Difference between revisions of "SpecIccForCairo"

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Line 17: Line 17:
   
   
  typedef struct cairo_color_profile cairo_color_profile_t;
  typedef struct cairo_color_profile cairo_color_profile_t;
 
  void
  void
  cairo_surface_set_color_profile(cairo_surface_t *surf,
  cairo_surface_set_color_profile(cairo_surface_t *surf,
Line 39: Line 39:
  cairo_color_intent_t
  cairo_color_intent_t
  cairo_surface_get_color_intent(cairo_surface_t *surf);
  cairo_surface_get_color_intent(cairo_surface_t *surf);
 
 
  void
  void
  cairo_set_source_icc_color(cairo_color_profile_t *profile,
  cairo_set_source_icc_color(cairo_color_profile_t *profile,

Revision as of 19:13, 23 February 2008

Why

In order for inkscape to produce CMYK PDFs and PSs with cairo, Cairo needs to support ICC. This is an intent to propose a Cairo API that would be suitable with inkscape needs.

Profiles

A set of profiles will apply to the whole Cairo surface. Cairo needs to be able to compute a transform from this set. We can get inspiration from the lcms api [1], in particular the cmsCreateMultiprofileTransform (more generic than cmsCreateTransform that handles only a single pair of color profiles).

So a proposal would be:

typedef enum cairo_color_intent {
  CAIRO_COLOR_INTENT_PERCEPTUAL,
  CAIRO_COLOR_INTENT_RELATIVE_COLORIMETRIC,
  CAIRO_COLOR_INTENT_SATURATION,
  CAIRO_COLOR_INTENT_ABSOLUTE_COLORIMETRIC
} cairo_color_intent_t;

typedef struct cairo_color_profile cairo_color_profile_t;

void
cairo_surface_set_color_profile(cairo_surface_t *surf,
                                cairo_color_profile_t *profile);

cairo_color_profile_t *
cairo_surface_get_color_profile(cairo_surface_t *surf);

void
cairo_surface_add_profile_mapping(cairo_surface_t *surf, 
                                  cairo_color_profile_t *in, 
                                  cairo_color_profile_t *out);

void
cairo_surface_remove_profile_mappings(cairo_surface_t *surf);

void
cairo_surface_set_color_intent(cairo_surface_t *surf,
                               cairo_color_intent_t intent);

cairo_color_intent_t
cairo_surface_get_color_intent(cairo_surface_t *surf);

void
cairo_set_source_icc_color(cairo_color_profile_t *profile,
                           const double *components,
                           int num_components);

Open issues

  • Should surface profile/color rendering changes be allowed once the surface is being actively used?
  • How should gradients work in this regime?