PanelBase
This is the base class for all the panels provided by the Views product. It allows custom panels to be built that animate the arrangement of the child elements, and can be used in the SwitchPanel.
Overview
The PanelBase provides the base functionality of all animated panels. It provides attached properties for storing state information, as well as the current animation rectangle.
When building a custom panel that derives from the native Panel, the ArrangeOverride and MeasureOverride methods are overridden. Similarly, when building a custom panel that derives from the PanelBase, the ArrangeElements and MeasureElements methods should be overridden. Additionally, the panel should not reference the Children collection, but instead arrange the list of elements specified. This allows the panel's layout logic to be leveraged by the SwitchPanel.
See the Building a Custom Panel topic for more information.
Arrange State
The PanelBase uses the ArrangeStateProperty attached property to storage state information about its child elements. The state is represented by an instance of ArrangeState, and captures the current status, current arrange rectangle, previous arrange rectangle, and an optional "from" point.
The ArrangeState.ArrangeStatus indicates the current status of the element. The valid statuses are: Entering, Leaving, ArrangeUpdating, and LayoutUpdating.
| Member | Description |
|---|---|
Entering Field |
Indicates that the element was just added to the panel and is "entering" the view. |
Leaving Field |
Indicates that the element was just removed from the panel and is "leaving" the view. |
ArrangeUpdating Field |
Indicates that the element is changing position or size in the panel due to the standard arrange phase. |
LayoutUpdating Field |
Indicates that the element is changing position or size because the layout logic of the panel changed (e.g., the orientation is changed). |
The current and previous arrange rectangles are captured in the ArrangeRect and PreviousArrangeRect properties, respectively.
Finally, the ArrangeFromPoint can be used to optionally change the location that an element starts its "move" animation from. This is usually leveraged by custom panels to customize the movement of elements.
Disabling Animations Per Element
Using the PanelBase.IsAnimatedProperty attached property, animations can be selectively disabled for individual elements. This property defaults to true and is supported by all panels that derive from PanelBase.
Important Members
The following PanelBase members are key to its use:
| Member | Description |
|---|---|
|
ArrangeAnimation Property |
Gets or sets the IArrangeAnimation that controls the animation of elements when arranging. |
|
ArrangeElement Method |
Arranges the specified element using the current arrange state. This can be used to force an element to arrange using its current arrange location, but does not typically need to be called directly. |
|
ArrangeElements Method |
Positions the specified elements and determines a size for a This method must be implemented by derivations of |
|
ArrangeHeightAnimatedProperty Attached Property |
Gets or sets the height used when arranging the associated element. NoteTypically, the property should never be set directly, as it is animated when the state of the element is changed. |
|
ArrangeStateProperty Attached Property |
Gets or sets the current state of the associated element, which can include an updated arrange rectangle. |
|
ArrangeWidthAnimatedProperty Attached Property |
Gets or sets the width used when arranging the associated element. NoteTypically, the property should never be set directly, as it is animated when the state of the element is changed. |
|
ArrangeXAnimatedProperty Attached Property |
Gets or sets the position along the X-axis of the parent panel used when arranging the associated element. NoteTypically, the property should never be set directly, as it is animated when the state of the element is changed. |
|
ArrangeYAnimatedProperty Attached Property |
Gets or sets the position along the Y-axis of the parent panel used when arranging the associated element. NoteTypically, the property should never be set directly, as it is animated when the state of the element is changed. |
|
IsLayoutUpdatePending Property |
Gets a value indicating whether a change to the layout logic has changed and the elements have yet to be arranged. This is typically used to distinguish between the |
|
MeasureElements Method |
Measures the size in layout required for child elements and determines a size for the This method must be implemented by derivations of |