/*
* Copyright 2014 Google Inc. All rights reserved.
*
* 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.google.samples.apps.iosched.ui.widget;
import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.Animation;
import android.view.animation.Animation.AnimationListener;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.Transformation;
import android.widget.AbsListView;
/**
* The SwipeRefreshLayout should be used whenever the user can refresh the
* contents of a view via a vertical swipe gesture. The activity that
* instantiates this view should add an OnRefreshListener to be notified
* whenever the swipe to refresh gesture is completed. The SwipeRefreshLayout
* will notify the listener each and every time the gesture is completed again;
* the listener is responsible for correctly determining when to actually
* initiate a refresh of its content. If the listener determines there should
* not be a refresh, it must call setRefreshing(false) to cancel any visual
* indication of a refresh. If an activity wishes to show just the progress
* animation, it should call setRefreshing(true). To disable the gesture and progress
* animation, call setEnabled(false) on the view.
*
* <p> This layout should be made the parent of the view that will be refreshed as a
* result of the gesture and can only support one direct child. This view will
* also be made the target of the gesture and will be forced to match both the
* width and the height supplied in this layout. The SwipeRefreshLayout does not
* provide accessibility events; instead, a menu item must be provided to allow
* refresh of the content wherever this gesture is used.</p>
*/
public class SwipeRefreshLayout extends ViewGroup {
private static final long RETURN_TO_ORIGINAL_POSITION_TIMEOUT = 300;
private static final float ACCELERATE_INTERPOLATION_FACTOR = 1.5f;
private static final float DECELERATE_INTERPOLATION_FACTOR = 2f;
private static final float PROGRESS_BAR_HEIGHT = 4;
private static final float MAX_SWIPE_DISTANCE_FACTOR = .6f;
private static final int REFRESH_TRIGGER_DISTANCE = 120;
private SwipeProgressBar mProgressBar; //the thing that shows progress is going
private View mTarget; //the content that gets pulled down
private int mOriginalOffsetTop;
private OnRefreshListener mListener;
private MotionEvent mDownEvent;
private int mFrom;
private boolean mRefreshing = false;
private int mTouchSlop;
private float mDistanceToTriggerSync = -1;
private float mPrevY;
private int mMediumAnimationDuration;
private float mFromPercentage = 0;
private float mCurrPercentage = 0;
private int mProgressBarHeight;
private int mCurrentTargetOffsetTop;
private int mProgressBarTop;
// Target is returning to its start offset because it was cancelled or a
// refresh was triggered.
private boolean mReturningToStart;
private final DecelerateInterpolator mDecelerateInterpolator;
private final AccelerateInterpolator mAccelerateInterpolator;
private static final int[] LAYOUT_ATTRS = new int[] {
android.R.attr.enabled
};
private final Animation mAnimateToStartPosition = new Animation() {
@Override
public void applyTransformation(float interpolatedTime, Transformation t) {
int targetTop = 0;
if (mFrom != mOriginalOffsetTop) {
targetTop = (mFrom + (int)((mOriginalOffsetTop - mFrom) * interpolatedTime));
}
int offset = targetTop - mTarget.getTop();
final int currentTop = mTarget.getTop();
if (offset + currentTop < 0) {
offset = 0 - currentTop;
}
setTargetOffsetTopAndBottom(offset);
}
};
private Animation mShrinkTrigger = new Animation() {
@Override
public void applyTransformation(float interpolatedTime, Transformation t) {
float percent = mFromPercentage + ((0 - mFromPercentage) * interpolatedTime);
mProgressBar.setTriggerPercentage(percent);
}
};
private final AnimationListener mReturnToStartPositionListener = new BaseAnimationListener() {
@Override
public void onAnimationEnd(Animation animation) {
// Once the target content has returned to its start position, reset
// the target offset to 0
mCurrentTargetOffsetTop = 0;
}
};
private final AnimationListener mShrinkAnimationListener = new BaseAnimationListener() {
@Override
public void onAnimationEnd(Animation animation) {
mCurrPercentage = 0;
}
};
private final Runnable mReturnToStartPosition = new Runnable() {
@Override
public void run() {
mReturningToStart = true;
animateOffsetToStartPosition(mCurrentTargetOffsetTop + getPaddingTop(),
mReturnToStartPositionListener);
}
};
// Cancel the refresh gesture and animate everything back to its original state.
private final Runnable mCancel = new Runnable() {
@Override
public void run() {
mReturningToStart = true;
// Timeout fired since the user last moved their finger; animate the
// trigger to 0 and put the target back at its original position
if (mProgressBar != null) {
mFromPercentage = mCurrPercentage;
mShrinkTrigger.setDuration(mMediumAnimationDuration);
mShrinkTrigger.setAnimationListener(mShrinkAnimationListener);
mShrinkTrigger.reset();
mShrinkTrigger.setInterpolator(mDecelerateInterpolator);
startAnimation(mShrinkTrigger);
}
animateOffsetToStartPosition(mCurrentTargetOffsetTop + getPaddingTop(),
mReturnToStartPositionListener);
}
};
/**
* Simple constructor to use when creating a SwipeRefreshLayout from code.
* @param context
*/
public SwipeRefreshLayout(Context context) {
this(context, null);
}
/**
* Constructor that is called when inflating SwipeRefreshLayout from XML.
* @param context
* @param attrs
*/
public SwipeRefreshLayout(Context context, AttributeSet attrs) {
super(context, attrs);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
mMediumAnimationDuration = getResources().getInteger(
android.R.integer.config_mediumAnimTime);
setWillNotDraw(false);
mProgressBar = new SwipeProgressBar(this);
final DisplayMetrics metrics = getResources().getDisplayMetrics();
mProgressBarHeight = (int) (metrics.density * PROGRESS_BAR_HEIGHT);
mDecelerateInterpolator = new DecelerateInterpolator(DECELERATE_INTERPOLATION_FACTOR);
mAccelerateInterpolator = new AccelerateInterpolator(ACCELERATE_INTERPOLATION_FACTOR);
final TypedArray a = context.obtainStyledAttributes(attrs, LAYOUT_ATTRS);
setEnabled(a.getBoolean(0, true));
a.recycle();
}
@Override
public void onAttachedToWindow() {
super.onAttachedToWindow();
removeCallbacks(mCancel);
removeCallbacks(mReturnToStartPosition);
}
@Override
public void onDetachedFromWindow() {
super.onDetachedFromWindow();
removeCallbacks(mReturnToStartPosition);
removeCallbacks(mCancel);
}
private void animateOffsetToStartPosition(int from, AnimationListener listener) {
mFrom = from;
mAnimateToStartPosition.reset();
mAnimateToStartPosition.setDuration(mMediumAnimationDuration);
mAnimateToStartPosition.setAnimationListener(listener);
mAnimateToStartPosition.setInterpolator(mDecelerateInterpolator);
mTarget.startAnimation(mAnimateToStartPosition);
}
/**
* Set the listener to be notified when a refresh is triggered via the swipe
* gesture.
*/
public void setOnRefreshListener(OnRefreshListener listener) {
mListener = listener;
}
private void setTriggerPercentage(float percent) {
if (percent == 0f) {
// No-op. A null trigger means it's uninitialized, and setting it to zero-percent
// means we're trying to reset state, so there's nothing to reset in this case.
mCurrPercentage = 0;
return;
}
mCurrPercentage = percent;
mProgressBar.setTriggerPercentage(percent);
}
/**
* Notify the widget that refresh state has changed. Do not call this when
* refresh is triggered by a swipe gesture.
*
* @param refreshing Whether or not the view should show refresh progress.
*/
public void setRefreshing(boolean refreshing) {
if (mRefreshing != refreshing) {
ensureTarget();
mCurrPercentage = 0;
mRefreshing = refreshing;
if (mRefreshing) {
mProgressBar.start();
} else {
mProgressBar.stop();
}
}
}
/**
* Set the four colors used in the progress animation. The first color will
* also be the color of the bar that grows in response to a user swipe
* gesture.
*
* @param colorRes1 Color resource.
* @param colorRes2 Color resource.
* @param colorRes3 Color resource.
* @param colorRes4 Color resource.
*/
public void setColorScheme(int colorRes1, int colorRes2, int colorRes3, int colorRes4) {
ensureTarget();
final Resources res = getResources();
final int color1 = res.getColor(colorRes1);
final int color2 = res.getColor(colorRes2);
final int color3 = res.getColor(colorRes3);
final int color4 = res.getColor(colorRes4);
mProgressBar.setColorScheme(color1, color2, color3,color4);
}
/**
* @return Whether the SwipeRefreshWidget is actively showing refresh
* progress.
*/
public boolean isRefreshing() {
return mRefreshing;
}
private void ensureTarget() {
// Don't bother getting the parent height if the parent hasn't been laid out yet.
if (mTarget == null) {
if (getChildCount() > 1 && !isInEditMode()) {
throw new IllegalStateException(
"SwipeRefreshLayout can host only one direct child");
}
mTarget = getChildAt(0);
mOriginalOffsetTop = mTarget.getTop() + getPaddingTop();
}
if (mDistanceToTriggerSync == -1) {
if (getParent() != null && ((View)getParent()).getHeight() > 0) {
final DisplayMetrics metrics = getResources().getDisplayMetrics();
mDistanceToTriggerSync = (int) Math.min(
((View) getParent()) .getHeight() * MAX_SWIPE_DISTANCE_FACTOR,
REFRESH_TRIGGER_DISTANCE * metrics.density);
}
}
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
mProgressBar.draw(canvas);
}
public void setProgressBarTop(int top) {
mProgressBarTop = top;
mProgressBar.setBounds(0, mProgressBarTop, getWidth(), mProgressBarTop + mProgressBarHeight);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
final int width = getMeasuredWidth();
final int height = getMeasuredHeight();
mProgressBar.setBounds(0, mProgressBarTop, getWidth(), mProgressBarTop + mProgressBarHeight);
if (getChildCount() == 0) {
return;
}
final View child = getChildAt(0);
final int childLeft = getPaddingLeft();
final int childTop = mCurrentTargetOffsetTop + getPaddingTop();
final int childWidth = width - getPaddingLeft() - getPaddingRight();
final int childHeight = height - getPaddingTop() - getPaddingBottom();
child.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);
}
@Override
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (getChildCount() > 1 && !isInEditMode()) {
throw new IllegalStateException("SwipeRefreshLayout can host only one direct child");
}
if (getChildCount() > 0) {
getChildAt(0).measure(
MeasureSpec.makeMeasureSpec(
getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(
getMeasuredHeight() - getPaddingTop() - getPaddingBottom(),
MeasureSpec.EXACTLY));
}
}
/**
* @return Whether it is possible for the child view of this layout to
* scroll up. Override this if the child view is a custom view.
*/
public boolean canChildScrollUp() {
if (android.os.Build.VERSION.SDK_INT < 14) {
if (mTarget instanceof AbsListView) {
final AbsListView absListView = (AbsListView) mTarget;
return absListView.getChildCount() > 0
&& (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0)
.getTop() < absListView.getPaddingTop());
} else {
return mTarget.getScrollY() > 0;
}
} else {
return ViewCompat.canScrollVertically(mTarget, -1);
}
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
ensureTarget();
boolean handled = false;
if (mReturningToStart && ev.getAction() == MotionEvent.ACTION_DOWN) {
mReturningToStart = false;
}
if (isEnabled() && !mReturningToStart && !canChildScrollUp()) {
handled = onTouchEvent(ev);
}
return !handled ? super.onInterceptTouchEvent(ev) : handled;
}
@Override
public void requestDisallowInterceptTouchEvent(boolean b) {
// Nope.
}
@Override
public boolean onTouchEvent(MotionEvent event) {
final int action = event.getAction();
boolean handled = false;
switch (action) {
case MotionEvent.ACTION_DOWN:
mCurrPercentage = 0;
mDownEvent = MotionEvent.obtain(event);
mPrevY = mDownEvent.getY();
break;
case MotionEvent.ACTION_MOVE:
if (mDownEvent != null && !mReturningToStart) {
final float eventY = event.getY();
float yDiff = eventY - mDownEvent.getY();
if (yDiff > mTouchSlop) {
// User velocity passed min velocity; trigger a refresh
if (yDiff > mDistanceToTriggerSync) {
// User movement passed distance; trigger a refresh
startRefresh();
handled = true;
break;
} else {
// Just track the user's movement
setTriggerPercentage(
mAccelerateInterpolator.getInterpolation(
yDiff / mDistanceToTriggerSync));
float offsetTop = yDiff;
if (mPrevY > eventY) {
offsetTop = yDiff - mTouchSlop;
}
updateContentOffsetTop((int) (offsetTop));
if (mPrevY > eventY && (mTarget.getTop() < mTouchSlop)) {
// If the user puts the view back at the top, we
// don't need to. This shouldn't be considered
// cancelling the gesture as the user can restart from the top.
removeCallbacks(mCancel);
} else {
updatePositionTimeout();
}
mPrevY = event.getY();
handled = true;
}
}
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
if (mDownEvent != null) {
mDownEvent.recycle();
mDownEvent = null;
}
break;
}
return handled;
}
private void startRefresh() {
removeCallbacks(mCancel);
mReturnToStartPosition.run();
setRefreshing(true);
mListener.onRefresh();
}
private void updateContentOffsetTop(int targetTop) {
final int currentTop = mTarget.getTop();
if (targetTop > mDistanceToTriggerSync) {
targetTop = (int) mDistanceToTriggerSync;
} else if (targetTop < 0) {
targetTop = 0;
}
setTargetOffsetTopAndBottom(targetTop - currentTop);
}
private void setTargetOffsetTopAndBottom(int offset) {
mTarget.offsetTopAndBottom(offset);
mCurrentTargetOffsetTop = mTarget.getTop();
}
private void updatePositionTimeout() {
removeCallbacks(mCancel);
postDelayed(mCancel, RETURN_TO_ORIGINAL_POSITION_TIMEOUT);
}
/**
* Classes that wish to be notified when the swipe gesture correctly
* triggers a refresh should implement this interface.
*/
public interface OnRefreshListener {
public void onRefresh();
}
/**
* Simple AnimationListener to avoid having to implement unneeded methods in
* AnimationListeners.
*/
private class BaseAnimationListener implements AnimationListener {
@Override
public void onAnimationStart(Animation animation) {
}
@Override
public void onAnimationEnd(Animation animation) {
}
@Override
public void onAnimationRepeat(Animation animation) {
}
}
}