Initializes the new BFont object as a copy of another font. If no font is specified, be_plain_font is used.

The system BFont objects, including be_plain_font, are initialized only when you create a BApplication object for your application. Therefore, the default settings of BFont objects constructed before the BApplication object will be invalid.

See also: BView::SetFont(), BTextView::SetFontAndColor

Returns a unicode_block object that identifies which Unicode blocks the font supports. You can then use the unicode_block::Includes() function to determine if specific blocks are supported.

Returns a BRect that can enclose the entire font in its current style and size.

Direction() returns a font_direction constant that describes the direction in which the object's text is meant to be read:

• B_FONT_LEFT_TO_RIGHT

• B_FONT_RIGHT_TO_LEFT

This is an inherent property of the font and cannot be set.

The direction of the font affects the direction in which DrawString() draws the characters in a string, but not the direction in which it moves the pen.

See also: BView::DrawString()

Returns the file format of the font (ie, whether it's a PostScript™ or TrueType™ font).

GetBoundingBoxesAsGlyphs() returns an array of BRect objects indicating the bounding rectangles of all the characters in an array. Each BRect returned corresponds to one character's glyph.

GetBoundingBoxesAsString() returns an array of BRect objects indicating the bounding rectangles of each character in a string.

GetBoundingBoxesForStrings() returns an array of BRect objects indicating the bounding rectangles for an array of strings, one BRect per string. These rectangles enclose the entire string they represent.

In all cases, the mode indicates whether the rectangles should be returned in the screen's metric (B_SCREEN_METRIC), or in printing metrics (B_PRINTING_METRIC).

The delta argument for GetBoundingBoxesAsString() and the deltas argument for GetBoundingBoxesForStrings() indicate escapement deltas that should be applied when making the bounding box calculations. This lets you indicate that the characters should be closer together or further apart than normal, for example.

struct escapement_delta {
    float nonspace;
    float space;
}

struct edge_info {
    float left;
    float right;
}

These two functions provide the information required to precisely position characters on the screen or printed page. For each character passed in the charArray, they write information about the horizontal dimension of the character into the escapementArray or the edgeArray. Both functions provide this information in "escapement units" that yield standard coordinate units (72.0 per inch) when multiplied by the font size.

GetEscapements() and GetEdges() expect the character array they're passed to contain at least numChar characters; neither function checks the charArray for a null terminator. Because the array may hold multibyte characters (in B_UNICODE_UTF8 encoding), the number of bytes in the array may be greater than the number of characters specified. The escapementArray and edgeArray should be long enough to hold an output value for every input character.

You can optionally request that escapement information be returned as an array of BPoint objects.

Escapements

A character's escapement measures the amount of horizontal space it requires. It includes the space needed to display the character itself, plus some extra room on the left and right edges to separate the character from its neighbors. The illustration below shows the approximate escapements for the letters 'l' and 'p'; the escapement for each character is the distance between the vertical lines:

GetEscapements() measures the same space that functions such as StringWidth() and BTextView's LineWidth() do, but it measures each character individually and records its width in per-point-size escapement units. To translate the escapement value to the width of the character, you must multiply by the point size of the font:

float width = escapementArray[i] * font.Size();

Because of rounding errors, there may be some difference between the value returned by StringWidth() and the width calculated from the individual escapements of the characters in the string.

The versions of GetEscapements() that use BPoints for the escapement value use the BPoint escapementArray to indicate a vector by which the pen is moved after drawing a character (this lets the escapement indicate both an X and a Y adjustment; the Y might need to be adjusted if the font is rotated, for example). The offsetArray is applied by the dynamic spacing in order to improve the relative position of the character's width with relation to another character, without altering the width.

The escapement value is scalable if the spacing mode of the font is B_CHAR_SPACING. In other words, given B_CHAR_SPACING and the same set of font characteristics, GetEscapements() will report the same measurement for a character regardless of the font size. You can cache one value per character and use it for all font sizes. For the other spacing modes, the reported escapement depends on the font size and therefore can't be scaled.

For most spacing modes, a character has a constant escapement in all contexts; it depends only on the font. However, for B_STRING_SPACING, each character's escapement is also contextually dependent on the string it's in. To find the escapement of a character within a particular string, you must pass the entire string in the input charArray.

In the B_BITMAP_SPACING and B_FIXED_SPACING modes, all characters have integral widths (without a fractional part). For these modes, multiplying an escapement by the font size should yield an integral value. In B_FIXED_SPACING mode, all characters have the same escapement.

If a delta argument is provided, GetEscapements() will adjust the escapements it reports so that, after multiplying by the font size, the character widths will include the specified increments. An escapement_delta structure contains two values:

float nonspace	The amount to add to the width of each character with a visible glyph.
float space	The amount to add to each whitespace character (characters like B_TAB and B_SPACE with an escapement but no visible glyph).

A similar argument can be passed to BView's DrawString() to adjust the spacing of the characters as they're drawn.

typedef struct {
    float left;
    float right;
} edge_info;

Given an array of characters, charArray, which contains numChars characters, and an array of BShape objects, glyphShapeArray, this function makes each element in the glyphShapeArray describe the shape of the corresponding glyph in the charArray.

This lets you create BShape objects in the shape of the outline of a font. You can then manipulate these BShapes to do interesting text effects.

Warning

The glyphShapeArray must contain already-allocated BShape objects. They will be cleared by this function before the glyphs' shapes are constructed into them, but the objects must already exist.

Fonts are drawn one pixel above the logical baseline; this affects BShape objects derived from fonts, too. The fonts are also one pixel above the baseline in the BShapes this function returns. If you want to apply a transform to these shapes, be sure to remove the offset before applying the transform, then add the offset back to the points before drawing the shape, or you won't get the expected results.

Given an array of characters in charArray (of which there are numChars members), this function fills out the array of booleans specified by hasArray such that each entry in hasArray is true if the corresponding character in charArray has a glyph in the font, and false if the character doesn't have a glyph.

This way, you can determine if you can use one or more characters without the user seeing "no glyph" symbols.

struct font_height {
    float ascent;
    float descent;
    float leading;
}

GetHeight() writes the three components that determine the height of the font into the structure that the height argument refers to. A font_height structure has the following fields:

If you need to round the font height, or any of its components, to an integral value (to figure the spacing between lines of text on-screen, for example), you should always round them up to reduce the amount of vertical character overlap.

See also: BView::GetFontHeight()

GetTruncatedStrings() truncates a set of strings so that each one (and an ellipsis to show where the string was cut) will fit into the maxWidth horizontal space. This function is useful for shortening long strings that are displayed to the user—for showing path names in a list, for example.

The numStrings argument states how many strings in the inputStringArray should be shortened. The mode argument states where the string should be cut. It can be:

Each output string is written to the truncatedStringArray—into memory that the caller must provide—at an index that matches the index of the full string in the inputStringArray. The truncatedStringArray is a list of pointers to string buffers. Each buffer should be allocated separately and should be at least 3 bytes longer than the matching input string. The 3 bytes allow for the worst-case scenario: GetTruncatedStrings() cuts a one-byte character from the input string and replaces it with an ellipsis character, which takes three bytes in UTF-8 encoding, for a net gain of 2 bytes. It then adds a null terminator for the third byte.

TruncateString() truncates the BString inOutString to be no longer than the width specified by maxWidth, using the given truncation mode.

The output strings are null-terminated. The input strings should likewise be null-terminated.

See also: StringWidth()

struct tuned_font_info {
      float size;
      float shear;
      float rotation;
      uint32 flags;
      uint16 face;
}

These functions are used to get information about fonts that have been "tuned" to look good when displayed on-screen. A tuned font is a set of character bitmaps, originally produced from the standard outline font and then modified so that the characters are well proportioned and spaced when displayed at the low resolution of the screen (1 pixel per point).

Because it's a bitmap font, a tuned font captures a specific configuration of font attributes, including size, style, shear, and rotation. A tuned font is a counterpart to an outline font with the same settings. If a BView's current font has a tuned counterpart, DrawString() automatically chooses it when drawing on-screen. Tuned fonts are not used for printing.

CountTuned() returns how many tuned fonts there are for the family and style represented by the BFont object. GetTunedInfo() writes information about the tuned font at index into the structure the info argument refers to. Indices begin at 0 and count only tuned fonts for the BFont's family and style.

With this information, you can set the BFont to values that match those of a tuned font. When a BView draws to the screen, it picks a tuned font if there's one that corresponds to its current font in all respects.

See also: get_font_family()

Returns true if the font is fixed; false otherwise.

This function is not yet supported.

Writes the following information about the font to the standard output (on a single line):

• family

• style

• size (in points)

• shear (in degrees)

• rotation (in degrees)

• ascent

• descent

• leading

These functions set and return the encoding that maps character values to characters. The following encodings are supported:

• B_UNICODE_UTF8 (UTF-8)

• B_ISO_8859_1 (Latin 1)

• B_ISO_8859_2 (Latin 2)

• B_ISO_8859_3 (Latin 3)

• B_ISO_8859_4 (Latin 4)

• B_ISO_8859_5 (Latin/Cyrillic)

• B_ISO_8859_6 (Latin/Arabic)

• B_ISO_8859_7 (Latin/Greek)

• B_ISO_8859_8 (Latin/Hebrew)

• B_ISO_8859_9 (Latin 5)

• B_ISO_8859_10 (Latin 6)

• B_MACINTOSH_ROMAN

UTF-8 is an 8-bit encoding for Unicode™ and is part of the Unicode™ standard. It matches ASCII values for all 7-bit character codes, but uses multibyte characters for values over 127. The other encodings take only a single byte to represent a character; they therefore necessarily encompass a far smaller set of characters. Most of them represent standards in the ISO/IEC 8859 family of character codes that extend the ASCII set. B_MACINTOSH_ROMAN stands for the standard encoding used by the Mac OS™.

The encoding affects both input and output functions of the BView. It determines how DrawString() interprets the character values it's passed and also how KeyDown() encodes character values for the keys the user pressed.

UTF-8 is the preferred encoding and the one that's most compatible with objects defined in the software kits. For example, a BTextView expects all text it takes from the clipboard or from a dragged and dropped message to be UTF-8 encoded. If it isn't, the results are not defined. The more that applications stick with UTF-8 encoding, the more freely they'll be able to exchange data.

See also: "Character Encoding" convert_to_utf8(), BView::DrawString(), BView::KeyDown()

These functions set and return a mask that record secondary characteristics of the font, such as whether characters are underlined or drawn in outline. The values that form the face mask are:

Sets the family and face of the font. The family passed to this function must be one of the families enumerated by the get_font_family() global function and face must be a combination of the face values described under SetFace(). If the family is NULL, SetFamilyAndFace() sets only the face.

typedef char font_family[B_FONT_FAMILY_LENGTH + 1]

typedef char font_style[B_FONT_STYLE_LENGTH + 1]

SetFamilyAndStyle() sets the family and style of the font. The family passed to this function must be one of the families enumerated by the get_font_family() global function and style must be one of the styles associated with that family, as reported by get_font_style(). If the family is NULL, SetFamilyAndStyle() sets only the style; if style is NULL, it sets only the family.

GetFamilyAndStyle() writes the names of the current family and style into the font_value and font_style variables provided.

Internally, the BFont class encodes each family and style combination as a unique integer. FamilyAndStyle() returns that code, which can then be passed to SetFamilyAndStyle() to set another BFont object. The integer code is not persistent; its meaning may change when the list of installed fonts changes and when the machine is rebooted.

These functions set and return a mask that records various behaviors of the font. There are two flags: B_DISABLE_ANTIALIASING, which turns off all antialiasing for characters displayed in the font, and B_FORCE_ANTIALIASING, which forces all font rendering to be anti-aliased. The default mask has antialiasing turned on.

These functions set and return the rotation of the baseline for characters displayed in the font. The baseline rotates counterclockwise from an axis on the left side of the character. The default (horizontal) baseline is at 0°. For example, this code

BFont font;
font.SetRotation(45.0);
myView->SetFont(&font, B_FONT_ROTATION);
myView->DrawString("to the northeast");

would draw a string that extended upwards and to the right.

Rotation is not supported by some Interface Kit classes, including BTextView.

These functions set and return the angle at which characters are drawn relative to the baseline. The default (perpendicular) shear for all font styles, including oblique and italic ones, is 90.0°. The shear is measured counterclockwise and can be adjusted within the range 45.0° (slanted to the right) through 135.0° (slanted to the left). If the shear passed falls outside this range, it will be adjusted to the closest value within range.

These functions set and return the size of the font in points. Valid sizes range from less than 1.0 point through 10,000 points.

See also: BView::SetFontSize()

These functions set and return the mode that determines how characters are horizontally spaced relative to each other when they're drawn. The mode also affects the width or "escapement" of each character as reported by GetEscapements().

There are four spacing modes:

The B_CHAR_SPACING mode is the preferred mode for printing. It's also somewhat faster than B_STRING_SPACING or B_BITMAP_SPACING. In all modes other than B_STRING_SPACING, it's possible to change the character displayed at the end of a string by erasing it and drawing a new character. However, in B_STRING_SPACING mode, it's necessary to erase the entire string and redraw it. The longer the string, the better the results.

The B_STRING_SPACING and B_BITMAP_SPACING modes are relevant only for font sizes in a range of about 7.0 points to 18.0 points. Above that range, B_CHAR_SPACING achieves reasonable results on-screen and may be used even where one of the other two modes is specified. Below that range, the screen resolution isn't great enough for the different modes to produce significantly different results, so again B_CHAR_SPACING is used.

In addition, B_CHAR_SPACING is always used for rotated or sheared text and when antialiasing is disabled.

See also: BView::DrawString(), GetEscapements()

StringWidth() returns how much room is required to draw a string in the font. It measures the characters encoded in length bytes of the string—or, if no length is specified, the entire string up to the null character, '0', which terminates it. The return value totals the width of all the characters in coordinate units; it's the length of the baseline required to draw the string.

GetStringWidth() provides the same information for a group of strings. It works its way through the stringArray looking at a total of numStrings. For each string, it gets the length at the corresponding index from the lengthArray and places the width of the string in the widthArray at the same index.

These functions take all the attributes of the font—including family, style, size, and spacing—into account.

See also: BView::StringWidth()

Assigns one BFont object to another. After the assignment, the two objects are identical to each other and do not share any data.

These operators test whether two BFont objects are identical in all respects. If all settable font attributes are the same in both objects, they're equal. If not, they're unequal.

Declared in: interface/Font.h

const BFont* be_plain_font
const BFont* be_bold_font
const BFont* be_fixed_font

These global BFont objects are created when the BApplication object is constructed. They encapsulate the three system fonts—the plain font which is used for labels and small stretches of text in the user interface, the bold font which is used for window and group titles, and the fixed font which is used in Terminal windows and other places where a fixed-width font is required.

These objects cannot be modified directly, nor are they modified when the user redefines a system font. The user's changed preferences don't affect running applications.

Declared in: interface/Font.h

The constants name the various character encodings that the BeOS supports. B_UNICODE_UTF8 is the default encoding. It matches ASCII values for 7-bit character codes but uses multiple bytes to encode other values in the Unicode standard.

See also: BFont::SetEncoding(), the "Character Encoding" section of this chapter

Declared in: interface/Font.h

The first flag, B_DISABLE_ANTIALIASING, is passed to a BFont object to turn antialiasing off. Antialiasing should be turned off when printing, but should generally be left on when drawing to the screen.

The other two flags enable get_font_family() and get_font_style() to give information about a font. B_IS_FIXED indicates that the font is nonproportional. B_HAS_TUNED_FONT indicates that the family or style has one or more tuned fonts—bitmap fonts that have been adjusted to look good on the screen—for some set of font properties (such as size and shear).

See also: BFont::SetFlags()

Declared in: interface/Font.h

These constants define the maximum length of names for font families and styles, exclusive of a null terminator. They're used in the definition of the font_family and font_style types.

See also: font_family under "Defined Types" below

Declared in: interface/View.h

These constants list the font properites that can be set for a BView individually or in combination. The constants form a mask that's passed, along with a BFont object, to BView's BView and BTextView's SetFontAndColor() functions. For example:

myView->SetFont(theFont, B_FONT_SIZE | B_FONT_ENCODING);

B_FONT_ALL stands for all properties of the BFont.

Declared in: interface/Font.h

These constants enumerate the four modes for positioning characters in a line of text.

See also: BFont::SetSpacing()

Declared In: interface/Font.h

The font_metric_mode constants above indicate whether a font calculation should be done with the screen or the printer in mind.

Declared In: interface/Font.h

The font_file_format constants are used to specify what type of file a font was loaded from. Currently, only Microsoft Windows™-format TrueType and PostScript Type 1 fonts are supported.

Declared in: interface/Font.h

enum font_direction {
    B_FONT_LEFT_TO_RIGHT,
    B_FONT_RIGHT_TO_LEFT
}

These constants tell whether a font is used for text that's read left-to-right or right-to-left. Thus is an inherent property of the font.

See also: BFont::Direction()

interface/Font.h

class unicode_block {
public:
   inline unicode_block();
   inline unicode_block(uint64 block2, uint64 block1);

   inline bool Includes(const unicode_block &block) const;
   inline unicode_block operator&(const unicode_block& block) const;
   inline unicode_block operator|(const unicode_block& block) const;
   inline unicode_block& operator=(const unicode_block &block);
   inline unicode_block operator==(const unicode_block &block) const;
   inline unicode_block operator!=(const unicode_block &block) const;

private:
   fData[2];
};

The unicode_block class describes the ranges of Unicode™ characters a font supports. You can get a unicode_block object for a font by calling the Blocks() function. Once you have this, you can check to see if a particular block is supported, or compare it to another block to see if it's inclusive, equal, unequal, and so forth.

In general, you won't instantiate a unicode_block object on your own.

The unicode_block::Includes() function lets you determine if another block is a subset of the unicode_block object.

There are a number of predefined Unicode™ blocks, as follows:

B_BASIC_LATIN_BLOCK
B_LATIN1_SUPPLEMENT_BLOCK
B_LATIN_EXTENDED_A_BLOCK
B_LATIN_EXTENDED_B_BLOCK
B_IPA_EXTENSIONS_BLOCK
B_SPACING_MODIFIER_LETTERS_BLOCK
B_COMBINING_DIACRITICAL_MARKS_BLOCK
B_BASIC_GREEK_BLOCK
B_GREEK_SYMBOLS_AND_COPTIC_BLOCK
B_CYRILLIC_BLOCK
B_ARMENIAN_BLOCK
B_BASIC_HEBREW_BLOCK
B_HEBREW_EXTENDED_BLOCK
B_BASIC_ARABIC_BLOCK
B_ARABIC_EXTENDED_BLOCK
B_DEVANAGARI_BLOCK
B_BENGALI_BLOCK
B_GURMUKHI_BLOCK
B_GUJARATI_BLOCK
B_ORIYA_BLOCK
B_TAMIL_BLOCK
B_TELUGU_BLOCK
B_KANNADA_BLOCK
B_MALAYALAM_BLOCK
B_THAI_BLOCK
B_LAO_BLOCK
B_BASIC_GEORGIAN_BLOCK
B_GEORGIAN_EXTENDED_BLOCK
B_HANGUL_JAMO_BLOCK
B_LATIN_EXTENDED_ADDITIONAL_BLOCK
B_GREEK_EXTENDED_BLOCK
B_GENERAL_PUNCTUATION_BLOCK
B_SUPERSCRIPTS_AND_SUBSCRIPTS_BLOCK
B_CURRENCY_SYMBOLS_BLOCK
B_COMBINING_MARKS_FOR_SYMBOLS_BLOCK
B_LETTERLIKE_SYMBOLS_BLOCK
B_NUMBER_FORMS_BLOCK
B_ARROWS_BLOCK
B_MATHEMATICAL_OPERATORS_BLOCK
B_MISCELLANEOUS_TECHNICAL_BLOCK
B_CONTROL_PICTURES_BLOCK
B_OPTICAL_CHARACTER_RECOGNITION_BLOCK
B_ENCLOSED_ALPHANUMERICS_BLOCK
B_BOX_DRAWING_BLOCK
B_BLOCK_ELEMENTS_BLOCK
B_GEOMETRIC_SHAPES_BLOCK
B_MISCELLANEOUS_SYMBOLS_BLOCK
B_DINGBATS_BLOCK
B_CJK_SYMBOLS_AND_PUNCTUATION_BLOCK
B_HIRAGANA_BLOCK
B_KATAKANA_BLOCK
B_BOPOMOFO_BLOCK
B_HANGUL_COMPATIBILITY_JAMO_BLOCK
B_CJK_MISCELLANEOUS_BLOCK
B_ENCLOSED_CJK_LETTERS_AND_MONTHS_BLOCK
B_CJK_COMPATIBILITY_BLOCK
B_HANGUL_BLOCK
B_HIGH_SURROGATES_BLOCK
B_LOW_SURROGATES_BLOCK
B_CJK_UNIFIED_IDEOGRAPHS_BLOCK
B_PRIVATE_USE_AREA_BLOCK
B_CJK_COMPATIBILITY_IDEOGRAPHS_BLOCK
B_ALPHABETIC_PRESENTATION_FORMS_BLOCK
B_ARABIC_PRESENTATION_FORMS_A_BLOCK
B_COMBINING_HALF_MARKS_BLOCK
B_CJK_COMPATIBILITY_FORMS_BLOCK
B_SMALL_FORM_VARIANTS_BLOCK
B_ARABIC_PRESENTATION_FORMS_B_BLOCK
B_HALFWIDTH_AND_FULLWIDTH_FORMS_BLOCK
B_SPECIALS_BLOCK
B_TIBETAN_BLOCK