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XamlCompositionBrushBase 類別

定義

提供基類,用來建立使用 CompositionBrush 繪製區域的 XAML 筆刷。

public ref class XamlCompositionBrushBase : Brush
/// [Windows.Foundation.Metadata.ContractVersion(Microsoft.UI.Xaml.WinUIContract, 65536)]
/// [Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
/// [Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
class XamlCompositionBrushBase : Brush
[Windows.Foundation.Metadata.ContractVersion(typeof(Microsoft.UI.Xaml.WinUIContract), 65536)]
[Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
[Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
public class XamlCompositionBrushBase : Brush
Public Class XamlCompositionBrushBase
Inherits Brush
繼承
Object Platform::Object IInspectable DependencyObject Brush XamlCompositionBrushBase
衍生
屬性

範例

此範例顯示自定義筆刷的定義,該筆刷會使用 Win2D 模糊效果和 CompositionBackdropBrush,繪製 UIElement 背後的模糊複本:

public sealed class BackdropBlurBrush : XamlCompositionBrushBase
{
    public static readonly DependencyProperty BlurAmountProperty = DependencyProperty.Register(
        "BlurAmount",
        typeof(double),
        typeof(BackdropBlurBrush),
        new PropertyMetadata(0.0, new PropertyChangedCallback(OnBlurAmountChanged)
        )
    );

    public double BlurAmount
    {
        get { return (double)GetValue(BlurAmountProperty); }
        set { SetValue(BlurAmountProperty, value); }
    }

    private static void OnBlurAmountChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var brush = (BackdropBlurBrush)d;
        // Unbox and set a new blur amount if the CompositionBrush exists.
        brush.CompositionBrush?.Properties.InsertScalar("Blur.BlurAmount", (float)(double)e.NewValue);            
    }

    public BackdropBlurBrush()
    {
    }

    protected override void OnConnected()
    {
        // Delay creating composition resources until they're required.
        if (CompositionBrush == null)
        {
            var backdrop = Window.Current.Compositor.CreateBackdropBrush();                

            // Use a Win2D blur affect applied to a CompositionBackdropBrush.
            var graphicsEffect = new GaussianBlurEffect
            {
                Name = "Blur",
                BlurAmount = (float)this.BlurAmount,
                Source = new CompositionEffectSourceParameter("backdrop")
            };

            var effectFactory = Window.Current.Compositor.CreateEffectFactory(graphicsEffect, new[] { "Blur.BlurAmount" });
            var effectBrush = effectFactory.CreateBrush();

            effectBrush.SetSourceParameter("backdrop", backdrop);

            CompositionBrush = effectBrush;
        }
    }

    protected override void OnDisconnected()
    {
        // Dispose of composition resources when no longer in use.
        if (CompositionBrush != null)
        {
            CompositionBrush.Dispose();
            CompositionBrush = null;
        }
    }
}

針對下列 C++/WinRT 程式代碼範例,您必須將 Midl 檔案 (.idl) 檔案新增至您的專案。

// BackdropBlurBrush.idl
namespace MyApp
{
    [default_interface]
    runtimeclass BackdropBlurBrush : Windows.UI.Xaml.Media.XamlCompositionBrushBase
    {
        BackdropBlurBrush();
        static Windows.UI.Xaml.DependencyProperty BlurAmountProperty{ get; };
        Double BlurAmount;
    }
}
// pch.h
// You'll need to install the Microsoft Win2D NuGet package for this code example.
#include <winrt/Microsoft.Graphics.Canvas.Effects.h>
#include <winrt/Windows.Graphics.Effects.h>

// BackdropBlurBrush.h.
struct BackdropBlurBrush : BackdropBlurBrushT<BackdropBlurBrush>
{
    BackdropBlurBrush() = default;

    static Windows::UI::Xaml::DependencyProperty BlurAmountProperty() { return m_blurAmountProperty; }

    double BlurAmount()
    {
        return winrt::unbox_value<double>(GetValue(m_blurAmountProperty));
    }

    void BlurAmount(double value)
    {
        SetValue(m_blurAmountProperty, winrt::box_value(value));
    }

    void OnConnected();
    void OnDisconnected();

    static void OnBlurAmountChanged(Windows::UI::Xaml::DependencyObject const& d, Windows::UI::Xaml::DependencyPropertyChangedEventArgs const& e);

private:
    static Windows::UI::Xaml::DependencyProperty m_blurAmountProperty;
};

// WindowBlurBrush.cpp.
Windows::UI::Xaml::DependencyProperty BackdropBlurBrush::m_blurAmountProperty =
    Windows::UI::Xaml::DependencyProperty::Register(
        L"BlurAmount",
        winrt::xaml_typename<double>(),
        winrt::xaml_typename<MyApp::BackdropBlurBrush>(),
        Windows::UI::Xaml::PropertyMetadata{ winrt::box_value(0.), Windows::UI::Xaml::PropertyChangedCallback{ &BackdropBlurBrush::OnBlurAmountChanged } }
);

void BackdropBlurBrush::OnBlurAmountChanged(Windows::UI::Xaml::DependencyObject const& d, Windows::UI::Xaml::DependencyPropertyChangedEventArgs const& e)
{
    auto brush{ d.as<MyApp::BackdropBlurBrush>() };
    // Unbox and set a new blur amount if the CompositionBrush exists.
    if (brush.CompositionBrush() != nullptr)
    {
        brush.CompositionBrush().Properties().InsertScalar(L"Blur.BlurAmount", (float)winrt::unbox_value<double>(e.NewValue()));
    }
}

void BackdropBlurBrush::OnConnected()
{
    // Delay creating composition resources until they're required.
    if (!CompositionBrush())
    {
        auto backdrop{ Windows::UI::Xaml::Window::Current().Compositor().CreateBackdropBrush() };

        // Use a Win2D blur affect applied to a CompositionBackdropBrush.
        Microsoft::Graphics::Canvas::Effects::GaussianBlurEffect graphicsEffect{};
        graphicsEffect.Name(L"Blur");
        graphicsEffect.BlurAmount(this->BlurAmount());
        graphicsEffect.Source(Windows::UI::Composition::CompositionEffectSourceParameter(L"backdrop"));

        auto effectFactory{ Windows::UI::Xaml::Window::Current().Compositor().CreateEffectFactory(graphicsEffect, { L"Blur.BlurAmount" }) };
        auto effectBrush{ effectFactory.CreateBrush() };

        effectBrush.SetSourceParameter(L"backdrop", backdrop);

        CompositionBrush(effectBrush);
    }
}

void BackdropBlurBrush::OnDisconnected()
{
    // Dispose of composition resources when no longer in use.
    if (CompositionBrush())
    {
        CompositionBrush(nullptr);
    }
}
// WindowBlurBrush.h:
public ref class BackdropBlurBrush sealed :
    public Windows::UI::Xaml::Media::XamlCompositionBrushBase
{
public:
    BackdropBlurBrush();

    static property Windows::UI::Xaml::DependencyProperty^ BlurAmountProperty
    {
        Windows::UI::Xaml::DependencyProperty^ get() { return m_blurAmountProperty; }
    };

    property double BlurAmount
    {
        double get() 
        {
            return static_cast<double>(GetValue(BlurAmountProperty));
        }
        void set(double value) 
        {
            SetValue(BlurAmountProperty, value);
        }
    };

protected:
    virtual void OnConnected() override;
    virtual void OnDisconnected() override;	
    private:
    static Windows::UI::Xaml::DependencyProperty^ m_blurAmountProperty;
    static void OnBlurAmountChanged(Windows::UI::Xaml::DependencyObject^ d, Windows::UI::Xaml::DependencyPropertyChangedEventArgs^ e);
};

// WindowBlurBrush.cpp:
DependencyProperty^ BackdropBlurBrush::m_blurAmountProperty = DependencyProperty::Register(
    "BlurAmount",
    Platform::String::typeid,
    BackdropBlurBrush::typeid,
    ref new PropertyMetadata(0.0, ref new PropertyChangedCallback(OnBlurAmountChanged))
);

BackdropBlurBrush::BackdropBlurBrush()
{
}

void BackdropBlurBrush::OnBlurAmountChanged(DependencyObject^ d, DependencyPropertyChangedEventArgs^ e)
{
    auto brush = static_cast<BackdropBlurBrush^>(d);
    // Unbox and set a new blur amount if the CompositionBrush exists
    if (brush->CompositionBrush != nullptr)
    {
        brush->CompositionBrush->Properties->InsertScalar("Blur.BlurAmount", (float)static_cast<double>(e->NewValue));
    }
}

void BackdropBlurBrush::OnConnected()
{
    // Delay creating composition resources until they're required
    if (CompositionBrush == nullptr)
    {
        auto backdrop = Window::Current->Compositor->CreateBackdropBrush();

        // Use a Win2D blur affect applied to a CompositionBackdropBrush
        auto graphicsEffect = ref new GaussianBlurEffect();
        graphicsEffect->Name = "Blur";
        graphicsEffect->BlurAmount = static_cast<float>(this->BlurAmount);
        graphicsEffect->Source = ref new CompositionEffectSourceParameter("backdrop");

        auto animatableProperties = ref new Platform::Collections::Vector<Platform::String^>();
        animatableProperties->Append("Blur.BlurAmount");

        auto effectFactory = Window::Current->Compositor->CreateEffectFactory(graphicsEffect, animatableProperties);
        auto effectBrush = effectFactory->CreateBrush();

        effectBrush->SetSourceParameter("backdrop", backdrop);

        CompositionBrush = effectBrush;
    }
}

void BackdropBlurBrush::OnDisconnected()
{
    // Dispose of composition resources when no longer in use
    if (CompositionBrush != nullptr)
    {
        delete CompositionBrush;
        CompositionBrush = nullptr;
    }
}

上述筆刷接著可以像任何其他 XAML 筆刷類型一樣使用來繪製 UIElements,例如:

針對 C++/WinRT,也會新增 #include "BackdropBlurBrush.h"MainPage.h

<Ellipse Width="100" Height="100">
    <Ellipse.Fill>
        <local:BackdropBlurBrush BlurAmount="10" />
    </Ellipse.Fill>
</Ellipse>

備註

您可以使用 XamlCompositionBrushBase 來建立自定義筆刷。

例如,它可以用來建立筆刷,以使用 CompositionEffectBrush效果套用至 XAML UIElements,或使用 SceneLightingEffect 控制元素的反射屬性,或鏈結在一起產生更複雜的一系列效果。

建立筆刷時,通常最好延遲建立 CompositionBrush 和任何相關資源,直到使用筆刷為止。 第一次在畫面上使用筆刷來繪製元素時,會呼叫 OnConnected 方法,因此您可以覆寫 OnConnected ,只在需要時安全地建立資源。 這表示您可以在 ResourceDictionary 中建立筆刷的實例,然後從 UI 定義的其他部分參考該筆刷資源,並且只在實際使用筆刷時支付建立組合資源的成本。

當組合資源不再使用時,也是一個很好的作法。 當筆刷實例不再使用在螢幕上的任何位置時,會呼叫 OnDisconnected 方法,因此您可以覆寫 OnDisconnected 以安全地處置資源。 如果在中斷連線之後再次使用筆刷,則會再次呼叫 OnConnected

建構函式

XamlCompositionBrushBase()

提供 XamlCompositionBrushBase 衍生類別的基類初始化行為。

屬性

CompositionBrush

取得或設定這個 XAML 筆刷所使用的 CompositionBrush

Dispatcher

一律會在 null Windows 應用程式 SDK 應用程式中傳回。 請改用 DispatcherQueue

(繼承來源 DependencyObject)
DispatcherQueue

DispatcherQueue取得與這個 物件相關聯的 。 DispatcherQueue表示即使程式代碼是由非 UI 線程起始,也可以存取 DependencyObject UI 線程上的 。

(繼承來源 DependencyObject)
FallbackColor

CompositionBrush 無法轉譯時所使用的色彩。

FallbackColorProperty

識別 FallbackColor 相依性屬性。

Opacity

取得或設定 Brush 不透明度的程度。

(繼承來源 Brush)
RelativeTransform

取得或設定使用相對座標套用到筆刷的轉換。

(繼承來源 Brush)
Transform

取得或設定套用到筆刷的轉換。

(繼承來源 Brush)

方法

ClearValue(DependencyProperty)

清除相依性屬性的本機值。

(繼承來源 DependencyObject)
GetAnimationBaseValue(DependencyProperty)

傳回針對相依性屬性所建立的任何基底值,如果動畫未使用中,則會套用。

(繼承來源 DependencyObject)
GetValue(DependencyProperty)

DependencyObject 傳回相依性屬性的目前有效值。

(繼承來源 DependencyObject)
OnConnected()

在螢幕第一次使用筆刷繪製元素時叫用。

在衍生類別中實作時,您可以建立 CompositionBrush 實例,並藉由設定 CompositionBrush 屬性將其提供給架構。

當筆刷不再用來繪製任何元素時,將會呼叫 OnDisconnected

OnDisconnected()

當筆刷不再用來繪製任何元素時叫用。

在衍生類別中實作時,您可以安全地處置撰寫筆刷和其他組合資源。

如果筆刷稍後用來在中斷連線之後繪製任何元素,將會再次呼叫 OnConnected

PopulatePropertyInfo(String, AnimationPropertyInfo)

定義可以產生動畫效果的屬性。

(繼承來源 Brush)
PopulatePropertyInfoOverride(String, AnimationPropertyInfo)

在衍生類別中覆寫時,定義可產生動畫效果的屬性。

(繼承來源 Brush)
ReadLocalValue(DependencyProperty)

如果已設定本機值,則傳回相依性屬性的本機值。

(繼承來源 DependencyObject)
RegisterPropertyChangedCallback(DependencyProperty, DependencyPropertyChangedCallback)

註冊通知函式,以接聽此 DependencyObject 實例上特定 DependencyProperty 的變更。

(繼承來源 DependencyObject)
SetValue(DependencyProperty, Object)

DependencyObject 上設定相依性屬性的本機值。

(繼承來源 DependencyObject)
UnregisterPropertyChangedCallback(DependencyProperty, Int64)

取消先前透過呼叫 RegisterPropertyChangedCallback 註冊的變更通知。

(繼承來源 DependencyObject)

適用於

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