BitmapCache Class
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Creates and caches a bitmap representation of a UIElement.
public ref class BitmapCache sealed : System::Windows::Media::CacheModepublic sealed class BitmapCache : System.Windows.Media.CacheModetype BitmapCache = class
inherit CacheModePublic NotInheritable Class BitmapCache
Inherits CacheMode- Inheritance
Examples
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>
Remarks
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.
Note
RenderOptions and TextOptions do not propagate through a cached element. You may have to set these options again in child elements below the cache.
Constructors
| BitmapCache() |
Initializes a new instance of the BitmapCache class. |
| BitmapCache(Double) |
Initializes a new instance of the BitmapCache class with the specified scale. |
Fields
| EnableClearTypeProperty |
Identifies the EnableClearType dependency property. |
| RenderAtScaleProperty |
Identifies the RenderAtScale dependency property. |
| SnapsToDevicePixelsProperty |
Identifies the SnapsToDevicePixels dependency property. |
Properties
| CanFreeze |
Gets a value that indicates whether the object can be made unmodifiable. (Inherited from Freezable) |
| DependencyObjectType |
Gets the DependencyObjectType that wraps the CLR type of this instance. (Inherited from DependencyObject) |
| Dispatcher |
Gets the Dispatcher this DispatcherObject is associated with. (Inherited from DispatcherObject) |
| EnableClearType |
Gets or sets a value that indicates whether the bitmap is rendered with ClearType activated. |
| HasAnimatedProperties |
Gets a value that indicates whether one or more AnimationClock objects is associated with any of this object's dependency properties. (Inherited from Animatable) |
| IsFrozen |
Gets a value that indicates whether the object is currently modifiable. (Inherited from Freezable) |
| IsSealed |
Gets a value that indicates whether this instance is currently sealed (read-only). (Inherited from DependencyObject) |
| RenderAtScale |
Gets or sets a value that indicates the scale that is applied to the bitmap. |
| SnapsToDevicePixels |
Gets or sets a value that indicates whether the bitmap is rendered with pixel snapping. |
Methods
| ApplyAnimationClock(DependencyProperty, AnimationClock, HandoffBehavior) |
Applies an AnimationClock to the specified DependencyProperty. If the property is already animated, the specified HandoffBehavior is used. (Inherited from Animatable) |
| ApplyAnimationClock(DependencyProperty, AnimationClock) |
Applies an AnimationClock to the specified DependencyProperty. If the property is already animated, the SnapshotAndReplace handoff behavior is used. (Inherited from Animatable) |
| BeginAnimation(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) |
| BeginAnimation(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) |
| CheckAccess() |
Determines whether the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject) |
| ClearValue(DependencyProperty) |
Clears the local value of a property. The property to be cleared is specified by a DependencyProperty identifier. (Inherited from DependencyObject) |
| ClearValue(DependencyPropertyKey) |
Clears the local value of a read-only property. The property to be cleared is specified by a DependencyPropertyKey. (Inherited from DependencyObject) |
| Clone() |
Creates 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. |
| CloneCore(Freezable) |
Makes the instance a clone (deep copy) of the specified Freezable using base (non-animated) property values. (Inherited from Freezable) |
| CloneCurrentValue() |
Creates a modifiable clone (deep copy) of the BitmapCache using its current values. |
| CloneCurrentValueCore(Freezable) |
Makes the instance a modifiable clone (deep copy) of the specified Freezable using current property values. (Inherited from Freezable) |
| CoerceValue(DependencyProperty) |
Coerces 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) |
| CreateInstance() |
Initializes a new instance of the Freezable class. (Inherited from Freezable) |
| CreateInstanceCore() |
When implemented in a derived class, creates a new instance of the Freezable derived class. (Inherited from Freezable) |
| Equals(Object) |
Determines whether a provided DependencyObject is equivalent to the current DependencyObject. (Inherited from DependencyObject) |
| Freeze() |
Makes the current object unmodifiable and sets its IsFrozen property to |
| FreezeCore(Boolean) |
Makes this Animatable object unmodifiable or determines whether it can be made unmodifiable. (Inherited from Animatable) |
| GetAnimationBaseValue(DependencyProperty) |
Returns the non-animated value of the specified DependencyProperty. (Inherited from Animatable) |
| GetAsFrozen() |
Creates 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) |
| GetAsFrozenCore(Freezable) |
Makes the instance a frozen clone of the specified Freezable using base (non-animated) property values. (Inherited from Freezable) |
| GetCurrentValueAsFrozen() |
Creates 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) |
| GetCurrentValueAsFrozenCore(Freezable) |
Makes the current instance a frozen clone of the specified Freezable. If the object has animated dependency properties, their current animated values are copied. (Inherited from Freezable) |
| GetHashCode() |
Gets a hash code for this DependencyObject. (Inherited from DependencyObject) |
| GetLocalValueEnumerator() |
Creates a specialized enumerator for determining which dependency properties have locally set values on this DependencyObject. (Inherited from DependencyObject) |
| GetType() |
Gets the Type of the current instance. (Inherited from Object) |
| GetValue(DependencyProperty) |
Returns the current effective value of a dependency property on this instance of a DependencyObject. (Inherited from DependencyObject) |
| InvalidateProperty(DependencyProperty) |
Re-evaluates the effective value for the specified dependency property. (Inherited from DependencyObject) |
| MemberwiseClone() |
Creates a shallow copy of the current Object. (Inherited from Object) |
| OnChanged() |
Called when the current Freezable object is modified. (Inherited from Freezable) |
| OnFreezablePropertyChanged(DependencyObject, DependencyObject, DependencyProperty) |
This member supports the Windows Presentation Foundation (WPF) infrastructure and is not intended to be used directly from your code. (Inherited from Freezable) |
| OnFreezablePropertyChanged(DependencyObject, DependencyObject) |
Ensures that appropriate context pointers are established for a DependencyObjectType data member that has just been set. (Inherited from Freezable) |
| OnPropertyChanged(DependencyPropertyChangedEventArgs) |
Overrides the DependencyObject implementation of OnPropertyChanged(DependencyPropertyChangedEventArgs) to also invoke any Changed handlers in response to a changing dependency property of type Freezable. (Inherited from Freezable) |
| ReadLocalValue(DependencyProperty) |
Returns the local value of a dependency property, if it exists. (Inherited from DependencyObject) |
| ReadPreamble() |
Ensures that the Freezable is being accessed from a valid thread. Inheritors of Freezable must call this method at the beginning of any API that reads data members that are not dependency properties. (Inherited from Freezable) |
| SetCurrentValue(DependencyProperty, Object) |
Sets the value of a dependency property without changing its value source. (Inherited from DependencyObject) |
| SetValue(DependencyProperty, Object) |
Sets the local value of a dependency property, specified by its dependency property identifier. (Inherited from DependencyObject) |
| SetValue(DependencyPropertyKey, Object) |
Sets the local value of a read-only dependency property, specified by the DependencyPropertyKey identifier of the dependency property. (Inherited from DependencyObject) |
| ShouldSerializeProperty(DependencyProperty) |
Returns a value that indicates whether serialization processes should serialize the value for the provided dependency property. (Inherited from DependencyObject) |
| ToString() |
Returns a string that represents the current object. (Inherited from Object) |
| VerifyAccess() |
Enforces that the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject) |
| WritePostscript() |
Raises the Changed event for the Freezable and invokes its OnChanged() method. Classes that derive from Freezable should call this method at the end of any API that modifies class members that are not stored as dependency properties. (Inherited from Freezable) |
| WritePreamble() |
Verifies that the Freezable is not frozen and that it is being accessed from a valid threading context. Freezable inheritors should call this method at the beginning of any API that writes to data members that are not dependency properties. (Inherited from Freezable) |
Events
| Changed |
Occurs when the Freezable or an object it contains is modified. (Inherited from Freezable) |
