How to: Add a scroll bar for CheckBoxList and RadioButtonList
- 2021-08-03 10:06:26
- OfStack
How do I add scroll bars to CheckBoxList and RadioButtonList?
Inherit the base classes CheckBoxList and RadioButtonList, add the scroll attribute, and override the Render method.
Attribute list:
#region Rolling control
private bool _ShowScrollBar = false;
/// <summary>
/// Show scroll bar
/// </summary>
[
System.ComponentModel.Description(" Whether to display the display scroll bar ")
, System.ComponentModel.DefaultValue(false)
, System.ComponentModel.Category(" Scroll bar settings ")
, System.ComponentModel.Bindable(System.ComponentModel.BindableSupport.Yes)
]
public bool ShowScrollBar
{
get { return _ShowScrollBar; }
set { _ShowScrollBar = value; }
}
private Overflow _OverflowY = Overflow.auto;
/// <summary>
/// Vertical scroll bar
/// </summary>
[
System.ComponentModel.Description(" Vertical scroll bar ")
, System.ComponentModel.DefaultValue(Overflow.auto)
, System.ComponentModel.Category(" Scroll bar settings ")
, System.ComponentModel.Bindable(System.ComponentModel.BindableSupport.Yes)
]
public Overflow OverflowY
{
get { return _OverflowY; }
set { _OverflowY = value; }
}
private Overflow _OverflowX = Overflow.auto;
/// <summary>
/// Horizontal scroll bar
/// </summary>
[
System.ComponentModel.Description(" Horizontal scroll bar ")
, System.ComponentModel.DefaultValue(Overflow.auto)
, System.ComponentModel.Category(" Scroll bar settings ")
, System.ComponentModel.Bindable(System.ComponentModel.BindableSupport.Yes)
]
public Overflow OverflowX
{
get { return _OverflowX; }
set { _OverflowX = value; }
}
private Unit _ScrollHeight = Unit.Parse("0px");
/// <summary>
/// Rolling height
/// </summary>
[
System.ComponentModel.Description(" Rolling height ")
, System.ComponentModel.Category(" Scroll bar settings ")
, DefaultValue("0px")
, System.ComponentModel.Bindable(System.ComponentModel.BindableSupport.Yes)
]
public Unit ScrollHeight
{
get { return _ScrollHeight; }
set { _ScrollHeight = value; }
}
private Unit _ScrollWidth = Unit.Parse("0px");
/// <summary>
/// Scroll width
/// </summary>
[
System.ComponentModel.Description(" Scroll width ")
, System.ComponentModel.Category(" Scroll bar settings ")
, DefaultValue("0px")
, System.ComponentModel.Bindable(System.ComponentModel.BindableSupport.Yes)
]
public Unit ScrollWidth
{
get { return _ScrollWidth; }
set { _ScrollWidth = value; }
}
private string _ScrollCssClass = "";
/// <summary>
/// Scroll style settings
/// </summary>
[
System.ComponentModel.Description(" Scroll style settings ")
, System.ComponentModel.Category(" Scroll bar settings ")
, System.ComponentModel.DefaultValue("")
, System.ComponentModel.Bindable(System.ComponentModel.BindableSupport.Yes)
]
public string ScrollCssClass
{
get { return _ScrollCssClass; }
set { _ScrollCssClass = value; }
}
#region Writing label
void WriteBeginSpan(HtmlTextWriter writer)
{
if (this._ShowScrollBar)
{
StringBuilder strSpan = new StringBuilder();
strSpan.Append("<span ");
strSpan.Append(string.Format("style='overflow-y:{0};overflow-x:{1};",
System.Enum.GetName(typeof(Overflow), this._OverflowY),
System.Enum.GetName(typeof(Overflow), this._OverflowX)));
if (this._ScrollHeight.ToString() != "0px")
{
strSpan.Append(string.Format("height:{0};", this._ScrollHeight));
}
if (this._ScrollWidth.ToString() != "0px")
{
strSpan.Append(string.Format("width:{0};", this._ScrollWidth));
}
strSpan.Append("';");
if (!string.IsNullOrEmpty(_ScrollCssClass))
{
strSpan.Append(string.Format(" class='{0}'", _ScrollCssClass));
}
strSpan.Append(">");
writer.Write(strSpan.ToString());
}
}
void WriteEndSpan(HtmlTextWriter writer)
{
if (this._ShowScrollBar)
{
writer.Write("</span>");
}
}
#endregion
#endregion
Override the Render method:
protected override void Render(HtmlTextWriter writer)
{
this.WriteBeginSpan(writer);
base.Render(writer);
this.WriteEndSpan(writer);
}
That's it.
Also define an enumeration:
public enum Overflow
{
auto = 0,
hidden = 1,
scroll = 2,
visible = 3,
inherit = 4
}