Watermark

{
  "type": "object",
  "description": "Decorative watermark: an image ('src') or a text stamp ('text'), exactly one of the two, with its opacity. An image is drawn once per slide, contained and centered in a fixed frame (the middle 40% of the slide width and height, from 30% to 70% on each axis). A text watermark is one line of text in the heading font and the theme text color at the given opacity, centered on the slide and rotated 30 degrees counterclockwise (rising to the right), sized to span at most 70% of the slide width and at most 30% of the shorter slide edge in height; it is drawn behind the slide content and above the background. There is no option to move, scale, rotate or tile either form. PPTX export writes one native picture (image) or one native text box (text) per slide with the opacity as alpha, and import restores the watermark. A string or Asset (no opacity) is the image watermark at opacity 0.08. A watermark object needs opacity and exactly one of src and text; use a plain string or Asset for an image at the default opacity. Use design.watermark = false to disable an inherited watermark.",
  "additionalProperties": false,
  "required": [
    "opacity"
  ],
  "oneOf": [
    {
      "required": [
        "src"
      ]
    },
    {
      "required": [
        "text"
      ]
    }
  ],
  "properties": {
    "src": {
      "type": "string",
      "description": "Source for the watermark image: an 'asset:<id>' reference, HTTPS URL, data URI, relative path or local path, as for Asset.src. Exactly one of src and text is set."
    },
    "text": {
      "type": "string",
      "minLength": 1,
      "description": "Text for a text watermark, such as DRAFT or CONFIDENTIAL; line breaks are drawn as spaces. Exactly one of src and text is set.",
      "examples": [
        "DRAFT",
        "CONFIDENTIAL"
      ]
    },
    "opacity": {
      "type": "number",
      "minimum": 0,
      "maximum": 1,
      "description": "Watermark opacity from 0 (fully transparent) to 1 (fully opaque)."
    }
  }
}