cairo_scaled_font_t

typedef struct _cairo_scaled_font cairo_scaled_font_t;

A cairo_scaled_font_t is a font scaled to a particular size and device resolution. A cairo_scaled_font_t is most useful for low-level font usage where a library or application wants to cache a reference to a scaled font to speed up the computation of metrics.

There are various types of scaled fonts, depending on the font backend they use. The type of a scaled font can be queried using cairo_scaled_font_get_type().

Memory management of cairo_scaled_font_t is done with cairo_scaled_font_reference() and cairo_scaled_font_destroy().

cairo_scaled_font_create ()

cairo_scaled_font_t* cairo_scaled_font_create           (cairo_font_face_t *font_face,
                                                         const cairo_matrix_t *font_matrix,
                                                         const cairo_matrix_t *ctm,
                                                         const cairo_font_options_t *options);

Creates a cairo_scaled_font_t object from a font face and matrices that describe the size of the font and the environment in which it will be used.

cairo_scaled_font_reference ()

cairo_scaled_font_t* cairo_scaled_font_reference        (cairo_scaled_font_t *scaled_font);

Increases the reference count on scaled_font by one. This prevents scaled_font from being destroyed until a matching call to cairo_scaled_font_destroy() is made.

The number of references to a cairo_scaled_font_t can be get using cairo_scaled_font_get_reference_count().

cairo_scaled_font_destroy ()

void                cairo_scaled_font_destroy           (cairo_scaled_font_t *scaled_font);

Decreases the reference count on font by one. If the result is zero, then font and all associated resources are freed. See cairo_scaled_font_reference().

cairo_scaled_font_status ()

cairo_status_t      cairo_scaled_font_status            (cairo_scaled_font_t *scaled_font);

Checks whether an error has previously occurred for this scaled_font.

cairo_font_extents_t

typedef struct {
    double ascent;
    double descent;
    double height;
    double max_x_advance;
    double max_y_advance;
} cairo_font_extents_t;

The cairo_font_extents_t structure stores metric information for a font. Values are given in the current user-space coordinate system.

Because font metrics are in user-space coordinates, they are mostly, but not entirely, independent of the current transformation matrix. If you call cairo_scale(cr, 2.0, 2.0), text will be drawn twice as big, but the reported text extents will not be doubled. They will change slightly due to hinting (so you can't assume that metrics are independent of the transformation matrix), but otherwise will remain unchanged.

cairo_scaled_font_extents ()

void                cairo_scaled_font_extents           (cairo_scaled_font_t *scaled_font,
                                                         cairo_font_extents_t *extents);

Gets the metrics for a cairo_scaled_font_t.

cairo_text_extents_t

typedef struct {
    double x_bearing;
    double y_bearing;
    double width;
    double height;
    double x_advance;
    double y_advance;
} cairo_text_extents_t;

The cairo_text_extents_t structure stores the extents of a single glyph or a string of glyphs in user-space coordinates. Because text extents are in user-space coordinates, they are mostly, but not entirely, independent of the current transformation matrix. If you call cairo_scale(cr, 2.0, 2.0), text will be drawn twice as big, but the reported text extents will not be doubled. They will change slightly due to hinting (so you can't assume that metrics are independent of the transformation matrix), but otherwise will remain unchanged.

cairo_scaled_font_text_extents ()

void                cairo_scaled_font_text_extents      (cairo_scaled_font_t *scaled_font,
                                                         const char *utf8,
                                                         cairo_text_extents_t *extents);

Gets the extents for a string of text. The extents describe a user-space rectangle that encloses the "inked" portion of the text drawn at the origin (0,0) (as it would be drawn by cairo_show_text() if the cairo graphics state were set to the same font_face, font_matrix, ctm, and font_options as scaled_font). Additionally, the x_advance and y_advance values indicate the amount by which the current point would be advanced by cairo_show_text().

Note that whitespace characters do not directly contribute to the size of the rectangle (extents.width and extents.height). They do contribute indirectly by changing the position of non-whitespace characters. In particular, trailing whitespace characters are likely to not affect the size of the rectangle, though they will affect the x_advance and y_advance values.

Since 1.2

cairo_scaled_font_glyph_extents ()

void                cairo_scaled_font_glyph_extents     (cairo_scaled_font_t *scaled_font,
                                                         const cairo_glyph_t *glyphs,
                                                         int num_glyphs,
                                                         cairo_text_extents_t *extents);

Gets the extents for an array of glyphs. The extents describe a user-space rectangle that encloses the "inked" portion of the glyphs, (as they would be drawn by cairo_show_glyphs() if the cairo graphics state were set to the same font_face, font_matrix, ctm, and font_options as scaled_font). Additionally, the x_advance and y_advance values indicate the amount by which the current point would be advanced by cairo_show_glyphs().

Note that whitespace glyphs do not contribute to the size of the rectangle (extents.width and extents.height).

cairo_scaled_font_get_font_face ()

cairo_font_face_t*  cairo_scaled_font_get_font_face     (cairo_scaled_font_t *scaled_font);

Gets the font face that this scaled font was created for.

Since 1.2

cairo_scaled_font_get_font_options ()

void                cairo_scaled_font_get_font_options  (cairo_scaled_font_t *scaled_font,
                                                         cairo_font_options_t *options);

Stores the font options with which scaled_font was created into options.

Since 1.2

cairo_scaled_font_get_font_matrix ()

void                cairo_scaled_font_get_font_matrix   (cairo_scaled_font_t *scaled_font,
                                                         cairo_matrix_t *font_matrix);

Stores the font matrix with which scaled_font was created into matrix.

Since 1.2

cairo_scaled_font_get_ctm ()

void                cairo_scaled_font_get_ctm           (cairo_scaled_font_t *scaled_font,
                                                         cairo_matrix_t *ctm);

Stores the CTM with which scaled_font was created into ctm.

Since 1.2

cairo_scaled_font_get_type ()

cairo_font_type_t   cairo_scaled_font_get_type          (cairo_scaled_font_t *scaled_font);

This function returns the type of the backend used to create a scaled font. See cairo_font_type_t for available types.

Since 1.2

cairo_scaled_font_get_reference_count ()

unsigned int        cairo_scaled_font_get_reference_count
                                                        (cairo_scaled_font_t *scaled_font);

Returns the current reference count of scaled_font.

Since 1.4

cairo_scaled_font_set_user_data ()

cairo_status_t      cairo_scaled_font_set_user_data     (cairo_scaled_font_t *scaled_font,
                                                         const cairo_user_data_key_t *key,
                                                         void *user_data,
                                                         cairo_destroy_func_t destroy);

Attach user data to scaled_font. To remove user data from a surface, call this function with the key that was used to set it and NULL for data.

Since 1.4

cairo_scaled_font_get_user_data ()

void*               cairo_scaled_font_get_user_data     (cairo_scaled_font_t *scaled_font,
                                                         const cairo_user_data_key_t *key);

Return user data previously attached to scaled_font using the specified key. If no user data has been attached with the given key this function returns NULL.

Since 1.4