Signal-Android/app/src/main/java/org/thoughtcrime/securesms/util/CachedInflater.java

134 lines
3.9 KiB
Java

package org.thoughtcrime.securesms.util;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.LayoutRes;
import androidx.annotation.MainThread;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.asynclayoutinflater.view.AsyncLayoutInflater;
import org.thoughtcrime.securesms.R;
import org.thoughtcrime.securesms.logging.Log;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
/**
* A class that can be used to pre-cache layouts. Usage flow:
*
* - At some point before you want to use the views, call {@link #cacheUntilLimit(int, ViewGroup, int)}.
* - Later, use {@link #inflate(int, ViewGroup, boolean)}, which will prefer using cached views
* before inflating new ones.
*/
public class CachedInflater {
private static final String TAG = Log.tag(CachedInflater.class);
private final Context context;
/**
* Does *not* work with the application context.
*/
public static CachedInflater from(@NonNull Context context) {
return new CachedInflater(context);
}
private CachedInflater(@NonNull Context context) {
this.context = context;
}
/**
* Identical to {@link LayoutInflater#inflate(int, ViewGroup, boolean)}, but will prioritize
* pulling a cached view first.
*/
@MainThread
@SuppressWarnings("unchecked")
public <V extends View> V inflate(@LayoutRes int layoutRes, @Nullable ViewGroup parent, boolean attachToRoot) {
View cached = ViewCache.getInstance().pull(layoutRes);
if (cached != null) {
if (parent != null && attachToRoot) {
parent.addView(cached);
}
return (V) cached;
} else {
return (V) LayoutInflater.from(context).inflate(layoutRes, parent, attachToRoot);
}
}
/**
* Will inflate as many views as necessary until the cache holds the amount you specify.
*/
@MainThread
public void cacheUntilLimit(@LayoutRes int layoutRes, @Nullable ViewGroup parent, int limit) {
ViewCache.getInstance().cacheUntilLimit(context, layoutRes, parent, limit);
}
/**
* Clears all cached views. This should be done if, for instance, the theme changes.
*/
@MainThread
public void clear() {
Log.d(TAG, "Clearing view cache.");
ViewCache.getInstance().clear();
}
private static class ViewCache {
private static final ViewCache INSTANCE = new ViewCache();
private final Map<Integer, List<View>> cache = new HashMap<>();
private long lastClearTime;
static ViewCache getInstance() {
return INSTANCE;
}
@MainThread
void cacheUntilLimit(Context context, @LayoutRes int layoutRes, @Nullable ViewGroup parent, int limit) {
AsyncLayoutInflater inflater = new AsyncLayoutInflater(context);
int existingCount = Util.getOrDefault(cache, layoutRes, Collections.emptyList()).size();
int inflateCount = Math.max(limit - existingCount, 0);
for (int i = 0; i < inflateCount; i++) {
final long enqueueTime = System.currentTimeMillis();
inflater.inflate(layoutRes, parent, (view, resId, p) -> {
Util.assertMainThread();
if (enqueueTime < lastClearTime) {
Log.d(TAG, "Prefetch is no longer valid. Ignoring.");
return;
}
List<View> views = cache.get(resId);
views = views == null ? new LinkedList<>() : views;
views.add(view);
cache.put(resId, views);
});
}
}
@MainThread
@Nullable View pull(@LayoutRes int layoutRes) {
List<View> views = cache.get(layoutRes);
return views != null && !views.isEmpty() ? views.remove(0)
: null;
}
@MainThread
void clear() {
lastClearTime = System.currentTimeMillis();
cache.clear();
}
}
}