PreferenceViewHolder.java
/*
* Copyright 2018 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 androidx.preference;
import android.content.res.ColorStateList;
import android.graphics.drawable.Drawable;
import android.util.SparseArray;
import android.view.View;
import android.widget.TextView;
import androidx.annotation.IdRes;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RestrictTo;
import androidx.core.view.ViewCompat;
import androidx.recyclerview.widget.RecyclerView;
/**
* A {@link RecyclerView.ViewHolder} class which caches views associated with the default
* {@link Preference} layouts. Cached views can be retrieved by calling {@link #findViewById(int)}.
*/
public class PreferenceViewHolder extends RecyclerView.ViewHolder {
@Nullable
private final Drawable mBackground;
private ColorStateList mTitleTextColors;
private final SparseArray<View> mCachedViews = new SparseArray<>(4);
private boolean mDividerAllowedAbove;
private boolean mDividerAllowedBelow;
PreferenceViewHolder(@NonNull View itemView) {
super(itemView);
final TextView titleView = itemView.findViewById(android.R.id.title);
// Pre-cache the views that we know in advance we'll want to find
mCachedViews.put(android.R.id.title, titleView);
mCachedViews.put(android.R.id.summary, itemView.findViewById(android.R.id.summary));
mCachedViews.put(android.R.id.icon, itemView.findViewById(android.R.id.icon));
mCachedViews.put(R.id.icon_frame, itemView.findViewById(R.id.icon_frame));
mCachedViews.put(AndroidResources.ANDROID_R_ICON_FRAME,
itemView.findViewById(AndroidResources.ANDROID_R_ICON_FRAME));
mBackground = itemView.getBackground();
if (titleView != null) {
mTitleTextColors = titleView.getTextColors();
}
}
/** @hide */
@RestrictTo(RestrictTo.Scope.TESTS)
@NonNull
public static PreferenceViewHolder createInstanceForTests(@NonNull View itemView) {
return new PreferenceViewHolder(itemView);
}
/**
* Returns a cached reference to a subview managed by this object. If the view reference is not
* yet cached, it falls back to calling {@link View#findViewById(int)} and caches the result.
*
* @param id Resource ID of the view to find
* @return The view, or {@code null} if no view with the requested ID is found
*/
public View findViewById(@IdRes int id) {
final View cachedView = mCachedViews.get(id);
if (cachedView != null) {
return cachedView;
} else {
final View v = itemView.findViewById(id);
if (v != null) {
mCachedViews.put(id, v);
}
return v;
}
}
/**
* Dividers are only drawn between items if both items allow it, or above the first and below
* the last item if that item allows it.
*
* @return {@code true} if dividers are allowed above this item
*/
public boolean isDividerAllowedAbove() {
return mDividerAllowedAbove;
}
/**
* Dividers are only drawn between items if both items allow it, or above the first and below
* the last item if that item allows it.
*
* By default, {@link Preference#onBindViewHolder(PreferenceViewHolder)} will set this to the
* same value as returned by {@link Preference#isSelectable()}, so that non-selectable items
* do not have a divider drawn above them.
*
* @param allowed False to prevent dividers being drawn above this item
*/
public void setDividerAllowedAbove(boolean allowed) {
mDividerAllowedAbove = allowed;
}
/**
* Dividers are only drawn between items if both items allow it, or above the first and below
* the last item if that item allows it.
*
* @return {@code true} if dividers are allowed below this item
*/
public boolean isDividerAllowedBelow() {
return mDividerAllowedBelow;
}
/**
* Dividers are only drawn between items if both items allow it, or above the first and below
* the last item if that item allows it.
*
* By default, {@link Preference#onBindViewHolder(PreferenceViewHolder)} will set this to the
* same value as returned by {@link Preference#isSelectable()}, so that non-selectable items
* do not have a divider drawn below them.
*
* @param allowed False to prevent dividers being drawn below this item
*/
public void setDividerAllowedBelow(boolean allowed) {
mDividerAllowedBelow = allowed;
}
/**
* Resets the state of properties modified by
* {@link Preference#onBindViewHolder(PreferenceViewHolder)} to ensure that we don't keep
* stale state for a different {@link Preference} around.
*/
void resetState() {
if (itemView.getBackground() != mBackground) {
ViewCompat.setBackground(itemView, mBackground);
}
final TextView titleView = (TextView) findViewById(android.R.id.title);
if (titleView != null && mTitleTextColors != null) {
if (!titleView.getTextColors().equals(mTitleTextColors)) {
titleView.setTextColor(mTitleTextColors);
}
}
}
}