# Options

# Color

Any color supported by chart.js (opens new window) is supported by the annotation plugin.

# Font

Fonts use the same format as chart.js (opens new window).

# Scriptable Options

As with most options in chart.js, the annotation plugin options are scriptable. This means that a function can be passed which returns the value as needed. In the example below, the annotation is hidden when the screen is less than 1000px wide. The function receives 2 arguments, first is the option context representing contextual information. An options resolver is passed as second argument, which can be used to access the options that were originally passed in to configure the annotation element.

const options = {
  plugins: {
    autocolors: false,
    annotation: {
      annotations: {
        box1: {
          drawTime: 'afterDatasetsDraw',
          display: (context, opts) => {
            const body = document.querySelector('body');
            const rect = body.getBoundingClientRect();
            return rect.width >= 1000;
          },
          type: 'box',
          xMin: 1,
          xMax: 2,
          yMin: 50,
          yMax: 70,
          backgroundColor: 'rgba(255, 99, 132, 0.5)'
        }
      }
    }
  }
};const options = {
  plugins: {
    autocolors: false,
    annotation: {
      annotations: {
        box1: {
          drawTime: 'afterDatasetsDraw',
          display: (context, opts) => {
            const body = document.querySelector('body');
            const rect = body.getBoundingClientRect();
            return rect.width >= 1000;
          },
          type: 'box',
          xMin: 1,
          xMax: 2,
          yMin: 50,
          yMax: 70,
          backgroundColor: 'rgba(255, 99, 132, 0.5)'
        }
      }
    }
  }
};

# Draw Time

The drawTime option for an annotation determines where in the chart lifecycle the drawing occurs. Four potential options are available:

Option	Notes
`'beforeDraw'`	Occurs before any drawing takes place
`'beforeDatasetsDraw'`	Occurs after drawing of axes, but before datasets
`'afterDatasetsDraw'`	Occurs after drawing of datasets but before items such as the tooltip
`'afterDraw'`	After other drawing is completed.

# Option Context

The option context is used to give contextual information when resolving options and only applies to scriptable options. The object is preserved, so it can be used to store and pass information between calls / options.

There are 2 levels of option context objects:

chart
- annotation

The context object contains the following properties:

# chart

chart: the associated chart
type: 'chart'

The chart option context is provided by Chart.js. It is passed to scriptable options when resolving annotation id, type and drawTime or adjusting scale ranges in afterDataLimits hook. The options resolved at that time are scaleID, xScaleID, yScaleID, value, endValue, xMin, xMax, yMin, yMax, xValue and yValue.

# annotation

In addition to chart

id: the annotation id
element: the annotation element
type: 'annotation'

The annotation option context is passed to scriptable options in all other cases, except when resolving id, type or adjusting scale ranges. The same values resolved in afterDataLimits with chart context are again evaluated in afterUpdate with annotation context.

Note that the annotation element may be undefined or partially uninitialized, since scriptable options may be invoked during the initial chart display, before everything's been resolved and initialized.

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