PANGO_SCALE

#define PANGO_SCALE 1024

The PANGO_SCALE macro represents the scale between dimensions used for Pango distances and device units. (The definition of device units is dependent on the output device; it will typically be pixels for a screen, and points for a printer.) PANGO_SCALE is currently 1024, but this may be changed in the future.

When setting font sizes, device units are always considered to be points (as in "12 point font"), rather than pixels.

PANGO_PIXELS()

#define PANGO_PIXELS(d) (((int)(d) + 512) >> 10)

Converts a dimension to device units by rounding.

PANGO_PIXELS_FLOOR()

#define PANGO_PIXELS_FLOOR(d) (((int)(d)) >> 10)

Converts a dimension to device units by flooring.

PANGO_PIXELS_CEIL()

#define PANGO_PIXELS_CEIL(d) (((int)(d) + 1023) >> 10)

Converts a dimension to device units by ceiling.

pango_units_to_double ()

double      pango_units_to_double           (int i);

Converts a number in Pango units to floating-point: divides it by PANGO_SCALE.

Since 1.16

pango_units_from_double ()

int         pango_units_from_double         (double d);

Converts a floating-point number to Pango units: multiplies it by PANGO_SCALE and rounds to nearest integer.

Since 1.16

PangoRectangle

typedef struct {
  int x;
  int y;
  int width;
  int height;
} PangoRectangle;

The PangoRectangle structure represents a rectangle. It is frequently used to represent the logical or ink extents of a single glyph or section of text. (See, for instance, pango_font_get_glyph_extents())

PANGO_ASCENT()

#define PANGO_ASCENT(rect) (-(rect).y)

Extracts the ascent from a PangoRectangle representing glyph extents. The ascent is the distance from the baseline to the highest point of the character. This is positive if the glyph ascends above the baseline.

PANGO_DESCENT()

#define PANGO_DESCENT(rect) ((rect).y + (rect).height)

Extracts the descent from a PangoRectangle representing glyph extents. The descent is the distance from the baseline to the lowest point of the character. This is positive if the glyph descends below the baseline.

PANGO_LBEARING()

#define PANGO_LBEARING(rect) ((rect).x)

Extracts the left bearing from a PangoRectangle representing glyph extents. The left bearing is the distance from the horizontal origin to the farthest left point of the character. This is positive for characters drawn completely to the right of the glyph origin.

PANGO_RBEARING()

#define PANGO_RBEARING(rect) ((rect).x + (rect).width)

Extracts the right bearing from a PangoRectangle representing glyph extents. The right bearing is the distance from the horizontal origin to the farthest right point of the character. This is positive except for characters drawn completely to the left of the horizontal origin.

pango_extents_to_pixels ()

void        pango_extents_to_pixels         (PangoRectangle *ink_rect,
                                             PangoRectangle *logical_rect);

Converts extents from Pango units to device units, dividing by the PANGO_SCALE factor and performing rounding.

The ink rectangle is converted by flooring the x/y coordinates and extending width/height, such that the final rectangle completely includes the original rectangle.

The logical rectangle is converted by rounding the coordinates of the rectangle to the nearest device unit.

Note that in certain situations you may want pass a logical extents rectangle to this function as ink_rect. The rule is: if you want the resulting device-space rectangle to completely contain the original rectangle, pass it in as ink_rect.

Since 1.16

PangoMatrix

typedef struct {
  double xx;
  double xy;
  double yx;
  double yy;
  double x0;
  double y0;
} PangoMatrix;

A structure specifying a transformation between user-space coordinates and device coordinates. The transformation is given by

x_device = x_user * matrix->xx + y_user * matrix->xy + matrix->x0;
y_device = x_user * matrix->yx + y_user * matrix->yy + matrix->y0;

Since 1.6

PANGO_TYPE_MATRIX

#define PANGO_TYPE_MATRIX (pango_matrix_get_type ())

The GObject type for PangoMatrix

PANGO_MATRIX_INIT

#define PANGO_MATRIX_INIT { 1., 0., 0., 1., 0., 0. }

Constant that can be used to initialize a PangoMatrix to the identity transform.

PangoMatrix matrix = PANGO_MATRIX_INIT;
pango_matrix_rotate (&matrix, 45.);

Since 1.6

pango_matrix_copy ()

PangoMatrix* pango_matrix_copy              (const PangoMatrix *matrix);

Copies a PangoMatrix.

Since 1.6

pango_matrix_free ()

void        pango_matrix_free               (PangoMatrix *matrix);

Free a PangoMatrix created with pango_matrix_copy(). Does nothing if matrix is NULL.

Since 1.6

pango_matrix_translate ()

void        pango_matrix_translate          (PangoMatrix *matrix,
                                             double tx,
                                             double ty);

Changes the transformation represented by matrix to be the transformation given by first translating by (tx, ty) then applying the original transformation.

Since 1.6

pango_matrix_scale ()

void        pango_matrix_scale              (PangoMatrix *matrix,
                                             double scale_x,
                                             double scale_y);

Changes the transformation represented by matrix to be the transformation given by first scaling by sx in the X direction and sy in the Y direction then applying the original transformation.

Since 1.6

pango_matrix_rotate ()

void        pango_matrix_rotate             (PangoMatrix *matrix,
                                             double degrees);

Changes the transformation represented by matrix to be the transformation given by first rotating by degrees degrees counter-clockwise then applying the original transformation.

Since 1.6

pango_matrix_concat ()

void        pango_matrix_concat             (PangoMatrix *matrix,
                                             const PangoMatrix *new_matrix);

Changes the transformation represented by matrix to be the transformation given by first applying transformation given by new_matrix then applying the original transformation.

Since 1.6

pango_matrix_transform_point ()

void        pango_matrix_transform_point    (const PangoMatrix *matrix,
                                             double *x,
                                             double *y);

Transforms the point (x, y) by matrix.

Since 1.16

pango_matrix_transform_distance ()

void        pango_matrix_transform_distance (const PangoMatrix *matrix,
                                             double *dx,
                                             double *dy);

Transforms the distance vector (dx,dy) by matrix. This is similar to pango_matrix_transform_point() except that the translation components of the transformation are ignored. The calculation of the returned vector is as follows:

dx2 = dx1 * xx + dy1 * xy;
dy2 = dx1 * yx + dy1 * yy;

Affine transformations are position invariant, so the same vector always transforms to the same vector. If (x1,y1) transforms to (x2,y2) then (x1+dx1,y1+dy1) will transform to (x1+dx2,y1+dy2) for all values of x1 and x2.

Since 1.16

pango_matrix_transform_rectangle ()

void        pango_matrix_transform_rectangle
                                            (const PangoMatrix *matrix,
                                             PangoRectangle *rect);

First transforms rect using matrix, then calculates the bounding box of the transformed rectangle. The rectangle should be in Pango units.

This function is useful for example when you want to draw a rotated PangoLayout to an image buffer, and want to know how large the image should be and how much you should shift the layout when rendering.

If you have a rectangle in device units (pixels), use pango_matrix_transform_pixel_rectangle().

If you have the rectangle in Pango units and want to convert to transformed pixel bounding box, it is more accurate to transform it first (using this function) and pass the result to pango_extents_to_pixels(), as ink_rect. However, there is a reason that you may want to convert to pixels first and then transform, and that is when the transformed coordinates may overflow in Pango units (large matrix translation for example).

Since 1.16

pango_matrix_transform_pixel_rectangle ()

void        pango_matrix_transform_pixel_rectangle
                                            (const PangoMatrix *matrix,
                                             PangoRectangle *rect);

First transforms the rect using matrix, then calculates the bounding box of the transformed rectangle. The rectangle should be in device units (pixels).

This function is useful for example when you want to draw a rotated PangoLayout to an image buffer, and want to know how large the image should be and how much you should shift the layout when rendering.

For better accuracy, you should use pango_matrix_transform_rectangle() on original rectangle in Pango units and convert to pixels afterward using pango_extents_to_pixels() as ink_rect.

Since 1.16

pango_matrix_get_font_scale_factor ()

double      pango_matrix_get_font_scale_factor
                                            (const PangoMatrix *matrix);

Returns the scale factor of a matrix on the height of the font. That is, the scale factor in the direction perpendicular to the vector that the X coordinate is mapped to.

Since 1.12

PangoGlyph

typedef guint32 PangoGlyph;

A PangoGlyph represents a single glyph in the output form of a string.

PANGO_GLYPH_EMPTY

#define PANGO_GLYPH_EMPTY           ((PangoGlyph)0x0FFFFFFF)

The PANGO_GLYPH_EMPTY macro represents a PangoGlyph value that has a special meaning, which is a zero-width empty glyph. This is useful for example in shaper modules, to use as the glyph for various zero-width Unicode characters (those passing pango_is_zero_width()).

PANGO_GLYPH_UNKNOWN_FLAG

#define PANGO_GLYPH_UNKNOWN_FLAG    ((PangoGlyph)0x10000000)

The PANGO_GLYPH_UNKNOWN_FLAG macro is a flag value that can be added to a gunichar value of a valid Unicode character, to produce a PangoGlyph value, representing an unknown-character glyph for the respective gunichar.

PANGO_GET_UNKNOWN_GLYPH()

#define PANGO_GET_UNKNOWN_GLYPH(wc) ((PangoGlyph)(wc)|PANGO_GLYPH_UNKNOWN_FLAG)

Returns a PangoGlyph value that means no glyph was found for wc. The way this unknown glyphs are rendered is backend specific. For example, a box with the hexadecimal Unicode code-point of the character written in it is what is done in the most common backends.

PangoGlyphInfo

typedef struct {
  PangoGlyph    glyph;
  PangoGlyphGeometry geometry;
  PangoGlyphVisAttr  attr;
} PangoGlyphInfo;

The PangoGlyphInfo structure represents a single glyph together with positioning information and visual attributes. It contains the following fields.

PangoGlyphGeometry

typedef struct {
  PangoGlyphUnit width;
  PangoGlyphUnit x_offset;
  PangoGlyphUnit y_offset;
} PangoGlyphGeometry;

The PangoGlyphGeometry structure contains width and positioning information for a single glyph.

PangoGlyphUnit

typedef gint32 PangoGlyphUnit;

The PangoGlyphUnit type is used to store dimensions within Pango. Dimensions are stored in 1/PANGO_SCALE of a device unit. (A device unit might be a pixel for screen display, or a point on a printer.) PANGO_SCALE is currently 1024, and may change in the future (unlikely though), but you should not depend on its exact value. The PANGO_PIXELS() macro can be used to convert from glyph units into device units with correct rounding.

PangoGlyphVisAttr

typedef struct {
  guint is_cluster_start : 1;
} PangoGlyphVisAttr;

The PangoGlyphVisAttr is used to communicate information between the shaping phase and the rendering phase. More attributes may be added in the future.

PangoGlyphString

typedef struct {
  gint num_glyphs;

  PangoGlyphInfo *glyphs;

  /* This is a memory inefficient way of representing the information
   * here - each value gives the byte index within the text
   * corresponding to the glyph string of the start of the cluster to
   * which the glyph belongs.
   */
  gint *log_clusters;
} PangoGlyphString;

The PangoGlyphString structure is used to store strings of glyphs with geometry and visual attribute information. The storage for the glyph information is owned by the structure which simplifies memory management.

PangoGlyphItem

typedef struct {
  PangoItem        *item;
  PangoGlyphString *glyphs;
} PangoGlyphItem;

A PangoGlyphItem is a pair of a PangoItem and the glyphs resulting from shaping the text corresponding to an item. As an example of the usage of PangoGlyphItem, the results of shaping text with PangoLayout is a list of PangoLayoutLine, each of which contains a list of PangoGlyphItem.

PANGO_TYPE_GLYPH_STRING

#define PANGO_TYPE_GLYPH_STRING (pango_glyph_string_get_type ())

The GObject type for PangoGlyphString.

pango_glyph_string_new ()

PangoGlyphString* pango_glyph_string_new    (void);

Create a new PangoGlyphString.

pango_glyph_string_copy ()

PangoGlyphString* pango_glyph_string_copy   (PangoGlyphString *string);

Copy a glyph string and associated storage.

pango_glyph_string_set_size ()

void        pango_glyph_string_set_size     (PangoGlyphString *string,
                                             gint new_len);

Resize a glyph string to the given length.

pango_glyph_string_free ()

void        pango_glyph_string_free         (PangoGlyphString *string);

Free a glyph string and associated storage.

pango_glyph_string_extents ()

void        pango_glyph_string_extents      (PangoGlyphString *glyphs,
                                             PangoFont *font,
                                             PangoRectangle *ink_rect,
                                             PangoRectangle *logical_rect);

Compute the logical and ink extents of a glyph string. See the documentation for pango_font_get_glyph_extents() for details about the interpretation of the rectangles.

pango_glyph_string_extents_range ()

void        pango_glyph_string_extents_range
                                            (PangoGlyphString *glyphs,
                                             int start,
                                             int end,
                                             PangoFont *font,
                                             PangoRectangle *ink_rect,
                                             PangoRectangle *logical_rect);

Computes the extents of a sub-portion of a glyph string. The extents are relative to the start of the glyph string range (the origin of their coordinate system is at the start of the range, not at the start of the entire glyph string).

pango_glyph_string_get_width ()

int         pango_glyph_string_get_width    (PangoGlyphString *glyphs);

Computes the logical width of the glyph string as can also be computed using pango_glyph_string_extents(). However, since this only computes the width, it's much faster. This is in fact only a convenience function that computes the sum of geometry.width for each glyph in the glyphs.

Since 1.14

pango_glyph_string_index_to_x ()

void        pango_glyph_string_index_to_x   (PangoGlyphString *glyphs,
                                             char *text,
                                             int length,
                                             PangoAnalysis *analysis,
                                             int index_,
                                             gboolean trailing,
                                             int *x_pos);

Converts from character position to x position. (X position is measured from the left edge of the run). Character positions are computed by dividing up each cluster into equal portions.

pango_glyph_string_x_to_index ()

void        pango_glyph_string_x_to_index   (PangoGlyphString *glyphs,
                                             char *text,
                                             int length,
                                             PangoAnalysis *analysis,
                                             int x_pos,
                                             int *index_,
                                             int *trailing);

Convert from x offset to character position. Character positions are computed by dividing up each cluster into equal portions. In scripts where positioning within a cluster is not allowed (such as Thai), the returned value may not be a valid cursor position; the caller must combine the result with the logical attributes for the text to compute the valid cursor position.

pango_glyph_string_get_logical_widths ()

void        pango_glyph_string_get_logical_widths
                                            (PangoGlyphString *glyphs,
                                             const char *text,
                                             int length,
                                             int embedding_level,
                                             int *logical_widths);

Given a PangoGlyphString resulting from pango_shape() and the corresponding text, determine the screen width corresponding to each character. When multiple characters compose a single cluster, the width of the entire cluster is divided equally among the characters.

pango_glyph_item_split ()

PangoGlyphItem* pango_glyph_item_split      (PangoGlyphItem *orig,
                                             const char *text,
                                             int split_index);

Modifies orig to cover only the text after split_index, and returns a new item that covers the text before split_index that used to be in orig. You can think of split_index as the length of the returned item. split_index may not be 0, and it may not be greater than or equal to the length of orig (that is, there must be at least one byte assigned to each item, you can't create a zero-length item).

This function is similar in function to pango_item_split() (and uses it internally.)

Since 1.2

pango_glyph_item_apply_attrs ()

GSList*     pango_glyph_item_apply_attrs    (PangoGlyphItem *glyph_item,
                                             const char *text,
                                             PangoAttrList *list);

Splits a shaped item (PangoGlyphItem) into multiple items based on an attribute list. The idea is that if you have attributes that don't affect shaping, such as color or underline, to avoid affecting shaping, you filter them out (pango_attr_list_filter()), apply the shaping process and then reapply them to the result using this function.

All attributes that start or end inside a cluster are applied to that cluster; for instance, if half of a cluster is underlined and the other-half strikethrough, then the cluster will end up with both underline and strikethrough attributes. In these cases, it may happen that item->extra_attrs for some of the result items can have multiple attributes of the same type.

This function takes ownership of glyph_item; it will be reused as one of the elements in the list.

Since 1.2

pango_glyph_item_letter_space ()

void        pango_glyph_item_letter_space   (PangoGlyphItem *glyph_item,
                                             const char *text,
                                             PangoLogAttr *log_attrs,
                                             int letter_spacing);

Adds spacing between the graphemes of glyph_item to give the effect of typographic letter spacing.

Since 1.6

pango_glyph_item_free ()

void        pango_glyph_item_free           (PangoGlyphItem *glyph_item);

Frees a PangoGlyphItem and memory to which it points.

Since 1.6