<div dir="ltr">Well, I think I will not come with anything better than SVG effect graph, but that could be overkill as well, no idea :)<div> </div><div> <div> </div><div> </div></div></div><div class="gmail_extra"> <div class="gmail_quote">On Wed, Oct 19, 2016 at 1:11 AM, Bryce Harrington <<a href="mailto:bryce@osg.samsung.com" target="_blank">bryce@osg.samsung.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Tue, Oct 18, 2016 at 11:01:03PM +0200, Petr Kobalíček wrote: > What about chaining effects, the API seems to only deal with one effect at > time, is that correct? I'd like the API to support chained effects, although you're right the API suggests there can be only one effect at a time. I'd like it to also support booleaned effects, which implies applying two effects and then a boolean on top to merge them together. However, I'm a bit vague on exactly how all that should work. Suggestions? Bryce <div class="HOEnZb"><div class="h5"> > On Tue, Oct 18, 2016 at 6:27 PM, Bill Spitzak <<a href="mailto:spitzak@gmail.com">spitzak@gmail.com</a>> wrote: > > > On Mon, Oct 17, 2016 at 11:15 AM, Bryce Harrington > > <<a href="mailto:bryce@osg.samsung.com">bryce@osg.samsung.com</a>> wrote: > > > In September 2013, Henry proposed[0] adding a feature for Gaussian blur > > > and shadow, based on work carried in his cairogles branch[1]. The > > > proposed API[2] was felt to have too many entry points to the context > > > for setting all the various parameters (shadow color and type, blur > > > direction, etc.), and Chris suggested[3] coming up with a more generic > > > API that would handle path effects in a way more analogous to patterns. > > > > > > In 2014 I posted[4] a rough cut at such an API, following > > > cairo_pattern's API design, and a v2 shortly thereafter[5]. Following > > > is a v3 of that proposal, incorporating some of Chris Wilson's suggested > > > changes. > > > > > > In particular, this divides the API into a base class (Effects), and > > > sub-class (Path Effects), allowing for future introduction of pen > > > effects, material effects, etc. This common API is intended to > > > provide a consistent way of handling all effects in the rendering > > > pipeline. > > > > > > v2: > > > + Add get_data, set_data, reference_count for the cairo_object_t api > > > + Rename enums > > > v3: > > > + Path Effects are handled as a subclass of Effects > > > > > > --- > > > > > > /* > > > * Effect lifecycle management > > > */ > > > cairo_public cairo_status_t > > > cairo_effect_status (cairo_effect_t *effect); > > > > > > cairo_public cairo_effect_t * > > > cairo_effect_reference (cairo_effect_t *effect); > > > > > > cairo_public void > > > cairo_effect_destroy (cairo_effect_t *effect); > > > > > > cairo_public unsigned int > > > cairo_effect_get_reference_count (cairo_effect_t *effect); > > > > > > cairo_public void * > > > cairo_effect_get_user_data (cairo_effect_t *effect, > > > const cairo_user_data_key_t *key); > > > cairo_public cairo_status_t > > > cairo_effect_set_user_data (cairo_effect_t *effect, > > > const cairo_user_data_key_t *key, > > > void *user_data, > > > cairo_destroy_funct_t destroy); > > > > > > /* > > > * Effect properties > > > */ > > > typedef enum _cairo_effect_type { > > > CAIRO_EFFECT_TYPE_NONE = 0, > > > CAIRO_EFFECT_TYPE_PATH > > > } cairo_effect_type_t; > > > > > > /* Future types might include: > > > * CAIRO_EFFECT_TYPE_PEN > > > * CAIRO_EFFECT_TYPE_MATERIAL > > > * CAIRO_EFFECT_TYPE_OPERATOR > > > * CAIRO_EFFECT_TYPE_CLIP > > > * ... > > > */ > > > > > > cairo_public cairo_effect_type_t > > > cairo_effect_get_type (cairo_effect_t *effect); > > > > > > > > > > > > /* ---------------------------------------------------------------------- > > */ > > > > > > /* > > > * Path effect creation > > > * > > > * These create effects of type CAIRO_EFFECT_TYPE_PATH. > > > */ > > > cairo_public cairo_effect_t * > > > cairo_effect_create_drop_shadow_path (double x_offset, double y_offset, > > > double x_blur, double y_blur); > > > > > > cairo_public cairo_effect_t * > > > cairo_effect_create_inset_shadow_path (double x_inset, double y_inset, > > > double x_blur, double y_blur); > > > > > > /* > > > * Applying path effects to the context > > > */ > > > cairo_public void > > > cairo_set_path_effect (cairo_t *cr, cairo_effect_t *source); > > > > > > cairo_public cairo_effect_t * > > > cairo_get_path_effect (cairo_t *cr); > > > > > > /* > > > * Path effect properties > > > */ > > > typedef enum _cairo_path_effect_type { > > > CAIRO_PATH_EFFECT_NONE = 0, > > > CAIRO_PATH_EFFECT_DROP_SHADOW, > > > CAIRO_PATH_EFFECT_INSET_SHADOW > > > } cairo_path_effect_type_t; > > > > > > /* Future path effect types could include: > > > * CAIRO_PATH_EFFECT_PATTERN > > > * CAIRO_PATH_EFFECT_UNION > > > * CAIRO_PATH_EFFECT_DIFFERENCE > > > * CAIRO_PATH_EFFECT_INTERSECTION > > > * ... > > > */ > > > > > > cairo_public cairo_path_effect_type_t > > > cairo_path_effect_get_subtype (cairo_effect_t *effect); > > > > > > cairo_public void > > > cairo_path_effect_set_rgba (cairo_path_effect_t *path_effect, > > > double red, double green, double blue, > > > double alpha); > > > > > > Internally, both the effect type and subtype can be tracked in a single > > > property, e.g.: > > > > > > type = CAIRO_EFFECT_TYPE_PATH << 24 | CAIRO_PATH_EFFECT_DROP_SHADOW; > > > > > > > > > Henry's API proposal included provision for shadow caching by the > > > application. That certainly made a huge difference in the demos, so > > > maybe it's still going to be needed. An idea is to provide a > > > backend/user preference as to whether effects should be cached or > > > applied on the fly, e.g. cairo_effect_set_cached. > > > > > > Bryce > > > > > > 0: <a href="https://lists.cairographics.org/archives/cairo/2013-" rel="noreferrer" target="_blank">https://lists.cairographics.org/archives/cairo/2013-</a> > > September/024596.html > > > 1: The cairogles branch is no longer available publically. The private > > > branch is at <a href="https://github.com/SRA-SiliconValley/cairogles" rel="noreferrer" target="_blank">https://github.com/SRA-SiliconValley/cairogles</a> > > > 2: <a href="https://lists.cairographics.org/archives/cairo/2013-" rel="noreferrer" target="_blank">https://lists.cairographics.org/archives/cairo/2013-</a> > > September/024598.html > > > 3: <a href="https://lists.cairographics.org/archives/cairo/2013-" rel="noreferrer" target="_blank">https://lists.cairographics.org/archives/cairo/2013-</a> > > September/024597.html > > > 4: <a href="https://lists.cairographics.org/archives/cairo/2014-" rel="noreferrer" target="_blank">https://lists.cairographics.org/archives/cairo/2014-</a> > > October/025748.html > > > 5: <a href="https://lists.cairographics.org/archives/cairo/2014-" rel="noreferrer" target="_blank">https://lists.cairographics.org/archives/cairo/2014-</a> > > October/025766.html > > > -- > > > cairo mailing list > > > <a href="mailto:cairo@cairographics.org">cairo@cairographics.org</a> > > > <a href="https://lists.cairographics.org/mailman/listinfo/cairo" rel="noreferrer" target="_blank">https://lists.cairographics.org/mailman/listinfo/cairo</a> > > > > Seems to me there is excessive namespacing here. There is no need for > > an "effect type", it should just be clear from the effect description > > whether it has an effect on stroke, fill, or text, or which parts of > > the inputs it changes. > > > > Possibly you are thinking that the effects would be mutually exclusive > > and that the type is to identify the mutually exclusive set, but that > > seems really limiting and I think you will end up with one "type" for > > each effect. Instead just allow arbitrary sets of effects to be > > active. If two effects can't be done at the same time, it is either an > > error, or one of them takes precedence. > > > > I would also remove "PATH" from all your enumerations and function > > names. Some of them are really confusing now, for instance > > "cairo_effect_create_inset_shadow_path" does not create a path, it > > creates an effect. > > -- > > cairo mailing list > > <a href="mailto:cairo@cairographics.org">cairo@cairographics.org</a> > > <a href="https://lists.cairographics.org/mailman/listinfo/cairo" rel="noreferrer" target="_blank">https://lists.cairographics.org/mailman/listinfo/cairo</a> > > </div></div></blockquote></div> </div>