wpf开发相关大杂烩（各种难点、常见问题的解决方案，不断更新中）

1.StaticResource和DynamicResource的区别。（留坑，有时间再补充）

2.RecognizesAccessKey。（留坑，有时间再补充）

3.设置界面默认焦点位置，比如将焦点设置为默认在用户名输入框usernameBox：FocusManager.FocusedElement="{Binding ElementName=usernameBox}

4.利用附加属性，扩展控件的属性，以便在重写控件的template里面使用。

比较常见的一个场景是，你有一个button，这个button的背景是图片，同时当鼠标进入时，是另外一张图片，这个时候就缺少两个属性，一个是BackImage，一个是BackImageEnter。你可以写一个附加属性类，如下：

internal class StyleExtension
    {
        public static ImageSource GetBackImageEnter(DependencyObject obj)
        {
            return (ImageSource)obj.GetValue(BackImageEnterProperty);
        }

        public static void SetBackImageEnter(DependencyObject obj, ImageSource value)
        {
            obj.SetValue(BackImageEnterProperty, value);
        }

        // Using a DependencyProperty as the backing store for BackImageEnter.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BackImageEnterProperty =
            DependencyProperty.RegisterAttached("BackImageEnter", typeof(ImageSource), typeof(StyleExtension), new PropertyMetadata(null));

        public static ImageSource GetBackImage(DependencyObject obj)
        {
            return (ImageSource)obj.GetValue(BackImageProperty);
        }

        public static void SetBackImage(DependencyObject obj, ImageSource value)
        {
            obj.SetValue(BackImageProperty, value);
        }

        // Using a DependencyProperty as the backing store for BackImage.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BackImageProperty =
            DependencyProperty.RegisterAttached("BackImage", typeof(ImageSource), typeof(StyleExtension), new PropertyMetadata(null));

        public static SolidColorBrush GetBackColorEnter(DependencyObject obj)
        {
            return (SolidColorBrush)obj.GetValue(BackColorEnterProperty);
        }

        public static void SetBackColorEnter(DependencyObject obj, SolidColorBrush value)
        {
            obj.SetValue(BackColorEnterProperty, value);
        }

        // Using a DependencyProperty as the backing store for BackColorEnter.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BackColorEnterProperty =
            DependencyProperty.RegisterAttached("BackColorEnter", typeof(SolidColorBrush), typeof(StyleExtension), new PropertyMetadata(null));
    }

然后在界面上这么使用（注意添加extension引用）：

<Button Grid.Column="1" Content="测试按钮" Style="{StaticResource MenuButtonStyle}"
                    extension:StyleExtension.BackImage="/Views;Component/Resources/nomal.png"
                    extension:StyleExtension.BackImageEnter="/Views;Component/Resources/pressed.png"
                    Command="{Binding ChangePageCommand}" CommandParameter="createFlight"/>

然后控件的style这么写：

<Style x:Key="MenuButtonStyle" TargetType="Button">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="Button">
                        <Border x:Name="border" CornerRadius="2" Background="Transparent" Padding="10,0">
                            <Grid Margin="1">
                                <BulletDecorator VerticalAlignment="Center">
                                    <BulletDecorator.Bullet>
                                        <Image x:Name="image" Source="{Binding (extension:StyleExtension.BackImage),RelativeSource={RelativeSource Mode=TemplatedParent}}" Stretch="None"/>
                                    </BulletDecorator.Bullet>
                                    <TextBlock x:Name="textblock" Text="{TemplateBinding Content}" VerticalAlignment="Center" HorizontalAlignment="Center" Foreground="#9AA5C0" FontSize="13" FontFamily="{StaticResource MainFontFamily}"/>
                                </BulletDecorator>
                            </Grid>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsMouseOver" Value="True">
                                <Setter TargetName="border" Property="Background" Value="#3479D3"/>
                                <Setter TargetName="image" Property="Source" Value="{Binding (extension:StyleExtension.BackImageEnter),RelativeSource={RelativeSource Mode=TemplatedParent}}"/>
                                <Setter TargetName="textblock" Property="Foreground" Value="#FFFFFF"/>
                            </Trigger>
                      &nb