Object styles

An object style is the page-item analogue of a text style: it supplies the fill, stroke, and corner defaults a frame inherits.

In short: Where paragraph and character styles format text, an object style formats a page item — a text frame, rectangle, oval, or other shape — supplying the fill, stroke, and corner defaults the frame falls back on when it carries no inline override of its own. Object styles live in <RootObjectStyleGroup> inside Resources/Styles.xml, cascade through BasedOn with the same first-setter-wins fold as the text styles, and bottom out at the [None] default that every frame in the reference packages applies. A frame names its object style with AppliedObjectStyle, and a colour attribute set to Swatch/None normalises to unset so the cascade can fall through to a real colour.

Where paragraph and character styles format text, an object style formats a page item — a text frame, rectangle, oval, or other shape. It supplies the fill, stroke, and corner defaults a frame inherits when the frame itself carries no inline override. Object styles cascade through BasedOn exactly like the text styles, and resolve with the same first-setter-wins fold (see the cascade).

Where they live

Each <ObjectStyle> sits inside <RootObjectStyleGroup> in Resources/Styles.xml (with optional <ObjectStyleGroup> nesting the parser flattens). InDesign always ships a set of defaults — [None], [Normal Graphics Frame], [Normal Text Frame], and [Normal Grid]. The one that matters most is [None].

The [None] default

ObjectStyle/$ID/[None] is the object style a frame applies when it wants no style-supplied formatting — it sets no fill or stroke of its own, so the frame's own inline attributes (or the bottom-of-cascade renderer defaults) stand. It is the object-style counterpart of the [No paragraph style] and [No character style] roots, and it is the style every frame in the reference packages applies via AppliedObjectStyle="ObjectStyle/$ID/[None]":

<RootObjectStyleGroup>
  <ObjectStyle Self="ObjectStyle/$ID/[None]" Name="$ID/[None]"
               FillColor="Swatch/None" StrokeColor="Swatch/None" StrokeWeight="0"
               AppliedParagraphStyle="ParagraphStyle/$ID/[No paragraph style]"
               CornerOption="None" CornerRadius="0"
               StrokeAlignment="CenterAlignment" StrokeType="StrokeStyle/$ID/Solid"
               Nonprinting="false"/>
</RootObjectStyleGroup>

A frame names its object style with AppliedObjectStyle="…". When a frame attribute is absent, the resolved object style fills it; Swatch/None on a colour attribute normalises to unset so a BasedOn chain can fall through to a real colour from a parent (so a placeholder rectangle can take its grey entirely from a style).

Attributes

The parser reads the fill / stroke / corner subset the renderer consumes. The Enable* category toggles and transparency / drop-shadow effect blocks that IDML also stores on <ObjectStyle> are not yet acted on.

(crates/paged-parse/src/styles.rs:216–243 defines the ObjectStyleDef fields this table mirrors.)

Object styles meet the page-item side of the document in frames and paths, where AppliedObjectStyle and a frame's own inline fill / stroke combine the same way a run's local override combines with its character style.

Frequently asked questions

What does an object style format? An object style formats a page item — a text frame, rectangle, oval, or other shape — supplying the fill, stroke, and corner defaults the frame inherits when it carries no inline override. It is the page-item counterpart of paragraph and character styles.

What is the [None] object style? ObjectStyle/$ID/[None] is the object style a frame applies when it wants no style-supplied formatting: it sets no fill or stroke of its own, so the frame's own inline attributes (or the renderer defaults) stand. It is the object-style counterpart of the [No paragraph style] and [No character style] roots, and it is the style every frame in the reference packages applies.

Which object-style attributes does the parser read? The parser reads the fill, stroke, and corner subset the renderer consumes — FillColor, StrokeColor, StrokeWeight, CornerOption, CornerRadius, and the like. The Enable* category toggles and the transparency and drop-shadow effect blocks IDML also stores on <ObjectStyle> are not yet acted on.

How do an object style and a frame's own attributes combine? A frame's own inline fill or stroke wins; whatever the frame leaves absent is filled by the resolved object style, with Swatch/None on a colour normalised to unset so a BasedOn chain can fall through. This is the same layering a run's local override uses against its character style.