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BitmapCache Class

Creates and caches a bitmap representation of a UIElement.

Namespace:  System.Windows.Media
Assembly:  PresentationCore (in PresentationCore.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation

public sealed class BitmapCache : CacheMode
<BitmapCache .../>

The BitmapCache type exposes the following members.

  NameDescription
Public methodBitmapCache()Initializes a new instance of the BitmapCache class.
Public methodBitmapCache(Double)Initializes a new instance of the BitmapCache class with the specified scale.
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  NameDescription
Public propertyCanFreezeGets a value that indicates whether the object can be made unmodifiable. (Inherited from Freezable.)
Public propertyDependencyObjectTypeGets the DependencyObjectType that wraps the CLR type of this instance.  (Inherited from DependencyObject.)
Public propertyDispatcherGets the Dispatcher this DispatcherObject is associated with. (Inherited from DispatcherObject.)
Public propertyEnableClearTypeGets or sets a value that indicates whether the bitmap is rendered with ClearType activated.
Public propertyHasAnimatedPropertiesGets a value that indicates whether one or more AnimationClock objects is associated with any of this object's dependency properties. (Inherited from Animatable.)
Public propertyIsFrozenGets a value that indicates whether the object is currently modifiable. (Inherited from Freezable.)
Public propertyIsSealedGets a value that indicates whether this instance is currently sealed (read-only). (Inherited from DependencyObject.)
Public propertyRenderAtScaleGets or sets a value that indicates the scale that is applied to the bitmap.
Public propertySnapsToDevicePixelsGets or sets a value that indicates whether the bitmap is rendered with pixel snapping.
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  NameDescription
Public methodApplyAnimationClock(DependencyProperty, AnimationClock)Applies an AnimationClock to the specified DependencyProperty. If the property is already animated, the SnapshotAndReplace handoff behavior is used. (Inherited from Animatable.)
Public methodApplyAnimationClock(DependencyProperty, AnimationClock, HandoffBehavior)Applies an AnimationClock to the specified DependencyProperty. If the property is already animated, the specified HandoffBehavior is used. (Inherited from Animatable.)
Public methodBeginAnimation(DependencyProperty, AnimationTimeline)Applies an animation to the specified DependencyProperty. The animation is started when the next frame is rendered. If the specified property is already animated, the SnapshotAndReplace handoff behavior is used. (Inherited from Animatable.)
Public methodBeginAnimation(DependencyProperty, AnimationTimeline, HandoffBehavior)Applies an animation to the specified DependencyProperty. The animation is started when the next frame is rendered. If the specified property is already animated, the specified HandoffBehavior is used. (Inherited from Animatable.)
Public methodCheckAccessDetermines whether the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.)
Public methodClearValue(DependencyProperty)Clears the local value of a property. The property to be cleared is specified by a DependencyProperty identifier. (Inherited from DependencyObject.)
Public methodClearValue(DependencyPropertyKey)Clears the local value of a read-only property. The property to be cleared is specified by a DependencyPropertyKey. (Inherited from DependencyObject.)
Public methodCloneCreates a modifiable clone of the BitmapCache, making deep copies of the object's values. When copying the object's dependency properties, this method copies expressions (which might no longer resolve) but not animations or their current values.
Public methodCloneCurrentValueCreates a modifiable clone (deep copy) of the BitmapCache using its current values.
Public methodCoerceValueCoerces the value of the specified dependency property. This is accomplished by invoking any CoerceValueCallback function specified in property metadata for the dependency property as it exists on the calling DependencyObject. (Inherited from DependencyObject.)
Public methodEqualsDetermines whether a provided DependencyObject is equivalent to the current DependencyObject. (Inherited from DependencyObject.)
Public methodFreeze()Makes the current object unmodifiable and sets its IsFrozen property to true. (Inherited from Freezable.)
Public methodGetAnimationBaseValueReturns the non-animated value of the specified DependencyProperty. (Inherited from Animatable.)
Public methodGetAsFrozenCreates a frozen copy of the Freezable, using base (non-animated) property values. Because the copy is frozen, any frozen sub-objects are copied by reference. (Inherited from Freezable.)
Public methodGetCurrentValueAsFrozenCreates a frozen copy of the Freezable using current property values. Because the copy is frozen, any frozen sub-objects are copied by reference. (Inherited from Freezable.)
Public methodGetHashCodeGets a hash code for this DependencyObject. (Inherited from DependencyObject.)
Public methodGetLocalValueEnumeratorCreates a specialized enumerator for determining which dependency properties have locally set values on this DependencyObject. (Inherited from DependencyObject.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodGetValueReturns the current effective value of a dependency property on this instance of a DependencyObject. (Inherited from DependencyObject.)
Public methodInvalidatePropertyRe-evaluates the effective value for the specified dependency property (Inherited from DependencyObject.)
Public methodReadLocalValueReturns the local value of a dependency property, if it exists. (Inherited from DependencyObject.)
Public methodSetCurrentValueSets the value of a dependency property without changing its value source. (Inherited from DependencyObject.)
Public methodSetValue(DependencyProperty, Object)Sets the local value of a dependency property, specified by its dependency property identifier. (Inherited from DependencyObject.)
Public methodSetValue(DependencyPropertyKey, Object)Sets the local value of a read-only dependency property, specified by the DependencyPropertyKey identifier of the dependency property. (Inherited from DependencyObject.)
Protected methodShouldSerializePropertyReturns a value that indicates whether serialization processes should serialize the value for the provided dependency property. (Inherited from DependencyObject.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodVerifyAccessEnforces that the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.)
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  NameDescription
Public eventChangedOccurs when the Freezable or an object it contains is modified. (Inherited from Freezable.)
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  NameDescription
Public fieldStatic memberEnableClearTypePropertyIdentifies the EnableClearType dependency property.
Public fieldStatic memberRenderAtScalePropertyIdentifies the RenderAtScale dependency property.
Public fieldStatic memberSnapsToDevicePixelsPropertyIdentifies the SnapsToDevicePixels dependency property.
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Use the BitmapCache class to improve rendering performance of a complex UIElement. Create a BitmapCache and assign it to the CacheMode property of a UIElement to cache the element and its subtree as a bitmap in video memory. This is useful when you need to animate, translate, or scale a UIElement as quickly as possible. This approach enables a tradeoff between performance and visual quality while content is cached.

Use the BitmapCacheBrush class to efficiently reuse a cached element.

Set the RenderAtScale property to scale the bitmap cache. This is useful if an element will be zoomed, and you want the element to render more clearly than it would if the cache were simply generated at the element’s native resolution.

Set the SnapsToDevicePixels property when the cache displays content that requires pixel-alignment to render correctly, such as ClearType text. This property is ignored by the BitmapCacheBrush and Viewport2DVisual3D classes.

Caching a control does not affect mouse-over behavior, so mouse-over hit testing operates as if it the bitmap were a live control.

Cache regeneration occurs only when the structure of the UIElement or its subtree changes, or when the CacheMode settings change. Setting the RenderAtScale or EnableClearType properties causes cache regeneration. Changes to the parent visual tree of the cached UIElement, such as transforms, scales, opacities, and effects, do not affect the cache.

The cache functions when hardware acceleration is not available. In this case, the bitmap is rendered in software, and the maximum bitmap dimensions are 2048 x 2048.

NoteNote

RenderOptions and TextOptions do not propagate through a cached element. You may have to set these options again in child elements below the cache.

The following XAML shows how to cache a Canvas element. For the complete code example, see How to: Improve Rendering Performance by Caching an Element.

<!-- //////////////////////////////////////////////////////////////// -->
<!-- // The following XAML creates a BitmapCache with default      // -->
<!-- // properties and assigns it as the CacheMode for the canvas. // -->
<!-- //////////////////////////////////////////////////////////////// -->
<Canvas.CacheMode>
    <BitmapCache EnableClearType="False" 
                 RenderAtScale="1" 
                 SnapsToDevicePixels="False"  />
</Canvas.CacheMode>

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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