Combining Calc with same_as

Combining calc() with same_as¶

same_as can be used to reuse another item in the same section.

This is useful when multiple items share most of their configuration, but only differ in one or two values.

hlines:
  - xpos: 50
    ypos: 64
    length: calc(4 * 20 + 5)
    styles:
      - stroke: var(--disabled-text-color)

  - same_as: 0
    same_as_dypos: calc(1 * 11)

  - same_as: 0
    same_as_dypos: calc(2 * 11)

This means:

Item	Source	Calculation	Result
`0`	original item	`length: calc(4 * 20 + 5)`	`length: 85`, `ypos: 64`
`1`	`same_as: 0`	`ypos: 64 + calc(1 * 11)`	`ypos: 75`
`2`	`same_as: 0`	`ypos: 64 + calc(2 * 11)`	`ypos: 86`

Internally this becomes:

hlines:
  - id: "0"
    xpos: 50
    ypos: 64
    length: 85
    styles:
      - stroke: var(--disabled-text-color)

  - id: "1"
    xpos: 50
    ypos: 75
    length: 85
    styles:
      - stroke: var(--disabled-text-color)

  - id: "2"
    xpos: 50
    ypos: 86
    length: 85
    styles:
      - stroke: var(--disabled-text-color)

So the external configuration stays short, while the internal configuration becomes complete.

Reuse with chained same_as

You can also build on the previous item.

hlines:
  - id: first
    xpos: 50
    ypos: 64
    length: calc(4 * 20 + 5)

  - id: second
    same_as: first
    same_as_dypos: 11

  - id: third
    same_as: second
    same_as_dypos: 11

This means:

second = first + 11
third  = second + 11

Result:

Item	Resulting `ypos`
`first`	`64`
`second`	`75`
`third`	`86`

Reuse from the same base item

Instead of chaining, you can also reuse the first item directly.

hlines:
  - id: first
    xpos: 50
    ypos: 64
    length: calc(4 * 20 + 5)

  - id: second
    same_as: first
    same_as_dypos: calc(1 * 11)

  - id: third
    same_as: first
    same_as_dypos: calc(2 * 11)

This means: second = first + 1 step third = first + 2 steps

This can be clearer when all items follow a fixed pattern from the same base item.

Delta fields¶

Delta fields use this pattern:

same_as_d<field>: <number>

The delta is added to the inherited value.

Delta field	Target field	Meaning
`same_as_dxpos`	`xpos`	Add to inherited `xpos`
`same_as_dypos`	`ypos`	Add to inherited `ypos`
`same_as_dlength`	`length`	Add to inherited `length`
`same_as_dradius`	`radius`	Add to inherited `radius`

Because this pattern is generic, it can work for any numeric field on the reused item.

Example:

circles:
  - id: outer
    xpos: 50
    ypos: 50
    radius: 40

  - id: inner
    same_as: outer
    same_as_dradius: -5

Result:

circles:
  - id: outer
    xpos: 50
    ypos: 50
    radius: 40

  - id: inner
    xpos: 50
    ypos: 50
    radius: 35

Positioning around the center¶

Many card layouts are designed around the center point 50,50.

With calc(), offsets from the center can stay visible in the configuration.

icons:
  - id: left
    xpos: calc(50 - 4)
    ypos: 50

  - id: right
    xpos: calc(50 + 4)
    ypos: 50

This is easier to understand than:

icons:
  - id: left
    xpos: 46
    ypos: 50

  - id: right
    xpos: 54
    ypos: 50

The calculated values are the same, but the intent is clearer.

Notes

Rule	Description
YAML does not calculate values	`calc()` is added by the card, not by YAML itself.
Static only	`calc()` is evaluated once during config setup.
Runtime templates are different	Templates like `[[[ return ... ]]]` are evaluated during runtime updates.
Numeric result required	`calc()` must return a finite number.
`same_as` is reuse	It copies another item from the same section.
`same_as_d...` is offset reuse	It copies another item and adds a numeric delta to one field.
List order matters	`same_as` can only refer to an earlier item in the same list.