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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.koushikdutta.ion;
 
 import  android.content.Context;
 import  android.graphics.Bitmap;
 import  android.text.TextUtils;
 import  android.util.AttributeSet;
 import  android.widget.ImageView;
 
 import  com.koushikdutta.async.future.Future;
 
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<Bitmap>> mBitmap;
 
     public NetworkImageView(Context context) {
         this(contextnull);
     }
 
     public NetworkImageView(Context context, AttributeSet attrs) {
         this(contextattrs, 0);
     }
 
     public NetworkImageView(Context context, AttributeSet attrsint defStyle) {
         super(contextattrsdefStyle);
     }

    
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 NetworkImageView.setDefaultImageResId(int) on the view. NOTE: If applicable, NetworkImageView.setDefaultImageResId(int) and NetworkImageView.setErrorImageResId(int) should be called prior to calling this function.

Parameters:
url The URL that should be loaded into this ImageView.
ion ImageLoader that will be used to make the request.
 
     public void setImageUrl(String urlIon ion) {
          = 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 NetworkImageView.setDefaultImageResId(int) on the view. NOTE: If applicable, NetworkImageView.setDefaultImageResId(int) and NetworkImageView.setErrorImageResId(int) should be called prior to calling this function.

Parameters:
url The URL that should be loaded into this ImageView.
 
     public void setImageUrl(String url) {
          = 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) {
         = 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) {
         = 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 = ;
         = url;
        // if the view's bounds aren't known yet, hold off on loading the image.
        if (width == 0 && height == 0) {
            return;
        }
        Future<Bitmap> bitmap;
        if ( == null)
            bitmap = null;
        else
            bitmap = .get();
        // if the URL to be loaded in this view is empty, cancel any old requests and clear the
        // currently loaded image.
        if (TextUtils.isEmpty()) {
            if (bitmap != null) {
                bitmap.cancel();
                 = null;
            }
            setImageBitmap(null);
            return;
        }
        // if there was an old request in this view, check if it needs to be canceled.
        if (bitmap != null && oldUrl != null) {
            if (oldUrl.equals()) {
                // 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.
                bitmap.cancel();
                setImageBitmap(null);
            }
        }
        // The pre-existing content of this view didn't match the current URL. Load the new image
        // from the network.
        bitmap = .build(this)
            .placeholder()
            .error()
            .load();
         = new WeakReference<Future<Bitmap>>(bitmap);
    }
    @Override
    protected void onLayout(boolean changedint leftint topint rightint bottom) {
        super.onLayout(changedlefttoprightbottom);
        loadImageIfNecessary();
    }
    @Override
    protected void onDetachedFromWindow() {
        Future<Bitmap> bitmap;
        if ( == null)
            bitmap = null;
        else
            bitmap = .get();
        if (bitmap != null) {
            // If the view was bound to an image request, cancel it and clear
            // out the image from the view.
            bitmap.cancel();
            setImageBitmap(null);
            // also clear out the container so we can reload the image if necessary.
             = null;
        }
        super.onDetachedFromWindow();
    }
    @Override
    protected void drawableStateChanged() {
        super.drawableStateChanged();
        invalidate();
    }
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