Chart Modifier APIs

Within the SciChart SDK, ChartModifiers are the classes which can be added to a chart to give it a certain behaviour. For instance, all zooming, panning operations, tooltips, legends and even selection of points or lines are handled by SCIChartModifierBase derived classes in the SciChart codebase.

There are many different ChartModifiers provided by SciChart and each one deserves an article by itself! This article is concerned with simply giving an overview of the modifiers and where you can find the examples in our SciChart iOS Examples Suite which demonstrate them.

There are also several individual articles on the ChartModifier’s and how to configure them in the SciChart iOS. Those could be grouped like the following:

Zoom and Pan Modifiers

The following modifiers can be used if you want to add scrolling or zooming behavior to a chart:

Modifier Name Description
SCIZoomExtentsModifier Resets the zoom to the data extents via double-tapping. Available almost everywhere, e.g. see the Sync Multi Chart example.
SCIPinchZoomModifier Zooms a chart in and out via the pinch and spread gestures correspondingly. Available almost everywhere, e.g. see the Multiple X-Axes example.
SCIZoomPanModifier Pans the chart in X, Y or both directions with inertia via finger sliding. Available almost everywhere, e,g. see the Multiple X-Axes example.
SCIXAxisDragModifier Scales or pans an X Axis via finger drag. See Drag Axis to Scale a Chart example.
SCIYAxisDragModifier Scales or pans an Y Axis via finger drag. See Drag Axis to Scale a Chart example.

Interactivity Modifiers

These modifiers allow to interact with chart series or inspect them:

Modifier Name Description
SCISeriesSelectionModifier Provides selection of a series via tapping on it. See the Series Selection example.
SCITooltipModifier Provides a tooltip for the nearest point on a series under the finger. See the Using TooltipModifier example.
SCIRolloverModifier Provides a vertical slice cursor with tooltips and markers rolling over a series. See the Using RolloverModifier example.
SCICursorModifier Provides a crosshairs with a tooltip and axis labels. See Using CursorModifier example.

Miscellaneous Modifiers

Modifiers below are used as helpers and can be a useful addition to a chart:

Modifier Name Description
SCIModifierGroup Can be used to group chart modifiers together. This can useful in multi-chart scenarios, to unite ModifierGroups into one EventGroup of modifiers. If an Event occurs on a chart, it will be propagated to modifiers from other charts that are in the same EventGroup. See the Multi-Panel Stock Chart example.
SCILegendModifier Allows to creates and configure a Legend for a chart. See the Legend Chart example.

NOTE: To learn more about ChartModifiers API, please read the Common ChartModifiers Features section. To find out more about a specific ChartModifier, please refer to a corresponding article about this Modifier type.

Adding a Chart Modifier

All 2D Chart Modifiers are inherited from SCIChartModifierBase, conforms to the ISCIChartModifier and are added to the SCIChartModifierCollection which is stored in ISCIChartSurface.chartModifiers property. Please see the code below, to see how to add SCIPinchZoomModifier to your SCIChartSurface:

// Assume a surface has been created and configured somewhere id<ISCIChartSurface> surface; // Create and add SCIPinchZoomModifier [self.surface.chartModifiers add:[SCIPinchZoomModifier new]];
// Assume a surface has been created and configured somewhere let surface: ISCIChartSurface // Create and add SCIPinchZoomModifier self.surface.chartModifiers.add(SCIPinchZoomModifier())
// Assume a surface has been created and configured somewhere IISCIChartSurface surface; // Create and add SCIPinchZoomModifier Surface.ChartModifiers.Add(new SCIPinchZoomModifier());

Common Chart Modifier Features

As mentioned above - all the ChartModifiers provided by SciChart conforms to the ISCIChartModifier protocol and derive from the SCIChartModifierBase class. These provide a powerful API which gives the full access to internals of a chart, axes, series, annotations. It is a must that Custom Modifiers implement ISCIChartModifier, and hence we recommend inheriting SCIChartModifierBase in such cases as well to get some base implementation for free.

Please see the list of common features below:

Feature Description
ISCIChartSurfaceProvider.parentSurface Provides the ISCIChartSurface which the modifier is attached to. See the ISCIAttachable.isAttached method below.
ISCIChartModifierCore.modifierSurface Returns the ModifierSurface from the parental SCIChartSurface. It is used to place Views like tooltips, etc. onto it.
ISCIAttachable.isAttached Value which indicates whether a modifier is attached to a SCIChartSurface or not. If it is - ISCIChartSurfaceProvider.parentSurface property will return the corresponding instance of SCIChartSurface.
ISCIChartModifierCore.isEnabled Allows to specify if a modifier should be available for interaction or not.
ISCIReceiveEvents.receiveHandledEvents Allows to specify whether a modifier should receive events handled by another modifier.

SCIModifierGroup Features

The SCIModifierGroup allows grouping of modifiers. This can be useful if modifiers create a logical group within which they are handled together. For example, all modifiers inside a SCIModifierGroup can be enabled/disabled together via the ISCIChartModifierCore.isEnabled property on the SCIModifierGroup itself.

Also, this is useful in multi-chart scenarios. Several SCIModifierGroups can be united to share events between charts. This can be done by setting SCIModifierGroup.eventGroup to be the same for ModifierGroups which belong to different SCIChartSurfaces.

Feature Description
SCIModifierGroup.eventGroup Allows to specify which EventGroup this modifier goes in. It is used to share events between modifiers that belong to different surfaces.
ISCIReceiveEventGroup.eventsSource Returns the ModifierSurface which is the source of the events.
SCIModifierGroup.childModifiers Assigns a collection of modifiers to a ModifierGroup. Also a collection can be passed into the class constructor during creation.