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.content.Context;
20 import android.graphics.drawable.BitmapDrawable;
21 import android.graphics.drawable.Drawable;
22 import android.util.Size;
23 import android.widget.ImageView;
24 
25 import androidx.annotation.Nullable;
26 
27 import com.android.car.apps.common.CommonFlags;
28 import com.android.car.apps.common.R;
29 
30 /**
31  * Binds images to an image view.<p/>
32  * While making a new image request (including passing a null {@link ImageBinder.ImageRef} in
33  * {@link #setImage}) will cancel the current image request (if any), RecyclerView doesn't
34  * always reuse all its views, causing multiple requests to not be canceled. On a slow network,
35  * those requests then take time to execute and can make it look like the application has
36  * stopped loading images if the user keeps browsing. To prevent that, override:
37  * {@link RecyclerView.Adapter#onViewDetachedFromWindow} and call {@link #maybeCancelLoading}
38  * {@link RecyclerView.Adapter#onViewAttachedToWindow} and call {@link #maybeRestartLoading}.
39  *
40  * @param <T> see {@link ImageRef}.
41  */
42 public class ImageViewBinder<T extends ImageBinder.ImageRef> extends ImageBinder<T> {
43 
44     @Nullable
45     private final ImageView mImageView;
46     private final boolean mFlagBitmaps;
47 
48     private T mSavedRef;
49     private boolean mCancelled;
50 
51     /** See {@link ImageViewBinder} and {@link ImageBinder}. */
ImageViewBinder(Size maxImageSize, @Nullable ImageView imageView)52     public ImageViewBinder(Size maxImageSize, @Nullable ImageView imageView) {
53         this(PlaceholderType.FOREGROUND, maxImageSize, imageView, false);
54     }
55 
56     /**
57      * See {@link ImageViewBinder} and {@link ImageBinder}.
58      * @param flagBitmaps whether this binder should flag bitmap drawables if flagging is enabled.
59      */
ImageViewBinder(PlaceholderType type, Size maxImageSize, @Nullable ImageView imageView, boolean flagBitmaps)60     public ImageViewBinder(PlaceholderType type, Size maxImageSize,
61             @Nullable ImageView imageView, boolean flagBitmaps) {
62         super(type, maxImageSize);
63         mImageView = imageView;
64         mFlagBitmaps = flagBitmaps;
65     }
66 
67     @Override
setDrawable(@ullable Drawable drawable)68     protected void setDrawable(@Nullable Drawable drawable) {
69         if (mImageView != null) {
70             mImageView.setImageDrawable(drawable);
71             if (mFlagBitmaps) {
72                 CommonFlags flags = CommonFlags.getInstance(mImageView.getContext());
73                 if (flags.shouldFlagImproperImageRefs()) {
74                     if (drawable instanceof BitmapDrawable) {
75                         int tint = mImageView.getContext().getColor(
76                                 R.color.improper_image_refs_tint_color);
77                         mImageView.setColorFilter(tint);
78                     } else {
79                         mImageView.clearColorFilter();
80                     }
81                 }
82             }
83         }
84     }
85 
86     /**
87      * Loads a new {@link ImageRef}. The previous request (if any) will be canceled.
88      */
89     @Override
setImage(Context context, @Nullable T newRef)90     public void setImage(Context context, @Nullable T newRef) {
91         mSavedRef = newRef;
92         mCancelled = false;
93         if (mImageView != null) {
94             super.setImage(context, newRef);
95         }
96     }
97 
98     /**
99      * Restarts the image loading request if {@link #setImage} was called with a valid reference
100      * that could not be loaded before {@link #maybeCancelLoading} was called.
101      */
maybeRestartLoading(Context context)102     public void maybeRestartLoading(Context context) {
103         if (mCancelled) {
104             setImage(context, mSavedRef);
105         }
106     }
107 
108     /**
109      * Cancels the current loading request (if any) so it doesn't take cycles when the imageView
110      * doesn't need the image (like when the view was moved off screen).
111      */
maybeCancelLoading(Context context)112     public void maybeCancelLoading(Context context) {
113         mCancelled = true;
114         if (mImageView != null) {
115             super.setImage(context, null); // Call super to keep mSavedRef.
116         }
117     }
118 
119     @Override
prepareForNewBinding(Context context)120     protected void prepareForNewBinding(Context context) {
121         mImageView.setImageBitmap(null);
122         mImageView.setImageDrawable(null);
123         mImageView.clearColorFilter();
124         // Call super last to setup the default loading drawable.
125         super.prepareForNewBinding(context);
126     }
127 
128 }
129