WPF创建仿迅雷下载地址下拉选择框—ComboBox

升级了迅雷7，感觉视觉上的确给人了耳目一新的感觉。我照葫芦画瓢吧仿造了一个迅雷选择下载的下拉框 

效果图如下：

它的结构是这样的：

  <Grid Height="113" Width="640">
        <Grid Margin="72,27,193,0" Height="29" VerticalAlignment="Top">
            <Border DataContext="{StaticResource plist}"
			 x:Name="control1" BorderThickness="3" Width="369" Height="28" 
			 HorizontalAlignment="Left" VerticalAlignment="Top" CornerRadius="5"
			 MouseDown="control1_MouseDown"  >
                <Border.BorderBrush>
                    <RadialGradientBrush>
                        <GradientStop Color="#FFF2C7D7" Offset="0" />
                        <GradientStop Color="#87EA5457" Offset="1" />
                    </RadialGradientBrush>
                </Border.BorderBrush>
                <Grid >
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="18*" />
                        <ColumnDefinition Width="345*" />
                    </Grid.ColumnDefinitions>
                    <StackPanel HorizontalAlignment="Left" Orientation="Horizontal" VerticalAlignment="Top" Grid.ColumnSpan="2">

                        <TextBox x:Name="textBox1"  Width="211" HorizontalAlignment="Left" BorderThickness="0" Margin="6,1,0,2" Padding="0" Text="{Binding Name}" />
                            <local:PopupNonTopmost Topmost="False" x:Name="Popup"  Placement="Bottom" AllowsTransparency="True" HorizontalOffset="-3"
                           VerticalOffset="2" Focusable="False" PopupAnimation="Fade">
                            <Border BorderThickness="3,0,3,3" Background="White" Height="100" HorizontalAlignment="Left"  x:Name="border3" VerticalAlignment="Top" Width="369" RenderTransformOrigin="0.5,0.5" CornerRadius="2">
                                <Border.BorderBrush>
                                    <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                        <GradientStop Color="#FFFD8C8C" Offset="0.014"/>
                                        <GradientStop Color="#FFFBB1B1" Offset="0.74"/>
                                    </LinearGradientBrush>
                                </Border.BorderBrush>
                             
                                <ListBox ItemTemplate="{StaticResource ListBoxControlTemplate1}"
 							            x:Name="listBox"  ItemsSource="{Binding}" BorderThickness="0" IsSynchronizedWithCurrentItem="True">
                                </ListBox>
                            </Border>
                        </local:PopupNonTopmost>
                        <TextBlock Height="18"  x:Name="textBlock1" Text="剩余70.15GB" VerticalAlignment="Center" Width="81"><TextBlock.Foreground><LinearGradientBrush EndPoint="1,0.5" StartPoint="0,0.5"><GradientStop Color="#FF4984B7" Offset="0" /><GradientStop Color="#FF008EFF" Offset="1" /></LinearGradientBrush></TextBlock.Foreground></TextBlock>
                        <Border Height="23" Width="2" BorderThickness="1">
                            <Border.BorderBrush>
                                <LinearGradientBrush EndPoint="1,0.5" StartPoint="0,0.5">
                                    <GradientStop Color="#FFD7C9C9" Offset="0" />
                                    <GradientStop Color="White" Offset="1" />
                                    <GradientStop Color="#FFFC8BCD" Offset="0.5" />
                                </LinearGradientBrush>
                            </Border.BorderBrush>
                        </Border>
                        <Border BorderThickness="0" Height="23"  x:Name="border1" VerticalAlignment="Top" Width="31"  MouseDown="border1_MouseDown">
                            <Border.Background>
                                <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                    <GradientStop Color="#FFE8D4D9" Offset="0" />
                                    <GradientStop Color="#FFF67BAE" Offset="1" />
                                </LinearGradientBrush>
                            </Border.Background>
                            <TextBlock Text="▲?" HorizontalAlignment="Center" Foreground="#FFEC82C1" Height="16">
                            <TextBlock.LayoutTransform>
                                <ScaleTransform  ScaleX="-1" ScaleY="-1"/>
                            </TextBlock.LayoutTransform>
                            </TextBlock>
                        </Border>
                        <Border Height="23" Width="2" BorderThickness="1">
                            <Border.BorderBrush>
                                <LinearGradientBrush EndPoint="1,0.5" StartPoint="0,0.5">
                                    <GradientStop Color="#FFD7C9C9" Offset="0" />
                                    <GradientStop Color="White" Offset="1" />
                                    <GradientStop Color="#FFFC8BCD" Offset="0.5" />
                                </LinearGradientBrush>
                            </Border.BorderBrush>
                        </Border>
                        <Border BorderThickness="0" Height="23"  x:Name="border2" VerticalAlignment="Top" Width="31">
                            <TextBlock HorizontalAlignment="Center" Text="选择" FontSize="12" Foreground="RosyBrown" />
                            <Border.Background>
                                <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                    <GradientStop Color="#FFE8D4D9" Offset="0" />
                                    <GradientStop Color="#FFF67BAE" Offset="1" />
                                </LinearGradientBrush>
                            </Border.Background>
                        </Border>
                    </StackPanel>
                </Grid>
            </Border>
        </Grid>

代码不多也很简单其中有一个local:PopupNonTopmost ，这个自定义控件是继承了Popup控件而得到的，因为Popup控件默认只能是Top Most的所以有时候会遮挡到其它窗体

  public class PopupNonTopmost : Popup
    {
        public static DependencyProperty TopmostProperty = Window.TopmostProperty.AddOwner(
            typeof(PopupNonTopmost),
            new FrameworkPropertyMetadata(false, OnTopmostChanged));

        public bool Topmost
        {
            get { return (bool)GetValue(TopmostProperty); }
            set { SetValue(TopmostProperty, value); }
        }

        private static void OnTopmostChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
        {
            (obj as PopupNonTopmost).UpdateWindow();
        }

        protected override void OnOpened(EventArgs e)
        {
            UpdateWindow();
        }

        private void UpdateWindow()
        {
            var hwnd = ((HwndSource)PresentationSource.FromVisual(this.Child)).Handle;
            RECT rect;

            if (GetWindowRect(hwnd, out rect))
            {
                SetWindowPos(hwnd, Topmost ? -1 : -2, rect.Left, rect.Top, (int)this.Width, (int)this.Height, 0);
            }
        }

        #region P/Invoke imports & definitions

        [StructLayout(LayoutKind.Sequential)]
        public struct RECT
        {
            public int Left;
            public int Top;
            public int Right;
            public int Bottom;
        }

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);

        [DllImport("user32", EntryPoint = "SetWindowPos")]
        private static extern int SetWindowPos(IntPtr hWnd, int hwndInsertAfter, int x, int y, int cx, int cy, int wFlags);

        #endregion
    }