DocumentationDynamic Media Image Serving and Rendering API

layer layer

Last update: Fri Nov 03 2023 00:00:00 GMT+0000 (Coordinated Universal Time)

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Select Layer. Selects a layer and starts a new layer definition segment in the command sequence.

layer= *n*|comp[, *name*]

layer= *name*

n
Number of layer to be selected (0 or greater int).
comp
Select the composite image.
name
Layer name.

All commands within the layer segment are applied to the specified layer. A layer segment is terminated by the next layer= or effect= command or the end of the request.

Specify layer=comp to select the composite image (or view, for some commands).

The layer number effectively specifies the z-order for the layer. Higher-numbered layers are placed on top of lower-numbered layers.

Layer numbers do not need to be consecutive. Layer 0 is required.

A name may be assigned to a layer with the layer= *n*, *name* command variant. Once a named layer is defined, it can be referenced with layer= *name*, without needing to know the layer number. Multiple names may be assigned to the same layer, using multiple layer= *n*, *name* commands.

NOTE
Layer 0 determines the overall size of the compositing canvas. All parts of layers falling outside the bounds of layer 0 are cropped off when the composite is built.

Properties section-499963ee52c14f2898f0d0f90c1d01be

Layer command. Substitution variable references are not supported in layer=.

comp is not permitted as a name string. An error is returned if the same name is assigned to more than one layer, or if a layer is referenced by name which has not been defined previously.

Default section-091859a03f8048c2b7092f0fec9c1006

layer=comp. Many commands and attributes apply to layer 0 if layer=comp.

Special Cases section-e087cb2e3562473e8d391abfa3b9489f

  • If the same name is mapped to multiple layers (for example: layer=1,image&layer=2,image), an error occurs.

  • If the same name is mapped to a single layer multiple times (for example: layer=1,image&layer=1,image), scope is set as usual, without errors.

  • Multiple names for the same layer are supported.

    Either name can be used to reference the layer (for example: layer=1,image&layer=1,picture).

  • If a referenced name is never mapped to a layer number (for example: layer=1,image&layer=picture), an error occurs.

  • Substitution variables are not supported in layer modifiers (for example: layer=$image$).

    This applies to all permutations, not only to layer names but to layer modifiers in general.

  • All merging and overriding rules should work exactly as when same layer is referenced in multiple sources (request, pre or post modifier catalog records, macros, and so on.).

Example section-cc40de6a0a754178aa752601539c815b

See the examples in Templates.

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