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Chasys Draw IES Help:


SDK - Layer Attachments
 

Rules for Layer Attachments

The following rules must be observed when adding or accessing metadata (attachments) on any layer:

  • All attachments must be identified by a type expressed as a four-letter code consisting of ASCII letters, numerals and underscores. These are called meta-types.
  • The first entry in the four letter code must not be a numeral except in specific cases
  • Some four-letter codes are reserved and should not be used by plug-ins
  • Custom/plugin-specific codes must not use uppercase letters
  • Attachments should be kept small (a few KB at most). If more data is needed, it should be stored in an external file and the reference kept in the attachment.

 

Accessing Layer Attachments

Layer attachments can be accessed via any FastExternalsTM interface that implements the meta_data parameter and any of meta_query(), meta_read() and meta_write().

Please note that these function pointers can be zero if the interface is not implemented or is disabled by the user. Also note that errors result in zero returns. The plug-in is expected to degrade gracefully in these circumstances.

 

Reserved meta-types

The following identifiers are reserved but can be used by your plug-in as long as you use them in the prescribed manner (click the link for detailed description):

  • APPL - Application linkage data
  • BLND - Custom Blend-mode data
  • MARK - Layer mark-up data
  • NOTE - Author's notes/comments/annotations

The following identifiers are reserved and restricted – they are normally not available to plug-ins except in very special circumstances:

  • ADJU - Adjustment layer data
  • ANIM - Animation control data
  • PATH - Pen and Path object data
  • TEXT - Text-art formatting information
  • TILE - Image tile/texture descriptor

The following identifiers are reserved for internal use only – they must not be used by your plug-in:

  • DESC - Descriptor fragment
  • DISP - Display control data
  • FILE - File fragment descriptor
  • HTML - HTML appendant data
  • META - Metadata container core
  • WAVE - Soundtrack/audio data