Class LocalResourceManager
- java.lang.Object
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- org.eclipse.jface.resource.ResourceManager
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- 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.
- Since:
- 3.1
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Constructor Summary
Constructors Constructor Description LocalResourceManager(ResourceManager parentRegistry)
Creates a local registry that delegates to the given global registry for all resource allocation and deallocation.LocalResourceManager(ResourceManager parentRegistry, Control owner)
Creates a local registry that wraps the given global registry.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected Object
allocate(DeviceResourceDescriptor descriptor)
Called the first time a resource is requested.Object
create(DeviceResourceDescriptor descriptor)
Returns the resource described by the given descriptor.protected void
deallocate(Object resource, DeviceResourceDescriptor descriptor)
Called the last time a resource is dereferenced.void
destroy(DeviceResourceDescriptor descriptor)
Deallocates a resource previously allocated byResourceManager.create(DeviceResourceDescriptor)
.void
dispose()
Deallocates any resources allocated by this registry that have not yet been deallocated.Object
find(DeviceResourceDescriptor descriptor)
Returns a previously allocated resource associated with the given descriptor, or null if none exists yet.protected Image
getDefaultImage()
Returns the default image that will be returned in the event that the intended image is missing.Device
getDevice()
Returns the Device for which this ResourceManager will create resources-
Methods inherited from class org.eclipse.jface.resource.ResourceManager
cancelDisposeExec, createColor, createColor, createFont, createImage, createImageWithDefault, destroyColor, destroyColor, destroyFont, destroyImage, disposeExec, get
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Constructor Detail
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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.- Parameters:
parentRegistry
- global registry
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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.- Parameters:
parentRegistry
- global registry that handles resource allocationowner
- control whose disposal will trigger cleanup of everything in the registry.
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Method Detail
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getDevice
public Device getDevice()
Description copied from class:ResourceManager
Returns the Device for which this ResourceManager will create resources- Specified by:
getDevice
in classResourceManager
- Returns:
- the Device associated with this ResourceManager
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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.- Parameters:
descriptor
- identifier for the resource to allocate- Returns:
- the newly allocated resource
- Throws:
DeviceResourceException
- Thrown when allocation of an SWT device resource fails
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deallocate
protected void deallocate(Object resource, DeviceResourceDescriptor descriptor)
Called the last time a resource is dereferenced. Should release any resources reserved by allocate(...).- Parameters:
resource
- resource being deallocateddescriptor
- identifier for the resource
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getDefaultImage
protected Image getDefaultImage()
Description copied from class:ResourceManager
Returns the default image that will be returned in the event that the intended image is missing.- Specified by:
getDefaultImage
in classResourceManager
- Returns:
- a default image that will be returned in the event that the intended image is missing.
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create
public final Object create(DeviceResourceDescriptor descriptor) throws DeviceResourceException
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 toResourceManager.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-livedLocalResourceManager
s, 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.
- Specified by:
create
in classResourceManager
- Parameters:
descriptor
- descriptor for the resource to allocate- Returns:
- the newly allocated resource (not null)
- Throws:
DeviceResourceException
- if unable to allocate the resource
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destroy
public final void destroy(DeviceResourceDescriptor descriptor)
Description copied from class:ResourceManager
Deallocates a resource previously allocated byResourceManager.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.- Specified by:
destroy
in classResourceManager
- Parameters:
descriptor
- identifier for the resource
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dispose
public void dispose()
Deallocates any resources allocated by this registry that have not yet been deallocated.- Overrides:
dispose
in classResourceManager
- Since:
- 3.1
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find
public Object find(DeviceResourceDescriptor descriptor)
Description copied from class:ResourceManager
Returns a previously allocated resource associated with the given descriptor, or null if none exists yet.- Specified by:
find
in classResourceManager
- Parameters:
descriptor
- descriptor to find- Returns:
- a previously allocated resource for the given descriptor or null if none.
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