/**
* 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.koushikdutta.ion;
import android.content.Context;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.widget.ImageView;
import com.koushikdutta.async.future.Future;
import java.lang.ref.WeakReference;
/**
* Handles fetching an image from a URL as well as the life-cycle of the
* associated request.
*/
public class NetworkImageView extends ImageView {
/** The URL of the network image to load */
private String mUrl;
/**
* Resource ID of the image to be used as a placeholder until the network image is loaded.
*/
private int mDefaultImageId;
/**
* Resource ID of the image to be used if the network response fails.
*/
private int mErrorImageId;
/** Local copy of the Ion. */
private Ion mIon;
/** Current Future<Bitmap. (either in-flight or finished) */
private WeakReference<Future<ImageView>> mFuture;
public NetworkImageView(Context context) {
this(context, null);
}
public NetworkImageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public NetworkImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
/**
* Sets URL of the image that should be loaded into this view. Note that calling this will
* immediately either set the cached image (if available) or the default image specified by
* {@link NetworkImageView#setDefaultImageResId(int)} on the view.
*
* NOTE: If applicable, {@link NetworkImageView#setDefaultImageResId(int)} and
* {@link NetworkImageView#setErrorImageResId(int)} should be called prior to calling
* this function.
*
* @param url The URL that should be loaded into this ImageView.
* @param ion ImageLoader that will be used to make the request.
*/
public void setImageUrl(String url, Ion ion) {
mIon = ion;
// The URL has potentially changed. See if we need to load it.
loadImageIfNecessary(url);
}
/**
* Sets URL of the image that should be loaded into this view. Note that calling this will
* immediately either set the cached image (if available) or the default image specified by
* {@link NetworkImageView#setDefaultImageResId(int)} on the view.
*
* NOTE: If applicable, {@link NetworkImageView#setDefaultImageResId(int)} and
* {@link NetworkImageView#setErrorImageResId(int)} should be called prior to calling
* this function.
*
* @param url The URL that should be loaded into this ImageView.
*/
public void setImageUrl(String url) {
mIon = Ion.getDefault(getContext());
// The URL has potentially changed. See if we need to load it.
loadImageIfNecessary(url);
}
/**
* Sets the default image resource ID to be used for this view until the attempt to load it
* completes.
*/
public void setDefaultImageResId(int defaultImage) {
mDefaultImageId = defaultImage;
}
/**
* Sets the error image resource ID to be used for this view in the event that the image
* requested fails to load.
*/
public void setErrorImageResId(int errorImage) {
mErrorImageId = errorImage;
}
/**
* Loads the image for the view if it isn't already loaded.
*/
private void loadImageIfNecessary(String url) {
int width = getWidth();
int height = getHeight();
String oldUrl = mUrl;
mUrl = url;
// if the view's bounds aren't known yet, hold off on loading the image.
if (width == 0 && height == 0) {
return;
}
Future<ImageView> future;
if (mFuture == null)
future = null;
else
future = mFuture.get();
// if the URL to be loaded in this view is empty, cancel any old requests and recycle the
// currently loaded image.
if (TextUtils.isEmpty(mUrl)) {
if (future != null) {
future.cancel();
mFuture = null;
}
setImageBitmap(null);
return;
}
// if there was an old request in this view, check if it needs to be canceled.
if (future != null && oldUrl != null) {
if (oldUrl.equals(mUrl)) {
// if the request is from the same URL, return.
return;
} else {
// if there is a pre-existing request, cancel it if it's fetching a different URL.
future.cancel();
setImageBitmap(null);
}
}
// The pre-existing content of this view didn't match the current URL. Load the new image
// from the network.
future = mIon.build(this)
.placeholder(mDefaultImageId)
.error(mErrorImageId)
.load(mUrl);
mFuture = new WeakReference<Future<ImageView>>(future);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
loadImageIfNecessary(mUrl);
}
@Override
protected void onDetachedFromWindow() {
Future<ImageView> future;
if (mFuture == null)
future = null;
else
future = mFuture.get();
if (future != null) {
// If the view was bound to an image request, cancel it and recycle
// out the image from the view.
future.cancel();
setImageBitmap(null);
// also recycle out the container so we can reload the image if necessary.
mFuture = null;
}
super.onDetachedFromWindow();
}
@Override
protected void drawableStateChanged() {
super.drawableStateChanged();
invalidate();
}
}