Provides data for the QueryAccessibilityHelp event.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
Thetype exposes the following members.
|QueryAccessibilityHelpEventArgs()||Initializes a new instance of the class.|
|QueryAccessibilityHelpEventArgs(String, String, String)||Initializes a new instance of the class.|
|Equals(Object)||Determines whether the specified object is equal to the current object. (Inherited from Object.)|
|Finalize||Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)|
|GetHashCode||Serves as the default hash function. (Inherited from Object.)|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|MemberwiseClone||Creates a shallow copy of the current Object. (Inherited from Object.)|
|ToString||Returns a string that represents the current object. (Inherited from Object.)|
The Control class exposes a public QueryAccessibilityHelp event. You can use the properties of the class to return custom help for a particular control to an accessible client, such as a screen reader. When you handle the QueryAccessibilityHelp event, you must set the values of the HelpNamespace, HelpKeyword, and HelpString properties to appropriate values.
The HelpKeyword property should be a string representation of a numeric Help topic ID.
The following code example demonstrates the creation of an accessibility-aware chart control, using the AccessibleObject and Control.ControlAccessibleObject classes to expose accessible information. The control plots two curves along with a legend. The ChartControlAccessibleObject class, which derives from ControlAccessibleObject, is used in the CreateAccessibilityInstance method to provide custom accessible information for the chart control. Because the chart legend is not an actual Control-based control, but instead is drawn by the chart control, it does not any built-in accessible information. Because of this, the ChartControlAccessibleObject class overrides the GetChild method to return the CurveLegendAccessibleObject that represents accessible information for each part of the legend. When an accessible-aware application uses this control, the control can provide the necessary accessible information.