the layout

-> Int32

y: the Y offset (in Pango units) from the top edge of the layout

-> m (Bool, Int32, Int32)

Returns: True if the coordinates were inside text, False otherwise

Converts from X and Y position within a layout to the byte index to the character at that logical position.

If the Y position is not inside the layout, the closest position is chosen (the position will be clamped inside the layout). If the X position is not within the layout, then the start or the end of the line is chosen as described for layoutLineXToIndex. If either the X or Y positions were not inside the layout, then the function returns False; on an exact hit, it returns True.