NSATSTypesetter Class Reference

Discussion

Returns the bounding rectangle for the control glyph at glyphIndex, at the given glyphPosition and character index charIndex, in textContainer. The proposed line fragment rectangle is specified by proposedRect.

The typesetter calls this method when it encounters an NSControlGlyph. The default behavior is to return zero width for control glyphs. A subclass can override this method to do something different, such as implement a way to display control characters.

NSGlyphGenerator can choose whether or not to map control characters to NSControlGlyph. Tab characters, for example, do not use this facility.

Discussion

If actualGlyphRange is non-NULL, expands the requested range as needed so that it identifies all glyphs mapped to those characters and returns the new range by reference in actualGlyphRange.

A subclass can override this method to interact with custom glyph storage.

Discussion

A subclass can override this method to interact with custom glyph storage.

Discussion

The charIndexBuffer contains the original characters for the glyphs. Note that a glyph at index 1 is not necessarily mapped to the character at index 1, since a glyph may be for a ligature or accent.

The inscribeBuffer contains the inscription attributes for each glyph, which are used to layout characters that are combined together. The possible values are described in the “Constants” section of the NSLayoutManager reference.

The elasticBuffer contains a Boolean value indicating whether a glyph is elastic for each glyph. An elastic glyph can be made longer at the end of a line or when needed for justification.

A subclass can override this method to interact with custom glyph storage.

Discussion

The method returns the calculated line fragment rectangle in lineFragmentRect, and it returns the used rectangle (the portion of the line fragment rectangle that actually contains marks) in lineFragmentUsedRect. The paragraphSeparatorGlyphRange is the range of glyphs under consideration, and lineOrigin is the origin point of the line fragment rectangle. A paragraphSeparatorGlyphRange with length 0 indicates an extra line fragment (which occurs if the last character in the paragraph is a line separator.)

Discussion

If actualCharRange is non-NULL, expands the requested range as needed so that it identifies all characters mapped to those glyphs and returns the new range by reference in actualCharRange.

A subclass can override this method to interact with custom glyph storage.

Discussion

The hyphenation factor is a value ranging from 0.0 to 1.0 that controls when hyphenation is attempted. By default, the value is 0.0, meaning hyphenation is off. A factor of 1.0 causes hyphenation to be attempted always.

Discussion

The hyphenation factor is a value ranging from 0.0 to 1.0 that controls when hyphenation is attempted. By default, the value is 0.0, meaning hyphenation is off. A factor of 1.0 causes hyphenation to be attempted always.

The typesetter calls this method with a proposed hyphenation point for a line break to find the hyphenation factor in effect at that time. A subclass can override this method to customize the text layout process.

Discussion

The typesetter calls this method before hyphenating. A subclass can override this method to return a different hyphen glyph.

Discussion

Inserts glyph into the glyph cache at glyphIndex and maps it to the character at charIndex. If the glyph is mapped to several characters, charIndex should indicate the first character to which it’s mapped.

The standard typesetter uses this method for inserting hyphenation glyphs. Because this method keeps the glyph caches synchronized, subclasses should always use this method to insert glyphs instead of calling layoutManager directly.

A subclass can override this method to interact with custom glyph storage.

Discussion

The lineFragmentOrigin specifies the upper-left corner of line fragment rectangle. On return, lineFragmentOrigin contains the next origin. This method returns the next glyph index. Usually it’s the index right after the paragraph separator, but it can be inside the paragraph range if, for example, the end of the text container is reached before the paragraph separator.

Discussion

Text is inset within the line fragment rectangle by this amount.

Discussion

The NSATSTypesetter calls this method to determine the number of points of space to include below the descenders in the used rectangle for the proposed line fragment rectangle rect.

Line spacing, also called leading, is an attribute of NSParagraphStyle, which you can set on an NSMutableParagraphStyle object. A font typically includes a default minimum line spacing metric used if none is set in the paragraph style.

If the typesetter behavior specified in the NSLayoutManager is NSTypesetterOriginalBehavior, the text system uses the original, private typesetter NSSimpleHorizontalTypesetter, which adds the line spacing above the ascender. Similarly, NSATSTypesetter adds the line spacing above the ascender if the value is negative.

Discussion

The rect argument specifies the line fragment rectangle of the last line in the paragraph.

The typesetter adds the number of points specified in the return value to the bottom of the line fragment rectangle specified by rect (but not to the used line fragment rectangle for that line). Paragraph spacing added after a paragraph correlates to the value returned by the paragraphSpacing method of NSParagraphStyle, which you can set using the setParagraphSpacing: method of NSMutableParagraphStyle.

Discussion

The rect argument specifies the line fragment rectangle of the first line in the paragraph.

The typesetter adds the number of points specified in the return value to the top of the line fragment rectangle specified by rect (but not to the used line fragment rectangle for that line). Paragraph spacing added before a paragraph correlates to the value returned by the paragraphSpacingBefore method of NSParagraphStyle, which you can set using the setParagraphSpacingBefore: method of NSMutableParagraphStyle.

Discussion

A subclass can override this method to interact with custom glyph storage.

Discussion

The string object is not retained.

Discussion

The value of levels can range from 0 to 61 as defined by Unicode Standard Annex #9.

A subclass can override this method to interact with custom glyph storage.

Discussion

You can use this method to disable the bidirectional layout stage if you know the paragraph does not need this stage; that is, if the characters in the backing store are in display order.

Discussion

This can happen when text is set at a fixed line height. For example, if the user specifies a fixed line height of 12 points and sets the font size to 24 points, the glyphs will exceed their layout rectangles.

A subclass can override this method to interact with custom glyph storage.

Discussion

The factor argument is in the range of 0.0 to 1.0. By default, the value is 0.0, meaning hyphenation is off. A factor of 1.0 causes hyphenation to be attempted always.

Discussion

Note that line fragment padding isn’t a suitable means for expressing margins; you should set the NSTextView object’s position and size for document margins or the paragraph margin attributes for text margins.

Discussion

The exact positions of the glyphs must be set after the line fragment rectangle with setLocation:forStartOfGlyphRange:.

The usedRect argument indicates the portion of fragmentRect, in the NSTextContainer object’s coordinate system, that actually contains glyphs or other marks that are drawn (including the text container’s line fragment padding). The usedRect must be equal to or contained within fragmentRect. The baselineOffset argument is the vertical distance in pixels from the line fragment origin to the baseline on which the glyphs align.

A subclass can override this method to interact with custom glyph storage.

Discussion

The x-coordinate of location is expressed relative to the line fragment rectangle origin, and the y-coordinate is expressed relative to the baseline previously specified by setLineFragmentRect:forGlyphRange:usedRect:baselineOffset:. The glyphRange defines a series of glyphs that can be displayed with a single PostScript show operation (a nominal range). Setting the location for a series of glyphs implies that the glyphs preceding it can’t be included in a single show operation. The advancements argument is the nominal glyph advance width specified in the font metric information.

Before setting the location for a glyph range, you must specify line fragment rectangle with setLineFragmentRect:forGlyphRange:usedRect:baselineOffset:.

A subclass can override this method to interact with custom glyph storage.

Discussion

For example, a tab or newline character doesn’t leave any marks; it just indicates where following glyphs are laid out.

A subclass can override this method to interact with custom glyph storage.

Discussion

The possible values for behavior are described in the “Constants” section of the NSLayoutManager reference.

Discussion

A subclass can override this method to customize the text layout process. If the method returns NO, the typesetter continues looking for a break point.

Discussion

A subclass can override this method to customize the text layout process. If the method returns NO, the typesetter continues looking for a break point.

Discussion

A screen font can be substituted if the receiver is set to use screen fonts and if no NSTextView associated with the receiver is scaled or rotated.

Discussion

This method does not alter the glyph-to-character mapping or invalidate layout information.

A subclass can override this method to interact with custom glyph storage.

Discussion

The typesetter calls this method whenever it finds a tab character. To determine the width to advance the next glyph, the typesetter examines the NSParagraphStyle tab array and the default tab interval.

Discussion

The possible return values are described in the “Constants” section of the NSLayoutManager reference.

Discussion

The lineRect argument is the rectangle in which the glyphs in glyphRange are laid out. The usedRect argument indicates the portion of lineRect, in the NSTextContainer object’s coordinate system, that actually contains glyphs or other marks that are drawn (including the text container’s line fragment padding). The usedRect must be equal to or contained within lineRect. The baselineOffset argument is the vertical distance in pixels from the line fragment origin to the baseline on which the glyphs align.

A subclass can override this method to customize the text layout process. For example, it could change the shape of the line fragment rectangle. The subclass is responsible for ensuring that the modified rectangle remains valid (for example, that it lies within the text container).