在我刚刚开始接触到WPF的DependencyProperty的时候,仅仅觉得是一个很巧妙的实现,随着学习WPF的深入,也来越觉得DependencyProperty其实是WPF的核心技术点之一。
DependencyProperty和DependencyObject配合,提供了WPF中基本的数据存储、访问和通知的机制。也正是因为这两个东西的存在,使得XAML,Binding,Animation都成为可能。
让我们来看一下重新实现后的数据层。
1
using System;
2
using System.Windows;
3
using System.Windows.Media;
4
5
namespace ColorPicker2
6

{
7
public class ColorPickerData : DependencyObject
8
{
9
public ColorPickerData()
10
{
11
}
12
public static DependencyProperty BackgroundProperty = DependencyProperty.Register(
13
"Background",
14
typeof(Brush),
15
typeof(ColorPickerData),
16
new PropertyMetadata(new SolidColorBrush(Colors.Black))
17
);
18
19
public static DependencyProperty RedProperty = DependencyProperty.Register(
20
"Red",
21
typeof(byte),
22
typeof(ColorPickerData)
23
);
24
25
public static DependencyProperty GreenProperty = DependencyProperty.Register(
26
"Green",
27
typeof(byte),
28
typeof(ColorPickerData)
29
);
30
31
public static DependencyProperty BlueProperty = DependencyProperty.Register(
32
"Blue",
33
typeof(byte),
34
typeof(ColorPickerData)
35
);
36
37
38
public Brush Background
39
{
40
get
{ return (Brush)GetValue(BackgroundProperty); }
41
set
{ SetValue(BackgroundProperty, value); }
42
}
43
44
public byte Red
45
{
46
get
{ return (byte)GetValue(RedProperty); }
47
set
{ SetValue(RedProperty, value); }
48
}
49
50
public byte Green
51
{
52
get
{ return (byte)GetValue(GreenProperty); }
53
set
{ SetValue(GreenProperty, value); }
54
}
55
56
public byte Blue
57
{
58
get
{ return (byte)GetValue(BlueProperty); }
59
set
{ SetValue(BlueProperty, value); }
60
}
61
62
protected override void OnPropertyChanged(DependencyPropertyChangedEventArgs e)
63
{
64
if (e.Property.Equals(RedProperty) ||
65
e.Property.Equals(GreenProperty) ||
66
e.Property.Equals(BlueProperty))
67
{
68
this.Background = new SolidColorBrush(Color.FromRgb(this.Red, this.Green, this.Blue));
69
}
70
71
base.OnPropertyChanged(e);
72
}
73
}
74
}
75
在行12-35,我们注册了4个DependencyProperty:RedProperty, GreenProperty, BlueProperty 和 BackgroundProperty。我们也不再使用成员字段去保存这些属性的具体值。而是直接使用DependencyObject上的GetValue和SetValue方法设置和读取值。
http://www.haogongju.net/art/356014