Recording Surfaces: Cairo: A Vector Graphics Library

+ + +

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:

+ + + + + + + +

1
+2
+3
+4
+5
+6

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

+ +

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

+++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + +

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