Cairo Interaction

Cairo Interaction — Functions to support using Cairo

Synopsis

#include <gdk/gdk.h>

cairo_t *           gdk_cairo_create                    (GdkDrawable *drawable);
void                gdk_cairo_set_source_color          (cairo_t *cr,
                                                         const GdkColor *color);
void                gdk_cairo_set_source_pixbuf         (cairo_t *cr,
                                                         const GdkPixbuf *pixbuf,
                                                         double pixbuf_x,
                                                         double pixbuf_y);
void                gdk_cairo_set_source_pixmap         (cairo_t *cr,
                                                         GdkPixmap *pixmap,
                                                         double pixmap_x,
                                                         double pixmap_y);
void                gdk_cairo_rectangle                 (cairo_t *cr,
                                                         const GdkRectangle *rectangle);
void                gdk_cairo_region                    (cairo_t *cr,
                                                         const GdkRegion *region);
void                gdk_cairo_reset_clip                (cairo_t *cr,
                                                         GdkDrawable *drawable);

Description

Cairo is a graphics library that supports vector graphics and image compositing that can be used with GDK. Since 2.8, GTK+ does most of its drawing using Cairo.

GDK does not wrap the Cairo API, instead it allows to create Cairo contexts which can be used to draw on GDK drawables. Additional functions allow to convert GDK's rectangles and regions into Cairo paths and to use pixbufs as sources for drawing operations.

Details

gdk_cairo_create ()

cairo_t *           gdk_cairo_create                    (GdkDrawable *drawable);

Creates a Cairo context for drawing to drawable.

Note

Note that due to double-buffering, Cairo contexts created in a GTK+ expose event handler cannot be cached and reused between different expose events.

drawable :

 a GdkDrawable

Returns :

 A newly created Cairo context. Free with cairo_destroy() when you are done drawing.

Since 2.8

gdk_cairo_set_source_color ()

void                gdk_cairo_set_source_color          (cairo_t *cr,
                                                         const GdkColor *color);

Sets the specified GdkColor as the source color of cr.

cr :

 a cairo_t

color :

 a GdkColor

Since 2.8

gdk_cairo_set_source_pixbuf ()

void                gdk_cairo_set_source_pixbuf         (cairo_t *cr,
                                                         const GdkPixbuf *pixbuf,
                                                         double pixbuf_x,
                                                         double pixbuf_y);

Sets the given pixbuf as the source pattern for the Cairo context. The pattern has an extend mode of CAIRO_EXTEND_NONE and is aligned so that the origin of pixbuf is pixbuf_x, pixbuf_y

cr :

 a Cairo context

pixbuf :

 a GdkPixbuf

pixbuf_x :

 X coordinate of location to place upper left corner of pixbuf

pixbuf_y :

 Y coordinate of location to place upper left corner of pixbuf

Since 2.8

gdk_cairo_set_source_pixmap ()

void                gdk_cairo_set_source_pixmap         (cairo_t *cr,
                                                         GdkPixmap *pixmap,
                                                         double pixmap_x,
                                                         double pixmap_y);

Sets the given pixmap as the source pattern for the Cairo context. The pattern has an extend mode of CAIRO_EXTEND_NONE and is aligned so that the origin of pixmap is pixmap_x, pixmap_y

cr :

 a Cairo context

pixmap :

 a GdkPixmap

pixmap_x :

 X coordinate of location to place upper left corner of pixmap

pixmap_y :

 Y coordinate of location to place upper left corner of pixmap

Since 2.10

gdk_cairo_rectangle ()

void                gdk_cairo_rectangle                 (cairo_t *cr,
                                                         const GdkRectangle *rectangle);

Adds the given rectangle to the current path of cr.

cr :

 a cairo_t

rectangle :

 a GdkRectangle

Since 2.8

gdk_cairo_region ()

void                gdk_cairo_region                    (cairo_t *cr,
                                                         const GdkRegion *region);

Adds the given region to the current path of cr.

cr :

 a cairo_t

region :

 a GdkRegion

Since 2.8

gdk_cairo_reset_clip ()

void                gdk_cairo_reset_clip                (cairo_t *cr,
                                                         GdkDrawable *drawable);

Resets the clip region for a Cairo context created by gdk_cairo_create().

This resets the clip region to the "empty" state for the given drawable. This is required for non-native windows since a direct call to cairo_reset_clip() would unset the clip region inherited from the drawable (i.e. the window clip region), and thus let you e.g. draw outside your window.

This is rarely needed though, since most code just create a new cairo_t using gdk_cairo_create() each time they want to draw something.

cr :

 a cairo_t

drawable :

 a GdkDrawable

Since 2.18

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