[英]Binding an Enum property values to ListView.Items(WinForms)
我有以下实体:
public class MyEntity
{
public int Id {get;set}
public Color SelectedColors
}
MyEntity
与Color
枚举具有One-to-Many
关系。
[Flags]
public enum Color
{
None=1,
White=2,
Red=3,
Blue=4
}
换句话说,每个myEntity
对象可能具有Color
枚举中的一个或多个值:
myEntity1.Color = Color.Red | Color.White;
我使用Entity Framewrok
保存了这些数据:
using (var ctx = new MyContext())
{
var entity1 = new MyEntity { SelectedColors = Color.Blue | Color.White };
ctx.MyEntities.Add(entity1);
ctx.SaveChanges();
}
并使用以下代码阅读:
using (var ctx = new MyContext())
{
var entity1 = ctx.MyEntities.Find(id);
}
我想显示所选颜色蜱chechboxes
,
我使用ListView
控件(WinForms项目)来完成此工作:
listView1.CheckBoxes = true;
listView1.HeaderStyle = None;
listView1.View = List;
并使用以下代码将所有Enum
值显示为ListView.Items
:
foreach (var value in Enum.GetValues(typeof(Color)).Cast<Color>())
{
listView1.Items.Add(new ListViewItem()
{
Name = value.ToString(),
Text = value.ToString(),
Tag = value
});
}
有什么方法可以将查询结果的SelectedColors
值绑定到listView1.Items
?
[更新]
我在此链接中看到了一个解决方案,即Nick-K从ListView
继承了一个新控件。 我认为该解决方案对我不好,因为继承的控件带有一个DataSource
和一个DataMember
,那么在我的情况下我应该为DataMember
设置什么( SelectedColors
可能有多个值)?
ListView类不支持设计时绑定
看这个
http://www.codeproject.com/Articles/10008/Data-binding-a-ListView
首先,您的枚举应如下所示:
[Flags]
public enum MyColors
{
None = 0,
White = 1,
Red = 2,
Blue = 4
}
使用此属性
public List<string> SelectedColorsList
{
get
{
return SelectedColors.ToString()
.Split(new[] { ", " }, StringSplitOptions.None)
.ToList();
}
set
{
if (value == null)
{
this.SelectedColors = MyColors.None;
return;
}
int s = 0;
foreach (var v in value)
{
s += (int)Enum.Parse(typeof(MyColors), v);
}
this.SelectedColors = (MyColors)s;
}
}
如果要编辑颜色,则可以从ListView继承自己的控件:
public class ColorListControl : ListView
{
public event EventHandler SelectedColorChanged;
private Color selectedColor = Color.None;
[DefaultValue( Color.None )]
public Color SelectedColor
{
get { return selectedColor; }
set
{
if( selectedColor != value )
{
selectedColor = value;
foreach( ListViewItem item in this.Items )
{
Color itemColor = (Color)item.Tag;
if( itemColor == Color.None ) //see http://stackoverflow.com/questions/15436616
item.Checked = value == Color.None;
else
item.Checked = value.HasFlag( itemColor );
}
SelectedColorChanged?.Invoke( this, EventArgs.Empty );
}
}
}
public ColorListControl()
{
this.CheckBoxes = true;
this.HeaderStyle = ColumnHeaderStyle.None;
this.View = View.List;
foreach( Color value in Enum.GetValues( typeof( Color ) ).Cast<Color>() )
{
this.Items.Add( new ListViewItem()
{
Name = value.ToString(),
Text = value.ToString(),
Tag = value
} );
}
}
protected override void OnItemChecked( ItemCheckedEventArgs e )
{
base.OnItemChecked( e );
Color checkedColor = (Color)e.Item.Tag;
if( e.Item.Checked )
SelectedColor |= checkedColor;
else
SelectedColor &= ~checkedColor;
}
}
然后,您可以绑定到其属性SelectedColor:
public class MainForm : Form
{
private ColorListControl listView1;
public MainForm()
{
InitializeComponent();
MyEntity entity = new MyEntity { SelectedColors = Color.Blue | Color.White };
listView1.DataBindings.Add( nameof( listView1.SelectedColor ), entity, nameof( entity.SelectedColors ) );
}
private void InitializeComponent()
{
this.listView1 = new ColorListControl();
this.SuspendLayout();
//
// listView1
//
this.listView1.Location = new System.Drawing.Point(16, 16);
this.listView1.Name = "listView1";
this.listView1.Size = new System.Drawing.Size(200, 128);
this.listView1.TabIndex = 0;
this.listView1.SelectedColorChanged += new System.EventHandler(this.listView1_SelectedColorChanged);
//
// MainForm
//
this.ClientSize = new System.Drawing.Size(318, 189);
this.Controls.Add(this.listView1);
this.Name = "MainForm";
this.Text = "Form";
this.ResumeLayout(false);
}
private void listView1_SelectedColorChanged( object sender, EventArgs e )
{
this.Text = listView1.SelectedColor.ToString();
}
}
正如@MSL已经说过的:您需要以2的幂(0、1、2、4、8、16 ...)定义Color枚举的数量。 请参阅https://msdn.microsoft.com/library/system.flagsattribute.aspx
要编译此示例,您需要C#6.0 / Visual Studio2015。否则,必须将nameof( listView1.SelectedColor )
替换为"SelectedColor"
。
除了考虑使用ListView之外,还可以考虑使用CheckedListBox:
public class ColorListControl : CheckedListBox
{
public event EventHandler SelectedColorChanged;
private Color selectedColor = Color.None;
[DefaultValue( Color.None )]
public Color SelectedColor
{
get { return selectedColor; }
set
{
if( selectedColor != value )
{
selectedColor = value;
for( int i = 0; i < this.Items.Count; i++ )
{
Color itemColor = (Color)this.Items[i];
if( itemColor == Color.None )
this.SetItemChecked( i, value == Color.None );
else
this.SetItemChecked( i, value.HasFlag( itemColor ) );
}
SelectedColorChanged?.Invoke( this, EventArgs.Empty );
}
}
}
public ColorListControl()
{
CheckOnClick = true;
foreach( Color value in Enum.GetValues( typeof( Color ) ) )
this.Items.Add( value );
}
protected override void OnItemCheck( ItemCheckEventArgs ice )
{
base.OnItemCheck( ice );
Color checkedColor = (Color)this.Items[ice.Index];
if( ice.NewValue == CheckState.Checked )
SelectedColor |= checkedColor;
else
SelectedColor &= ~checkedColor;
}
}
如果只想查看颜色,则可以仅设置ListViewItem
Checked
-property,而无需任何数据绑定或自定义控件:
foreach (var value in Enum.GetValues(typeof(Color)).Cast<Color>())
{
listView1.Items.Add(new ListViewItem()
{
Name = value.ToString(),
Text = value.ToString(),
Checked = entity1.SelectedColors.HasFlag( value ),
Tag = value
});
}
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