ListBoxExItemCollection 类视图
ListBoxExItemCollection 类源码：
[ListBindable(false)]
public class ListBoxExItemCollection
: IList,ICollection,IEnumerable
{
Fields Fields
private ListBoxEx _owner;
#endregion
Constructors Constructors
public ListBoxExItemCollection(ListBoxEx owner)
{
_owner = owner;
}
#endregion
Properties Properties
internal ListBoxEx Owner
{
get { return _owner; }
}
public ListBoxExItem this[int index]
{
get { return Owner.OldItems[index] as ListBoxExItem; }
set { Owner.OldItems[index] = value; }
}
public int Count
{
get { return Owner.OldItems.Count; }
}
public bool IsReadOnly
{
get { return Owner.OldItems.IsReadOnly; }
}
#endregion
Public Methods Public Methods
public int Add(ListBoxExItem item)
{
if (item == null)
{
throw new ArgumentNullException("item");
}
return Owner.OldItems.Add(item);
}
public void AddRange(ListBoxExItemCollection value)
{
foreach (ListBoxExItem item in value)
{
Add(item);
}
}
public void AddRange(ListBoxExItem[] items)
{
Owner.OldItems.AddRange(items);
}
public void Clear()
{
Owner.OldItems.Clear();
}
public bool Contains(ListBoxExItem item)
{
return Owner.OldItems.Contains(item);
}
public void CopyTo(
ListBoxExItem[] destination,
int arrayIndex)
{
Owner.OldItems.CopyTo(destination, arrayIndex);
}
public int IndexOf(ListBoxExItem item)
{
return Owner.OldItems.IndexOf(item);
}
public void Insert(int index, ListBoxExItem item)
{
if (item == null)
{
throw new ArgumentNullException("item");
}
Owner.OldItems.Insert(index, item);
}
public void Remove(ListBoxExItem item)
{
Owner.OldItems.Remove(item);
}
public void RemoveAt(int index)
{
Owner.OldItems.RemoveAt(index);
}
public IEnumerator GetEnumerator()
{
return Owner.OldItems.GetEnumerator();
}
#endregion
IList 成员 IList 成员
int IList.Add(object value)
{
if (!(value is ListBoxExItem))
{
throw new ArgumentException();
}
return Add(value as ListBoxExItem);
}
void IList.Clear()
{
Clear();
}
bool IList.Contains(object value)
{
return Contains(value as ListBoxExItem);
}
int IList.IndexOf(object value)
{
return IndexOf(value as ListBoxExItem);
}
void IList.Insert(int index, object value)
{
if (!(value is ListBoxExItem))
{
throw new ArgumentException();
}
Insert(index, value as ListBoxExItem);
}
bool IList.IsFixedSize
{
get { return false; }
}
bool IList.IsReadOnly
{
get { return IsReadOnly; }
}
void IList.Remove(object value)
{
Remove(value as ListBoxExItem);
}
void IList.RemoveAt(int index)
{
RemoveAt(index);
}
object IList.this[int index]
{
get
{
return this[index];
}
set
{
if (!(value is ListBoxExItem))
{
throw new ArgumentException();
}
this[index] = value as ListBoxExItem;
}
}
#endregion
ICollection 成员 ICollection 成员
void ICollection.CopyTo(Array array, int index)
{
CopyTo((ListBoxExItem[])array, index);
}
int ICollection.Count
{
get { return Count; }
}
bool ICollection.IsSynchronized
{
get { return false; }
}
object ICollection.SyncRoot
{
get { return this; }
}
#endregion
IEnumerable 成员 IEnumerable 成员
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
#endregion
}
准备工作做好了，现在我们来动一动ListBox了，先给它加一个OldItems属性，表示的是它原来的Items属性，然后我们需要用我们自己定义的ListBoxExItemCollection集合来定义一个Items属性，覆盖原来的Items属性，这样在设计的时候就是设计我们自己定义的ListBoxExItem项了，我们就可以设置我们自己的项的图标和文本了。看看这两个属性的定义：
internal ListBox.ObjectCollection OldItems
{
get { return base.Items; }
}
[Localizable(true)]
[MergableProperty(false)]
[DesignerSerializationVisibility(
DesignerSerializationVisibility.Content)]
public new ListBoxExItemCollection Items
{
get { return _items; }
}
最后就是DrawItem了，我们直接用我们自己自定义的Items就可以获取需要绘制的ListBoxExItem项了，我们把图标和文本绘好就OK了。看看绘制的代码：
protected override void OnDrawItem(DrawItemEventArgs e)
{
base.OnDrawItem(e);
if (e.Index != -1 && base.Items.Count > 0)
{
System.Diagnostics.Debug.WriteLine(e.State);
Rectangle bounds = e.Bounds;
ListBoxExItem item = Items[e.Index];
Graphics g = e.Graphics;
if ((e.State & DrawItemState.Selected)
== DrawItemState.Selected)
{
RenderBackgroundInternal(
g,
bounds,
_selectedColor,
_selectedColor,
Color.FromArgb(200, 255, 255, 255),
0.45f,
true,
LinearGradientMode.Vertical);
}
else
{
Color backColor;
if (e.Index % 2 == 0)
{
backColor = _rowBackColor2;
}
else
{
backColor = _rowBackColor1;
}
using (SolidBrush brush = new SolidBrush(backColor))
{
g.FillRectangle(brush, bounds);
}
}
Image image = item.Image;
Rectangle imageRect = new Rectangle(
bounds.X + 2,
bounds.Y + 2,
bounds.Height - 4,
bounds.Height - 4);
Rectangle textRect = new Rectangle(
imageRect.Right + 2,
bounds.Y,
bounds.Width - imageRect.Right - 2,
bounds.Height);
string text = item.ToString();
TextFormatFlags formatFlags =
TextFormatFlags.VerticalCenter;
if (RightToLeft == RightToLeft.Yes)
{
imageRect.X = bounds.Right - imageRect.Right;
textRect.X = bounds.Right - textRect.Right;
formatFlags |= TextFormatFlags.RightToLeft;
formatFlags |= TextFormatFlags.Right;
}
else
{
formatFlags |= TextFormatFlags.Left;
}
if (image != null)
{
g.InterpolationMode =
InterpolationMode.HighQualityBilinear;
g.DrawImage(
image,
imageRect,
0,
0,
image.Width,
image.Height,
GraphicsUnit.Pixel);
}
TextRenderer.DrawText(
g,
text,
Font,
textRect,
ForeColor,
v formatFlags);
if ((e.State & DrawItemState.Focus) ==
DrawItemState.Focus)
{
e.DrawFocusRectangle();
}
}
}
接下来开始换ListBox控件的边框颜色，这个功能需要用到一些API函数，简单的介绍一下实现的原理，首先我们需要获取ListBox控件非客户区的区域，这个需要注意的地方是需要排除滚动条的区域，应为这个区域系统会自己绘制滚动条的，我们不需要处理。获取非客户区域后，我们就用ListBox控件的背景色来填充它，然后再绘制边框，这些绘制需要在WM_NCPAINT消息中绘制，具体的实现大家可以下载源码看，由于涉及的源码比较多，这里就不贴源码了。
好了，现在整个ListBox控件的扩展和美化就完成了，希望你能喜欢，也希望对你有所帮助。最后希望大家继续支持CS程序员之窗。
