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/*
* Copyright (C) 2013 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 android.support.v4.widget;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;
import android.widget.ProgressBar;
/**
* ContentLoadingProgressBar implements a ProgressBar that waits a minimum time to be
* dismissed before showing. Once visible, the progress bar will be visible for
* a minimum amount of time to avoid "flashes" in the UI when an event could take
* a largely variable time to complete (from none, to a user perceivable amount)
*/
public class ContentLoadingProgressBar extends ProgressBar {
private static final int MIN_SHOW_TIME = 500; // ms
private static final int MIN_DELAY = 500; // ms
long mStartTime = -1;
boolean mPostedHide = false;
boolean mPostedShow = false;
boolean mDismissed = false;
private final Runnable mDelayedHide = new Runnable() {
@Override
public void run() {
mPostedHide = false;
mStartTime = -1;
setVisibility(View.GONE);
}
};
private final Runnable mDelayedShow = new Runnable() {
@Override
public void run() {
mPostedShow = false;
if (!mDismissed) {
mStartTime = System.currentTimeMillis();
setVisibility(View.VISIBLE);
}
}
};
public ContentLoadingProgressBar(@NonNull Context context) {
this(context, null);
}
public ContentLoadingProgressBar(@NonNull Context context, @Nullable AttributeSet attrs) {
super(context, attrs, 0);
}
@Override
public void onAttachedToWindow() {
super.onAttachedToWindow();
removeCallbacks();
}
@Override
public void onDetachedFromWindow() {
super.onDetachedFromWindow();
removeCallbacks();
}
private void removeCallbacks() {
removeCallbacks(mDelayedHide);
removeCallbacks(mDelayedShow);
}
/**
* Hide the progress view if it is visible. The progress view will not be
* hidden until it has been shown for at least a minimum show time. If the
* progress view was not yet visible, cancels showing the progress view.
*/
public void hide() {
mDismissed = true;
removeCallbacks(mDelayedShow);
long diff = System.currentTimeMillis() - mStartTime;
if (diff >= MIN_SHOW_TIME || mStartTime == -1) {
// The progress spinner has been shown long enough
// OR was not shown yet. If it wasn't shown yet,
// it will just never be shown.
setVisibility(View.GONE);
} else {
// The progress spinner is shown, but not long enough,
// so put a delayed message in to hide it when its been
// shown long enough.
if (!mPostedHide) {
postDelayed(mDelayedHide, MIN_SHOW_TIME - diff);
mPostedHide = true;
}
}
}
/**
* Show the progress view after waiting for a minimum delay. If
* during that time, hide() is called, the view is never made visible.
*/
public void show() {
// Reset the start time.
mStartTime = -1;
mDismissed = false;
removeCallbacks(mDelayedHide);
if (!mPostedShow) {
postDelayed(mDelayedShow, MIN_DELAY);
mPostedShow = true;
}
}
}
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