Annotation plugin

Charba provides out of the box the feature to enable Annotation which can add annotations on a chart instance.

It can draw lines, boxes, points and ellipses on the chart area.

The annotation plugin work with line, bar, scatter and bubble charts that use linear, logarithmic, time or category scales.

info

The annotation plugin will not work on any chart that does not have exactly two axes, including pie, radar and polar area charts.

Activation

The annotation plugin is injected directly in the document.

The plugin ID is a constant everywhere available, AnnotationPlugin.ID, in AnnotationPlugin entry point.

This plugin registers itself globally, meaning that once injected, all charts will display annotations. In case you want it enabled only for a few charts, you can enable it as following:

// --------------------------------------
// enabling the plugin without any parameter
// the plugin is NOT registered to all charts
// --------------------------------------
AnnotationPlugin.enable();

// --------------------------------------
// enabling the plugin with `true` parameter
// the plugin is registered to all charts
// --------------------------------------
AnnotationPlugin.enable(true);

To activate the plugin in a specific chart, it's enough to provide the configuration options (see below) or enabling it by:

// --------------------------------------
// ENABLING the plugin to a chart instance 
// storing a plugin options 
// --------------------------------------
// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// sets default draw time
options.setDrawTime(DrawTime.BEFORE_DRAW);
// stores the plugin options directly by the options
options.store(chart);

// --------------------------------------
// ENABLING the plugin to a chart instance 
// by a boolean using default plugin 
// options
// --------------------------------------
chart.getOptions().getPlugins().setEnabled(AnnotationPlugin.ID, true);

Configuration

The plugin options can be changed at 2 different levels and are evaluated with the following priority:

• per chart by chart.getOptions().getPlugins().setOptions method
• or globally by Defaults.get().getGlobal().getPlugins().setOptions method

The configuration AnnotationOptions class is the entry point of plugin configuration.

// -------------------------
// CONFIGURES the annotation
// by AnnotationId id
// -------------------------
// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
LineAnnotation line = new LineAnnotation();
... // additional label configuration
// sets the line annotation to the options
options.setAnnotations(line);
// stores the plugin options directly by the options
options.store();

You can also change the default for all charts instances, as following:

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
LineAnnotation line = new LineAnnotation();
... // additional label configuration
// sets the line annotation to the options
options.setAnnotations(line);

// --------------------------------------
// STORING plugin options
// --------------------------------------
// stores the plugin options by plugin ID
Defaults.get().getGlobal().getPlugin().setOptions(AnnotationPlugin.ID, options);
// stores the plugin options without plugin ID
Defaults.get().getGlobal().getPlugin().setOptions(options);
// stores the plugin options directly by the options
options.store();

If you need to read the plugin options, there is the specific factory, AnnotationOptionsFactory as static reference inside the AnnotationPlugin entry point which can be used to retrieve the options from chart as following:

// gets options reference
AnnotationOptions options;

// --------------------------------------
// GETTING plugin options from chart
// --------------------------------------
if (chart.getOptions().getPlugin().hasOptions(AnnotationPlugin.ID)){
   // retrieves the plugin options by plugin ID
   options = chart.getOptions().getPlugin().getOptions(AnnotationPlugin.ID, AnnotationPlugin.FACTORY);
   //retrieves the plugin options without plugin ID
   options = chart.getOptions().getPlugin().getOptions(AnnotationPlugin.FACTORY);
}

Identifier

Every annotation configuration can be add to the AnnotationOptions, assigning a unique identifier.

The identifier of a label configuration can be set by a string or by a specific class, AnnotationId.

// -------------------------
// CONFIGURES the annotation
// by AnnotationId id
// -------------------------
// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates annotation id
AnnotationId annotationId = AnnotationId.create("myAnnotation1");
// creates and adds a line annotation by "myAnnotation1" id
LineAnnotation line = new LineAnnotation(annotationId);
// configures the line annotation
line.setDrawTime(DrawTime.AFTER_DATASETS_DRAW);
line.setBorderColor(HtmlColor.BLACK);
line.setBorderWidth(5);
... // additional label configuration
// sets the line annotation to the options
options.setAnnotations(line);
// stores the plugin options directly by the options
options.store();

caution

If the annotation id is not provided, a unique id for the annotation is created automatically, which can be retrieve by getId() method of the annotation.

You can access to the configured annotations configurations as following:

// ------------------------
// GETS the configured 
// annotations
// ------------------------
// retrieves the plugin options by plugin ID
AnnotationOptions options = chart.getOptions().getPlugin().getOptions(AnnotationPlugin.FACTORY);
// gets all annotations configurations
List<AbstractAnnotation> allAnnotations = options.getAnnotations();
// gets "myAnnotation1" annotation configuration
AbstractAnnotation annotation1 = options.getAnnotation(AnnotationId.create("myAnnotation1"));
// gets "myAnnotation2" annotation configuration
AbstractAnnotation annotation2 = options.getAnnotation("myAnnotation2");

Options

The configuration class AnnotationOptions contains all properties needed to configure the plugin.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// sets default draw time
options.setDrawTime(DrawTime.BEFORE_DRAW);

The following options are available at the top level. They apply to all annotations unless they are overwritten on a per-annotation basis:

Name	Type	Default	Description
drawTime	DrawTime	DrawTime.AFTER_DATASETS_DRAW	Defines when the annotations are drawn. This allows positioning of the annotation relative to the other elements of the graph.
dblClickSpeed	int	350	Double-click speed in milliseconds used to distinguish single-clicks from double-clicks whenever you need to capture both. When listening for both click and dblclick, click events will be delayed by this amount.
events	Event[]	Defaults.get().getGlobal() .getEvents()	The events option defines the browser events that the plugin should listen to. This overrides the options at chart level.

Draw time

The DrawTime option for an annotation determines where in the chart life cycle the drawing occurs. Four potential options are available:

Option	Description
BEFORE_DRAW	Occurs before any drawing takes place
BEFORE_DATASETS_DRAW	Occurs after drawing of axes, but before data sets
AFTER_DATASETS_DRAW	Occurs after drawing of data sets but before items such as the tooltip
AFTER_DRAW	After other drawing is completed.

Box

Box annotations are used to draw rectangles on the chart area. This can be useful for highlighting different areas of a chart.

Every plugin options can have an unlimited number of boxes annotations.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
// without id (a unique one is created automatically)
BoxAnnotation box = new BoxAnnotation();
box.setDrawTime(DrawTime.BEFORE_DATASETS_DRAW);
box.setXScaleID(DefaultScaleId.X);
box.setYScaleID(DefaultScaleId.Y);
box.setXMin("January");
box.setXMax("April");
box.setBackgroundColor(GwtMaterialColor.YELLOW_LIGHTEN_3.alpha(0.3D));
box.setBorderWidth(0);
// stores the annotation in the main options
options.setAnnotations(box);

If one of the axes does not match an axis in the chart, the box will take the entire chart dimension.

The 4 coordinates, xMin, xMax, yMin, yMax are optional. If not specified, the box is expanded out to the edges in the respective direction.

The complete options are described by following table:

Name	Type	Default	Scriptable	Description
adjustScaleRange	boolean	true	Yes	If true, the scale range should be adjusted if this annotation is out of range.
backgroundColor	String - IsColor	Defaults.get().getGlobal() .getColorAsString()	Yes	The fill color of the box. See default colors.
borderColor	String - IsColor	Defaults.get().getGlobal() .getColorAsString()	Yes	The stroke color of the box. See default colors.
borderDash	int[]	[]	Yes	The length and spacing of dashes. See MDN.
borderDashOffset	double	0	Yes	The offset for line dashes. See MDN.
borderWidth	int	1	Yes	The stroke width of the box.
cornerRadius	int	0	Yes	The radius in pixels of box rectangle.
display	boolean	true	Yes	Whether or not this annotation is visible.
drawTime	DrawTime	DrawTime. AFTER_DATASETS_DRAW	Yes	Defines when the annotation is drawn. This allows positioning of the annotation relative to the other elements of the graph.
xMax	String - double - Date	null	Yes	Right edge of the box in units along the x axis.
xMin	String - double - Date	null	Yes	Left edge of the box in units along the x axis.
xScaleID	String - ScaleId	DefaultScaleId.X	-	The ID of the X scale to bind onto.
yMax	String - double - Date	null	Yes	Top edge of the box in units along the y axis.
yMin	String - double - Date	null	Yes	Bottom edge of the box in units along the y axis.
yScaleID	String - ScaleId	DefaultScaleId.Y	-	The ID of the Y scale to bind onto.

Box scriptable options

Some options also accept a callback which is called at runtime and that takes the context as single argument, see here the details, which is representing contextual information and chart instance.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
BoxAnnotation box = new BoxAnnotation();
// sets callback for border width options
box.setBorderWidth(new WidthCallback<AnnotationContext>(){

   @Override
   public Integer invoke(DatasetContext context){
      // logic
      return borderWidth;
   }
});
// stores the annotation in the main options
options.setAnnotations(box);

The following options can be set by a callback:

Name	Callback	Returned types
adjustScaleRange	AdjustScaleRangeCallback	boolean
backgroundColor	ColorCallback<AnnotationContext>	String - IsColor - Pattern
borderColor	ColorCallback<AnnotationContext>	String - IsColor
borderDash	BorderDashCallback<AnnotationContext>	List<Integer>
borderDashOffset	BorderDashOffsetCallback<AnnotationContext>	double
borderWidth	WidthCallback<AnnotationContext>	int
cornerRadius	CornerRadiusCallback<AnnotationContext>	int
display	DisplayCallback<AnnotationContext>	boolean
drawTime	DrawTimeCallback	DrawTime
xMax	ValueCallback	String - double - Date
xMin	ValueCallback	String - double - Date
yMax	ValueCallback	String - double - Date
yMin	ValueCallback	String - double - Date

Ellipse

Ellipse annotations are used to draw ellipses on the chart area. This can be useful for highlighting different areas of a chart.

Every plugin options can have an unlimited number of ellipses annotations.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
// without id (a unique one is created automatically)
EllipseAnnotation ellipse = new EllipseAnnotation();
ellipse.setDrawTime(DrawTime.BEFORE_DATASETS_DRAW);
ellipse.setXScaleID(DefaultScaleId.X);
ellipse.setYScaleID(DefaultScaleId.Y);
ellipse.setXMin("February");
ellipse.setXMax("April");
ellipse.setYMin(10);
ellipse.setYMax(60);
ellipse.setBackgroundColor(GwtMaterialColor.INDIGO_LIGHTEN_3.alpha(0.3D));
ellipse.setBorderWidth(4);
ellipse.setBorderColor(GwtMaterialColor.INDIGO_LIGHTEN_3);
ellipse.setBorderDash(3,3);
// stores the annotation in the main options
options.setAnnotations(ellipse);

If one of the axes does not match an axis in the chart, the ellipse will take the entire chart dimension.

The 4 coordinates, xMin, xMax, yMin, yMax are optional. If not specified, the ellipse is expanded out to the edges in the respective direction.

The complete options are described by following table:

Name	Type	Default	Scriptable	Description
adjustScaleRange	boolean	true	Yes	If true, the scale range should be adjusted if this annotation is out of range.
backgroundColor	String - IsColor	Defaults.get().getGlobal() .getColorAsString()	Yes	The fill color of the ellipse. See default colors.
borderColor	String - IsColor	Defaults.get().getGlobal() .getColorAsString()	Yes	The stroke color of the ellipse. See default colors.
borderDash	int[]	[]	Yes	The length and spacing of dashes. See MDN.
borderDashOffset	double	0	Yes	The offset for line dashes. See MDN.
borderWidth	int	1	Yes	The stroke width of the ellipse.
display	boolean	true	Yes	Whether or not this annotation is visible.
drawTime	DrawTime	DrawTime. AFTER_DATASETS_DRAW	Yes	Defines when the annotation is drawn. This allows positioning of the annotation relative to the other elements of the graph.
xMax	String - double - Date	null	Yes	Right edge of the ellipse in units along the x axis.
xMin	String - double - Date	null	Yes	Left edge of the ellipse in units along the x axis.
xScaleID	String - ScaleId	DefaultScaleId.X	-	The ID of the X scale to bind onto.
yMax	String - double - Date	null	Yes	Top edge of the ellipse in units along the y axis.
yMin	String - double - Date	null	Yes	Bottom edge of the ellipse in units along the y axis.
yScaleID	String - ScaleId	DefaultScaleId.Y	-	The ID of the Y scale to bind onto.

Ellipse scriptable options

Some options also accept a callback which is called at runtime and that takes the context as single argument, see here the details, which is representing contextual information and chart instance.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
EllipseAnnotation ellipse = new EllipseAnnotation();
// sets callback for border width options
ellipse.setBorderWidth(new WidthCallback<AnnotationContext>(){

   @Override
   public Integer invoke(DatasetContext context){
      // logic
      return borderWidth;
   }
});
// stores the annotation in the main options
options.setAnnotations(ellipse);

The following options can be set by a callback:

Name	Callback	Returned types
adjustScaleRange	AdjustScaleRangeCallback	boolean
backgroundColor	ColorCallback<AnnotationContext>	String - IsColor - Pattern
borderColor	ColorCallback<AnnotationContext>	String - IsColor
borderDash	BorderDashCallback<AnnotationContext>	List<Integer>
borderDashOffset	BorderDashOffsetCallback<AnnotationContext>	double
borderWidth	WidthCallback<AnnotationContext>	int
display	DisplayCallback<AnnotationContext>	boolean
drawTime	DrawTimeCallback	DrawTime
xMax	ValueCallback	String - double - Date
xMin	ValueCallback	String - double - Date
yMax	ValueCallback	String - double - Date
yMin	ValueCallback	String - double - Date

Line

Line annotations are used to draw lines on the chart area. This can be useful for highlighting information such as a threshold.

Every plugin options can have an unlimited number of lines annotations.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
// without id (a unique one is created automatically)
LineAnnotation line = new LineAnnotation();
line.setDrawTime(DrawTime.AFTER_DRAW);
line.setScaleID(DefaultScaleId.X.value());
line.setBorderColor(HtmlColor.DARK_GRAY);
line.setBorderWidth(2);
line.setValue(new Date());
// sets label configuration
line.getLabel().setDisplay(true);
line.getLabel().setContent("Now");
line.getLabel().setPosition(LabelPosition.START);
// stores the annotation in the main options
options.setAnnotations(line);

If one of the axes does not match an axis in the chart, the line will take the entire chart dimension.

The 4 coordinates, xMin, xMax, yMin, yMax are optional. If not specified, the line is expanded out to the edges in the respective direction.

The line can be positioned in two different ways:

• if scaleID is set, then value and endValue must also be set to indicate the end points of the line. The line will be perpendicular to the axis identified by scaleID.
• if scaleID is unset, then xScaleID and yScaleID are used to draw a line from (xMin, yMin) to (xMax, yMax).

The complete options are described by following table:

Name	Type	Default	Scriptable	Description
adjustScaleRange	boolean	true	Yes	If true, the scale range should be adjusted if this annotation is out of range.
borderColor	String - IsColor	Defaults.get().getGlobal() .getColorAsString()	Yes	The stroke color of the line.
borderDash	int[]	[]	Yes	the line dash pattern used when stroking lines, using an array of values which specify alternating lengths of lines and gaps which describe the pattern.
borderDashOffset	int	0	Yes	Offset for line dashes. See MDN
borderWidth	int	1	Yes	The stroke width of the line.
display	boolean	true	Yes	Whether or not this annotation is visible.
drawTime	DrawTime	DrawTime. AFTER_DATASETS_DRAW	Yes	Defines when the annotation is drawn. This allows positioning of the annotation relative to the other elements of the graph.
endValue	String - double - Date	null	Yes	End two of the line when a single scale is specified.
scaleID	String - ScaleId	DefaultScaleId.Y	-	ID of the scale in single scale mode. If unset, xScaleID and yScaleID are used.
value	String - double - Date	null	Yes	End one of the line when a single scale is specified.
xMax	String - double - Date	null	Yes	X coordinate of end two of the line in units along the x axis.
xMin	String - double - Date	null	Yes	X coordinate of end one of the line in units along the x axis.
xScaleID	String - ScaleId	DefaultScaleId.X	-	The ID of the X scale to bind onto.
yMax	String - double - Date	null	Yes	Y coordinate of end one of the line in units along the y axis.
yMin	String - double - Date	null	Yes	Y coordinate of end one of the line in units along the y axis.
yScaleID	String - ScaleId	DefaultScaleId.Y	-	The ID of the Y scale to bind onto.

Line scriptable options

Some options also accept a callback which is called at runtime and that takes the context as single argument, see here the details, which is representing contextual information and chart instance.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
LineAnnotation line = new LineAnnotation();
// sets callback for border width options
line.setBorderWidth(new WidthCallback<AnnotationContext>(){

   @Override
   public Integer invoke(DatasetContext context){
      // logic
      return borderWidth;
   }
});
// stores the annotation in the main options
options.setAnnotations(line);

The following options can be set by a callback:

Name	Callback	Returned types
adjustScaleRange	AdjustScaleRangeCallback	boolean
borderColor	ColorCallback<AnnotationContext>	String - IsColor
borderDash	BorderDashCallback<AnnotationContext>	List<Integer>
borderDashOffset	BorderDashOffsetCallback<AnnotationContext>	double
borderWidth	WidthCallback<AnnotationContext>	int
display	DisplayCallback<AnnotationContext>	boolean
drawTime	DrawTimeCallback	DrawTime
endValue	ValueCallback	String - double - Date
value	ValueCallback	String - double - Date
xMax	ValueCallback	String - double - Date
xMin	ValueCallback	String - double - Date
yMax	ValueCallback	String - double - Date
yMin	ValueCallback	String - double - Date

Label

A line annotation can have a label to draw on the line.

Every line annotation can have ONLY 1 label.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
// without id (a unique one is created automatically)
LineAnnotation line = new LineAnnotation();
// sets label configuration
line.getLabel().setDisplay(true);
line.getLabel().setContent("My threshold");
line.getLabel().setBackgroundColor(HtmlColor.RED);
// stores the annotation in the main options
options.setAnnotations(line);

The complete options are described by following table:

Name	Type	Default	Scriptable	Description
autoRotation	boolean	false	-	If true, the rotation option is ignored and the label uses the degrees of the line.
backgroundColor	String - IsColor	rgba(0,0,0,0.8) -	Yes	Background color of the label container.
color	String - IsColor	#fff -	Yes	The text color of the label.
content	String - String[] - Img	null	Yes	The content to show in the label. Provide an array to display values on a new line.
cornerRadius	int	6	Yes	The radius of label box in pixels.
display	boolean	false	Yes	Whether or not the label is shown.
drawTime	DrawTime	See description	-	Defines when the label is drawn. Defaults to the line annotation draw time if unset.
font	Font	See description	Yes	The text font of the label. The default value is the global font with the style set to FontStyle.BOLD. See Font.
imageHeight	int - String	Undefined.INTEGER - null	Yes	Overrides the height of the image. Could be set in pixel by a number, or in percentage of current height of image by a string. If uset, uses the height of the image. It is used only when the content is an image.
imageWidth	int - String	Undefined.INTEGER - null	Yes	Overrides the width of the image. Could be set in pixel by a number, or in percentage of current width of image by a string. If unset, uses the width of the image. It is used only when the content is an image.
position	LabelPosition	LabelPosition.CENTER	Yes	Anchor position of label on line.
rotation	double	0	Yes	The rotation of label, in degrees.
textAlign	TextAlign	TextAlign.CENTER	Yes	Horizontal alignment on the label content when is set as a multiple lines text.
xAdjust	double	0	Yes	Adjustment along x-axis (left-right) of label relative to computed position. Negative values move the label left, positive right.
xPadding	int	6	Yes	Padding of label to add left/right.
yAdjust	double	0	Yes	Adjustment along y-axis (top-bottom) of label relative to computed position. Negative values move the label up, positive down.
yPadding	int	6	Yes	Padding of label to add top/bottom.

Label scriptable options

Some options also accept a callback which is called at runtime and that takes the context as single argument, see here the details, which is representing contextual information and chart instance.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
LineAnnotation line = new LineAnnotation();
// sets callback for background color options
line.getLabel().setBackgroundColor(new ColorCallback<AnnotationContext>(){

   @Override
   public IsColor invoke(DatasetContext context){
      // logic
      return color;
   }
});
// stores the annotation in the main options
options.setAnnotations(line);

The following options can be set by a callback:

Name	Callback	Returned types
backgroundColor	ColorCallback<AnnotationContext>	String - IsColor - Pattern
color	ColorCallback<AnnotationContext>	String - IsColor
content	ContentCallback	String - List<String> - Img
cornerRadius	CornerRadiusCallback<AnnotationContext>	int
display	DisplayCallback<AnnotationContext>	boolean
font	FontCallback<AnnotationContext>	FontItem
imageHeight	ImageSizeCallback	String - int
imageWidth	ImageSizeCallback	String - int
position	LabelPositionCallback	LabelPosition
rotation	RotationCallback<AnnotationContext>	double(1)
textAlign	TextAlignCallback<AnnotationContext>	TextAlign
xAdjust	AdjustSizeCallback	double
xPadding	PaddingSizeCallback	int
yAdjust	AdjustSizeCallback	double
yPadding	PaddingSizeCallback	int

⁽¹⁾To enable autoRotation by the rotation callback, the value to return must be Double.NaN.

// sets callback for auto rotation
line.getLabel().setRotation(new RotationCallback<AnnotationContext>(){

   @Override
   public Double invoke(DatasetContext context){
      return Double.NaN; // autoRotation is set
   }
});

Point

Point annotations are used to mark points on the chart area. This can be useful for highlighting values that are of interest.

Every plugin options can have an unlimited number of points annotations.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
// without id (a unique one is created automatically)
PointAnnotation point = new PointAnnotation();
// sets annotation configuration
point.setXScaleID(DefaultScaleId.X);
point.setYScaleID(DefaultScaleId.Y);
point.setXValue("February");
point.setYValue(50);
point.setRadius(10);
point.setBackgroundColor(HtmlColor.YELLOW.alpha(0.3D));
point.setBorderWidth(2);
point.setBorderColor(HtmlColor.YELLOW.darker());
// stores the annotation in the main options
options.setAnnotations(point);

The complete options are described by following table:

Name	Type	Default	Scriptable	Description
adjustScaleRange	boolean	true	Yes	If true, the scale range should be adjusted if this annotation is out of range.
backgroundColor	String - IsColor	Defaults.get().getGlobal() .getColorAsString()	Yes	The fill color of the point. See default colors.
borderColor	String - IsColor	Defaults.get().getGlobal() .getColorAsString()	Yes	The stroke color of the point.
borderDash	int[]	[]	Yes	The line dash pattern used when stroking lines, using an array of values which specify alternating lengths of lines and gaps which describe the pattern.
borderDashOffset	int	0	Yes	Offset for border dashes. See MDN
borderWidth	int	1	Yes	The stroke width of the point.
display	boolean	true	Yes	Whether or not this annotation is visible.
drawTime	DrawTime	DrawTime. AFTER_DATASETS_DRAW	Yes	Defines when the annotation is drawn. This allows positioning of the annotation relative to the other elements of the graph.
radius	double	10	Yes	Size of the point in pixels.
xValue	String - double - Date	null	Yes	X coordinate of the point in units along the x axis.
xScaleID	String - ScaleId	DefaultScaleId.X	-	The ID of the X scale to bind onto.
yValue	String - double - Date	null	Yes	Y coordinate of the point in units along the y axis.
yScaleID	String - ScaleId	DefaultScaleId.Y	-	The ID of the Y scale to bind onto.

Point scriptable options

Some options also accept a callback which is called at runtime and that takes the context as single argument, see here the details, which is representing contextual information and chart instance.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
PointAnnotation point = new PointAnnotation();
// sets callback for border width options
point.setBorderWidth(new WidthCallback<AnnotationContext>(){

   @Override
   public Integer invoke(DatasetContext context){
      // logic
      return borderWidth;
   }
});
// stores the annotation in the main options
options.setAnnotations(point);

The following options can be set by a callback:

Name	Callback	Returned types
adjustScaleRange	AdjustScaleRangeCallback	boolean
backgroundColor	ColorCallback<AnnotationContext>	String - IsColor - Pattern
borderColor	ColorCallback<AnnotationContext>	String - IsColor
borderDash	BorderDashCallback<AnnotationContext>	List<Integer>
borderDashOffset	BorderDashOffsetCallback<AnnotationContext>	double
borderWidth	WidthCallback<AnnotationContext>	int
display	DisplayCallback<AnnotationContext>	boolean
drawTime	DrawTimeCallback	DrawTime
radius	RadiusCallback<AnnotationContext>	double
xValue	ValueCallback	String - double - Date
yValue	ValueCallback	String - double - Date

Events

All annotations provide a set of callbacks which can be enabled to catch events on them.

To catch events is enough to set the events which you want to catch at AnnotationOptions and set a callback instance in the annotation.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
// without id (a unique one is created automatically)
BoxAnnotation box = new BoxAnnotation();
// sets callback
box.setClickCallback(new ClickCallback(){
            
    @Override
    public void onClick(IsChart chart, AbstractAnnotation annotation, ChartEventContext event){
        // logic
    }
});

These are the table of callbacks to implement:

Event	Callback type	Description
enter	EnterCallback	Called when the mouse enters the annotation.
leave	LeaveCallback	Called when the mouse leaves the annotation.
click	ClickCallback	Called when a single click occurs on the annotation.
dblClick	DoubleClickCallback	Called when a double click occurs on the annotation.

Scriptable context

Some options also accept a callback which is called at runtime and that takes the context as single argument, AnnotationContext representing contextual information and chart instance.

// creates a plugin options
AnnotationOptions options = new AnnotationOptions();
// creates an annotation
BoxAnnotation box = new BoxAnnotation();
// sets callback for border width options
box.setBorderWidth(new WidthCallback<AnnotationContext>(){

   @Override
   public Integer invoke(DatasetContext context){
      // logic
      return borderWidth;
   }
});
// stores the annotation in the main options
options.setAnnotations(box);

The context object contains the following properties:

Name	Type	Description
annotation	AbstractAnnotation	The annotation configuration where the options is defined as scriptable.
attributes	NativeObjectContainer	User object which you can store your options at runtime.
chart	IsChart	Chart instance.
type	ContextType	The type of the context. It can be ContextType.CHART or ContextType.ANNOTATION