Recording Surfaces: Cairo: A Vector Graphics Library

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Recording Surfaces

Recording Surfaces — Records all drawing operations

Functions

---- - - - - - - - - - - - - - - -

-cairo_surface_t * -	-cairo_recording_surface_create () -
-void -	-cairo_recording_surface_ink_extents () -
-cairo_bool_t -	-cairo_recording_surface_get_extents () -

Types and Values

---- - - - - -

#define

CAIRO_HAS_RECORDING_SURFACE

Description

A recording surface is a surface that records all drawing operations at -the highest level of the surface backend interface, (that is, the -level of paint, mask, stroke, fill, and show_text_glyphs). The recording -surface can then be "replayed" against any target surface by using it -as a source surface.

If you want to replay a surface so that the results in target will be -identical to the results that would have been obtained if the original -operations applied to the recording surface had instead been applied to the -target surface, you can use code like this:

- - - - - - - -

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cairo_t *cr;
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-cr = cairo_create (target);
-cairo_set_source_surface (cr, recording_surface, 0.0, 0.0);
-cairo_paint (cr);
-cairo_destroy (cr);

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A recording surface is logically unbounded, i.e. it has no implicit constraint -on the size of the drawing surface. However, in practice this is rarely -useful as you wish to replay against a particular target surface with -known bounds. For this case, it is more efficient to specify the target -extents to the recording surface upon creation.

The recording phase of the recording surface is careful to snapshot all -necessary objects (paths, patterns, etc.), in order to achieve -accurate replay. The efficiency of the recording surface could be -improved by improving the implementation of snapshot for the -various objects. For example, it would be nice to have a -copy-on-write implementation for _cairo_surface_snapshot.

Functions

cairo_recording_surface_create ()

cairo_surface_t *
-cairo_recording_surface_create (cairo_content_t content,
-                                const cairo_rectangle_t *extents);

Creates a recording-surface which can be used to record all drawing operations -at the highest level (that is, the level of paint, mask, stroke, fill -and show_text_glyphs). The recording surface can then be "replayed" against -any target surface by using it as a source to drawing operations.

The recording phase of the recording surface is careful to snapshot all -necessary objects (paths, patterns, etc.), in order to achieve -accurate replay.

Parameters

----- - - - - - - - - - - - - -

content	the content of the recording surface
extents	the extents to record in pixels, can be `NULL` to record -unbounded operations.

Returns

a pointer to the newly created surface. The caller -owns the surface and should call cairo_surface_destroy() when done -with it.

Since: 1.10

cairo_recording_surface_ink_extents ()

void
-cairo_recording_surface_ink_extents (cairo_surface_t *surface,
-                                     double *x0,
-                                     double *y0,
-                                     double *width,
-                                     double *height);

Measures the extents of the operations stored within the recording-surface. -This is useful to compute the required size of an image surface (or -equivalent) into which to replay the full sequence of drawing operations.

Parameters

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surface	a cairo_recording_surface_t
x0	the x-coordinate of the top-left of the ink bounding box
y0	the y-coordinate of the top-left of the ink bounding box
width	the width of the ink bounding box
height	the height of the ink bounding box

Since: 1.10

cairo_recording_surface_get_extents ()

cairo_bool_t
-cairo_recording_surface_get_extents (cairo_surface_t *surface,
-                                     cairo_rectangle_t *extents);

Get the extents of the recording-surface.

Parameters

----- - - - - - - - - - - - - -

surface	a cairo_recording_surface_t
extents	the cairo_rectangle_t to be assigned the extents

Returns

TRUE if the surface is bounded, of recording type, and -not in an error state, otherwise FALSE

Since: 1.12

Types and Values

CAIRO_HAS_RECORDING_SURFACE

#define CAIRO_HAS_RECORDING_SURFACE 1
-

Defined if the recording surface backend is available. -The recording surface backend is always built in. -This macro was added for completeness in cairo 1.10.

Since: 1.10