bug(Density): Setting the density via mat.all-component-densities gives different result than setting via mat.theme density

[kathrine0]

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

When defining the density via mat.theme, e.g.

@include mat.theme(
    (
      color: (
        theme-type: light,
        primary: mat.$azure-palette,
        tertiary: mat.$blue-palette,
      ),
      typography: Roboto,
      density: (
        scale: 0,
      ),
    )
);

the button height is 40px (--mdc-text-button-container-height).

However, using the mat.all-component-densities(0) mixin results in button height equals to 36px.

Similar issue applies to other densities - setting the density through the mixin results in different height values than setting it through the mat.theme mixin.

Reproduction

StackBlitz link: https://stackblitz.com/edit/czrubf43?file=src%2Fstyles.scss
Steps to reproduce:

1. inspect the button height without setting the density. Height is 40px
2. set the density height with the dropdown to 0. Height changes to 36px.

changing density through the dropdown adds respectively classes to the body: .density0, .density-1 ... .density-5

the scss for those is (see styles.scss)

.body {
  &.density0 {
    @include mat.all-component-densities(0);
  }

...

  &.density-5 {
    @include mat.all-component-densities(-5);
  }

}

Expected Behavior

densities (component heights) set through mat.all-component-densities(0) should be the same when set through
mat.theme((density: 0))

Actual Behavior

densities (component heights) set through mat.all-component-densities(0) are different when set through
mat.theme((density: 0))

Environment

• Angular: 19.2.5
• CDK/Material: 19.2.5
• Browser(s): Chrome
• Operating System (e.g. Windows, macOS, Ubuntu): macOS

[crisbeto]

I suspect it's because a theme still needs to be passed into all-component-densities. We should update our validation to detect cases like this.