1 /**
2  * Copyright (C) 2013 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package com.android.volley.toolbox;
17 
18 import android.content.Context;
19 import android.text.TextUtils;
20 import android.util.AttributeSet;
21 import android.view.ViewGroup.LayoutParams;
22 import android.widget.ImageView;
23 
24 import com.android.volley.VolleyError;
25 import com.android.volley.toolbox.ImageLoader.ImageContainer;
26 import com.android.volley.toolbox.ImageLoader.ImageListener;
27 
28 /**
29  * Handles fetching an image from a URL as well as the life-cycle of the
30  * associated request.
31  */
32 public class NetworkImageView extends ImageView {
33     /** The URL of the network image to load */
34     private String mUrl;
35 
36     /**
37      * Resource ID of the image to be used as a placeholder until the network image is loaded.
38      */
39     private int mDefaultImageId;
40 
41     /**
42      * Resource ID of the image to be used if the network response fails.
43      */
44     private int mErrorImageId;
45 
46     /** Local copy of the ImageLoader. */
47     private ImageLoader mImageLoader;
48 
49     /** Current ImageContainer. (either in-flight or finished) */
50     private ImageContainer mImageContainer;
51 
NetworkImageView(Context context)52     public NetworkImageView(Context context) {
53         this(context, null);
54     }
55 
NetworkImageView(Context context, AttributeSet attrs)56     public NetworkImageView(Context context, AttributeSet attrs) {
57         this(context, attrs, 0);
58     }
59 
NetworkImageView(Context context, AttributeSet attrs, int defStyle)60     public NetworkImageView(Context context, AttributeSet attrs, int defStyle) {
61         super(context, attrs, defStyle);
62     }
63 
64     /**
65      * Sets URL of the image that should be loaded into this view. Note that calling this will
66      * immediately either set the cached image (if available) or the default image specified by
67      * {@link NetworkImageView#setDefaultImageResId(int)} on the view.
68      *
69      * NOTE: If applicable, {@link NetworkImageView#setDefaultImageResId(int)} and
70      * {@link NetworkImageView#setErrorImageResId(int)} should be called prior to calling
71      * this function.
72      *
73      * @param url The URL that should be loaded into this ImageView.
74      * @param imageLoader ImageLoader that will be used to make the request.
75      */
setImageUrl(String url, ImageLoader imageLoader)76     public void setImageUrl(String url, ImageLoader imageLoader) {
77         mUrl = url;
78         mImageLoader = imageLoader;
79         // The URL has potentially changed. See if we need to load it.
80         loadImageIfNecessary(false);
81     }
82 
83     /**
84      * Sets the default image resource ID to be used for this view until the attempt to load it
85      * completes.
86      */
setDefaultImageResId(int defaultImage)87     public void setDefaultImageResId(int defaultImage) {
88         mDefaultImageId = defaultImage;
89     }
90 
91     /**
92      * Sets the error image resource ID to be used for this view in the event that the image
93      * requested fails to load.
94      */
setErrorImageResId(int errorImage)95     public void setErrorImageResId(int errorImage) {
96         mErrorImageId = errorImage;
97     }
98 
99     /**
100      * Loads the image for the view if it isn't already loaded.
101      * @param isInLayoutPass True if this was invoked from a layout pass, false otherwise.
102      */
loadImageIfNecessary(final boolean isInLayoutPass)103     void loadImageIfNecessary(final boolean isInLayoutPass) {
104         int width = getWidth();
105         int height = getHeight();
106 
107         boolean wrapWidth = false, wrapHeight = false;
108         if (getLayoutParams() != null) {
109             wrapWidth = getLayoutParams().width == LayoutParams.WRAP_CONTENT;
110             wrapHeight = getLayoutParams().height == LayoutParams.WRAP_CONTENT;
111         }
112 
113         // if the view's bounds aren't known yet, and this is not a wrap-content/wrap-content
114         // view, hold off on loading the image.
115         boolean isFullyWrapContent = wrapWidth && wrapHeight;
116         if (width == 0 && height == 0 && !isFullyWrapContent) {
117             return;
118         }
119 
120         // if the URL to be loaded in this view is empty, cancel any old requests and clear the
121         // currently loaded image.
122         if (TextUtils.isEmpty(mUrl)) {
123             if (mImageContainer != null) {
124                 mImageContainer.cancelRequest();
125                 mImageContainer = null;
126             }
127             setDefaultImageOrNull();
128             return;
129         }
130 
131         // if there was an old request in this view, check if it needs to be canceled.
132         if (mImageContainer != null && mImageContainer.getRequestUrl() != null) {
133             if (mImageContainer.getRequestUrl().equals(mUrl)) {
134                 // if the request is from the same URL, return.
135                 return;
136             } else {
137                 // if there is a pre-existing request, cancel it if it's fetching a different URL.
138                 mImageContainer.cancelRequest();
139                 setDefaultImageOrNull();
140             }
141         }
142 
143         // Calculate the max image width / height to use while ignoring WRAP_CONTENT dimens.
144         int maxWidth = wrapWidth ? 0 : width;
145         int maxHeight = wrapHeight ? 0 : height;
146 
147         // The pre-existing content of this view didn't match the current URL. Load the new image
148         // from the network.
149         ImageContainer newContainer = mImageLoader.get(mUrl,
150                 new ImageListener() {
151                     @Override
152                     public void onErrorResponse(VolleyError error) {
153                         if (mErrorImageId != 0) {
154                             setImageResource(mErrorImageId);
155                         }
156                     }
157 
158                     @Override
159                     public void onResponse(final ImageContainer response, boolean isImmediate) {
160                         // If this was an immediate response that was delivered inside of a layout
161                         // pass do not set the image immediately as it will trigger a requestLayout
162                         // inside of a layout. Instead, defer setting the image by posting back to
163                         // the main thread.
164                         if (isImmediate && isInLayoutPass) {
165                             post(new Runnable() {
166                                 @Override
167                                 public void run() {
168                                     onResponse(response, false);
169                                 }
170                             });
171                             return;
172                         }
173 
174                         if (response.getBitmap() != null) {
175                             setImageBitmap(response.getBitmap());
176                         } else if (mDefaultImageId != 0) {
177                             setImageResource(mDefaultImageId);
178                         }
179                     }
180                 }, maxWidth, maxHeight);
181 
182         // update the ImageContainer to be the new bitmap container.
183         mImageContainer = newContainer;
184     }
185 
setDefaultImageOrNull()186     private void setDefaultImageOrNull() {
187         if(mDefaultImageId != 0) {
188             setImageResource(mDefaultImageId);
189         }
190         else {
191             setImageBitmap(null);
192         }
193     }
194 
195     @Override
onLayout(boolean changed, int left, int top, int right, int bottom)196     protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
197         super.onLayout(changed, left, top, right, bottom);
198         loadImageIfNecessary(true);
199     }
200 
201     @Override
onDetachedFromWindow()202     protected void onDetachedFromWindow() {
203         if (mImageContainer != null) {
204             // If the view was bound to an image request, cancel it and clear
205             // out the image from the view.
206             mImageContainer.cancelRequest();
207             setImageBitmap(null);
208             // also clear out the container so we can reload the image if necessary.
209             mImageContainer = null;
210         }
211         super.onDetachedFromWindow();
212     }
213 
214     @Override
drawableStateChanged()215     protected void drawableStateChanged() {
216         super.drawableStateChanged();
217         invalidate();
218     }
219 }
220