Online Help for Chasys Draw IES: SDK - Layer Attachments

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):

  • PHYS - Physical Dimensions
  • HOTS - Hotspot Information
  • APPL - Applet Linkage Data
  • BLND - Custom Blend-mode data
  • MARK - Layer Mark-up Data
  • NOTE - Author’s Notes/Comments/Annotations
  • CPAL - Color Palette
  • FONT - Embedded Font (raw file data)

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 Data
  • TEXT - Text Formatting Data
  • TILE - Image Tile/Texture Descriptor
  • SPRT - Sprite-sheet Information

The following identifiers are reserved for internal use only – they MUST NEVER be used by your plug-in:

  • META - Metadata Container, DO NOT TOUCH!!
  • LINK - Linked Layer Information

The following identifiers are reserved for future use are therefore not available for use by your plug-in:

  • DISP - Display control data
  • WAVE - Soundtrack/audio data
  • FILE - File fragment descriptor
  • DATA - Unstructured data fragment
  • DESC - Descriptor fragment
  • HTML - HTML appendant data
  • ICCP - ICC Profile data
  • EXIF - Raw EXIF data
  • XMPP - Raw XMP data