WPF中用戶控件和自定義控件如何使用

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介紹

無(wú)論是在WPF中還是WinForm中，都有用戶控件（UserControl）和自定義控件（CustomControl），這兩種控件都是對(duì)已有控件的封裝，實(shí)現(xiàn)功能重用。但是兩者還是有一些區(qū)別，本文對(duì)這兩種控件進(jìn)行講解。

1.用戶控件

• 注重復(fù)合控件的使用，也就是多個(gè)現(xiàn)有控件組成一個(gè)可復(fù)用的控件組

• XAML和后臺(tái)代碼組成，綁定緊密

• 不支持模板重寫

• 繼承自UserControl

2.自定義控件

• 完全自己實(shí)現(xiàn)一個(gè)控件，如繼承現(xiàn)有控件進(jìn)行功能擴(kuò)展，并添加新功能

• 后臺(tái)代碼和Generic.xaml進(jìn)行組合

• 在使用時(shí)支持模板重寫

• 繼承自Control

用戶控件

用戶控件比較容易理解，與常見(jiàn)的WPF窗體類似，值得注意一點(diǎn)的地方是內(nèi)部在使用綁定的時(shí)候，需要使用RelativeSource的方式來(lái)綁定，以實(shí)現(xiàn)良好的封裝。一個(gè)簡(jiǎn)單的案例：

定義用戶控件

<UserControl
    x:Class="WpfApp19.UserControl1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:local="clr-namespace:WpfApp19"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    d:DesignHeight="450"
    d:DesignWidth="800"
    mc:Ignorable="d">
    <Grid>
        <!--下面綁定都要用RelativeSource作為源-->
        <StackPanel>
            <TextBox
                Width="100"
                BorderThickness="2"
                Text="{Binding value, RelativeSource={RelativeSource AncestorType=UserControl}}" />
            <Button
                Width="100"
                Command="{Binding Command, RelativeSource={RelativeSource AncestorType=UserControl}}"
                Content="Ok" />
        </StackPanel>
    </Grid>
</UserControl>

后臺(tái)代碼

//根據(jù)需要定義依賴屬性 
//所需要綁定的值
 public int value
 {
     get { return (int)GetValue(valueProperty); }
     set { SetValue(valueProperty, value); }
 }
 public static readonly DependencyProperty valueProperty =
     DependencyProperty.Register("value", typeof(int), typeof(UserControl1), new PropertyMetadata(0));

 //所需要綁定的命令
 public ICommand Command
 {
     get { return (ICommand)GetValue(CommandProperty); }
     set { SetValue(CommandProperty, value); }
 }
 public static readonly DependencyProperty CommandProperty =
     DependencyProperty.Register("Command", typeof(ICommand), typeof(UserControl1), new PropertyMetadata(default(ICommand)));


 //所需要綁定的命令參數(shù)
 public object CommandParemeter
 {
     get { return (object)GetValue(CommandParemeterProperty); }
     set { SetValue(CommandParemeterProperty, value); }
 }
 public static readonly DependencyProperty CommandParemeterProperty =
     DependencyProperty.Register("CommandParemeter", typeof(object), typeof(UserControl1), new PropertyMetadata(0));

使用用戶控件

<Window x:Class="WpfApp19.MainWindow"
        ...
        xmlns:local="clr-namespace:WpfApp19"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <local:UserControl1 value="{Binding }" Command="{Binding }"/>
    </Grid>
</Window>

自定義控件

點(diǎn)擊添加自定義控件后，會(huì)增加一個(gè)CustomControl1.cs文件以及一個(gè)Themes目錄，在該目錄下有一個(gè)Generic.xaml文件，該文件就是自定義控件的style。我們經(jīng)常針對(duì)某些控件進(jìn)行編輯模板-創(chuàng)建副本的操作而產(chǎn)生的style，其實(shí)就是Generic.xaml中定義的style。另外，有時(shí)我們可能遇到一種情況，也就是相同的軟件在不同的Windows版本下運(yùn)行，表現(xiàn)形式可能會(huì)不同，甚至某些系統(tǒng)下運(yùn)行不了，這就是和不同系統(tǒng)下的默認(rèn)的Theme不同。其實(shí)wpf控件找不到自定義的樣式時(shí)，會(huì)從系統(tǒng)獲取樣式，查找順序是，先查找所在的程序集，如果程序集定義了ThemeInfo特性，那么會(huì)查看ThemeInfoDictionaryLocation的屬性值，該屬性如果是None則說(shuō)明沒(méi)有特定的主題資源，值為SourceAssembly，說(shuō)明特定資源定義在程序集內(nèi)部，值為ExternalAssembly則說(shuō)明在外部，如果還是沒(méi)有找到，則程序會(huì)在自身的themes/generic.xaml中獲取，在generic.xaml中獲取的其實(shí)就和系統(tǒng)默認(rèn)樣式相關(guān)。

不同xaml所對(duì)應(yīng)的系統(tǒng)主題

按鈕案例

C#文件

public class Switch : ToggleButton
{
    static Switch()
    {
        //通過(guò)重寫Metadata，控件就會(huì)通過(guò)程序集themes文件夾下的generic.xaml來(lái)尋找系統(tǒng)默認(rèn)樣式
        DefaultStyleKeyProperty.OverrideMetadata(typeof(Switch), new FrameworkPropertyMetadata(typeof(Switch)));
    }
}

Themes文件夾下的Generic.xaml文件

注意在該文件中不能有中文，注釋也不行

<Style TargetType="{x:Type local:Switch}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:Switch}">
                <Grid>
                    <Border
                        Name="dropdown"
                        Width="{Binding RelativeSource={RelativeSource Self}, Path=ActualHeight}"
                        Margin="-23"
                        CornerRadius="{Binding RelativeSource={RelativeSource Self}, Path=ActualHeight}"
                        Visibility="Collapsed">
                        <Border.Background>
                            <RadialGradientBrush>
                                <GradientStop Offset="1" Color="Transparent" />
                                <GradientStop Offset="0.7" Color="#5500D787" />
                                <GradientStop Offset="0.59" Color="Transparent" />
                            </RadialGradientBrush>
                        </Border.Background>
                    </Border>
                    <Border
                        Name="bor"
                        Width="{Binding RelativeSource={RelativeSource Self}, Path=ActualHeight}"
                        Background="Gray"
                        BorderBrush="DarkGreen"
                        BorderThickness="5"
                        CornerRadius="{Binding RelativeSource={RelativeSource Self}, Path=ActualHeight}">
                        <Border
                            Name="bor1"
                            Width="{Binding RelativeSource={RelativeSource Self}, Path=ActualHeight}"
                            Margin="2"
                            Background="#FF00C88C"
                            CornerRadius="{Binding RelativeSource={RelativeSource Self}, Path=ActualHeight}" />
                    </Border>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsChecked" Value="True">
                        <Trigger.EnterActions>
                            <BeginStoryboard>
                                <Storyboard>
                                    <ColorAnimation
                                        Storyboard.TargetName="bor1"
                                        Storyboard.TargetProperty="Background.Color"
                                        To="White"
                                        Duration="0:0:0.5" />
                                    <ColorAnimation
                                        Storyboard.TargetName="bor"
                                        Storyboard.TargetProperty="BorderBrush.Color"
                                        To="#FF32FAC8"
                                        Duration="0:0:0.5" />
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="dropdown" Storyboard.TargetProperty="Visibil
                                        <DiscreteObjectKeyFrame KeyTime="0:0:0.3">
                                            <DiscreteObjectKeyFrame.Value>
                                                <Visibility>Visible</Visibility>
                                            </DiscreteObjectKeyFrame.Value>
                                        </DiscreteObjectKeyFrame>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </BeginStoryboard>
                        </Trigger.EnterActions>
                        <Trigger.ExitActions>
                            <BeginStoryboard>
                                <Storyboard>
                                    <ColorAnimation Storyboard.TargetName="bor1" Storyboard.TargetProperty="Background.Color" />
                                    <ColorAnimation Storyboard.TargetName="bor" Storyboard.TargetProperty="BorderBrush.Color" />
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="dropdown" Storyboard.TargetProperty="Visibil
                                        <DiscreteObjectKeyFrame KeyTime="0:0:0.3">
                                            <DiscreteObjectKeyFrame.Value>
                                                <Visibility>Collapsed</Visibility>
                                            </DiscreteObjectKeyFrame.Value>
                                        </DiscreteObjectKeyFrame>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </BeginStoryboard>
                        </Trigger.ExitActions>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

使用自定控件

<Grid>
    <local:Switch Width="100" Height="100" />
</Grid>

自定義控件中常用的知識(shí)點(diǎn)

TemplatePart特性

在自定義控件中，有些控件是需要有名稱的以便于調(diào)用，如在重寫的OnApplyTemplate()方法中得到指定的button。這就要求用戶在使用控件時(shí)，不能夠修改模板中的名稱。

//應(yīng)用該控件時(shí)調(diào)用
public override void OnApplyTemplate()
{
    UpButtonElement = GetTemplateChild("UpButton") as RepeatButton;
    DownButtonElement = GetTemplateChild("DownButton") as RepeatButton;
}

所以在類前面使用特性進(jìn)行標(biāo)注

[TemplatePart(Name = "UpButton", Type = typeof(RepeatButton))]
[TemplatePart(Name = "DownButton", Type = typeof(RepeatButton))]
public class Numeric : Control{}

視覺(jué)狀態(tài)的定義與調(diào)用

自定義控件中可以定義視覺(jué)狀態(tài)來(lái)呈現(xiàn)不同狀態(tài)下的效果。

在xml中定義視覺(jué)狀態(tài)，不同組下的視覺(jué)狀態(tài)是互斥的

<VisualStateManager.VisualStateGroups>
    <VisualStateGroup Name="FocusStates">
        <VisualState Name="Focused">
            <Storyboard>
                <ObjectAnimationUsingKeyFrames Storyboard.TargetName="FocusVisual" 
                           Storyboard.TargetProperty="Visibility" Duration="0">
                    <DiscreteObjectKeyFrame KeyTime="0">
                        <DiscreteObjectKeyFrame.Value>
                            <Visibility>Visible</Visibility>
                        </DiscreteObjectKeyFrame.Value>
                    </DiscreteObjectKeyFrame>
                </ObjectAnimationUsingKeyFrames>
            </Storyboard>
        </VisualState>
        <VisualState Name="Unfocused"/>
    </VisualStateGroup>
</VisualStateManager.VisualStateGroups>

在C#中對(duì)應(yīng)視覺(jué)狀態(tài)的切換

private void UpdateStates(bool useTransitions)
{
    if (IsFocused)
    {
        VisualStateManager.GoToState(this, "Focused", false);
    }
    else
    {
        VisualStateManager.GoToState(this, "Unfocused", false);
    }
}

同時(shí)可以在后臺(tái)類中使用特性來(lái)標(biāo)注

[TemplateVisualState(Name = "Focused", GroupName = "FocusedStates")]
[TemplateVisualState(Name = "Unfocused", GroupName = "FocusedStates")]
public class Numeric : Control{}

其實(shí)完全可以使用Trigger來(lái)實(shí)現(xiàn)該功能

到此，相信大家對(duì)“WPF中用戶控件和自定義控件如何使用”有了更深的了解，不妨來(lái)實(shí)際操作一番吧！這里是億速云網(wǎng)站，更多相關(guān)內(nèi)容可以進(jìn)入相關(guān)頻道進(jìn)行查詢，關(guān)注我們，繼續(xù)學(xué)習(xí)！