AccessibleObject.Role 屬性
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
取得這個可存取之物件的角色。
public:
virtual property System::Windows::Forms::AccessibleRole Role { System::Windows::Forms::AccessibleRole get(); };public virtual System.Windows.Forms.AccessibleRole Role { get; }member this.Role : System.Windows.Forms.AccessibleRolePublic Overridable ReadOnly Property Role As AccessibleRole屬性值
其中一個 AccessibleRole 值；如果尚未指定角色，則為 None。
範例
下列範例示範如何使用 AccessibleObject 和 Control.ControlAccessibleObject 類別來公開無障礙資訊，來建立協助工具感知圖表控制項。 控制項會繪製兩個曲線以及圖例。 ChartControlAccessibleObject衍生自 ControlAccessibleObject 的 類別會用於 方法中 CreateAccessibilityInstance ，以提供圖表控制項的自訂可存取訊號。 由於圖表圖例不是實際的 Control 控制項，而是由圖表控制項繪製，因此它沒有任何內建的可存取訊號。 因此，類別 ChartControlAccessibleObject 會 GetChild 覆寫 方法，以傳回 CurveLegendAccessibleObject ，代表圖例每個部分的可存取訊號。 當可存取感知應用程式使用此控制項時，控制項可以提供必要的可存取訊號。
此程式碼摘錄示範覆 Role 寫 屬性。 AccessibleObject如需完整的程式碼範例，請參閱類別概觀。
// Inner class ChartControlAccessibleObject represents accessible information associated with the ChartControl.
// The ChartControlAccessibleObject is returned in the ChartControl::CreateAccessibilityInstance .
ref class ChartControlAccessibleObject: public ControlAccessibleObject
{
private:
ChartControl^ chartControl;
public:
ChartControlAccessibleObject( ChartControl^ ctrl )
: ControlAccessibleObject( ctrl )
{
chartControl = ctrl;
}
property System::Windows::Forms::AccessibleRole Role
{
// Gets the role for the Chart. This is used by accessibility programs.
virtual System::Windows::Forms::AccessibleRole get() override
{
return ::AccessibleRole::Chart;
}
}
property AccessibleStates State
{
// Gets the state for the Chart. This is used by accessibility programs.
virtual AccessibleStates get() override
{
return AccessibleStates::ReadOnly;
}
}
// The CurveLegend objects are "child" controls in terms of accessibility so
// return the number of ChartLengend objects.
virtual int GetChildCount() override
{
return chartControl->Legends->Length;
}
// Gets the Accessibility object of the child CurveLegend idetified by index.
virtual AccessibleObject^ GetChild( int index ) override
{
if ( index >= 0 && index < chartControl->Legends->Length )
{
return chartControl->Legends[ index ]->AccessibilityObject;
}
return nullptr;
}
internal:
// Helper function that is used by the CurveLegend's accessibility object
// to navigate between sibiling controls. Specifically, this function is used in
// the CurveLegend::CurveLegendAccessibleObject.Navigate function.
AccessibleObject^ NavigateFromChild( CurveLegend::CurveLegendAccessibleObject^ child, AccessibleNavigation navdir )
{
switch ( navdir )
{
case AccessibleNavigation::Down:
case AccessibleNavigation::Next:
return GetChild( child->ID + 1 );
case AccessibleNavigation::Up:
case AccessibleNavigation::Previous:
return GetChild( child->ID - 1 );
}
return nullptr;
}
// Helper function that is used by the CurveLegend's accessibility object
// to select a specific CurveLegend control. Specifically, this function is used
// in the CurveLegend::CurveLegendAccessibleObject.Select function.
void SelectChild( CurveLegend::CurveLegendAccessibleObject^ child, AccessibleSelection selection )
{
int childID = child->ID;
// Determine which selection action should occur, based on the
// AccessibleSelection value.
if ( (selection & AccessibleSelection::TakeSelection) != (AccessibleSelection)0 )
{
for ( int i = 0; i < chartControl->Legends->Length; i++ )
{
if ( i == childID )
{
chartControl->Legends[ i ]->Selected = true;
}
else
{
chartControl->Legends[ i ]->Selected = false;
}
}
// AccessibleSelection->AddSelection means that the CurveLegend will be selected.
if ( (selection & AccessibleSelection::AddSelection) != (AccessibleSelection)0 )
{
chartControl->Legends[ childID ]->Selected = true;
}
// AccessibleSelection->AddSelection means that the CurveLegend will be unselected.
if ( (selection & AccessibleSelection::RemoveSelection) != (AccessibleSelection)0 )
{
chartControl->Legends[ childID ]->Selected = false;
}
}
}
};
// class ChartControlAccessibleObject
// Inner class ChartControlAccessibleObject represents accessible information associated with the ChartControl.
// The ChartControlAccessibleObject is returned in the ChartControl.CreateAccessibilityInstance override.
public class ChartControlAccessibleObject : ControlAccessibleObject
{
ChartControl chartControl;
public ChartControlAccessibleObject(ChartControl ctrl) : base(ctrl)
{
chartControl = ctrl;
}
// Gets the role for the Chart. This is used by accessibility programs.
public override AccessibleRole Role
{
get {
return AccessibleRole.Chart;
}
}
// Gets the state for the Chart. This is used by accessibility programs.
public override AccessibleStates State
{
get {
return AccessibleStates.ReadOnly;
}
}
// The CurveLegend objects are "child" controls in terms of accessibility so
// return the number of ChartLengend objects.
public override int GetChildCount()
{
return chartControl.Legends.Length;
}
// Gets the Accessibility object of the child CurveLegend idetified by index.
public override AccessibleObject GetChild(int index)
{
if (index >= 0 && index < chartControl.Legends.Length) {
return chartControl.Legends[index].AccessibilityObject;
}
return null;
}
// Helper function that is used by the CurveLegend's accessibility object
// to navigate between sibiling controls. Specifically, this function is used in
// the CurveLegend.CurveLegendAccessibleObject.Navigate function.
internal AccessibleObject NavigateFromChild(CurveLegend.CurveLegendAccessibleObject child,
AccessibleNavigation navdir)
{
switch(navdir) {
case AccessibleNavigation.Down:
case AccessibleNavigation.Next:
return GetChild(child.ID + 1);
case AccessibleNavigation.Up:
case AccessibleNavigation.Previous:
return GetChild(child.ID - 1);
}
return null;
}
// Helper function that is used by the CurveLegend's accessibility object
// to select a specific CurveLegend control. Specifically, this function is used
// in the CurveLegend.CurveLegendAccessibleObject.Select function.
internal void SelectChild(CurveLegend.CurveLegendAccessibleObject child, AccessibleSelection selection)
{
int childID = child.ID;
// Determine which selection action should occur, based on the
// AccessibleSelection value.
if ((selection & AccessibleSelection.TakeSelection) != 0) {
for(int i = 0; i < chartControl.Legends.Length; i++) {
if (i == childID) {
chartControl.Legends[i].Selected = true;
} else {
chartControl.Legends[i].Selected = false;
}
}
// AccessibleSelection.AddSelection means that the CurveLegend will be selected.
if ((selection & AccessibleSelection.AddSelection) != 0) {
chartControl.Legends[childID].Selected = true;
}
// AccessibleSelection.AddSelection means that the CurveLegend will be unselected.
if ((selection & AccessibleSelection.RemoveSelection) != 0) {
chartControl.Legends[childID].Selected = false;
}
}
}
}
' Inner Class ChartControlAccessibleObject represents accessible information
' associated with the ChartControl.
' The ChartControlAccessibleObject is returned in the ' ChartControl.CreateAccessibilityInstance override.
Public Class ChartControlAccessibleObject
Inherits Control.ControlAccessibleObject
Private chartControl As ChartControl
Public Sub New(ctrl As ChartControl)
MyBase.New(ctrl)
chartControl = ctrl
End Sub
' Get the role for the Chart. This is used by accessibility programs.
Public Overrides ReadOnly Property Role() As AccessibleRole
Get
Return System.Windows.Forms.AccessibleRole.Chart
End Get
End Property
' Get the state for the Chart. This is used by accessibility programs.
Public Overrides ReadOnly Property State() As AccessibleStates
Get
Return AccessibleStates.ReadOnly
End Get
End Property
' The CurveLegend objects are "child" controls in terms of accessibility so
' return the number of ChartLengend objects.
Public Overrides Function GetChildCount() As Integer
Return chartControl.Legends.Length
End Function
' Get the Accessibility object of the child CurveLegend idetified by index.
Public Overrides Function GetChild(index As Integer) As AccessibleObject
If index >= 0 And index < chartControl.Legends.Length Then
Return chartControl.Legends(index).AccessibilityObject
End If
Return Nothing
End Function
' Helper function that is used by the CurveLegend's accessibility object
' to navigate between sibiling controls. Specifically, this function is used in
' the CurveLegend.CurveLegendAccessibleObject.Navigate function.
Friend Function NavigateFromChild(child As CurveLegend.CurveLegendAccessibleObject, _
navdir As AccessibleNavigation) As AccessibleObject
Select Case navdir
Case AccessibleNavigation.Down, AccessibleNavigation.Next
Return GetChild(child.ID + 1)
Case AccessibleNavigation.Up, AccessibleNavigation.Previous
Return GetChild(child.ID - 1)
End Select
Return Nothing
End Function
' Helper function that is used by the CurveLegend's accessibility object
' to select a specific CurveLegend control. Specifically, this function is used
' in the CurveLegend.CurveLegendAccessibleObject.Select function.
Friend Sub SelectChild(child As CurveLegend.CurveLegendAccessibleObject, selection As AccessibleSelection)
Dim childID As Integer = child.ID
' Determine which selection action should occur, based on the
' AccessibleSelection value.
If (selection And AccessibleSelection.TakeSelection) <> 0 Then
Dim i As Integer
For i = 0 To chartControl.Legends.Length - 1
If i = childID Then
chartControl.Legends(i).Selected = True
Else
chartControl.Legends(i).Selected = False
End If
Next i
' AccessibleSelection.AddSelection means that the CurveLegend will be selected.
If (selection And AccessibleSelection.AddSelection) <> 0 Then
chartControl.Legends(childID).Selected = True
End If
' AccessibleSelection.AddSelection means that the CurveLegend will be unselected.
If (selection And AccessibleSelection.RemoveSelection) <> 0 Then
chartControl.Legends(childID).Selected = False
End If
End If
End Sub
End Class
備註
物件的角色有助於描述 物件的函式。
給繼承者的注意事項
所有物件都應該支援這個屬性。