Re: Accessing Context Properties

[tisimst]

Paul,

On Thu, Feb 25, 2016 at 11:08 AM, Paul Morris [via Lilypond] <[hidden email]> wrote:

Hi Abraham,

On Feb 25, 2016, at 12:28 PM, tisimst <[hidden email]> wrote:

I'm asking this because I know that if I can get my hands on a grob, I know how to access its properties (with ly:grob-property) and use that property's value to make a change if I want (e.g., with ly:grob-set-property!). I just don't know the equivalent process for getting my hands on a context to access its properties. I know there's ly:context-property, but I just don't have as much experience with it as normal grobs.

You may want a custom engraver, as they have access to contexts and context properties.

As I understand it there are three main ways of intervening:

1. music functions (and scheme, void, and markup functions)

2. custom engravers

3. grob property callback procedures

1: let you do fancy things with the input, early on, before LilyPond processes it

3: let you do things with graphical output very late in the game

2: are earlier than 3, exist within contexts and thus have access to context properties (and can do things with grobs as well like with 3)

As far as I know context properties can’t be accessed from a grob callback and not from music functions as David has said.  So that leaves custom engravers (although I don’t really know how \applyContext fits into this).

Maybe that helps?

Very much! Thank you.

Best,
Abraham

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