PangoRenderer

PangoRenderer — Rendering driver base class

Types and Values

Object Hierarchy

    GEnum
    ╰── PangoRenderPart
    GObject
    ╰── PangoRenderer
        ╰── PangoXftRenderer

Description

PangoRenderer is a base class that contains the necessary logic for rendering a PangoLayout or PangoLayoutLine. By subclassing PangoRenderer and overriding operations such as draw_glyphs and draw_rectangle , renderers for particular font backends and destinations can be created.

Functions

pango_renderer_draw_layout ()

void
pango_renderer_draw_layout (PangoRenderer *renderer,
                            PangoLayout *layout,
                            int x,
                            int y);

Draws layout with the specified PangoRenderer.

Parameters

renderer

a PangoRenderer

 

layout

a PangoLayout

 

x

X position of left edge of baseline, in user space coordinates in Pango units.

 

y

Y position of left edge of baseline, in user space coordinates in Pango units.

 

Since: 1.8


pango_renderer_draw_layout_line ()

void
pango_renderer_draw_layout_line (PangoRenderer *renderer,
                                 PangoLayoutLine *line,
                                 int x,
                                 int y);

Draws line with the specified PangoRenderer.

Parameters

renderer

a PangoRenderer

 

line

a PangoLayoutLine

 

x

X position of left edge of baseline, in user space coordinates in Pango units.

 

y

Y position of left edge of baseline, in user space coordinates in Pango units.

 

Since: 1.8


pango_renderer_draw_glyphs ()

void
pango_renderer_draw_glyphs (PangoRenderer *renderer,
                            PangoFont *font,
                            PangoGlyphString *glyphs,
                            int x,
                            int y);

Draws the glyphs in glyphs with the specified PangoRenderer.

Parameters

renderer

a PangoRenderer

 

font

a PangoFont

 

glyphs

a PangoGlyphString

 

x

X position of left edge of baseline, in user space coordinates in Pango units.

 

y

Y position of left edge of baseline, in user space coordinates in Pango units.

 

Since: 1.8


pango_renderer_draw_glyph_item ()

void
pango_renderer_draw_glyph_item (PangoRenderer *renderer,
                                const char *text,
                                PangoGlyphItem *glyph_item,
                                int x,
                                int y);

Draws the glyphs in glyph_item with the specified PangoRenderer, embedding the text associated with the glyphs in the output if the output format supports it (PDF for example).

Note that text is the start of the text for layout, which is then indexed by glyph_item->item->offset .

If text is NULL, this simply calls pango_renderer_draw_glyphs().

The default implementation of this method simply falls back to pango_renderer_draw_glyphs().

Parameters

renderer

a PangoRenderer

 

text

the UTF-8 text that glyph_item refers to, or NULL.

[allow-none]

glyph_item

a PangoGlyphItem

 

x

X position of left edge of baseline, in user space coordinates in Pango units.

 

y

Y position of left edge of baseline, in user space coordinates in Pango units.

 

Since: 1.22


pango_renderer_draw_rectangle ()

void
pango_renderer_draw_rectangle (PangoRenderer *renderer,
                               PangoRenderPart part,
                               int x,
                               int y,
                               int width,
                               int height);

Draws an axis-aligned rectangle in user space coordinates with the specified PangoRenderer.

This should be called while renderer is already active. Use pango_renderer_activate() to activate a renderer.

Parameters

renderer

a PangoRenderer

 

part

type of object this rectangle is part of

 

x

X position at which to draw rectangle, in user space coordinates in Pango units

 

y

Y position at which to draw rectangle, in user space coordinates in Pango units

 

width

width of rectangle in Pango units in user space coordinates

 

height

height of rectangle in Pango units in user space coordinates

 

Since: 1.8


pango_renderer_draw_error_underline ()

void
pango_renderer_draw_error_underline (PangoRenderer *renderer,
                                     int x,
                                     int y,
                                     int width,
                                     int height);

Draw a squiggly line that approximately covers the given rectangle in the style of an underline used to indicate a spelling error. (The width of the underline is rounded to an integer number of up/down segments and the resulting rectangle is centered in the original rectangle)

This should be called while renderer is already active. Use pango_renderer_activate() to activate a renderer.

Parameters

renderer

a PangoRenderer

 

x

X coordinate of underline, in Pango units in user coordinate system

 

y

Y coordinate of underline, in Pango units in user coordinate system

 

width

width of underline, in Pango units in user coordinate system

 

height

height of underline, in Pango units in user coordinate system

 

Since: 1.8


pango_renderer_draw_trapezoid ()

void
pango_renderer_draw_trapezoid (PangoRenderer *renderer,
                               PangoRenderPart part,
                               double y1_,
                               double x11,
                               double x21,
                               double y2,
                               double x12,
                               double x22);

Draws a trapezoid with the parallel sides aligned with the X axis using the given PangoRenderer; coordinates are in device space.

Parameters

renderer

a PangoRenderer

 

part

type of object this trapezoid is part of

 

y1_

Y coordinate of top of trapezoid

 

x11

X coordinate of left end of top of trapezoid

 

x21

X coordinate of right end of top of trapezoid

 

y2

Y coordinate of bottom of trapezoid

 

x12

X coordinate of left end of bottom of trapezoid

 

x22

X coordinate of right end of bottom of trapezoid

 

Since: 1.8


pango_renderer_draw_glyph ()

void
pango_renderer_draw_glyph (PangoRenderer *renderer,
                           PangoFont *font,
                           PangoGlyph glyph,
                           double x,
                           double y);

Draws a single glyph with coordinates in device space.

Parameters

renderer

a PangoRenderer

 

font

a PangoFont

 

glyph

the glyph index of a single glyph

 

x

X coordinate of left edge of baseline of glyph

 

y

Y coordinate of left edge of baseline of glyph

 

Since: 1.8


pango_renderer_activate ()

void
pango_renderer_activate (PangoRenderer *renderer);

Does initial setup before rendering operations on renderer . pango_renderer_deactivate() should be called when done drawing. Calls such as pango_renderer_draw_layout() automatically activate the layout before drawing on it. Calls to pango_renderer_activate() and pango_renderer_deactivate() can be nested and the renderer will only be initialized and deinitialized once.

Parameters

renderer

a PangoRenderer

 

Since: 1.8


pango_renderer_deactivate ()

void
pango_renderer_deactivate (PangoRenderer *renderer);

Cleans up after rendering operations on renderer . See docs for pango_renderer_activate().

Parameters

renderer

a PangoRenderer

 

Since: 1.8


pango_renderer_part_changed ()

void
pango_renderer_part_changed (PangoRenderer *renderer,
                             PangoRenderPart part);

Informs Pango that the way that the rendering is done for part has changed in a way that would prevent multiple pieces being joined together into one drawing call. For instance, if a subclass of PangoRenderer was to add a stipple option for drawing underlines, it needs to call

When the stipple changes or underlines with different stipples might be joined together. Pango automatically calls this for changes to colors. (See pango_renderer_set_color())

Parameters

renderer

a PangoRenderer

 

part

the part for which rendering has changed.

 

Since: 1.8


pango_renderer_set_color ()

void
pango_renderer_set_color (PangoRenderer *renderer,
                          PangoRenderPart part,
                          const PangoColor *color);

Sets the color for part of the rendering. Also see pango_renderer_set_alpha().

Parameters

renderer

a PangoRenderer

 

part

the part to change the color of

 

color

the new color or NULL to unset the current color.

[allow-none]

Since: 1.8


pango_renderer_get_color ()

PangoColor *
pango_renderer_get_color (PangoRenderer *renderer,
                          PangoRenderPart part);

Gets the current rendering color for the specified part.

Parameters

renderer

a PangoRenderer

 

part

the part to get the color for

 

Returns

the color for the specified part, or NULL if it hasn't been set and should be inherited from the environment.

[transfer none][nullable]

Since: 1.8


pango_renderer_set_alpha ()

void
pango_renderer_set_alpha (PangoRenderer *renderer,
                          PangoRenderPart part,
                          guint16 alpha);

Sets the alpha for part of the rendering. Note that the alpha may only be used if a color is specified for part as well.

Parameters

renderer

a PangoRenderer

 

part

the part to set the alpha for

 

alpha

an alpha value between 1 and 65536, or 0 to unset the alpha

 

Since: 1.38


pango_renderer_get_alpha ()

guint16
pango_renderer_get_alpha (PangoRenderer *renderer,
                          PangoRenderPart part);

Gets the current alpha for the specified part.

Parameters

renderer

a PangoRenderer

 

part

the part to get the alpha for

 

Returns

the alpha for the specified part, or 0 if it hasn't been set and should be inherited from the environment.

Since: 1.38


pango_renderer_set_matrix ()

void
pango_renderer_set_matrix (PangoRenderer *renderer,
                           const PangoMatrix *matrix);

Sets the transformation matrix that will be applied when rendering.

Parameters

renderer

a PangoRenderer

 

matrix

a PangoMatrix, or NULL to unset any existing matrix. (No matrix set is the same as setting the identity matrix.).

[allow-none]

Since: 1.8


pango_renderer_get_matrix ()

const PangoMatrix *
pango_renderer_get_matrix (PangoRenderer *renderer);

Gets the transformation matrix that will be applied when rendering. See pango_renderer_set_matrix().

Parameters

renderer

a PangoRenderer

 

Returns

the matrix, or NULL if no matrix has been set (which is the same as the identity matrix). The returned matrix is owned by Pango and must not be modified or freed.

[nullable]

Since: 1.8


pango_renderer_get_layout ()

PangoLayout *
pango_renderer_get_layout (PangoRenderer *renderer);

Gets the layout currently being rendered using renderer . Calling this function only makes sense from inside a subclass's methods, like in its draw_shape vfunc, for example.

The returned layout should not be modified while still being rendered.

Parameters

renderer

a PangoRenderer

 

Returns

the layout, or NULL if no layout is being rendered using renderer at this time.

[transfer none][nullable]

Since: 1.20


pango_renderer_get_layout_line ()

PangoLayoutLine *
pango_renderer_get_layout_line (PangoRenderer *renderer);

Gets the layout line currently being rendered using renderer . Calling this function only makes sense from inside a subclass's methods, like in its draw_shape vfunc, for example.

The returned layout line should not be modified while still being rendered.

Parameters

renderer

a PangoRenderer

 

Returns

the layout line, or NULL if no layout line is being rendered using renderer at this time.

[transfer none][nullable]

Since: 1.20

Types and Values

struct PangoRenderer

struct PangoRenderer {
  PangoMatrix *matrix;          /* May be NULL */
};

PangoRenderer is a base class for objects that are used to render Pango objects such as PangoGlyphString and PangoLayout.

Members

PangoMatrix *matrix;

the current transformation matrix for the Renderer; may be NULL, which should be treated the same as the identity matrix.

[nullable]

Since: 1.8


enum PangoRenderPart

PangoRenderPart defines different items to render for such purposes as setting colors.

Members

PANGO_RENDER_PART_FOREGROUND

the text itself

 

PANGO_RENDER_PART_BACKGROUND

the area behind the text

 

PANGO_RENDER_PART_UNDERLINE

underlines

 

PANGO_RENDER_PART_STRIKETHROUGH

strikethrough lines

 

Since: 1.8


PANGO_TYPE_RENDER_PART

#define PANGO_TYPE_RENDER_PART (pango_render_part_get_type ())

struct PangoRendererClass

struct PangoRendererClass {
  void (*draw_glyphs)          (PangoRenderer    *renderer,
                                PangoFont        *font,
                                PangoGlyphString *glyphs,
                                int               x,
                                int               y);
  void (*draw_rectangle)       (PangoRenderer    *renderer,
                                PangoRenderPart   part,
                                int               x,
                                int               y,
                                int               width,
                                int               height);
  void (*draw_error_underline) (PangoRenderer    *renderer,
                                int               x,
                                int               y,
                                int               width,
                                int               height);
  void (*draw_shape)           (PangoRenderer    *renderer,
                                PangoAttrShape   *attr,
                                int               x,
                                int               y);

  void (*draw_trapezoid)       (PangoRenderer    *renderer,
                                PangoRenderPart   part,
                                double            y1_,
                                double            x11,
                                double            x21,
                                double            y2,
                                double            x12,
                                double            x22);
  void (*draw_glyph)           (PangoRenderer    *renderer,
                                PangoFont        *font,
                                PangoGlyph        glyph,
                                double            x,
                                double            y);

  void (*part_changed)         (PangoRenderer    *renderer,
                                PangoRenderPart   part);

  void (*begin)                (PangoRenderer    *renderer);
  void (*end)                  (PangoRenderer    *renderer);

  void (*prepare_run)          (PangoRenderer    *renderer,
                                PangoLayoutRun   *run);

  void (*draw_glyph_item)      (PangoRenderer    *renderer,
                                const char       *text,
                                PangoGlyphItem   *glyph_item,
                                int               x,
                                int               y);
};

Class structure for PangoRenderer.

The following vfuncs take user space coordinates in Pango units and have default implementations:

  • draw_glyphs

  • draw_rectangle

  • draw_error_underline

  • draw_shape

  • draw_glyph_item

The default draw_shape implementation draws nothing.

The following vfuncs take device space coordinates as doubles and must be implemented:

  • draw_trapezoid

  • draw_glyph

Members

draw_glyphs ()

draws a PangoGlyphString

 

draw_rectangle ()

draws a rectangle

 

draw_error_underline ()

draws a squiggly line that approximately covers the given rectangle in the style of an underline used to indicate a spelling error.

 

draw_shape ()

draw content for a glyph shaped with PangoAttrShape. x , y are the coordinates of the left edge of the baseline, in user coordinates.

 

draw_trapezoid ()

draws a trapezoidal filled area

 

draw_glyph ()

draws a single glyph

 

part_changed ()

do renderer specific processing when rendering attributes change

 

begin ()

Do renderer-specific initialization before drawing

 

end ()

Do renderer-specific cleanup after drawing

 

prepare_run ()

updates the renderer for a new run

 

draw_glyph_item ()

draws a PangoGlyphItem

 

Since: 1.8