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/*
* Copyright (C) 2011 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 com.android.gallery3d.util;
import android.app.Activity;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import java.util.WeakHashMap;
/**
* This class manages the visibility of the progress spinner in the action bar for an
* Activity. It filters out short-lived appearances of the progress spinner by only
* showing the spinner if it hasn't been hidden again before the end of a specified
* delay period. It also enforces a minimum display time once the spinner is made visible.
* This meant to cut down on the frequent "flashes" of the progress spinner.
*/
public class SpinnerVisibilitySetter {
private static final int MSG_SHOW_SPINNER = 1;
private static final int MSG_HIDE_SPINNER = 2;
// Amount of time after a show request that the progress spinner is actually made visible.
// This means that any show/hide requests that happen subsequently within this period
// of time will be ignored.
private static final long SPINNER_DISPLAY_DELAY = 1000;
// The minimum amount of time the progress spinner must be visible before it can be hidden.
private static final long MIN_SPINNER_DISPLAY_TIME = 2000;
static final WeakHashMap<Activity, SpinnerVisibilitySetter> sInstanceMap =
new WeakHashMap<Activity, SpinnerVisibilitySetter>();
private long mSpinnerVisibilityStartTime = -1;
private Activity mActivity;
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch(msg.what) {
case MSG_SHOW_SPINNER:
removeMessages(MSG_SHOW_SPINNER);
if (mSpinnerVisibilityStartTime >= 0) break;
mSpinnerVisibilityStartTime = SystemClock.elapsedRealtime();
mActivity.setProgressBarIndeterminateVisibility(true);
break;
case MSG_HIDE_SPINNER:
removeMessages(MSG_HIDE_SPINNER);
if (mSpinnerVisibilityStartTime < 0) break;
long t = SystemClock.elapsedRealtime() - mSpinnerVisibilityStartTime;
if (t >= MIN_SPINNER_DISPLAY_TIME) {
mSpinnerVisibilityStartTime = -1;
mActivity.setProgressBarIndeterminateVisibility(false);
} else {
sendEmptyMessageDelayed(MSG_HIDE_SPINNER, MIN_SPINNER_DISPLAY_TIME - t);
}
break;
}
}
};
/**
* Gets the <code>SpinnerVisibilitySetter</code> for the given <code>activity</code>.
*
* This method must be called from the main thread.
*/
public static SpinnerVisibilitySetter getInstance(Activity activity) {
synchronized(sInstanceMap) {
SpinnerVisibilitySetter setter = sInstanceMap.get(activity);
if (setter == null) {
setter = new SpinnerVisibilitySetter(activity);
sInstanceMap.put(activity, setter);
}
return setter;
}
}
private SpinnerVisibilitySetter(Activity activity) {
mActivity = activity;
}
public void setSpinnerVisibility(boolean visible) {
if (visible) {
mHandler.removeMessages(MSG_HIDE_SPINNER);
mHandler.sendEmptyMessageDelayed(MSG_SHOW_SPINNER, SPINNER_DISPLAY_DELAY);
} else {
mHandler.removeMessages(MSG_SHOW_SPINNER);
mHandler.sendEmptyMessage(MSG_HIDE_SPINNER);
}
}
}
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