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Andy De George
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---
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title: "Popup Placement Behavior"
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description: Learn how to specify the position of a Windows Presentation Foundation Popup relative to a control, the mouse, or the screen by using properties.
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ms.date: "03/30/2017"
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helpviewer_keywords:
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- "popups [WPF]"
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- "Popup control [WPF], placing"
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- "placing popups [WPF]"
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- "positioning popups [WPF]"
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ms.assetid: fbf642e9-f670-4efd-a7af-a67468a1c8e1
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---
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# Popup Placement Behavior
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A <xref:System.Windows.Controls.Primitives.Popup> control displays content in a separate window that floats over an application. You can specify the position of a <xref:System.Windows.Controls.Primitives.Popup> relative to a control, the mouse, or the screen by using the <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A>, <xref:System.Windows.Controls.Primitives.Popup.Placement%2A>, <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A>, <xref:System.Windows.Controls.Primitives.Popup.HorizontalOffset%2A>, and <xref:System.Windows.Controls.Primitives.Popup.VerticalOffset%2A> properties. These properties work together to give you flexibility in specifying the position of the <xref:System.Windows.Controls.Primitives.Popup>.
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> [!NOTE]
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> The <xref:System.Windows.Controls.ToolTip> and <xref:System.Windows.Controls.ContextMenu> classes also define these five properties and behave similarly.
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<a name="Positioning"></a>
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## Positioning the Popup
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The placement of a <xref:System.Windows.Controls.Primitives.Popup> can be relative to a <xref:System.Windows.UIElement> or to the entire screen. The following example creates four <xref:System.Windows.Controls.Primitives.Popup> controls that are relative to a <xref:System.Windows.UIElement>—in this case, an image. All of the <xref:System.Windows.Controls.Primitives.Popup> controls have the <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> property set to `image1`, but each <xref:System.Windows.Controls.Primitives.Popup> has a different value for the placement property.
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[!code-xaml[PopupPositionSnippet#3](~/samples/snippets/csharp/VS_Snippets_Wpf/PopupPositionSnippet/CS/Window1.xaml#3)]
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The following illustration shows the image and the <xref:System.Windows.Controls.Primitives.Popup> controls
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This simple example demonstrates how to set the <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> and <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> properties, but by using the <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A>, <xref:System.Windows.Controls.Primitives.Popup.HorizontalOffset%2A>, and <xref:System.Windows.Controls.Primitives.Popup.VerticalOffset%2A> properties, you have even more control over where the <xref:System.Windows.Controls.Primitives.Popup> is positioned.
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<a name="Definitions"></a>
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## Definitions of Terms: The Anatomy of a Popup
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The following terms are useful in understanding how the <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A>, <xref:System.Windows.Controls.Primitives.Popup.Placement%2A>, <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A>, <xref:System.Windows.Controls.Primitives.Popup.HorizontalOffset%2A>, and <xref:System.Windows.Controls.Primitives.Popup.VerticalOffset%2A> properties relate to each other and the <xref:System.Windows.Controls.Primitives.Popup>:
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- Target object
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- Target area
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- Target origin
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- Popup alignment point
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These terms provide a convenient way to refer to various aspects of the <xref:System.Windows.Controls.Primitives.Popup> and the control that it is associated with.
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### Target Object
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The *target object* is the element that the <xref:System.Windows.Controls.Primitives.Popup> is associated with. If the <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> property is set, it specifies the target object. If <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> is not set, and the <xref:System.Windows.Controls.Primitives.Popup> has a parent, the parent is the target object. If there is no <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> value and no parent, there is no target object, and the <xref:System.Windows.Controls.Primitives.Popup> is positioned relative to the screen.
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The following example creates a <xref:System.Windows.Controls.Primitives.Popup> that is the child of a <xref:System.Windows.Controls.Canvas>. The example does not set the <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> property on the <xref:System.Windows.Controls.Primitives.Popup>. The default value for <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Bottom?displayProperty=nameWithType>, so the <xref:System.Windows.Controls.Primitives.Popup> appears below the <xref:System.Windows.Controls.Canvas>.
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[!code-xaml[PopupPositionSnippet#1](~/samples/snippets/csharp/VS_Snippets_Wpf/PopupPositionSnippet/CS/Window1.xaml#1)]
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The following illustration shows that the <xref:System.Windows.Controls.Primitives.Popup> is positioned relative to the <xref:System.Windows.Controls.Canvas>.
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The following example creates a <xref:System.Windows.Controls.Primitives.Popup> that is the child of a <xref:System.Windows.Controls.Canvas>, but this time the <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> is set to `ellipse1`, so the popup appears below the <xref:System.Windows.Shapes.Ellipse>.
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[!code-xaml[PopupPositionSnippet#2](~/samples/snippets/csharp/VS_Snippets_Wpf/PopupPositionSnippet/CS/Window1.xaml#2)]
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The following illustration shows that the <xref:System.Windows.Controls.Primitives.Popup> is positioned relative to the <xref:System.Windows.Shapes.Ellipse>.
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> [!NOTE]
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> For <xref:System.Windows.Controls.ToolTip>, the default value of <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Mouse>. For <xref:System.Windows.Controls.ContextMenu>, the default value of <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.MousePoint>. These values are explained later, in "How the Properties Work Together."
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### Target Area
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The *target area* is the area on the screen that the <xref:System.Windows.Controls.Primitives.Popup> is relative to. In the previous examples, the <xref:System.Windows.Controls.Primitives.Popup> is aligned with the bounds of the target object, but in some cases, the <xref:System.Windows.Controls.Primitives.Popup> is aligned to other bounds, even if the <xref:System.Windows.Controls.Primitives.Popup> has a target object. If the <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> property is set, the target area is different than the bounds of the target object.
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The following example creates two <xref:System.Windows.Controls.Canvas> objects, each one containing a <xref:System.Windows.Shapes.Rectangle> and a <xref:System.Windows.Controls.Primitives.Popup>. In both cases, the target object for the <xref:System.Windows.Controls.Primitives.Popup> is the <xref:System.Windows.Controls.Canvas>. The <xref:System.Windows.Controls.Primitives.Popup> in the first <xref:System.Windows.Controls.Canvas> has the <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> set, with its <xref:System.Windows.Rect.X%2A>, <xref:System.Windows.Rect.Y%2A>, <xref:System.Windows.Rect.Width%2A>, and <xref:System.Windows.Rect.Height%2A> properties set to 50, 50, 50, and 100, respectively. The <xref:System.Windows.Controls.Primitives.Popup> in the second <xref:System.Windows.Controls.Canvas> does not have the <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> set. As a result, the first <xref:System.Windows.Controls.Primitives.Popup> is positioned below the <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> and the second <xref:System.Windows.Controls.Primitives.Popup> is positioned below the <xref:System.Windows.Controls.Canvas>. Each <xref:System.Windows.Controls.Canvas> also contains a <xref:System.Windows.Shapes.Rectangle> that has the same bounds as the <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> for the first <xref:System.Windows.Controls.Primitives.Popup>. Note that the <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> does not create a visible element in the application; the example creates a <xref:System.Windows.Shapes.Rectangle> to represent the <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A>.
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[!code-xaml[PopupPositionSnippet#4](~/samples/snippets/csharp/VS_Snippets_Wpf/PopupPositionSnippet/CS/Window1.xaml#4)]
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The following illustration shows the result of the preceding example.
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### Target Origin and Popup Alignment Point
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The *target origin* and *popup alignment point* are reference points on the target area and popup, respectively, that are used for positioning. You can use the <xref:System.Windows.Controls.Primitives.Popup.HorizontalOffset%2A> and <xref:System.Windows.Controls.Primitives.Popup.VerticalOffset%2A> properties to offset the popup from the target area. The <xref:System.Windows.Controls.Primitives.Popup.HorizontalOffset%2A> and <xref:System.Windows.Controls.Primitives.Popup.VerticalOffset%2A> are relative to the target origin and the popup alignment point. The value of the <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> property determines where the target origin and popup alignment point are located.
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The following example creates a <xref:System.Windows.Controls.Primitives.Popup> and sets the <xref:System.Windows.Controls.Primitives.Popup.HorizontalOffset%2A> and <xref:System.Windows.Controls.Primitives.Popup.VerticalOffset%2A> properties to 20. The <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> property is set to <xref:System.Windows.Controls.Primitives.PlacementMode.Bottom> (the default), so the target origin is the bottom-left corner of the target area and the popup alignment point is the top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.
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[!code-xaml[PopupPositionSnippet#5](~/samples/snippets/csharp/VS_Snippets_Wpf/PopupPositionSnippet/CS/Window1.xaml#5)]
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The following illustration shows the result of the preceding example.
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<a name="How"></a>
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## How the Properties Work Together
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The values of <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A>, <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A>, and <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> need to be considered together to figure out the correct target area, target origin, and popup alignment point. For example, if the value of <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Mouse>, there is no target object, the <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is ignored, and the target area is the bounds of the mouse pointer. On the other hand, if <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Bottom>, the <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> or parent determines the target object and <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> determines the target area.
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The following table describes the target object, target area, target origin, and popup alignment point and indicates whether <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> and <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> are used for each <xref:System.Windows.Controls.Primitives.PlacementMode> enumeration value.
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|PlacementMode|Target object|Target area|Target origin|Popup alignment point|
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|-------------------|-------------------|-----------------|-------------------|---------------------------|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Absolute>|Not applicable. <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> is ignored.|The screen, or <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> if it is set. The <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is relative to the screen.|The top-left corner of the target area.|The top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.AbsolutePoint>|Not applicable. <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> is ignored.|The screen, or <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> if it is set. The <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is relative to the screen.|The top-left corner of the target area.|The top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Bottom>|<xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> or parent.|The target object, or <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> if it is set. The <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is relative to the target object.|The bottom-left corner of the target area.|The top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Center>|<xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> or parent.|The target object, or <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> if it is set. The <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is relative to the target object.|The center of the target area.|The center of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Custom>|<xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> or parent.|The target object, or <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> if it is set. The <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is relative to the target object.|Defined by the <xref:System.Windows.Controls.Primitives.CustomPopupPlacementCallback>.|Defined by the <xref:System.Windows.Controls.Primitives.CustomPopupPlacementCallback>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Left>|<xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> or parent.|The target object, or <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> if it is set. The <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is relative to the target object.|The top-left corner of the target area.|The top-right corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Mouse>|Not applicable. <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> is ignored.|The bounds of the mouse pointer. <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is ignored.|The bottom-left corner of the target area.|The top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.MousePoint>|Not applicable. <xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> is ignored.|The bounds of the mouse pointer. <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is ignored.|The top-left corner of the target area.|The top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Relative>|<xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> or parent.|The target object, or <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> if it is set. The <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is relative to the target object.|The top-left corner of the target area.|The top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.RelativePoint>|<xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> or parent.|The target object, or <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> if it is set. The <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is relative to the target object.|The top-left corner of the target area.|The top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Right>|<xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> or parent.|The target object, or <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> if it is set. The <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is relative to the target object.|The top-right corner of the target area.|The top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Top>|<xref:System.Windows.Controls.Primitives.Popup.PlacementTarget%2A> or parent.|The target object, or <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> if it is set. The <xref:System.Windows.Controls.Primitives.Popup.PlacementRectangle%2A> is relative to the target object.|The top-left corner of the target area.|The bottom-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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The following illustrations show the <xref:System.Windows.Controls.Primitives.Popup>, target area, target origin, and popup alignment point for each <xref:System.Windows.Controls.Primitives.PlacementMode> value. In each figure, the target area is yellow, and the <xref:System.Windows.Controls.Primitives.Popup> is blue.
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<a name="When"></a>
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## When the Popup Encounters the Edge of the Screen
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For security reasons, a <xref:System.Windows.Controls.Primitives.Popup> cannot be hidden by the edge of a screen. One of the following three things happens when the <xref:System.Windows.Controls.Primitives.Popup> encounters a screen edge:
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- The popup realigns itself along the screen edge that would obscure the <xref:System.Windows.Controls.Primitives.Popup>.
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- The popup uses a different popup alignment point.
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- The popup uses a different target origin and popup alignment point.
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These options are described further later in this section.
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The behavior of the <xref:System.Windows.Controls.Primitives.Popup> when it encounters a screen edge depends on the value of the <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> property and which screen edge the popup encounters. The following table summarizes the behavior when the <xref:System.Windows.Controls.Primitives.Popup> encounters a screen edge for each <xref:System.Windows.Controls.Primitives.PlacementMode> value.
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|PlacementMode|Top edge|Bottom edge|Left edge|Right edge|
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|-------------------|--------------|-----------------|---------------|----------------|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Absolute>|Aligns to the top edge.|Aligns to the bottom edge.|Aligns to the left edge.|Aligns to the right edge.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.AbsolutePoint>|Aligns to the top edge.|The popup alignment point changes to the bottom-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|Aligns to the left edge.|The popup alignment point changes to the top-right corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Bottom>|Aligns to the top edge.|The target origin changes to the top-left corner of the target area and the popup alignment point changes to the bottom-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|Aligns to the left edge.|Aligns to the right edge.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Center>|Aligns to the top edge.|Aligns to the bottom edge.|Aligns to the left edge.|Aligns to the right edge.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Left>|Aligns to the top edge.|Aligns to the bottom edge.|The target origin changes to the top-right corner of the target area and the popup alignment point changes to the top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|Aligns to the right edge.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Mouse>|Aligns to the top edge.|The target origin changes to the top-left corner of the target area (the bounds of the mouse pointer) and the popup alignment point changes to the bottom-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|Aligns to the left edge.|Aligns to the right edge.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.MousePoint>|Aligns to the top edge.|The popup alignment point changes to the bottom-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|Aligns to the left edge.|The popup alignment point changes to the top-right corner of the popup.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Relative>|Aligns to the top edge.|Aligns to the bottom edge.|Aligns to the left edge.|Aligns to the right edge.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.RelativePoint>|Aligns to the top edge.|The popup alignment point changes to the bottom-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.|Aligns to the left edge.|The popup alignment point changes to the top-right corner of the popup.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Right>|Aligns to the top edge.|Aligns to the bottom edge.|Aligns to the left edge.|The target origin changes to the top-left corner of the target area and the popup alignment point changes to the top-right corner of the <xref:System.Windows.Controls.Primitives.Popup>.|
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|<xref:System.Windows.Controls.Primitives.PlacementMode.Top>|The target origin changes to the bottom-left corner of the target area and the popup alignment point changes to the top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>. In effect, this is the same as when <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Bottom>.|Aligns to the bottom edge.|Aligns to the left edge.|Aligns to the right edge.|
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### Aligning to the Screen Edge
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A <xref:System.Windows.Controls.Primitives.Popup> can align to the edge of the screen by repositioning itself so the entire <xref:System.Windows.Controls.Primitives.Popup> is visible on the screen. When this occurs, the distance between the target origin and popup alignment point might differ from the values of <xref:System.Windows.Controls.Primitives.Popup.HorizontalOffset%2A> and <xref:System.Windows.Controls.Primitives.Popup.VerticalOffset%2A>. When <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Absolute>, <xref:System.Windows.Controls.Primitives.PlacementMode.Center>, or <xref:System.Windows.Controls.Primitives.PlacementMode.Relative>, the <xref:System.Windows.Controls.Primitives.Popup> aligns itself to every screen edge. For example, assume that a <xref:System.Windows.Controls.Primitives.Popup> has <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> set to <xref:System.Windows.Controls.Primitives.PlacementMode.Relative> and <xref:System.Windows.Controls.Primitives.Popup.VerticalOffset%2A> set to 100. If the bottom edge of the screen hides all or part of the <xref:System.Windows.Controls.Primitives.Popup>, the <xref:System.Windows.Controls.Primitives.Popup> repositions itself along the bottom edge of the screen and the vertical distance between the target origin and popup alignment point is less than 100. The following illustration demonstrates this.
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||||
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### Changing the Popup Alignment Point
|
||||
If <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.AbsolutePoint>, <xref:System.Windows.Controls.Primitives.PlacementMode.RelativePoint>, or <xref:System.Windows.Controls.Primitives.PlacementMode.MousePoint>, the popup alignment point changes when the popup encounters the bottom or right screen edge.
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||||
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||||
The following illustration demonstrates that when the bottom screen edge hides all or part of the <xref:System.Windows.Controls.Primitives.Popup>, the popup alignment point is the bottom-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.
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||||
|
||||
|
||||
|
||||
The following illustration demonstrates that when the <xref:System.Windows.Controls.Primitives.Popup> is hidden by the right screen edge, the popup alignment point is the top-right corner of the <xref:System.Windows.Controls.Primitives.Popup>.
|
||||
|
||||
|
||||
|
||||
If the <xref:System.Windows.Controls.Primitives.Popup> encounters the bottom and right screen edges, the popup alignment point is the bottom-right corner of the <xref:System.Windows.Controls.Primitives.Popup>.
|
||||
|
||||
### Changing the Target Origin and Popup Alignment Point
|
||||
When <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Bottom>, <xref:System.Windows.Controls.Primitives.PlacementMode.Left>, <xref:System.Windows.Controls.Primitives.PlacementMode.Mouse>, <xref:System.Windows.Controls.Primitives.PlacementMode.Right>, or <xref:System.Windows.Controls.Primitives.PlacementMode.Top>, the target origin and popup alignment point change if a certain screen edge is encountered. The screen edge that causes the position to change depends on the <xref:System.Windows.Controls.Primitives.PlacementMode> value.
|
||||
|
||||
The following illustration demonstrates that when <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Bottom> and the <xref:System.Windows.Controls.Primitives.Popup> encounters the bottom screen edge, the target origin is the top-left corner of the target area and the popup alignment point is the bottom-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.
|
||||
|
||||
|
||||
|
||||
The following illustration demonstrates that when <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Left> and the <xref:System.Windows.Controls.Primitives.Popup> encounters the left screen edge, the target origin is the top-right corner of the target area and the popup alignment point is the top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.
|
||||
|
||||
|
||||
|
||||
The following illustration demonstrates that when <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Right> and the <xref:System.Windows.Controls.Primitives.Popup> encounters the right screen edge, the target origin is the top-left corner of the target area and the popup alignment point is the top-right corner of the <xref:System.Windows.Controls.Primitives.Popup>.
|
||||
|
||||
|
||||
|
||||
The following illustration demonstrates that when <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Top> and the <xref:System.Windows.Controls.Primitives.Popup> encounters the top screen edge, the target origin is the bottom-left corner of the target area and the popup alignment point is the top-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.
|
||||
|
||||
|
||||
|
||||
The following illustration demonstrates that when <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> is <xref:System.Windows.Controls.Primitives.PlacementMode.Mouse> and the <xref:System.Windows.Controls.Primitives.Popup> encounters the bottom screen edge, the target origin is the top-left corner of the target area (the bounds of the mouse pointer) and the popup alignment point is the bottom-left corner of the <xref:System.Windows.Controls.Primitives.Popup>.
|
||||
|
||||
|
||||
|
||||
### Customizing Popup Placement
|
||||
You can customize the target origin and popup alignment point by setting the <xref:System.Windows.Controls.Primitives.Popup.Placement%2A> property to <xref:System.Windows.Controls.Primitives.PlacementMode.Custom>. Then define a <xref:System.Windows.Controls.Primitives.CustomPopupPlacementCallback> delegate that returns a set of possible placement points and primary axes (in order of preference) for the <xref:System.Windows.Controls.Primitives.Popup>. The point that shows the largest portion of the <xref:System.Windows.Controls.Primitives.Popup> is selected. The position of the <xref:System.Windows.Controls.Primitives.Popup> is automatically adjusted if the <xref:System.Windows.Controls.Primitives.Popup> is hidden by the edge of the screen. For an example, see [Specify a Custom Popup Position](how-to-specify-a-custom-popup-position.md).
|
||||
|
||||
## See also
|
||||
|
||||
- [Popup Placement Sample](https://github.com/dotnet/docs/tree/master/samples/snippets/csharp/VS_Snippets_Wpf/PopupPositionSnippet/CS)
|
||||
Reference in New Issue
Block a user