class Pango::Layout
- Pango::Layout
- GObject::Object
- Reference
- Object
Overview
A Pango::Layout
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. Pango::Layout
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 Pango::Layout
is initialized with a Pango::Context
, 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
Pango::Layout
. The following image shows adjustable parameters
(on the left) and font metrics (on the right):
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 Pango::Layout
as a list of lines.
Defined in:
lib/gi-crystal/src/auto/pango-1.0/layout.crlib/gtk4/src/bindings/pango/layout.cr
Constructors
-
.new(context : Pango::Context) : self
Create a new
Pango::Layout
object with attributes initialized to default values for a particularPango::Context
. -
.new
Initialize a new
Layout
.
Class Method Summary
-
.g_type : UInt64
Returns the type id (GType) registered in GLib type system.
Instance Method Summary
-
#alignment : Pango::Alignment
Gets the alignment for the layout: how partial lines are positioned within the horizontal space available.
-
#alignment=(alignment : Pango::Alignment) : Nil
Sets the alignment for the layout: how partial lines are positioned within the horizontal space available.
-
#attributes : Pango::AttrList?
Gets the attribute list for the layout, if any.
-
#attributes=(attrs : Pango::AttrList?) : Nil
Sets the text attributes for a layout object.
-
#auto_dir : Bool
Gets whether to calculate the base direction for the layout according to its contents.
-
#auto_dir=(auto_dir : Bool) : Nil
Sets whether to calculate the base direction for the layout according to its contents.
-
#baseline : Int32
Gets the Y position of baseline of the first line in @layout.
-
#caret_pos(index_ : Int32) : Pango::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.
-
#character_count : Int32
Returns the number of Unicode characters in the the text of @layout.
-
#context : Pango::Context
Retrieves the
Pango::Context
used for this layout. -
#context_changed : Nil
Forces recomputation of any state in the
Pango::Layout
that might depend on the layout's context. -
#copy : Pango::Layout
Creates a deep copy-by-value of the layout.
-
#cursor_pos(index_ : Int32) : Pango::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.
- #deserialize(context : Pango::Context, bytes : GLib::Bytes, flags : Pango::LayoutDeserializeFlags) : Pango::Layout?
-
#direction(index : Int32) : Pango::Direction
Gets the text direction at the given character position in @layout.
-
#ellipsize : Pango::EllipsizeMode
Gets the type of ellipsization being performed for @layout.
-
#ellipsize=(ellipsize : Pango::EllipsizeMode) : Nil
Sets the type of ellipsization being performed for @layout.
-
#extents : Pango::Rectangle
Computes the logical and ink extents of @layout.
-
#font_description : Pango::FontDescription?
Gets the font description for the layout, if any.
-
#font_description=(desc : Pango::FontDescription?) : Nil
Sets the default font description for the layout.
-
#height : Int32
Gets the height of layout used for ellipsization.
-
#height=(height : Int32) : Nil
Sets the height to which the
Pango::Layout
should be ellipsized at. -
#indent : Int32
Gets the paragraph indent width in Pango units.
-
#indent=(indent : Int32) : Nil
Sets the width in Pango units to indent each paragraph.
-
#index_to_line_x(index_ : Int32, trailing : Bool) : Nil
Converts from byte @index_ within the @layout to line and X position.
-
#index_to_pos(index_ : Int32) : Pango::Rectangle
Converts from an index within a
Pango::Layout
to the onscreen position corresponding to the grapheme at that index. -
#is_ellipsized : Bool
Queries whether the layout had to ellipsize any paragraphs.
-
#is_wrapped : Bool
Queries whether the layout had to wrap any paragraphs.
-
#iter : Pango::LayoutIter
Returns an iterator to iterate over the visual extents of the layout.
-
#justify : Bool
Gets whether each complete line should be stretched to fill the entire width of the layout.
-
#justify=(justify : Bool) : Nil
Sets whether each complete line should be stretched to fill the entire width of the layout.
-
#justify_last_line : Bool
Gets whether the last line should be stretched to fill the entire width of the layout.
-
#justify_last_line=(justify : Bool) : Nil
Sets whether the last line should be stretched to fill the entire width of the layout.
-
#line(line : Int32) : Pango::LayoutLine?
Retrieves a particular line from a
Pango::Layout
. -
#line_count : Int32
Retrieves the count of lines for the @layout.
-
#line_readonly(line : Int32) : Pango::LayoutLine?
Retrieves a particular line from a
Pango::Layout
. -
#line_spacing : Float32
Gets the line spacing factor of @layout.
-
#line_spacing=(factor : Float32) : Nil
Sets a factor for line spacing.
-
#lines : GLib::SList
Returns the lines of the @layout as a list.
-
#lines_readonly : GLib::SList
Returns the lines of the @layout as a list.
-
#log_attrs(attrs : Enumerable(Pango::LogAttr)) : Nil
Retrieves an array of logical attributes for each character in the @layout.
- #log_attrs(*attrs : Pango::LogAttr)
-
#log_attrs_readonly : Enumerable(Pango::LogAttr)
Retrieves an array of logical attributes for each character in the @layout.
-
#move_cursor_visually(strong : Bool, old_index : Int32, old_trailing : Int32, direction : Int32, new_index : Int32, new_trailing : Int32) : Nil
Computes a new cursor position from an old position and a direction.
-
#pixel_extents : Pango::Rectangle
Computes the logical and ink extents of @layout in device units.
-
#pixel_size : Nil
Determines the logical width and height of a
Pango::Layout
in device units. -
#serial : UInt32
Returns the current serial number of @layout.
-
#serialize(flags : Pango::LayoutSerializeFlags) : GLib::Bytes
Serializes the @layout for later deserialization via
Pango::Layout#deserialize
. -
#set_markup(markup : String, length : Int32) : Nil
Sets the layout text and attribute list from marked-up text.
-
#set_markup_with_accel(markup : String, length : Int32, accel_marker : UInt32) : UInt32
Sets the layout text and attribute list from marked-up text.
-
#set_text(text : String, length : Int32) : Nil
Sets the text of the layout.
-
#single_paragraph_mode : Bool
Obtains whether @layout is in single paragraph mode.
-
#single_paragraph_mode=(setting : Bool) : Nil
Sets the single paragraph mode of @layout.
-
#size : Nil
Determines the logical width and height of a
Pango::Layout
in Pango units. -
#spacing : Int32
Gets the amount of spacing between the lines of the layout.
-
#spacing=(spacing : Int32) : Nil
Sets the amount of spacing in Pango units between the lines of the layout.
-
#tabs : Pango::TabArray?
Gets the current
Pango::TabArray
used by this layout. -
#tabs=(tabs : Pango::TabArray?) : Nil
Sets the tabs to use for @layout, overriding the default tabs.
-
#text : String
Gets the text in the layout.
-
#unknown_glyphs_count : Int32
Counts the number of unknown glyphs in @layout.
-
#width : Int32
Gets the width to which the lines of the
Pango::Layout
should wrap. -
#width=(width : Int32) : Nil
Sets the width to which the lines of the
Pango::Layout
should wrap or ellipsized. -
#wrap : Pango::WrapMode
Gets the wrap mode for the layout.
-
#wrap=(wrap : Pango::WrapMode) : Nil
Sets the wrap mode.
-
#write_to_file(flags : Pango::LayoutSerializeFlags, filename : String) : Bool
A convenience method to serialize a layout to a file.
-
#xy_to_index(x : Int32, y : Int32, index_ : Int32, trailing : Int32) : Bool
Converts from X and Y position within a layout to the byte index to the character at that logical position.
Instance methods inherited from class GObject::Object
bind_property(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags) : GObject::Binding
bind_property,
bind_property_full(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags, transform_to : GObject::Closure, transform_from : GObject::Closure) : GObject::Binding
bind_property_full,
data(key : String) : Pointer(Void)?
data,
finalize
finalize,
freeze_notify : Nil
freeze_notify,
getv(names : Enumerable(String), values : Enumerable(_)) : Nil
getv,
notify(property_name : String) : Nil
notify,
notify_by_pspec(pspec : GObject::ParamSpec) : Nil
notify_by_pspec,
notify_signal
notify_signal,
property(property_name : String, value : _) : Nil
property,
qdata(quark : UInt32) : Pointer(Void)?
qdata,
ref_count : UInt32
ref_count,
run_dispose : Nil
run_dispose,
set_data(key : String, data : Pointer(Void)?) : Nil
set_data,
set_property(property_name : String, value : _) : Nil
set_property,
steal_data(key : String) : Pointer(Void)?
steal_data,
steal_qdata(quark : UInt32) : Pointer(Void)?
steal_qdata,
thaw_notify : Nil
thaw_notify,
to_unsafe : Pointer(Void)
to_unsafe,
watch_closure(closure : GObject::Closure) : Nil
watch_closure
Constructor methods inherited from class GObject::Object
cast(obj : GObject::Object) : self
cast,
cast?(obj : GObject::Object) : self?
cast?,
new(pointer : Pointer(Void), transfer : GICrystal::Transfer)new new, newv(object_type : UInt64, parameters : Enumerable(GObject::Parameter)) : self newv
Class methods inherited from class GObject::Object
compat_control(what : UInt64, data : Pointer(Void)?) : UInt64
compat_control,
g_type : UInt64
g_type,
interface_find_property(g_iface : GObject::TypeInterface, property_name : String) : GObject::ParamSpec
interface_find_property,
interface_list_properties(g_iface : GObject::TypeInterface) : Enumerable(GObject::ParamSpec)
interface_list_properties
Constructor Detail
Create a new Pango::Layout
object with attributes initialized to
default values for a particular Pango::Context
.
Class Method Detail
Instance Method Detail
Gets the alignment for the layout: how partial lines are positioned within the horizontal space available.
Sets the alignment for the layout: how partial lines are positioned within the horizontal space available.
The default alignment is %PANGO_ALIGN_LEFT.
Sets the text attributes for a layout object.
References @attrs, so the caller can unref its reference.
Gets whether to calculate the base direction for the layout according to its contents.
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
Pango::Context
. (See Pango::Context#base_dir=
).
When the auto-computed direction of a paragraph differs from the base direction of the context, the interpretation of %PANGO_ALIGN_LEFT and %PANGO_ALIGN_RIGHT are swapped.
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 Pango::Layout#cursor_pos
that applies
font metric information about caret slope and offset to the positions
it returns.
Forces recomputation of any state in the Pango::Layout
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.
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.
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.
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.
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.
Gets the text direction at the given character position in @layout.
Gets the type of ellipsization being performed for @layout.
Use Pango::Layout#is_ellipsized?
to query whether any
paragraphs were actually ellipsized.
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
Pango::Layout#width=
and Pango::Layout#height=
.
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 %PANGO_ELLIPSIZE_NONE.
See Pango::Layout#height=
for details.
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.
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.
Sets the height to which the Pango::Layout
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 %PANGO_ELLIPSIZE_NONE. The behavior is undefined if a height other than -1 is set and ellipsization mode is set to %PANGO_ELLIPSIZE_NONE, and may change in the future.
Gets the paragraph indent width in Pango units.
A negative value indicates a hanging indentation.
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 %PANGO_ALIGN_CENTER.
The default value is 0.
Converts from byte @index_ within the @layout to line and X position.
The X position is measured from the left edge of the line.
Converts from an index within a Pango::Layout
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.
Queries whether the layout had to ellipsize any paragraphs.
This returns true
if the ellipsization mode for @layout
is not %PANGO_ELLIPSIZE_NONE, a positive width is set on @layout,
and there are paragraphs exceeding that width that have to be
ellipsized.
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 %PANGO_ELLIPSIZE_NONE,
and there are paragraphs exceeding the layout width that have
to be wrapped.
Returns an iterator to iterate over the visual extents of the layout.
Gets whether each complete line should be stretched to fill the entire width of the layout.
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 Pango::Layout#justify_last_line=
.
Gets whether the last line should be stretched to fill the entire width of the layout.
Sets whether the last line should be stretched to fill the entire width of the layout.
This only has an effect if Pango::Layout#justify=
has
been called as well.
The default value is false
.
Retrieves a particular line from a Pango::Layout
.
Use the faster Pango::Layout#line_readonly
if you do not
plan to modify the contents of the line (glyphs, glyph widths, etc.).
Retrieves a particular line from a Pango::Layout
.
This is a faster alternative to Pango::Layout#line
,
but the user is not expected to modify the contents of the line
(glyphs, glyph widths, etc.).
Gets the line spacing factor of @layout.
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 Pango::Layout#spacing=
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 Pango::attr_line_height_new
.
Returns the lines of the @layout as a list.
Use the faster Pango::Layout#lines_readonly
if you do not
plan to modify the contents of the lines (glyphs, glyph widths, etc.).
Returns the lines of the @layout as a list.
This is a faster alternative to Pango::Layout#lines
,
but the user is not expected to modify the contents of the lines
(glyphs, glyph widths, etc.).
Retrieves an array of logical attributes for each character in the @layout.
Retrieves an array of logical attributes for each character in the @layout.
This is a faster alternative to Pango::Layout#log_attrs
.
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 @n_attrs 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.
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.
Computes the logical and ink extents of @layout in device units.
This function just calls Pango::Layout#extents
followed by
two #extents_to_pixels
calls, rounding @ink_rect and @logical_rect
such that the rounded rectangles fully contain the unrounded one (that is,
passes them as first argument to Pango::extents_to_pixels
).
Determines the logical width and height of a Pango::Layout
in device
units.
Pango::Layout#size
returns the width and height
scaled by %PANGO_SCALE. This is simply a convenience function
around Pango::Layout#pixel_extents
.
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 Pango::Context
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 Pango::Layout
,
and is useful for example to decide whether a layout needs redrawing.
To force the serial to be increased, use
Pango::Layout#context_changed
.
Serializes the @layout for later deserialization via Pango::Layout#deserialize
.
There are no guarantees about the format of the output across different
versions of Pango and Pango::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.
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 Pango::Layout#markup_with_accel=
,
but the markup text isn't scanned for accelerators.
Sets the layout text and attribute list from marked-up text.
See Pango Markup).
Replaces the current text and attribute list.
If @accel_marker is nonzero, the given character will mark the character following it as an accelerator. For example, @accel_marker might be an ampersand or underscore. All characters marked as an accelerator will receive a %PANGO_UNDERLINE_LOW attribute, and the first character so marked will be returned in @accel_char. Two @accel_marker characters following each other produce a single literal @accel_marker character.
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 Pango::Layout#markup=
or
Pango::Layout#markup_with_accel=
on @layout before, you
may want to call Pango::Layout#attributes=
to clear the
attributes set on the layout from the markup as this function does
not clear attributes.
Obtains whether @layout is in single paragraph mode.
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
.
Determines the logical width and height of a Pango::Layout
in Pango
units.
This is simply a convenience function around Pango::Layout#extents
.
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 Pango::Layout#line_spacing=
.
In that case, the @spacing set with this function is ignored.
Note: for semantics that are closer to the CSS line-height
property, see Pango::attr_line_height_new
.
Gets the current Pango::TabArray
used by this layout.
If no Pango::TabArray
has been set, then the default tabs are
in use and nil
is returned. Default tabs are every 8 spaces.
The return value should be freed with Pango::TabArray#free
.
Sets the tabs to use for @layout, overriding the default tabs.
Pango::Layout
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 nil
, 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 %PANGO_ALIGN_LEFT.
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 %PANGO_ATTR_FALLBACK, to check if a certain font supports all the characters in the string.
Sets the width to which the lines of the Pango::Layout
should wrap or
ellipsized.
The default value is -1: no width set.
Gets the wrap mode for the layout.
Use Pango::Layout#is_wrapped?
to query whether
any paragraphs were actually wrapped.
Sets the wrap mode.
The wrap mode only has effect if a width is set on the layout
with Pango::Layout#width=
. To turn off wrapping,
set the width to -1.
The default value is %PANGO_WRAP_WORD.
A convenience method to serialize a layout to a file.
It is equivalent to calling Pango::Layout#serialize
followed by GLib::file_set_contents
.
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.
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 Pango::LayoutLine#x_to_index
. If either
the X or Y positions were not inside the layout, then the function returns
false
; on an exact hit, it returns true
.