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): 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.
Members
handleObj
lib
retainedCallbacks
signalHandlerNames
signalSetterHandlers
Methods
PangoLayout (context = null)
Create a new PangoLayout object with attributes initialized to default values for a particular PangoContext.
@pcontext is a PangoContext.
toNativeHandle (Source)
Normalizes a constructor argument into a raw pointer carrier. Accepts a raw NativeHandle, a raw NativeBuffer returned from fn.call(...), another generated wrapper exposing handle(), or null. Returns null when the argument carries no pointer.
@pSource is the raw handle, raw buffer, wrapper, or null.
@rA raw pointer carrier or null when no pointer is present.
getLib ()
Returns the opened native library for this generated wrapper.
@rThe opened native library.
handle ()
Returns the wrapped NativeHandle.
@rThe wrapped NativeHandle.
isNull ()
Returns true when the wrapped handle is null.
@rA bool.
describe ()
Returns a small string for debugging generated wrappers.
@rA string.
asObject ()
Wraps this handle as GObject.
@rAGObject object.
context_changed ()
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.
@rNone.
copy ()
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.
@rthe newly allocated PangoLayout.
get_alignment ()
Gets the alignment for the layout: how partial lines are positioned within the horizontal space available.
@rthe alignment.
get_attributes ()
Gets the attribute list for the layout, if any.
@raPangoAttrList.
get_auto_dir ()
Gets whether to calculate the base direction for the layout according to its contents. See [method@Pango.Layout.set_auto_dir].
@r%TRUE if the bidirectional base direction is computed from the layout's contents, %FALSE otherwise.
get_baseline ()
Gets the Y position of baseline of the first line in @layout.
@rbaseline of first line, from top of @layout.
get_caret_pos (int index_)
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 [method@Pango.Layout.get_cursor_pos] that applies font metric information about caret slope and offset to the positions it returns.
@pindex_ is the byte index of the cursor.
@pstrong_pos is location to store the strong cursor position.
@pweak_pos is location to store the weak cursor position.
@rNone.
get_character_count ()
Returns the number of Unicode characters in the the text of @layout.
@rthe number of Unicode characters in the text of @layout.
get_context ()
Retrieves the PangoContext used for this layout.
@rthePangoContext for the layout.
get_cursor_pos (int index_)
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.
@pindex_ is the byte index of the cursor.
@pstrong_pos is location to store the strong cursor position.
@pweak_pos is location to store the weak cursor position.
@rNone.
get_direction (int index)
Gets the text direction at the given character position in @layout.
@pindex is the byte index of the char.
@rthe text direction at @index.
get_ellipsize ()
Gets the type of ellipsization being performed for @layout. See [method@Pango.Layout.set_ellipsize]. Use [method@Pango.Layout.is_ellipsized] to query whether any paragraphs were actually ellipsized.
@rthe current ellipsization mode for @layout.
get_extents ()
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.
@pink_rect is rectangle used to store the extents of the layout as drawn.
@plogical_rect is rectangle used to store the logical extents of the layout.
@rNone.
get_font_description ()
Gets the font description for the layout, if any.
@ra pointer to the layout's font description, or %NULL if the font description from the layout's context is inherited..
get_height ()
Gets the height of layout used for ellipsization. See [method@Pango.Layout.set_height] for details.
@rthe height, in Pango units if positive, or number of lines if negative..
get_indent ()
Gets the paragraph indent width in Pango units. A negative value indicates a hanging indentation.
@rthe indent in Pango units.
get_iter ()
Returns an iterator to iterate over the visual extents of the layout.
@rthe new PangoLayoutIter.
get_justify ()
Gets whether each complete line should be stretched to fill the entire width of the layout.
@rthe justify value.
get_justify_last_line ()
Gets whether the last line should be stretched to fill the entire width of the layout.
@rthe justify value.
get_line (int line)
Retrieves a particular line from a PangoLayout. Use the faster [method@Pango.Layout.get_line_readonly] if you do not plan to modify the contents of the line (glyphs, glyph widths, etc.).
@pline is the index of a line, which must be between 0 and pango_layout_get_line_count(layout) - 1, inclusive..
@rthe requested PangoLayoutLine, or %NULL 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..
get_line_count ()
Retrieves the count of lines for the @layout.
@rthe line count.
get_line_readonly (int line)
Retrieves a particular line from a PangoLayout. This is a faster alternative to [method@Pango.Layout.get_line], but the user is not expected to modify the contents of the line (glyphs, glyph widths, etc.).
@pline is the index of a line, which must be between 0 and pango_layout_get_line_count(layout) - 1, inclusive..
@rthe requested PangoLayoutLine, or %NULL 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..
get_line_spacing ()
Gets the line spacing factor of @layout. See [method@Pango.Layout.set_line_spacing].
get_lines ()
Returns the lines of the @layout as a list. Use the faster [method@Pango.Layout.get_lines_readonly] if you do not plan to modify the contents of the lines (glyphs, glyph widths, etc.).
@raGSList 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..
get_lines_readonly ()
Returns the lines of the @layout as a list. This is a faster alternative to [method@Pango.Layout.get_lines], but the user is not expected to modify the contents of the lines (glyphs, glyph widths, etc.).
@raGSList 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..
get_log_attrs ()
Retrieves an array of logical attributes for each character in the
@layout. ``
@pattrs is location to store a pointer to an array of logical attributes. This value must be freed with g_free()..
@pn_attrs is location to store the number of the attributes in the array. (The stored value 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.).
@rNone.
get_log_attrs_readonly ()
Retrieves an array of logical attributes for each character in the
@layout.This is a faster alternative to [method@Pango.Layout.get_log_attrs]. The returned array is part of
@layoutand 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.
@pn_attrs is location to store the number of the attributes in the array.
@ran array of logical attributes.
get_pixel_extents ()
Computes the logical and ink extents of @layout in device units. This function just calls [method@Pango.Layout.get_extents] followed by two [func@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 [func@Pango.extents_to_pixels]).
@pink_rect is rectangle used to store the extents of the layout as drawn.
@plogical_rect is rectangle used to store the logical extents of the layout.
@rNone.
get_pixel_size ()
Determines the logical width and height of a PangoLayout in device units. [method@Pango.Layout.get_size] returns the width and height scaled by %PANGO_SCALE. This is simply a convenience function around [method@Pango.Layout.get_pixel_extents].
@pwidth is location to store the logical width.
@pheight is location to store the logical height.
@rNone.
get_serial ()
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 [method@Pango.Layout.context_changed].
@rThe current serial number of @layout..
get_single_paragraph_mode ()
Obtains whether @layout is in single paragraph mode. See [method@Pango.Layout.set_single_paragraph_mode].
@r%TRUE if the layout does not break paragraphs at paragraph separator characters, %FALSE otherwise.
get_size ()
Determines the logical width and height of a PangoLayout in Pango units. This is simply a convenience function around [method@Pango.Layout.get_extents].
@pwidth is location to store the logical width.
@pheight is location to store the logical height.
@rNone.
get_spacing ()
Gets the amount of spacing between the lines of the layout.
@rthe spacing in Pango units.
get_tabs ()
Gets the current PangoTabArray used by this layout. If no PangoTabArray has been set, then the default tabs are in use and %NULL is returned. Default tabs are every 8 spaces. The return value should be freed with [method@Pango.TabArray.free].
@ra copy of the tabs for this layout.
get_text ()
Gets the text in the layout. The returned text should not be freed or modified.
@rthe text in the @layout.
get_unknown_glyphs_count ()
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.
@rThe number of unknown glyphs in @layout.
get_width ()
Gets the width to which the lines of the PangoLayout should wrap.
@rthe width in Pango units, or -1 if no width set..
get_wrap ()
Gets the wrap mode for the layout. Use [method@Pango.Layout.is_wrapped] to query whether any paragraphs were actually wrapped.
@ractive wrap mode..
index_to_line_x (int index_, bool trailing)
Converts from byte @index_ within the @layout to line and X position. The X position is measured from the left edge of the line.
@pindex_ is the byte index of a grapheme within the layout.
@ptrailing is 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.
@pline is location to store resulting line index. (which will between 0 and pango_layout_get_line_count(layout) - 1).
@px_pos is location to store resulting position within line (%PANGO_SCALE units per device unit).
@rNone.
index_to_pos (int index_)
Converts from an index within a PangoLayout to the onscreen position corresponding to the grapheme at that index. The returns 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.
@pindex_ is byte index within @layout.
@ppos is rectangle in which to store the position of the grapheme.
@rNone.
is_ellipsized ()
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.
@r%TRUE if any paragraphs had to be ellipsized, %FALSE otherwise.
is_wrapped ()
Queries whether the layout had to wrap any paragraphs. This returns %TRUE if a positive width is set on @layout, and there are paragraphs exceeding the layout width that have to be wrapped.
@r%TRUE if any paragraphs had to be wrapped, %FALSE otherwise.
move_cursor_visually (bool strong, int old_index, int old_trailing, int direction)
Computes a new cursor position from an old position and a direction. If
@directionis 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.
@pstrong is 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..
@pold_index is the byte index of the current cursor position.
@pold_trailing is if 0, the cursor was at the leading edge of the grapheme indicated by @old_index, if > 0, the cursor was at the trailing edge..
@pdirection is direction to move cursor. A negative value indicates motion to the left.
@pnew_index is location to store the new cursor byte index. A value of -1 indicates that the cursor has been moved off the beginning of the layout. A value of %G_MAXINT indicates that the cursor has been moved off the end of the layout..
@pnew_trailing is number of characters to move forward from the location returned for @new_index to get the position where the cursor should be displayed. This allows distinguishing the position at the beginning of one line from the position at the end of the preceding line.
@new_indexis always on the line where the cursor should be displayed..
@rNone.
serialize (string flags)
Serializes the @layout for later deserialization via [func@Pango.Layout.deserialize]. There are no guarantees about the format of the output across different versions of Pango and [func@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.
@pflags is PangoLayoutSerializeFlags.
@raGBytes containing the serialized form of @layout.
set_alignment (string alignment)
Sets the alignment for the layout: how partial lines are positioned within the horizontal space available. The default alignment is %PANGO_ALIGN_LEFT.
@palignment is the alignment.
@rNone.
set_attributes (object attrs)
Sets the text attributes for a layout object. References @attrs, so the caller can unref its reference.
@pattrs is a PangoAttrList.
@rNone.
set_auto_dir (bool auto_dir)
Sets whether to calculate the base direction for the layout according to its contents. When this flag is on (the default), then paragraphs in
@layoutthat 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 [method@Pango.Context.set_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.
@pauto_dir is if %TRUE, compute the bidirectional base direction from the layout's contents.
@rNone.
set_ellipsize (string ellipsize)
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 [method@Pango.Layout.set_width] and [method@Pango.Layout.set_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 [method@Pango.Layout.set_height] for details.
@pellipsize is the new ellipsization mode for @layout.
@rNone.
set_font_description (object desc)
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.
@pdesc is the new PangoFontDescription to unset the current font description.
@rNone.
set_height (int height)
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 %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.
@pheight is the desired height of the layout in Pango units if positive, or desired number of lines if negative..
@rNone.
set_indent (int indent)
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.
@pindent is the amount by which to indent.
@rNone.
set_justify (bool justify)
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 [method@Pango.Layout.set_justify_last_line].
@pjustify is whether the lines in the layout should be justified.
@rNone.
set_justify_last_line (bool justify)
Sets whether the last line should be stretched to fill the entire width of the layout. This only has an effect if [method@Pango.Layout.set_justify] has been called as well. The default value is %FALSE.
@pjustify is whether the last line in the layout should be justified.
@rNone.
set_line_spacing (double factor)
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 [method@Pango.Layout.set_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 [func@Pango.attr_line_height_new].
@pfactor is the new line spacing factor.
@rNone.
set_markup (string markup, int length)
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 [method@Pango.Layout.set_markup_with_accel], but the markup text isn't scanned for accelerators.
@pmarkup is marked-up text.
@plength is length of marked-up text in bytes, or -1 if @markup is NUL-terminated.
@rNone.
set_markup_with_accel (string markup, int length, int accel_marker)
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.
@plength is length of marked-up text in bytes, or -1 if @markup is NUL-terminated.
@paccel_marker is marker for accelerators in the text.
@paccel_char is return location for first located accelerator.
@rNone.
set_single_paragraph_mode (bool setting)
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.
@psetting is new setting.
@rNone.
set_spacing (int spacing)
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 [method@Pango.Layout.set_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 [func@Pango.attr_line_height_new].
@pspacing is the amount of spacing.
@rNone.
set_tabs (object tabs)
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
@tabsis %NULL, 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.
@ptabs is a PangoTabArray.
@rNone.
set_text (string text, int length)
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 [method@Pango.Layout.set_markup] or [method@Pango.Layout.set_markup_with_accel] on @layout before, you may want to call [method@Pango.Layout.set_attributes] to clear the attributes set on the layout from the markup as this function does not clear attributes.
@ptext is the text.
@plength is 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
@lengthis positive..
@rNone.
set_width (int width)
Sets the width to which the lines of the PangoLayout should wrap or get ellipsized. The default value is -1: no width set.
@pwidth is the desired width in Pango units, or -1 to indicate that no wrapping or ellipsization should be performed..
@rNone.
set_wrap (string wrap)
Sets the wrap mode. The wrap mode only has effect if a width is set on the layout with [method@Pango.Layout.set_width]. To turn off wrapping, set the width to -1. The default value is %PANGO_WRAP_WORD.
@pwrap is the wrap mode.
@rNone.
write_to_file (string flags, string filename)
A convenience method to serialize a layout to a file. It is equivalent to calling [method@Pango.Layout.serialize] followed by [func@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.
@pflags is PangoLayoutSerializeFlags.
@pfilename is the file to save it to.
@r%TRUE if saving was successful.
xy_to_index (int x, int y)
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 [method@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.
@px is the X offset (in Pango units) from the left edge of the layout.
@py is the Y offset (in Pango units) from the top edge of the layout.
@pindex_ is location to store calculated byte index.
@ptrailing is location to store a integer indicating where in the grapheme the user clicked. It will either be zero, or the number of characters in the grapheme. 0 represents the leading edge of the grapheme..
@r%TRUE if the coordinates were inside text, %FALSE otherwise.
lines ()
Returns get_lines as an Aussom list of wrapper objects. This companion method materializes the full collection up front; use get_lines() when lazy or change-notify access is required.
@rAn Aussom list of elements.
lines_readonly ()
Returns get_lines_readonly as an Aussom list of wrapper objects. This companion method materializes the full collection up front; use get_lines_readonly() when lazy or change-notify access is required.