Class DeviceResourceManager
- java.lang.Object
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- org.eclipse.jface.resource.ResourceManager
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- org.eclipse.jface.resource.DeviceResourceManager
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public final class DeviceResourceManager extends ResourceManager
Manages SWT resources for a particular device.IMPORTANT: in most cases clients should use a
LocalResourceManager
instead of aDeviceResourceManager
. To create a resource manager on a particular display, usenew LocalResourceManager(JFaceResources.getResources(myDisplay))
.DeviceResourceManager
should only be used directly when managing resources for a device other than a Display (such as a printer).- Since:
- 3.1
- See Also:
LocalResourceManager
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Constructor Summary
Constructors Constructor Description DeviceResourceManager(Device device)
Creates a new registry for the given device.
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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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DeviceResourceManager
public DeviceResourceManager(Device device)
Creates a new registry for the given device.- Parameters:
device
- device to manage
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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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dispose
public void dispose()
Deallocates any resources allocated by this registry that have not yet been deallocated.
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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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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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