PangoRenderer

PangoRenderer — Rendering driver base class

Synopsis

                    PangoRenderer;
enum                PangoRenderPart;
#define             PANGO_TYPE_RENDER_PART
                    PangoRendererClass;
void                pango_renderer_draw_layout          (PangoRenderer *renderer,
                                                         PangoLayout *layout,
                                                         int x,
                                                         int y);
void                pango_renderer_draw_layout_line     (PangoRenderer *renderer,
                                                         PangoLayoutLine *line,
                                                         int x,
                                                         int y);
void                pango_renderer_draw_glyphs          (PangoRenderer *renderer,
                                                         PangoFont *font,
                                                         PangoGlyphString *glyphs,
                                                         int x,
                                                         int y);
void                pango_renderer_draw_glyph_item      (PangoRenderer *renderer,
                                                         const char *text,
                                                         PangoGlyphItem *glyph_item,
                                                         int x,
                                                         int y);
void                pango_renderer_draw_rectangle       (PangoRenderer *renderer,
                                                         PangoRenderPart part,
                                                         int x,
                                                         int y,
                                                         int width,
                                                         int height);
void                pango_renderer_draw_error_underline (PangoRenderer *renderer,
                                                         int x,
                                                         int y,
                                                         int width,
                                                         int height);
void                pango_renderer_draw_trapezoid       (PangoRenderer *renderer,
                                                         PangoRenderPart part,
                                                         double y1_,
                                                         double x11,
                                                         double x21,
                                                         double y2,
                                                         double x12,
                                                         double x22);
void                pango_renderer_draw_glyph           (PangoRenderer *renderer,
                                                         PangoFont *font,
                                                         PangoGlyph glyph,
                                                         double x,
                                                         double y);
void                pango_renderer_activate             (PangoRenderer *renderer);
void                pango_renderer_deactivate           (PangoRenderer *renderer);
void                pango_renderer_part_changed         (PangoRenderer *renderer,
                                                         PangoRenderPart part);
void                pango_renderer_set_color            (PangoRenderer *renderer,
                                                         PangoRenderPart part,
                                                         const PangoColor *color);
PangoColor *        pango_renderer_get_color            (PangoRenderer *renderer,
                                                         PangoRenderPart part);
void                pango_renderer_set_matrix           (PangoRenderer *renderer,
                                                         const PangoMatrix *matrix);
const PangoMatrix * pango_renderer_get_matrix           (PangoRenderer *renderer);
PangoLayout *       pango_renderer_get_layout           (PangoRenderer *renderer);
PangoLayoutLine *   pango_renderer_get_layout_line      (PangoRenderer *renderer);

Object Hierarchy

  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.

Details

PangoRenderer

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

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

PangoMatrix *matrix;

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

Since 1.8

enum PangoRenderPart

typedef enum
{
  PANGO_RENDER_PART_FOREGROUND,
  PANGO_RENDER_PART_BACKGROUND,
  PANGO_RENDER_PART_UNDERLINE,
  PANGO_RENDER_PART_STRIKETHROUGH
} PangoRenderPart;

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

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())

The GObject type for PangoRenderPart.

PangoRendererClass

typedef struct {
  /* All of the following have default implementations
   * and take as coordinates user coordinates in Pango units
   */
  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);

  /* Nothing is drawn for shaped glyphs unless this is implemented */
  void (*draw_shape) (PangoRenderer  *renderer,
		      PangoAttrShape *attr,
		      int             x,
		      int             y);

  /* These two must be implemented and take coordinates in
   * device space as doubles.
   */
  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);

  /* Notification of change in rendering attributes
   */
  void (*part_changed) (PangoRenderer   *renderer,
			PangoRenderPart  part);

  /* Paired around drawing operations
   */
  void (*begin) (PangoRenderer *renderer);
  void (*end)   (PangoRenderer *renderer);

  /* Hooks into the details of layout rendering
   */
  void (*prepare_run) (PangoRenderer  *renderer,
		       PangoLayoutRun *run);

  /* All of the following have default implementations
   * and take as coordinates user coordinates in Pango units
   */
  void (*draw_glyph_item) (PangoRenderer     *renderer,
			   const char        *text,
			   PangoGlyphItem    *glyph_item,
			   int                x,
			   int                y);
} PangoRendererClass;

Class structure for PangoRenderer.

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

pango_renderer_draw_layout ()

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

Draws layout with the specified PangoRenderer.

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.

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.

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().

renderer :

 a PangoRenderer

text :

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

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.

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.

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.

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.

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.

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().

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 

1
 
pango_renderer_part_changed (render, PANGO_RENDER_PART_UNDERLINE);

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())

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.

renderer :

 a PangoRenderer

part :

 the part to change the color of

color :

 the new color or NULL to unset the current color

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.

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.

Since 1.8

pango_renderer_set_matrix ()

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

Sets the transformation matrix that will be applied when rendering.

renderer :

 a PangoRenderer

matrix :

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

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().

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.

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() for example.

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

renderer :

 a PangoRenderer

Returns :

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

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() for example.

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

renderer :

 a PangoRenderer

Returns :

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

Since 1.20

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