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org.eclipse.jface.resource
Class LocalResourceManager
java.lang.Object
org.eclipse.jface.resource.ResourceManager
org.eclipse.jface.resource.LocalResourceManager
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public final class LocalResourceManager
- extends
ResourceManager
A local registry that shares its resources with some global registry.
LocalResourceManager is typically used to safeguard against leaks. Clients
can use a nested registry to allocate and deallocate resources in the
global registry. Calling dispose() on the nested registry will deallocate
everything allocated for the nested registry without affecting the rest
of the global registry.
A nested registry can be used to manage the resources for, say, a dialog
box.
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Since:
- 3.1
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Methods inherited from class org.eclipse.jface.resource.
ResourceManager
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cancelDisposeExec,
createColor,
createColor,
createFont,
createImage,
createImageWithDefault,
destroyColor,
destroyColor,
destroyFont,
destroyImage,
disposeExec,
get
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Methods inherited from class java.lang.
Object
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clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
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LocalResourceManager
public LocalResourceManager(
ResourceManager parentRegistry)
- Creates a local registry that delegates to the given global registry
for all resource allocation and deallocation.
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Parameters:
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parentRegistry - global registry
LocalResourceManager
public LocalResourceManager(
ResourceManager parentRegistry,
Control owner)
- Creates a local registry that wraps the given global registry. Anything
allocated by this registry will be automatically cleaned up with the given
control is disposed. Note that registries created in this way should not
be used to allocate any resource that must outlive the given control.
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Parameters:
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parentRegistry - global registry that handles resource allocation -
owner - control whose disposal will trigger cleanup of everything
in the registry.
getDevice
public
Device getDevice()
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Description copied from class:
ResourceManager
- Returns the Device for which this ResourceManager will create resources
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Specified by:
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getDevice
in class
ResourceManager
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Returns:
- the Device associated with this ResourceManager
allocate
protected
Object allocate(
DeviceResourceDescriptor descriptor)
throws
DeviceResourceException
- Called the first time a resource is requested. Should allocate and return a resource
of the correct type.
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Parameters:
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descriptor - identifier for the resource to allocate
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Returns:
- the newly allocated resource
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Throws:
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DeviceResourceException
- Thrown when allocation of an SWT device resource fails
deallocate
protected void deallocate(
Object resource,
DeviceResourceDescriptor descriptor)
- Called the last time a resource is dereferenced. Should release any resources reserved by
allocate(...).
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Parameters:
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resource - resource being deallocated -
descriptor - identifier for the resource
getDefaultImage
protected
Image getDefaultImage()
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Description copied from class:
ResourceManager
- Returns the default image that will be returned in the event that the intended
image is missing.
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Specified by:
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getDefaultImage
in class
ResourceManager
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Returns:
- a default image that will be returned in the event that the intended
image is missing.
create
public final
Object create(
DeviceResourceDescriptor descriptor)
throws
DeviceResourceException
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Description copied from class:
ResourceManager
- Returns the resource described by the given descriptor. If the resource already
exists, the reference count is incremented and the exiting resource is returned.
Otherwise, a new resource is allocated. Every call to this method should have
a corresponding call to
ResourceManager.destroy(DeviceResourceDescriptor).
If the resource is intended to live for entire lifetime of the resource manager,
a subsequent call to
ResourceManager.destroy(DeviceResourceDescriptor) may be omitted and the
resource will be cleaned up when the resource manager is disposed. This pattern
is useful for short-lived
LocalResourceManagers, but should never be used
with the global resource manager since doing so effectively leaks the resource.
The resources returned from this method are reference counted and may be shared
internally with other resource managers. They should never be disposed outside of the
ResourceManager framework, or it will cause exceptions in other code that shares
them. For example, never call
Resource.dispose()
on anything returned from this method.
Callers may safely downcast the result to the resource type associated with
the descriptor. For example, when given an ImageDescriptor, the return
value of this method will always be an Image.
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Specified by:
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create
in class
ResourceManager
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Parameters:
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descriptor - descriptor for the resource to allocate
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Returns:
- the newly allocated resource (not null)
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Throws:
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DeviceResourceException
- if unable to allocate the resource
destroy
public final void destroy(
DeviceResourceDescriptor descriptor)
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Description copied from class:
ResourceManager
- Deallocates a resource previously allocated by
ResourceManager.create(DeviceResourceDescriptor).
Descriptors are compared by equality, not identity. If the same resource was
created multiple times, this may decrement a reference count rather than
disposing the actual resource.
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Specified by:
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destroy
in class
ResourceManager
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Parameters:
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descriptor - identifier for the resource
dispose
public void dispose()
- Deallocates any resources allocated by this registry that have not yet been
deallocated.
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Overrides:
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dispose
in class
ResourceManager
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Since:
- 3.1
find
public
Object find(
DeviceResourceDescriptor descriptor)
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Description copied from class:
ResourceManager
- Returns a previously allocated resource associated with the given descriptor, or
null if none exists yet.
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Specified by:
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find
in class
ResourceManager
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Parameters:
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descriptor - descriptor to find
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Returns:
- a previously allocated resource for the given descriptor or null if none.
Guidelines for using Eclipse APIs.
Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.
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