winform下重畫ListBox

Windows Forms是由Win32 API封裝的開發組件，最初是爲了替代mfc，但卻沒有體現與Model View Controller架構對應的特點，進而在.net framework 3.0中推出了wpf，富控件數據顯示方面，利用模板功能輕鬆實現。

在winform下要想自定義一些用戶控件，就須要運用的2D繪畫類。下圖咱們爲ListBox從新排列了數據顯示方式，併爲每個item加入了刪除按鈕。

首先咱們設計一個承載數據的類ListBoxItem。

 1 public class ListBoxItem : IDisposable
 2 {
 3     public Guid Id { get; set; }
 4 
 5     public string Name { get; set; }
 6 
 7     public string IP { get; set; }
 8 
 9     public string Mac { get; set; }
10 
11     [System.ComponentModel.DefaultValue(typeof(System.Drawing.Image), "null")]
12     public System.Drawing.Image Image { get; set; }
13 
14     public bool IsFocus { get; set; }
15 
16     public ListBoxItem() { }
17 
18     public ListBoxItem(Guid id, string name, string ip, string mac, System.Drawing.Image image)
19     {
20         this.Id = id;
21         this.Name = name;
22         this.IP = ip;
23         this.Mac = mac;
24         this.Image = image;
25         this.IsFocus = false;
26     }
27 
28     public void Dispose()
29     {
30         this.Image = null;
31     }
32 }

而後咱們再爲ListBox寫一個用於展示數據的數據源ListBoxItemCollection，這裏實現了迭代和集合操做接口，能夠根據須要擴展數據操做方法。

[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
}

下面能夠爲工程new一個新項——自定義控件，命名爲UserListBox。

這裏有幾個地方要說明一下，首先在默認構造函數裏面的參數：

DrawMode.OwnerDrawVariable啓用控件重繪功能。

DoubleBuffer開啓後避免複雜繪畫形成窗體閃爍，這個緩衝的原理是將繪畫操做放在內存裏操做，完成後纔會複製到圖形界面上，進而避免的閃爍。

OnPaint進行了重寫，這個方法是根據pc屏幕分辨率刷新頻率來執行的，會不斷的重複執行，進而持久化圖形界面。

Invalidate方法，會當即刷新UI。

Item上的按鈕事件，是經過ListBox的click事件，取到鼠標的在界面上的定位，調用相對應的方法。

  1 public partial class UserListBox : ListBox
  2 {
  3     public ListBoxItem mouseItem;
  4     private ListBoxItemCollection m_Items;
  5 
  6     public UserListBox() : base()
  7     {
  8         InitializeComponent();
  9 
 10         m_Items = new ListBoxItemCollection(this);
 11 
 12         base.DrawMode = DrawMode.OwnerDrawVariable;
 13         this.SetStyle(ControlStyles.UserPaint, true);
 14         this.SetStyle(ControlStyles.DoubleBuffer, true); // 雙緩衝
 15         this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true); // 雙緩衝   
 16         this.SetStyle(ControlStyles.ResizeRedraw, true); // 調整大小時重繪
 17         this.SetStyle(ControlStyles.AllPaintingInWmPaint, true); // 禁止擦除背景. 
 18         this.SetStyle(ControlStyles.SupportsTransparentBackColor, true); // 開啓控件透明
 19     }
 20 
 21     public new ListBoxItemCollection Items
 22     {
 23         get { return m_Items; }
 24     }
 25 
 26     internal ListBox.ObjectCollection OldItemSource
 27     {
 28         get { return base.Items; }
 29     }
 30 
 31     protected override void OnPaint(PaintEventArgs e)
 32     {
 33         Graphics g = e.Graphics;
 34         
 35         // you can set SeletedItem background
 36         if (this.Focused && this.SelectedItem != null)
 37         {
 38         }
 39 
 40         for (int i = 0; i < Items.Count; i++)
 41         {
 42             Rectangle bounds = this.GetItemRectangle(i);
 43 
 44             if (mouseItem == Items[i])
 45             {
 46                 Color leftColor = Color.FromArgb(200, 192, 224, 248);
 47                 using (SolidBrush brush = new SolidBrush(leftColor))
 48                 {
 49                     g.FillRectangle(brush, new Rectangle(bounds.X, bounds.Y, bounds.Width, bounds.Height));
 50                 }
 51 
 52                 Color rightColor = Color.FromArgb(252, 233, 161);
 53                 using (SolidBrush brush = new SolidBrush(rightColor))
 54                 {
 55                     g.FillRectangle(brush, new Rectangle(bounds.Width - 40, bounds.Y, 40, bounds.Height));
 56                 }
 57             }
 58 
 59             int fontLeft = bounds.Left + 40 + 15;
 60             System.Drawing.Font font = new System.Drawing.Font("微軟雅黑", 9);
 61             g.DrawString(Items[i].Name, font, new SolidBrush(this.ForeColor), fontLeft, bounds.Top + 5);
 62             g.DrawString(Items[i].IP, font, new SolidBrush(Color.FromArgb(128, 128, 128)), fontLeft, bounds.Top + 20);
 63             g.DrawString(Items[i].Mac, font, new SolidBrush(Color.FromArgb(128, 128, 128)), fontLeft, bounds.Top + 35);
 64 
 65             if (Items[i].Image != null)
 66             {
 67                 g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBilinear;
 68                 g.DrawImage(Items[i].Image, new Rectangle(bounds.X + 5, (bounds.Height - 40) / 2 + bounds.Top, 40, 40));
 69             }
 70             g.DrawImage(Properties.Resources.error, new Rectangle(bounds.Width - 28, (bounds.Height - 16) / 2 + bounds.Top, 16, 16));
 71         }
 72         base.OnPaint(e);
 73     }
 74 
 75     protected override void OnMeasureItem(MeasureItemEventArgs e)
 76     {
 77         base.OnMeasureItem(e);
 78         if (Items.Count > 0)
 79         {
 80             ListBoxItem item = Items[e.Index];
 81             e.ItemHeight = 54;
 82         }
 83         
 84     }
 85 
 86     protected override void OnSelectedIndexChanged(EventArgs e)
 87     {
 88         base.OnSelectedIndexChanged(e);
 89     }
 90 
 91     protected override void OnMouseMove(MouseEventArgs e)
 92     {
 93         base.OnMouseMove(e);
 94         for (int i = 0; i < Items.Count; i++)
 95         {
 96             Rectangle bounds = this.GetItemRectangle(i);
 97             Rectangle deleteBounds = new Rectangle(bounds.Width - 28, (bounds.Height - 16) / 2 + bounds.Top, 16, 16);
 98 
 99             if (bounds.Contains(e.X, e.Y))
100             {
101                 if (Items[i] != mouseItem)
102                 {
103                     mouseItem = Items[i];
104                 }
105 
106                 if (deleteBounds.Contains(e.X, e.Y))
107                 {
108                     mouseItem.IsFocus = true;
109                     this.Cursor = Cursors.Hand;
110                 }
111                 else
112                 {
113                     mouseItem.IsFocus = false;
114                     this.Cursor = Cursors.Arrow;
115                 }
116 
117                 this.Invalidate();
118                 break;
119             }
120         }
121     }
122 
123     protected override void OnMouseClick(MouseEventArgs e)
124     {
125         base.OnMouseClick(e);
126         if (mouseItem.IsFocus)
127         {
128             ListBoxItem deleteItem = mouseItem;
129             if(MessageBox.Show("confirm to delete", "", MessageBoxButtons.OKCancel) == DialogResult.OK)
130             {
131                 this.Items.Remove(deleteItem);
132             }
133         }
134     }
135 
136     protected override void OnMouseLeave(EventArgs e)
137     {
138         base.OnMouseLeave(e);
139         this.mouseItem = null;
140         this.Invalidate();
141     }
142 }