1 /*
2  * Copyright 2019 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 
17 package com.android.car.apps.common.imaging;
18 
19 import android.annotation.Nullable;
20 import android.content.Context;
21 import android.graphics.drawable.BitmapDrawable;
22 import android.graphics.drawable.Drawable;
23 import android.util.Size;
24 import android.widget.ImageView;
25 
26 import com.android.car.apps.common.CommonFlags;
27 import com.android.car.apps.common.R;
28 
29 /**
30  * Binds images to an image view.<p/>
31  * While making a new image request (including passing a null {@link ImageBinder.ImageRef} in
32  * {@link #setImage}) will cancel the current image request (if any), RecyclerView doesn't
33  * always reuse all its views, causing multiple requests to not be canceled. On a slow network,
34  * those requests then take time to execute and can make it look like the application has
35  * stopped loading images if the user keeps browsing. To prevent that, override:
36  * {@link RecyclerView.Adapter#onViewDetachedFromWindow} and call {@link #maybeCancelLoading}
37  * {@link RecyclerView.Adapter#onViewAttachedToWindow} and call {@link #maybeRestartLoading}.
38  *
39  * @param <T> see {@link ImageRef}.
40  */
41 public class ImageViewBinder<T extends ImageBinder.ImageRef> extends ImageBinder<T> {
42 
43     @Nullable
44     private final ImageView mImageView;
45     private final boolean mFlagBitmaps;
46 
47     private T mSavedRef;
48     private boolean mCancelled;
49 
50     /** See {@link ImageViewBinder} and {@link ImageBinder}. */
ImageViewBinder(Size maxImageSize, @Nullable ImageView imageView)51     public ImageViewBinder(Size maxImageSize, @Nullable ImageView imageView) {
52         this(PlaceholderType.FOREGROUND, maxImageSize, imageView, false);
53     }
54 
55     /**
56      * See {@link ImageViewBinder} and {@link ImageBinder}.
57      * @param flagBitmaps whether this binder should flag bitmap drawables if flagging is enabled.
58      */
ImageViewBinder(PlaceholderType type, Size maxImageSize, @Nullable ImageView imageView, boolean flagBitmaps)59     public ImageViewBinder(PlaceholderType type, Size maxImageSize,
60             @Nullable ImageView imageView, boolean flagBitmaps) {
61         super(type, maxImageSize);
62         mImageView = imageView;
63         mFlagBitmaps = flagBitmaps;
64     }
65 
66     @Override
setDrawable(@ullable Drawable drawable)67     protected void setDrawable(@Nullable Drawable drawable) {
68         if (mImageView != null) {
69             mImageView.setImageDrawable(drawable);
70             if (mFlagBitmaps) {
71                 CommonFlags flags = CommonFlags.getInstance(mImageView.getContext());
72                 if (flags.shouldFlagImproperImageRefs()) {
73                     if (drawable instanceof BitmapDrawable) {
74                         int tint = mImageView.getContext().getColor(
75                                 R.color.improper_image_refs_tint_color);
76                         mImageView.setColorFilter(tint);
77                     } else {
78                         mImageView.clearColorFilter();
79                     }
80                 }
81             }
82         }
83     }
84 
85     /**
86      * Loads a new {@link ImageRef}. The previous request (if any) will be canceled.
87      */
88     @Override
setImage(Context context, @Nullable T newRef)89     public void setImage(Context context, @Nullable T newRef) {
90         mSavedRef = newRef;
91         mCancelled = false;
92         if (mImageView != null) {
93             super.setImage(context, newRef);
94         }
95     }
96 
97     /**
98      * Restarts the image loading request if {@link #setImage} was called with a valid reference
99      * that could not be loaded before {@link #maybeCancelLoading} was called.
100      */
maybeRestartLoading(Context context)101     public void maybeRestartLoading(Context context) {
102         if (mCancelled) {
103             setImage(context, mSavedRef);
104         }
105     }
106 
107     /**
108      * Cancels the current loading request (if any) so it doesn't take cycles when the imageView
109      * doesn't need the image (like when the view was moved off screen).
110      */
maybeCancelLoading(Context context)111     public void maybeCancelLoading(Context context) {
112         mCancelled = true;
113         if (mImageView != null) {
114             super.setImage(context, null); // Call super to keep mSavedRef.
115         }
116     }
117 
118     @Override
prepareForNewBinding(Context context)119     protected void prepareForNewBinding(Context context) {
120         mImageView.setImageBitmap(null);
121         mImageView.setImageDrawable(null);
122         mImageView.clearColorFilter();
123         // Call super last to setup the default loading drawable.
124         super.prepareForNewBinding(context);
125     }
126 
127 }
128