Xft Fonts and Rendering: Pango Reference Manual

## Xft Fonts and Rendering Xft Fonts and Rendering — Font handling and rendering with the Xft backend |

## Functions

PangoContext * | pango_xft_get_context ()
PangoFontMap * | pango_xft_get_font_map ()
void | pango_xft_set_default_substitute ()
void | (*PangoXftSubstituteFunc) ()
void | pango_xft_substitute_changed ()
void | pango_xft_shutdown_display ()
XftFont * | pango_xft_font_get_font ()
Display * | pango_xft_font_get_display ()
gboolean | pango_xft_font_has_char ()
FT_Face | pango_xft_font_lock_face ()
void | pango_xft_font_unlock_face ()
guint | pango_xft_font_get_glyph ()
PangoGlyph | pango_xft_font_get_unknown_glyph ()
PangoRenderer * | pango_xft_renderer_new ()
void | pango_xft_renderer_set_draw ()
void | pango_xft_renderer_set_default_color ()
void | pango_xft_render ()
void | pango_xft_picture_render ()
void | pango_xft_render_transformed ()
void | pango_xft_render_layout_line ()
void | pango_xft_render_layout ()

## Properties

gpointer | display | Write / Construct Only
gint | screen | Write / Construct Only

## Types and Values

| PangoXftFont
| PangoXftFontMap
#define | PANGO_RENDER_TYPE_XFT
struct | PangoXftRenderer
struct | PangoXftRendererClass

## Object Hierarchy

        GObject
        ├── PangoFont
        │   ╰── PangoFcFont
        │       ╰── PangoXftFont
        ├── PangoFontMap
        │   ╰── PangoFcFontMap
        │       ╰── PangoXftFontMap
        ╰── PangoRenderer
            ╰── PangoXftRenderer

## Description

The Xft library is a library for displaying fonts on the X window system; internally it uses the fontconfig library to locate font files, and the FreeType library to load and render fonts. The Xft backend is the recommended Pango font backend for screen display with X. (The Cairo back end is another possibility.)

Using the Xft backend is generally straightforward; `pango_xft_get_context()` creates a context for a specified display and screen. You can then create a PangoLayout with that context and render it with `pango_xft_render_layout()`. At a more advanced level, the low-level fontconfig options used for rendering fonts can be affected using `pango_xft_set_default_substitute()`, and `pango_xft_substitute_changed()`.

A range of functions for drawing pieces of a layout, such as individual layout lines and glyphs strings are provided. You can also directly create a PangoXftRenderer. Finally, in some advanced cases, it is useful to derive from PangoXftRenderer. Deriving from PangoXftRenderer is useful for two reasons. One reason is be to support custom attributes by overriding PangoRendererClass virtual functions like 'prepare_run' or 'draw_shape'. The reason is to customize exactly how the final bits are drawn to the destination by overriding the PangoXftRendererClass virtual functions 'composite_glyphs' and 'composite_trapezoids'.

## Functions

### pango_xft_get_context ()

    PangoContext *
    pango_xft_get_context (Display *display,
                           int screen);

`pango_xft_get_context` has been deprecated since version 1.22 and should not be used in newly-written code.

Use `pango_xft_get_font_map()` followed by `pango_font_map_create_context()` instead.

Retrieves a PangoContext appropriate for rendering with Xft fonts on the given screen of the given display.

[skip]

#### Parameters

display | an X display. |
screen | an X screen. |

#### Returns

the new PangoContext.

### pango_xft_get_font_map ()

    PangoFontMap *
    pango_xft_get_font_map (Display *display,
                            int screen);

Returns the PangoXftFontMap for the given display and screen. The fontmap is owned by Pango and will be valid until the display is closed.

#### Parameters

display | an X display |
screen | the screen number of a screen within `display` |

#### Returns

a PangoFontMap object, owned by Pango.

[transfer none]

Since: 1.2

### pango_xft_set_default_substitute ()

    void
    pango_xft_set_default_substitute (Display *display,
                                      int screen,
                                      PangoXftSubstituteFunc func,
                                      gpointer data,
                                      GDestroyNotify notify);

Sets a function that will be called to do final configuration substitution on a FcPattern before it is used to load the font. This function can be used to do things like set hinting and antialiasing options.

#### Parameters

display | an X Display |
screen | the screen number of a screen within `display` |
func | function to call to to do final config tweaking on FcPattern objects. |
data | data to pass to `func` |
notify | function to call when `data` is no longer used. |

Since: 1.2

### PangoXftSubstituteFunc ()

    void
    (*PangoXftSubstituteFunc) (FcPattern *pattern,
                               gpointer data);

Function type for doing final config tweaking on prepared FcPatterns.

#### Parameters

pattern | the FcPattern to tweak. |
data | user data. |

### pango_xft_substitute_changed ()

    void
    pango_xft_substitute_changed (Display *display,
                                  int screen);

Call this function any time the results of the default substitution function set with `pango_xft_set_default_substitute()` change. That is, if your substitution function will return different results for the same input pattern, you must call this function.

#### Parameters

display | an X Display |
screen | the screen number of a screen within `display` |

Since: 1.2

### pango_xft_shutdown_display ()

    void
    pango_xft_shutdown_display (Display *display,
                                int screen);

Release any resources that have been cached for the combination of `display` and `screen` . Note that when the X display is closed, resources are released automatically, without needing to call this function.

#### Parameters

display | an X display |
screen | the screen number of a screen within `display` |

Since: 1.2

### pango_xft_font_get_font ()

    XftFont *
    pango_xft_font_get_font (PangoFont *font);

Returns the XftFont of a font.

#### Parameters

font | a PangoFont. | [nullable]

#### Returns

the XftFont associated to `font` , or `NULL` if `font` is `NULL`.

[nullable]

### pango_xft_font_get_display ()

    Display *
    pango_xft_font_get_display (PangoFont *font);

Returns the X display of the XftFont of a font.

#### Parameters

font | a PangoFont. |

#### Returns

the X display of the XftFont associated to `font` .

### pango_xft_font_has_char ()

    gboolean
    pango_xft_font_has_char (PangoFont *font,
                             gunichar wc);

`pango_xft_font_has_char` is deprecated and should not be used in newly-written code.

Determines whether `font` has a glyph for the codepoint `wc` .

Use `pango_fc_font_has_char()` instead.

#### Parameters

font | a PangoFont for the Xft backend |
wc | Unicode codepoint to look up |

#### Returns

`TRUE` if `font` has the requested codepoint.

Since: 1.2

### pango_xft_font_lock_face ()

    FT_Face
    pango_xft_font_lock_face (PangoFont *font);

`pango_xft_font_lock_face` is deprecated and should not be used in newly-written code.

Gets the FreeType FT_Face associated with a font, This face will be kept around until you call `pango_xft_font_unlock_face()`.

Use `pango_fc_font_lock_face()` instead.

#### Parameters

font | a PangoFont. |

#### Returns

the FreeType FT_Face associated with `font` .

Since: 1.2

### pango_xft_font_unlock_face ()

    void
    pango_xft_font_unlock_face (PangoFont *font);

`pango_xft_font_unlock_face` is deprecated and should not be used in newly-written code.

Releases a font previously obtained with `pango_xft_font_lock_face()`.

Use `pango_fc_font_unlock_face()` instead.

#### Parameters

font | a PangoFont. |

Since: 1.2

### pango_xft_font_get_glyph ()

    guint
    pango_xft_font_get_glyph (PangoFont *font,
                              gunichar wc);

`pango_xft_font_get_glyph` is deprecated and should not be used in newly-written code.

Gets the glyph index for a given Unicode character for `font` . If you only want to determine whether the font has the glyph, use `pango_xft_font_has_char()`.

Use `pango_fc_font_get_glyph()` instead.

#### Parameters

font | a PangoFont for the Xft backend |
wc | Unicode codepoint to look up |

#### Returns

the glyph index, or 0, if the Unicode character does not exist in the font.

Since: 1.2

### pango_xft_font_get_unknown_glyph ()

    PangoGlyph
    pango_xft_font_get_unknown_glyph (PangoFont *font,
                                      gunichar wc);

`pango_xft_font_get_unknown_glyph` is deprecated and should not be used in newly-written code.

Returns the index of a glyph suitable for drawing `wc` as an unknown character.

Use `PANGO_GET_UNKNOWN_GLYPH()` instead.

#### Parameters

font | a PangoFont. |
wc | the Unicode character for which a glyph is needed. |

#### Returns

a glyph index into `font` .

### pango_xft_renderer_new ()

    PangoRenderer *
    pango_xft_renderer_new (Display *display,
                            int screen);

Create a new PangoXftRenderer to allow rendering Pango objects with the Xft library. You must call `pango_xft_renderer_set_draw()` before using the renderer.

#### Parameters

display | an X display |
screen | the index of the screen for `display` to which rendering will be done |

#### Returns

the newly created PangoXftRenderer, which should be freed with `g_object_unref()`.

Since: 1.8

### pango_xft_renderer_set_draw ()

    void
    pango_xft_renderer_set_draw (PangoXftRenderer *xftrenderer,
                                 XftDraw *draw);

Sets the XftDraw object that the renderer is drawing to. The renderer must not be currently active.

#### Parameters

xftrenderer | a PangoXftRenderer |
draw | a XftDraw |

Since: 1.8

### pango_xft_renderer_set_default_color ()

    void
    pango_xft_renderer_set_default_color (PangoXftRenderer *xftrenderer,
                                          PangoColor *default_color);

Sets the default foreground color for a XftRenderer.

#### Parameters

xftrenderer | a XftRenderer |
default_color | the default foreground color |

Since: 1.8

### pango_xft_render ()

    void
    pango_xft_render (XftDraw *draw,
                      XftColor *color,
                      PangoFont *font,
                      PangoGlyphString *glyphs,
                      gint x,
                      gint y);

Renders a PangoGlyphString onto an XftDraw object wrapping an X drawable.

#### Parameters

draw | the XftDraw object. |
color | the color in which to draw the string |
font | the font in which to draw the string |
glyphs | the glyph string to draw |
x | the x position of start of string (in pixels) |
y | the y position of baseline (in pixels) |

### pango_xft_picture_render ()

    void
    pango_xft_picture_render (Display *display,
                              Picture src_picture,
                              Picture dest_picture,
                              PangoFont *font,
                              PangoGlyphString *glyphs,
                              gint x,
                              gint y);

Renders a PangoGlyphString onto an Xrender Picture object.

#### Parameters

display | an X display |
src_picture | the source picture to draw the string with |
dest_picture | the destination picture to draw the string onto |
font | the font in which to draw the string |
glyphs | the glyph string to draw |
x | the x position of start of string (in pixels) |
y | the y position of baseline (in pixels) |

### pango_xft_render_transformed ()

    void
    pango_xft_render_transformed (XftDraw *draw,
                                  XftColor *color,
                                  PangoMatrix *matrix,
                                  PangoFont *font,
                                  PangoGlyphString *glyphs,
                                  int x,
                                  int y);

Renders a PangoGlyphString onto a XftDraw, possibly transforming the layed-out coordinates through a transformation matrix. Note that the transformation matrix for `font` is not changed, so to produce correct rendering results, the `font` must have been loaded using a PangoContext with an identical transformation matrix to that passed in to this function.

#### Parameters

draw | an XftDraw |
color | the color in which to draw the glyphs |
font | the font in which to draw the string |
matrix | a PangoMatrix, or `NULL` to use an identity transformation. | [nullable]
glyphs | the glyph string to draw |
x | the x position of the start of the string (in Pango units in user space coordinates) |
y | the y position of the baseline (in Pango units in user space coordinates) |

Since: 1.8

### pango_xft_render_layout_line ()

    void
    pango_xft_render_layout_line (XftDraw *draw,
                                  XftColor *color,
                                  PangoLayoutLine *line,
                                  int x,
                                  int y);

Render a PangoLayoutLine onto a XftDraw

#### Parameters

draw | an XftDraw |
color | the foreground color in which to draw the layout line (may be overridden by color attributes) |
line | a PangoLayoutLine |
x | the x position of start of string (in Pango units) |
y | the y position of baseline (in Pango units) |

Since: 1.8

### pango_xft_render_layout ()

    void
    pango_xft_render_layout (XftDraw *draw,
                             XftColor *color,
                             PangoLayout *layout,
                             int x,
                             int y);

Render a PangoLayout onto a XftDraw

#### Parameters

draw | an XftDraw |
color | the foreground color in which to draw the layout (may be overridden by color attributes) |
layout | a PangoLayout |
x | the X position of the left of the layout (in Pango units) |
y | the Y position of the top of the layout (in Pango units) |

Since: 1.8

## Types and Values

### PangoXftFont

    typedef struct _PangoXftFont PangoXftFont;

PangoXftFont is an implementation of PangoFcFont using the Xft library for rendering. It is used in conjunction with PangoXftFontMap.

### PangoXftFontMap

    typedef struct _PangoXftFontMap PangoXftFontMap;

PangoXftFontMap is an implementation of PangoFcFontMap suitable for the Xft library as the renderer. It is used in to create fonts of type PangoXftFont.

### PANGO_RENDER_TYPE_XFT

    #define PANGO_RENDER_TYPE_XFT "PangoRenderXft"

`PANGO_RENDER_TYPE_XFT` is deprecated and should not be used in newly-written code.

A string constant that was used to identify shape engines that work with the Xft backend. See `PANGO_RENDER_TYPE_FC` for the replacement.

### struct PangoXftRenderer

    struct PangoXftRenderer;

PangoXftRenderer is a subclass of PangoRenderer used for rendering with Pango's Xft backend. It can be used directly, or it can be further subclassed to modify exactly how drawing of individual elements occurs.

Since: 1.8

### struct PangoXftRendererClass

    struct PangoXftRendererClass {
      void (*composite_trapezoids) (PangoXftRenderer *xftrenderer,
    				PangoRenderPart   part,
    				XTrapezoid       *trapezoids,
    				int               n_trapezoids);
      void (*composite_glyphs)     (PangoXftRenderer *xftrenderer,
    				XftFont          *xft_font,
    				XftGlyphSpec     *glyphs,
    				int               n_glyphs);
    };

The class structure for PangoXftRenderer

#### Members

`composite_trapezoids` () | draw the specified trapezoids using the current color and other attributes for `part` |
`composite_glyphs` () | draw the specified glyphs using the current foreground color and other foreground attributes |

Since: 1.8

## Property Details

### The `“display”` property

      “display”                  gpointer

The display being rendered to.

Flags: Write / Construct Only

### The `“screen”` property

      “screen”                   gint

The screen being rendered to.

Flags: Write / Construct Only

Allowed values: >= 0

Default value: 0