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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.bitmap;
import android.os.ParcelFileDescriptor;
import java.io.IOException;
import java.io.InputStream;
/**
* The decode task uses this class to get input to decode. You must implement at least one of
* {@link #createFileDescriptorFactoryAsync(RequestKey, Callback)} or {@link #createInputStream()}.
* {@link DecodeTask} will prioritize
* {@link #createFileDescriptorFactoryAsync(RequestKey, Callback)} before falling back to
* {@link #createInputStream()}.
*
*
* Clients of this interface must also implement {@link #equals(Object)} and {@link #hashCode()} as
* this object will be used as a cache key.
*
*
* The following is a high level view of the interactions between RequestKey and the rest of the
* system.
*
* BasicBitmapDrawable
* UI Thread
* ++
* bind() || Background Thread
* |+-------------------->+
* || createFDFasync() ||
* || || Download from url
* || || Cache on disk
* || ||
* || vv
* |<--------------------+x
* || FDFcreated()
* ||
* ||
* || DecodeTask
* || AsyncTask Thread
* |+-------------------->+
* || new().execute() ||
* || || Decode from FDF
* || || or createInputStream()
* || ||
* || vv
* |<--------------------+x
* || onDecodeComplete()
* vv
* invalidate() xx
*/
public interface RequestKey {
/**
* Create an {@link FileDescriptorFactory} for a local file stored on the device and pass it to
* the given callback. This method will be called in favor of {@link #createInputStream()}},
* which will only be called if null is returned from this method,
* or {@link Callback#fileDescriptorFactoryCreated(RequestKey, FileDescriptorFactory)} is called
* with a null FileDescriptorFactory.
*
* Clients should implement this method if files are in the local cache folder, or if files must
* be downloaded and cached.
*
* This method must be called from the UI thread.
*
* @param key The key to create a FileDescriptorFactory for. This key will be passed to the
* callback so it can check whether the key has changed.
* @param callback The callback to notify once the FileDescriptorFactory is created or has failed
* to be created.
* Do not invoke the callback directly from this method. Instead, create a handler
* and post a Runnable.
*
* @return If the client will attempt to create a FileDescriptorFactory, return a Cancelable
* object to cancel the asynchronous task. If the client wants to create an InputStream instead,
* return null. The callback must be notified if and only if the client returns a Cancelable
* object and not null.
*/
public Cancelable createFileDescriptorFactoryAsync(RequestKey key, Callback callback);
/**
* Create an {@link InputStream} for the source. This method will be called if
* {@link #createFileDescriptorFactoryAsync(RequestKey, Callback)} returns null.
*
* Clients should implement this method if files exist in the assets/ folder, or for prototypes
* that open a connection directly on a URL (be warned that this will cause GCs).
*
* This method can be called from any thread.
*/
public InputStream createInputStream() throws IOException;
/**
* Return true if the image source may have be oriented in either portrait or landscape, and
* will need to be automatically re-oriented based on accompanying Exif metadata.
*
* This method can be called from any thread.
*/
public boolean hasOrientationExif() throws IOException;
/**
* Callback for creating the {@link FileDescriptorFactory} asynchronously.
*/
public interface Callback {
/**
* Notifies that the {@link FileDescriptorFactory} has been created. This must be called on
* the UI thread.
* @param key The key that the FileDescriptorFactory was created for. The callback should
* check that the key has not changed.
* @param factory The FileDescriptorFactory to decode from. Pass null to cancel decode.
*/
void fileDescriptorFactoryCreated(RequestKey key, FileDescriptorFactory factory);
}
public interface FileDescriptorFactory {
ParcelFileDescriptor createFileDescriptor();
}
/**
* Interface for a background task that is cancelable.
*/
public interface Cancelable {
/**
* Cancel the background task. This must be called on the UI thread.
*/
void cancel();
}
}