public event ASPxCardViewCustomButtonEventHandler CustomButtonInitialize

Public Event CustomButtonInitialize As ASPxCardViewCustomButtonEventHandler

<dx:ASPxCardView ID="ASPxCardView1" runat="server" DataSourceID="AccessDataSource1"         
    OnCustomButtonInitialize="ASPxCardView1_CustomButtonInitialize" 
    OnCommandButtonInitialize="ASPxCardView1_CommandButtonInitialize" 
    KeyFieldName="ProductID" AutoGenerateColumns="False">
    <ClientSideEvents CustomButtonClick="function(s, e) {alert('keyValue = ' + s.GetCardKey(e.visibleIndex));}" />
    <SettingsBehavior AllowFocusedCard="true" />
    <Columns>
        <dx:CardViewTextColumn FieldName="ProductName" />
        <dx:CardViewTextColumn FieldName="UnitPrice" />
        <dx:CardViewTextColumn FieldName="ProductID" ReadOnly="True">
    </Columns>
    <CardLayoutProperties>
        <Items>
            <dx:CardViewCommandLayoutItem HorizontalAlign="Right" 
                                          ShowDeleteButton="True" 
                                          ShowEditButton="True" />
            <dx:CardViewColumnLayoutItem ColumnName="ProductID" />
            <dx:CardViewColumnLayoutItem ColumnName="Product Name" />
            <dx:CardViewColumnLayoutItem ColumnName="UnitPrice" />
        </Items>
    </CardLayoutProperties>
</dx:ASPxCardView>

protected void Page_Load(object sender, EventArgs e) {
    if (!IsPostBack) {
        (ASPxCardView1.CardLayoutProperties.Items[0] as CardViewCommandLayoutItem).CustomButtons.Add(CreateCustomButton());
    }
}
CardViewCustomCommandButton CreateCustomButton() {
    CardViewCustomCommandButton customBtn = new CardViewCustomCommandButton();
    customBtn.ID = "CustomBtn";
    customBtn.Text = "Custom button";
    return customBtn;
}
protected void ASPxCardView1_CommandButtonInitialize(object sender, ASPxCardViewCommandButtonEventArgs e) {
    if (e.VisibleIndex == -1) return;
    switch (e.ButtonType) {
        case CardViewCommandButtonType.Edit:
            e.Visible = EditButtonVisibleCriteria((ASPxCardView)sender, e.VisibleIndex);
            break;
        case CardViewCommandButtonType.Delete:
            e.Visible = DeleteButtonVisibleCriteria((ASPxCardView)sender, e.VisibleIndex);
            break;
    }
}
private bool EditButtonVisibleCriteria(ASPxCardView grid, int visibleIndex) {
    object card = grid.GetDataRow(visibleIndex);
    return ((DataRow)card)["ProductName"].ToString().Contains("a");
}
private bool DeleteButtonVisibleCriteria(ASPxCardView grid, int visibleIndex) {
    object card = grid.GetDataRow(visibleIndex);
    return ((DataRow)card)["ProductName"].ToString().Contains("b");
}
protected void ASPxCardView1_CustomButtonInitialize(object sender, ASPxCardViewCustomCommandButtonEventArgs e) {
    if (e.VisibleIndex == -1) return;
    if (e.ButtonID == "CustomBtn" && e.VisibleIndex % 2 != 0)
        e.Visible = DefaultBoolean.False;
}

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
    If Not IsPostBack Then
        TryCast(ASPxCardView1.CardLayoutProperties.Items(0), CardViewCommandLayoutItem).CustomButtons.Add(CreateCustomButton())
    End If
End Sub
Private Function CreateCustomButton() As CardViewCustomCommandButton
    Dim customBtn As New CardViewCustomCommandButton()
    customBtn.ID = "CustomBtn"
    customBtn.Text = "Custom button"
    Return customBtn
End Function
Protected Sub ASPxCardView1_CommandButtonInitialize(ByVal sender As Object, ByVal e As ASPxCardViewCommandButtonEventArgs)
    If e.VisibleIndex = -1 Then
        Return
    End If
    Select Case e.ButtonType
        Case CardViewCommandButtonType.Edit
            e.Visible = EditButtonVisibleCriteria(DirectCast(sender, ASPxCardView), e.VisibleIndex)
        Case CardViewCommandButtonType.Delete
            e.Visible = DeleteButtonVisibleCriteria(DirectCast(sender, ASPxCardView), e.VisibleIndex)
    End Select
End Sub
Private Function EditButtonVisibleCriteria(ByVal grid As ASPxCardView, ByVal visibleIndex As Integer) As Boolean
    Dim card As Object = grid.GetDataRow(visibleIndex)
    Return DirectCast(card, DataRow)("ProductName").ToString().Contains("a")
End Function
Private Function DeleteButtonVisibleCriteria(ByVal grid As ASPxCardView, ByVal visibleIndex As Integer) As Boolean
    Dim card As Object = grid.GetDataRow(visibleIndex)
    Return DirectCast(card, DataRow)("ProductName").ToString().Contains("b")
End Function
Protected Sub ASPxCardView1_CustomButtonInitialize(ByVal sender As Object, ByVal e As ASPxCardViewCustomCommandButtonEventArgs)
    If e.VisibleIndex = -1 Then
        Return
    End If
    If e.ButtonID = "CustomBtn" AndAlso e.VisibleIndex Mod 2 <> 0 Then
        e.Visible = DefaultBoolean.False
    End If
End Sub