pyglet.text.document

Formatted and unformatted document interfaces used by text layout.

Abstract representation

Styled text in pyglet is represented by one of the AbstractDocument classes, which manage the state representation of text and style independently of how it is loaded or rendered.

A document consists of the document text (a Unicode string) and a set of named style ranges. For example, consider the following (artificial) example:

0    5   10   15   20
The cat sat on the mat.
+++++++        +++++++    "bold"
            ++++++      "italic"

If this example were to be rendered, “The cat” and “the mat” would be in bold, and “on the” in italics. Note that the second “the” is both bold and italic.

The document styles recorded for this example would be "bold" over ranges (0-7, 15-22) and "italic" over range (12-18). Overlapping styles are permitted; unlike HTML and other structured markup, the ranges need not be nested.

The document has no knowledge of the semantics of "bold" or "italic", it stores only the style names. The pyglet layout classes give meaning to these style names in the way they are rendered; but you are also free to invent your own style names (which will be ignored by the layout classes). This can be useful to tag areas of interest in a document, or maintain references back to the source material.

As well as text, the document can contain arbitrary elements represented by InlineElement. An inline element behaves like a single character in the documented, but can be rendered by the application.

Paragraph breaks

Paragraph breaks are marked with a “newline” character (U+0010). The Unicode paragraph break (U+2029) can also be used.

Line breaks (U+2028) can be used to force a line break within a paragraph.

See Unicode recommendation UTR #13 for more information: http://unicode.org/reports/tr13/tr13-5.html.

Document classes

Any class implementing AbstractDocument provides an interface to a document model as described above. In theory a structured document such as HTML or XML could export this model, though the classes provided by pyglet implement only unstructured documents.

The UnformattedDocument class assumes any styles set are set over the entire document. So, regardless of the range specified when setting a "bold" style attribute, for example, the entire document will receive that style.

The FormattedDocument class implements the document model directly, using the RunList class to represent style runs efficiently.

Style attributes

The following character style attribute names are recognised by pyglet:

font_name

Font family name, as given to pyglet.font.load().

font_size

Font size, in points.

bold

Boolean.

italic

Boolean.

underline

4-tuple of ints in range (0, 255) giving RGBA underline color, or None (default) for no underline.

kerning

Additional space to insert between glyphs, in points. Defaults to 0.

baseline

Offset of glyph baseline from line baseline, in points. Positive values give a superscript, negative values give a subscript. Defaults to 0.

color

4-tuple of ints in range (0, 255) giving RGBA text color

background_color

4-tuple of ints in range (0, 255) giving RGBA text background color; or None for no background fill.

The following paragraph style attribute names are recognised by pyglet. Note that paragraph styles are handled no differently from character styles by the document: it is the application’s responsibility to set the style over an entire paragraph, otherwise results are undefined.

align

left (default), center or right.

indent

Additional horizontal space to insert before the first

leading

Additional space to insert between consecutive lines within a paragraph, in points. Defaults to 0.

line_spacing

Distance between consecutive baselines in a paragraph, in points. Defaults to None, which automatically calculates the tightest line spacing for each line based on the font ascent and descent.

margin_left

Left paragraph margin, in pixels.

margin_right

Right paragraph margin, in pixels.

margin_top

Margin above paragraph, in pixels.

margin_bottom

Margin below paragraph, in pixels. Adjacent margins do not collapse.

tab_stops

List of horizontal tab stops, in pixels, measured from the left edge of the text layout. Defaults to the empty list. When the tab stops are exhausted, they implicitly continue at 50 pixel intervals.

wrap

Boolean. If True (the default), text wraps within the width of the layout.

Other attributes can be used to store additional style information within the document; it will be ignored by the built-in text classes.

All style attributes (including those not present in a document) default to None (including the so-called “boolean” styles listed above). The meaning of a None style is style- and application-dependent.

New in version 1.1.

class AbstractDocument(text=”)

Abstract document interface used by all pyglet.text classes.

This class can be overridden to interface pyglet with a third-party document format. It may be easier to implement the document format in terms of one of the supplied concrete classes FormattedDocument or UnformattedDocument.

delete_text(start, end)

Delete text from the document.

Parameters:

• start (int) – Starting character position to delete from.
• end (int) – Ending character position to delete to (exclusive).

get_element(position)

Get the element at a specified position.

Parameters:position (int) – Position in the document of the element. Return type:InlineElement

get_font(position, dpi=None)

Get the font instance used at the given position.

See:

get_font_runs

Parameters:

• position (int) – Character position of document to query.
• dpi (float) – Optional resolution to construct fonts at. See pyglet.font.load().

Return type:

pyglet.font.Font

Returns:

The font at the given position.

get_font_runs(dpi=None)

Get a style iterator over the pyglet.font.Font instances used in the document.

The font instances are created on-demand by inspection of the font_name, font_size, bold and italic style attributes.

Parameters:dpi (float) – Optional resolution to construct fonts at. See pyglet.font.load(). Return type:AbstractRunIterator

get_paragraph_end(pos)

Get the end position of a paragraph.

Parameters:pos (int) – Character position within paragraph. Return type:int

get_paragraph_start(pos)

Get the starting position of a paragraph.

Parameters:pos (int) – Character position within paragraph. Return type:int

get_style(attribute, position=0)

Get an attribute style at the given position.

Parameters:

• attribute (str) – Name of style attribute to query.
• position (int) – Character position of document to query.

Returns:

The style set for the attribute at the given position.

get_style_range(attribute, start, end)

Get an attribute style over the given range.

If the style varies over the range, STYLE_INDETERMINATE is returned.

Parameters:

• attribute (str) – Name of style attribute to query.
• start (int) – Starting character position.
• end (int) – Ending character position (exclusive).

Returns:

The style set for the attribute over the given range, or STYLE_INDETERMINATE if more than one value is set.

get_style_runs(attribute)

Get a style iterator over the given style attribute.

Parameters:attribute (str) – Name of style attribute to query. Return type:AbstractRunIterator

insert_element(position, element, attributes=None)

Insert a element into the document.

See the InlineElement class documentation for details of usage.

Parameters:

• position (int) – Character insertion point within document.
• element (InlineElement) – Element to insert.
• attributes (dict) – Optional dictionary giving named style attributes of the inserted text.

insert_text(start, text, attributes=None)

Insert text into the document.

Parameters:

• start (int) – Character insertion point within document.
• text (str) – Text to insert.
• attributes (dict) – Optional dictionary giving named style attributes of the inserted text.

on_delete_text(start, end)

Text was deleted from the document.

Parameters:

• start (int) – Starting character position of deleted text.
• end (int) – Ending character position of deleted text (exclusive).

on_insert_text(start, text)

Text was inserted into the document.

Parameters:

• start (int) – Character insertion point within document.
• text (str) – The text that was inserted.

on_style_text(start, end, attributes)

Text character style was modified.

Parameters:

• start (int) – Starting character position of modified text.
• end (int) – Ending character position of modified text (exclusive).
• attributes (dict) – Dictionary giving updated named style attributes of the text.

set_paragraph_style(start, end, attributes)

Set the style for a range of paragraphs.

This is a convenience method for set_style that aligns the character range to the enclosing paragraph(s).

Parameters:

• start (int) – Starting character position.
• end (int) – Ending character position (exclusive).
• attributes (dict) – Dictionary giving named style attributes of the paragraphs.

set_style(start, end, attributes)

Set text style of some or all of the document.

Parameters:

• start (int) – Starting character position.
• end (int) – Ending character position (exclusive).
• attributes (dict) – Dictionary giving named style attributes of the text.

event_types = [‘on_insert_text’, ‘on_delete_text’, ‘on_style_text’]

text

Document text.

For efficient incremental updates, use the insert_text() and delete_text() methods instead of replacing this property.

Type:str

class FormattedDocument(text=”)

Simple implementation of a document that maintains text formatting.

Changes to text style are applied according to the description in AbstractDocument. All styles default to None.

get_element_runs()

get_font(position, dpi=None)

get_font_runs(dpi=None)

get_style(attribute, position=0)

get_style_runs(attribute)

class InlineElement(ascent, descent, advance)

Arbitrary inline element positioned within a formatted document.

Elements behave like a single glyph in the document. They are measured by their horizontal advance, ascent above the baseline, and descent below the baseline.

The pyglet layout classes reserve space in the layout for elements and call the element’s methods to ensure they are rendered at the appropriate position.

If the size of a element (any of the advance, ascent, or descent instance variables) is modified it is the application’s responsibility to trigger a reflow of the appropriate area in the affected layouts. This can be done by forcing a style change over the element’s position.

Variables:

• ascent (int) – Ascent of the element above the baseline, in pixels.
• descent (int) – Descent of the element below the baseline, in pixels. Typically negative.
• advance (int) – Width of the element, in pixels.

place(layout, x, y)

Construct an instance of the element at the given coordinates.

Called when the element’s position within a layout changes, either due to the initial condition, changes in the document or changes in the layout size.

It is the responsibility of the element to clip itself against the layout boundaries, and position itself appropriately with respect to the layout’s position and viewport offset.

The TextLayout.top_state graphics state implements this transform and clipping into window space.

Parameters:

• layout (pyglet.text.layout.TextLayout) – The layout the element moved within.
• x (int) – Position of the left edge of the element, relative to the left edge of the document, in pixels.
• y (int) – Position of the baseline, relative to the top edge of the document, in pixels. Note that this is typically negative.

remove(layout)

Remove this element from a layout.

The counterpart of place; called when the element is no longer visible in the given layout.

Parameters:layout (pyglet.text.layout.TextLayout) – The layout the element was removed from.

position

Position of the element within the document. Read-only.

Type:int

class UnformattedDocument(text=”)

A document having uniform style over all text.

Changes to the style of text within the document affects the entire document. For convenience, the position parameters of the style methods may therefore be omitted.

get_element_runs()

get_font(position=None, dpi=None)

get_font_runs(dpi=None)

get_style(attribute, position=None)

get_style_runs(attribute)

set_paragraph_style(start, end, attributes)

set_style(start, end, attributes)

STYLE_INDETERMINATE = ‘indeterminate’

The style attribute takes on multiple values in the document.