winform下重画ListBox
Windows Forms是由Win32 API封装的开发组件，最初是为了替代mfc，但却没有体现与Model View Controller架构对应的特色，进而在.net framework 3.0中推出了wpf，富控件数据显示方面，利用模板功能轻松实现。
在winform下要想自定义一些用户控件，就需要运用的2D绘画类。下图我们为ListBox重新排列了数据显示方式，并为每一个item加入了删除按钮。
首先我们设计一个承载数据的类ListBoxItem。
public class ListBoxItem : IDisposable
{
public Guid Id { get; set; }
public string Name { get; set; }
public string IP { get; set; }
public string Mac { get; set; }
[System.ComponentModel.DefaultValue(typeof(System.Drawing.Image), "null")]
public System.Drawing.Image Image { get; set; }
public bool IsFocus { get; set; }
public ListBoxItem() { }
public ListBoxItem(Guid id, string name, string ip, string mac, System.Drawing.Image image)
{
this.Id = id;
this.Name = name;
this.IP = ip;
this.Mac = mac;
this.Image = image;
this.IsFocus = false;
}
public void Dispose()
{
this.Image = null;
}
}
然后我们再为ListBox写一个用于展现数据的数据源ListBoxItemCollection，这里实现了迭代和集合操作接口，可以根据需要扩展数据操作方法。
[System.ComponentModel.ListBindable(false)]
public class ListBoxItemCollection : IList, ICollection, IEnumerable
{
private UserListBox m_owner;
public ListBoxItemCollection(UserListBox owner)
{
this.m_owner = owner;
}
internal UserListBox Owner
{
get { return this.m_owner; }
}
#region override
public ListBoxItem this[int index]
{
get { return Owner.OldItemSource[index] as ListBoxItem; }
set { Owner.OldItemSource[index] = value; }
}
public int Count
{
get { return Owner.OldItemSource.Count; }
}
public bool IsReadOnly
{
get { return Owner.OldItemSource.IsReadOnly; }
}
public int Add(ListBoxItem item)
{
if (item == null)
{
throw new ArgumentException("item is null");
}
return Owner.OldItemSource.Add(item);
}
public void AddRange(ListBoxItem[] items)
{
Owner.OldItemSource.AddRange(items);
}
public void Clear()
{
if (Owner.OldItemSource.Count > 0)
{
Owner.OldItemSource.Clear();
}
}
public bool Contains(ListBoxItem item)
{
bool rst = false;
foreach (ListBoxItem oldItem in Owner.OldItemSource)
{
if (oldItem.Id == item.Id)
{
rst = true;
break;
}
}
return rst;
}
public void CopyTo(ListBoxItem[] destination, int arrayIndex)
{
Owner.OldItemSource.CopyTo(destination, arrayIndex);
}
public int IndexOf(ListBoxItem item)
{
return Owner.OldItemSource.IndexOf(item);
}
public void Insert(int index, ListBoxItem item)
{
if (item == null)
{
throw new ArgumentException("item is null");
}
Owner.OldItemSource.Insert(index, item);
}
public void Remove(ListBoxItem item)
{
Owner.OldItemSource.Remove(item);
}
public void RemoveAt(int index)
{
Owner.OldItemSource.RemoveAt(index);
}
public IEnumerator GetEnumerator()
{
return Owner.OldItemSource.GetEnumerator();
}
int IList.Add(object value)
{
if (!(value is ListBoxItem))
{
throw new ArgumentException();
}
return Add(value as ListBoxItem);
}
void IList.Clear()
{
Clear();
}
bool IList.Contains(object value)
{
return Contains(value as ListBoxItem);
}
int IList.IndexOf(object value)
{
return IndexOf(value as ListBoxItem);
}
void IList.Insert(int index, object value)
{
if (!(value is ListBoxItem))
{
throw new ArgumentException();
}
Insert(index, value as ListBoxItem);
}
bool IList.IsFixedSize
{
get { return false; }
}
bool IList.IsReadOnly
{
get { return IsReadOnly; }
}
void IList.Remove(object value)
{
Remove(value as ListBoxItem);
}
void IList.RemoveAt(int index)
{
RemoveAt(index);
}
object IList.this[int index]
{
get { return this[index]; }
set
{
if (!(value is ListBoxItem))
{
throw new ArgumentException();
}
this[index] = value as ListBoxItem;
}
}
void ICollection.CopyTo(Array array, int index)
{
CopyTo((ListBoxItem[])array, index);
}
int ICollection.Count
{
get { return Count; }
}
bool ICollection.IsSynchronized
{
get { return false; }
}
object ICollection.SyncRoot
{
get { return false; }
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
#endregion
#region extention
public ListBoxItem FindByMac(string mac)
{
foreach (ListBoxItem item in Owner.OldItemSource)
{
if (item.Mac == mac)
{
return item;
}
}
return null;
}
#endregion
}
下面可以为工程new一个新项——自定义控件，命名为UserListBox。
这里有几个地方要说明一下，首先在默认构造函数里面的参数：
DrawMode.OwnerDrawVariable启用控件重绘功能。
DoubleBuffer开启后避免复杂绘画造成窗体闪烁，这个缓冲的原理是将绘画操作放在内存里操作，完成后才会复制到图形界面上，进而避免的闪烁。
OnPaint进行了重写，这个方法是根据pc屏幕分辨率刷新频率来执行的，会不断的重复执行，进而持久化图形界面。
Invalidate方法，会立即刷新UI。
Item上的按钮事件，是通过ListBox的click事件，取到鼠标的在界面上的定位，调用相对应的方法。
public partial class UserListBox : ListBox
{
public ListBoxItem mouseItem;
private ListBoxItemCollection m_Items;
public UserListBox() : base()
{
InitializeComponent();
m_Items = new ListBoxItemCollection(this);
base.DrawMode = DrawMode.OwnerDrawVariable;
this.SetStyle(ControlStyles.UserPaint, true);
this.SetStyle(ControlStyles.DoubleBuffer, true); // 双缓冲
this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true); // 双缓冲
this.SetStyle(ControlStyles.ResizeRedraw, true); // 调整大小时重绘
this.SetStyle(ControlStyles.AllPaintingInWmPaint, true); // 禁止擦除背景.
this.SetStyle(ControlStyles.SupportsTransparentBackColor, true); // 开启控件透明
}
public new ListBoxItemCollection Items
{
get { return m_Items; }
}
internal ListBox.ObjectCollection OldItemSource
{
get { return base.Items; }
}
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
// you can set SeletedItem background
if (this.Focused && this.SelectedItem != null)
{
}
for (int i = 0; i < Items.Count; i++)
{
Rectangle bounds = this.GetItemRectangle(i);
if (mouseItem == Items[i])
{
Color leftColor = Color.FromArgb(200, 192, 224, 248);
using (SolidBrush brush = new SolidBrush(leftColor))
{
g.FillRectangle(brush, new Rectangle(bounds.X, bounds.Y, bounds.Width, bounds.Height));
}
Color rightColor = Color.FromArgb(252, 233, 161);
using (SolidBrush brush = new SolidBrush(rightColor))
{
g.FillRectangle(brush, new Rectangle(bounds.Width - 40, bounds.Y, 40, bounds.Height));
}
}
int fontLeft = bounds.Left + 40 + 15;
System.Drawing.Font font = new System.Drawing.Font("微软雅黑", 9);
g.DrawString(Items[i].Name, font, new SolidBrush(this.ForeColor), fontLeft, bounds.Top + 5);
g.DrawString(Items[i].IP, font, new SolidBrush(Color.FromArgb(128, 128, 128)), fontLeft, bounds.Top + 20);
g.DrawString(Items[i].Mac, font, new SolidBrush(Color.FromArgb(128, 128, 128)), fontLeft, bounds.Top + 35);
if (Items[i].Image != null)
{
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBilinear;
g.DrawImage(Items[i].Image, new Rectangle(bounds.X + 5, (bounds.Height - 40) / 2 + bounds.Top, 40, 40));
}
g.DrawImage(Properties.Resources.error, new Rectangle(bounds.Width - 28, (bounds.Height - 16) / 2 + bounds.Top, 16, 16));
}
base.OnPaint(e);
}
protected override void OnMeasureItem(MeasureItemEventArgs e)
{
base.OnMeasureItem(e);
if (Items.Count > 0)
{
ListBoxItem item = Items[e.Index];
e.ItemHeight = 54;
}
}
protected override void OnSelectedIndexChanged(EventArgs e)
{
base.OnSelectedIndexChanged(e);
}
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
for (int i = 0; i < Items.Count; i++)
{
Rectangle bounds = this.GetItemRectangle(i);
Rectangle deleteBounds = new Rectangle(bounds.Width - 28, (bounds.Height - 16) / 2 + bounds.Top, 16, 16);
if (bounds.Contains(e.X, e.Y))
{
if (Items[i] != mouseItem)
{
mouseItem = Items[i];
}
if (deleteBounds.Contains(e.X, e.Y))
{
mouseItem.IsFocus = true;
this.Cursor = Cursors.Hand;
}
else
{
mouseItem.IsFocus = false;
this.Cursor = Cursors.Arrow;
}
this.Invalidate();
break;
}
}
}
protected override void OnMouseClick(MouseEventArgs e)
{
base.OnMouseClick(e);
if (mouseItem.IsFocus)
{
ListBoxItem deleteItem = mouseItem;
if(MessageBox.Show("confirm to delete", "", MessageBoxButtons.OKCancel) == DialogResult.OK)
{
this.Items.Remove(deleteItem);
}
}
}
protected override void OnMouseLeave(EventArgs e)
{
base.OnMouseLeave(e);
this.mouseItem = null;
this.Invalidate();
}
}