ListBoxExItemCollection 类视图
ListBoxExItemCollection 类源码：
[ListBindable(false)]
public classListBoxExItemCollection
: IList,ICollection,IEnumerable
{
FieldsFields
privateListBoxEx _owner;
#endregion
ConstructorsConstructors
publicListBoxExItemCollection(ListBoxEx owner)
{
_owner =owner;
}
#endregion
PropertiesProperties
internalListBoxEx Owner
{
get { return_owner; }
}
publicListBoxExItem this[intindex]
{
get { returnOwner.OldItems[index] asListBoxExItem; }
set { Owner.OldItems[index] =value; }
}
public intCount
{
get { returnOwner.OldItems.Count; }
}
public boolIsReadOnly
{
get { returnOwner.OldItems.IsReadOnly; }
}
#endregion
Public MethodsPublic Methods
public intAdd(ListBoxExItem item)
{
if(item == null)
{
throw newArgumentNullException("item");
}
returnOwner.OldItems.Add(item);
}
public voidAddRange(ListBoxExItemCollection value)
{
foreach(ListBoxExItem item invalue)
{
Add(item);
}
}
public voidAddRange(ListBoxExItem[] items)
{
Owner.OldItems.AddRange(items);
}
public voidClear()
{
Owner.OldItems.Clear();
}
public boolContains(ListBoxExItem item)
{
returnOwner.OldItems.Contains(item);
}
public voidCopyTo(
ListBoxExItem[] destination,
intarrayIndex)
{
Owner.OldItems.CopyTo(destination, arrayIndex);
}
public intIndexOf(ListBoxExItem item)
{
returnOwner.OldItems.IndexOf(item);
}
public voidInsert(intindex, ListBoxExItem item)
{
if(item == null)
{
throw newArgumentNullException("item");
}
Owner.OldItems.Insert(index, item);
}
public voidRemove(ListBoxExItem item)
{
Owner.OldItems.Remove(item);
}
public voidRemoveAt(intindex)
{
Owner.OldItems.RemoveAt(index);
}
publicIEnumerator GetEnumerator()
{
returnOwner.OldItems.GetEnumerator();
}
#endregion
IList 成员IList 成员
intIList.Add(objectvalue)
{
if(!(value isListBoxExItem))
{
throw newArgumentException();
}
returnAdd(value asListBoxExItem);
}
voidIList.Clear()
{
Clear();
}
boolIList.Contains(objectvalue)
{
returnContains(value asListBoxExItem);
}
intIList.IndexOf(objectvalue)
{
returnIndexOf(value asListBoxExItem);
}
voidIList.Insert(intindex, objectvalue)
{
if(!(value isListBoxExItem))
{
throw newArgumentException();
}
Insert(index, value asListBoxExItem);
}
boolIList.IsFixedSize
{
get { return false; }
}
boolIList.IsReadOnly
{
get { returnIsReadOnly; }
}
voidIList.Remove(objectvalue)
{
Remove(value asListBoxExItem);
}
voidIList.RemoveAt(intindex)
{
RemoveAt(index);
}
objectIList.this[intindex]
{
get
{
return this[index];
}
set
{
if(!(value isListBoxExItem))
{
throw newArgumentException();
}
this[index] =value asListBoxExItem;
}
}
#endregion
ICollection 成员ICollection 成员
voidICollection.CopyTo(Array array, intindex)
{
CopyTo((ListBoxExItem[])array, index);
}
intICollection.Count
{
get { returnCount; }
}
boolICollection.IsSynchronized
{
get { return false; }
}
objectICollection.SyncRoot
{
get { return this; }
}
#endregion
IEnumerable 成员IEnumerable 成员
IEnumerator IEnumerable.GetEnumerator()
{
returnGetEnumerator();
}
#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：
internalListBox.ObjectCollection OldItems
{
get { return base.Items; }
}
[Localizable(true)]
[MergableProperty(false)]
[DesignerSerializationVisibility(
DesignerSerializationVisibility.Content)]
public newListBoxExItemCollection 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 voidOnDrawItem(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 = newSolidBrush(backColor))
{
g.FillRectangle(brush, bounds);
}
}
Image image =item.Image;
Rectangle imageRect = newRectangle(
bounds.X + 2,
bounds.Y + 2,
bounds.Height - 4,
bounds.Height - 4);
Rectangle textRect = newRectangle(
imageRect.Right + 2,
bounds.Y,
bounds.Width -imageRect.Right - 2,
bounds.Height);
stringtext =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。