/*
* Copyright (C) 2016 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.settings.widget;
import static android.view.animation.AnimationUtils.loadInterpolator;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.AnimatorSet;
import android.animation.ValueAnimator;
import android.content.Context;
import android.content.res.TypedArray;
import android.database.DataSetObserver;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.os.Build;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.Interpolator;
import com.android.settings.R;
import java.util.Arrays;
/**
* Custom pager indicator for use with a {@code ViewPager}.
*/
public class DotsPageIndicator extends View implements ViewPager.OnPageChangeListener {
public static final String TAG = DotsPageIndicator.class.getSimpleName();
// defaults
private static final int DEFAULT_DOT_SIZE = 8; // dp
private static final int DEFAULT_GAP = 12; // dp
private static final int DEFAULT_ANIM_DURATION = 400; // ms
private static final int DEFAULT_UNSELECTED_COLOUR = 0x80ffffff; // 50% white
private static final int DEFAULT_SELECTED_COLOUR = 0xffffffff; // 100% white
// constants
private static final float INVALID_FRACTION = -1f;
private static final float MINIMAL_REVEAL = 0.00001f;
// configurable attributes
private int dotDiameter;
private int gap;
private long animDuration;
private int unselectedColour;
private int selectedColour;
// derived from attributes
private float dotRadius;
private float halfDotRadius;
private long animHalfDuration;
private float dotTopY;
private float dotCenterY;
private float dotBottomY;
// ViewPager
private ViewPager viewPager;
private ViewPager.OnPageChangeListener pageChangeListener;
// state
private int pageCount;
private int currentPage;
private float selectedDotX;
private boolean selectedDotInPosition;
private float[] dotCenterX;
private float[] joiningFractions;
private float retreatingJoinX1;
private float retreatingJoinX2;
private float[] dotRevealFractions;
private boolean attachedState;
// drawing
private final Paint unselectedPaint;
private final Paint selectedPaint;
private final Path combinedUnselectedPath;
private final Path unselectedDotPath;
private final Path unselectedDotLeftPath;
private final Path unselectedDotRightPath;
private final RectF rectF;
// animation
private ValueAnimator moveAnimation;
private ValueAnimator[] joiningAnimations;
private AnimatorSet joiningAnimationSet;
private PendingRetreatAnimator retreatAnimation;
private PendingRevealAnimator[] revealAnimations;
private final Interpolator interpolator;
// working values for beziers
float endX1;
float endY1;
float endX2;
float endY2;
float controlX1;
float controlY1;
float controlX2;
float controlY2;
public DotsPageIndicator(Context context) {
this(context, null, 0);
}
public DotsPageIndicator(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public DotsPageIndicator(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
final int scaledDensity = (int) context.getResources().getDisplayMetrics().scaledDensity;
// Load attributes
final TypedArray typedArray = getContext().obtainStyledAttributes(
attrs, R.styleable.DotsPageIndicator, defStyle, 0);
dotDiameter = typedArray.getDimensionPixelSize(R.styleable.DotsPageIndicator_dotDiameter,
DEFAULT_DOT_SIZE * scaledDensity);
dotRadius = dotDiameter / 2;
halfDotRadius = dotRadius / 2;
gap = typedArray.getDimensionPixelSize(R.styleable.DotsPageIndicator_dotGap,
DEFAULT_GAP * scaledDensity);
animDuration = (long) typedArray.getInteger(R.styleable.DotsPageIndicator_animationDuration,
DEFAULT_ANIM_DURATION);
animHalfDuration = animDuration / 2;
unselectedColour = typedArray.getColor(R.styleable.DotsPageIndicator_pageIndicatorColor,
DEFAULT_UNSELECTED_COLOUR);
selectedColour = typedArray.getColor(R.styleable.DotsPageIndicator_currentPageIndicatorColor,
DEFAULT_SELECTED_COLOUR);
typedArray.recycle();
unselectedPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
unselectedPaint.setColor(unselectedColour);
selectedPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
selectedPaint.setColor(selectedColour);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
interpolator = loadInterpolator(context, android.R.interpolator.fast_out_slow_in);
} else {
interpolator = loadInterpolator(context, android.R.anim.accelerate_decelerate_interpolator);
}
// create paths & rect now – reuse & rewind later
combinedUnselectedPath = new Path();
unselectedDotPath = new Path();
unselectedDotLeftPath = new Path();
unselectedDotRightPath = new Path();
rectF = new RectF();
addOnAttachStateChangeListener(new OnAttachStateChangeListener() {
@Override
public void onViewAttachedToWindow(View v) {
attachedState = true;
}
@Override
public void onViewDetachedFromWindow(View v) {
attachedState = false;
}
});
}
public void setViewPager(ViewPager viewPager) {
this.viewPager = viewPager;
viewPager.setOnPageChangeListener(this);
setPageCount(viewPager.getAdapter().getCount());
viewPager.getAdapter().registerDataSetObserver(new DataSetObserver() {
@Override
public void onChanged() {
setPageCount(DotsPageIndicator.this.viewPager.getAdapter().getCount());
}
});
setCurrentPageImmediate();
}
/***
* As this class <b>must</b> act as the {@link ViewPager.OnPageChangeListener} for the ViewPager
* (as set by {@link #setViewPager(android.support.v4.view.ViewPager)}). Applications may set a
* listener here to be notified of the ViewPager events.
*
* @param onPageChangeListener
*/
public void setOnPageChangeListener(ViewPager.OnPageChangeListener onPageChangeListener) {
pageChangeListener = onPageChangeListener;
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
// nothing to do – just forward onward to any registered listener
if (pageChangeListener != null) {
pageChangeListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
}
}
@Override
public void onPageSelected(int position) {
if (attachedState) {
// this is the main event we're interested in!
setSelectedPage(position);
} else {
// when not attached, don't animate the move, just store immediately
setCurrentPageImmediate();
}
// forward onward to any registered listener
if (pageChangeListener != null) {
pageChangeListener.onPageSelected(position);
}
}
@Override
public void onPageScrollStateChanged(int state) {
// nothing to do – just forward onward to any registered listener
if (pageChangeListener != null) {
pageChangeListener.onPageScrollStateChanged(state);
}
}
private void setPageCount(int pages) {
pageCount = pages;
calculateDotPositions();
resetState();
}
private void calculateDotPositions() {
int left = getPaddingLeft();
int top = getPaddingTop();
int right = getWidth() - getPaddingRight();
int requiredWidth = getRequiredWidth();
float startLeft = left + ((right - left - requiredWidth) / 2) + dotRadius;
dotCenterX = new float[pageCount];
for (int i = 0; i < pageCount; i++) {
dotCenterX[i] = startLeft + i * (dotDiameter + gap);
}
// todo just top aligning for now… should make this smarter
dotTopY = top;
dotCenterY = top + dotRadius;
dotBottomY = top + dotDiameter;
setCurrentPageImmediate();
}
private void setCurrentPageImmediate() {
if (viewPager != null) {
currentPage = viewPager.getCurrentItem();
} else {
currentPage = 0;
}
if (pageCount > 0) {
selectedDotX = dotCenterX[currentPage];
}
}
private void resetState() {
if (pageCount > 0) {
joiningFractions = new float[pageCount - 1];
Arrays.fill(joiningFractions, 0f);
dotRevealFractions = new float[pageCount];
Arrays.fill(dotRevealFractions, 0f);
retreatingJoinX1 = INVALID_FRACTION;
retreatingJoinX2 = INVALID_FRACTION;
selectedDotInPosition = true;
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int desiredHeight = getDesiredHeight();
int height;
switch (MeasureSpec.getMode(heightMeasureSpec)) {
case MeasureSpec.EXACTLY:
height = MeasureSpec.getSize(heightMeasureSpec);
break;
case MeasureSpec.AT_MOST:
height = Math.min(desiredHeight, MeasureSpec.getSize(heightMeasureSpec));
break;
default: // MeasureSpec.UNSPECIFIED
height = desiredHeight;
break;
}
int desiredWidth = getDesiredWidth();
int width;
switch (MeasureSpec.getMode(widthMeasureSpec)) {
case MeasureSpec.EXACTLY:
width = MeasureSpec.getSize(widthMeasureSpec);
break;
case MeasureSpec.AT_MOST:
width = Math.min(desiredWidth, MeasureSpec.getSize(widthMeasureSpec));
break;
default: // MeasureSpec.UNSPECIFIED
width = desiredWidth;
break;
}
setMeasuredDimension(width, height);
calculateDotPositions();
}
@Override
protected void onSizeChanged(int width, int height, int oldWidth, int oldHeight) {
setMeasuredDimension(width, height);
calculateDotPositions();
}
@Override
public void clearAnimation() {
super.clearAnimation();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
cancelRunningAnimations();
}
}
private int getDesiredHeight() {
return getPaddingTop() + dotDiameter + getPaddingBottom();
}
private int getRequiredWidth() {
return pageCount * dotDiameter + (pageCount - 1) * gap;
}
private int getDesiredWidth() {
return getPaddingLeft() + getRequiredWidth() + getPaddingRight();
}
@Override
protected void onDraw(Canvas canvas) {
if (viewPager == null || pageCount == 0) {
return;
}
drawUnselected(canvas);
drawSelected(canvas);
}
private void drawUnselected(Canvas canvas) {
combinedUnselectedPath.rewind();
// draw any settled, revealing or joining dots
for (int page = 0; page < pageCount; page++) {
int nextXIndex = page == pageCount - 1 ? page : page + 1;
// todo Path.op should be supported in KitKat but causes the app to hang for Nexus 5.
// For now disabling for all pre-L devices.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
Path unselectedPath = getUnselectedPath(page,
dotCenterX[page],
dotCenterX[nextXIndex],
page == pageCount - 1 ? INVALID_FRACTION : joiningFractions[page],
dotRevealFractions[page]);
combinedUnselectedPath.op(unselectedPath, Path.Op.UNION);
} else {
canvas.drawCircle(dotCenterX[page], dotCenterY, dotRadius, unselectedPaint);
}
}
// draw any retreating joins
if (retreatingJoinX1 != INVALID_FRACTION) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
combinedUnselectedPath.op(getRetreatingJoinPath(), Path.Op.UNION);
}
}
canvas.drawPath(combinedUnselectedPath, unselectedPaint);
}
/**
* Unselected dots can be in 6 states:
*
* #1 At rest
* #2 Joining neighbour, still separate
* #3 Joining neighbour, combined curved
* #4 Joining neighbour, combined straight
* #5 Join retreating
* #6 Dot re-showing / revealing
*
* It can also be in a combination of these states e.g. joining one neighbour while
* retreating from another. We therefore create a Path so that we can examine each
* dot pair separately and later take the union for these cases.
*
* This function returns a path for the given dot **and any action to it's right** e.g. joining
* or retreating from it's neighbour
*
* @param page
*/
private Path getUnselectedPath(int page,
float centerX,
float nextCenterX,
float joiningFraction,
float dotRevealFraction) {
unselectedDotPath.rewind();
if ((joiningFraction == 0f || joiningFraction == INVALID_FRACTION)
&& dotRevealFraction == 0f
&& !(page == currentPage && selectedDotInPosition == true)) {
// case #1 – At rest
unselectedDotPath.addCircle(dotCenterX[page], dotCenterY, dotRadius, Path.Direction.CW);
}
if (joiningFraction > 0f && joiningFraction < 0.5f && retreatingJoinX1 == INVALID_FRACTION) {
// case #2 – Joining neighbour, still separate
// start with the left dot
unselectedDotLeftPath.rewind();
// start at the bottom center
unselectedDotLeftPath.moveTo(centerX, dotBottomY);
// semi circle to the top center
rectF.set(centerX - dotRadius, dotTopY, centerX + dotRadius, dotBottomY);
unselectedDotLeftPath.arcTo(rectF, 90, 180, true);
// cubic to the right middle
endX1 = centerX + dotRadius + (joiningFraction * gap);
endY1 = dotCenterY;
controlX1 = centerX + halfDotRadius;
controlY1 = dotTopY;
controlX2 = endX1;
controlY2 = endY1 - halfDotRadius;
unselectedDotLeftPath.cubicTo(controlX1, controlY1, controlX2, controlY2, endX1, endY1);
// cubic back to the bottom center
endX2 = centerX;
endY2 = dotBottomY;
controlX1 = endX1;
controlY1 = endY1 + halfDotRadius;
controlX2 = centerX + halfDotRadius;
controlY2 = dotBottomY;
unselectedDotLeftPath.cubicTo(controlX1, controlY1, controlX2, controlY2, endX2, endY2);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
unselectedDotPath.op(unselectedDotLeftPath, Path.Op.UNION);
}
// now do the next dot to the right
unselectedDotRightPath.rewind();
// start at the bottom center
unselectedDotRightPath.moveTo(nextCenterX, dotBottomY);
// semi circle to the top center
rectF.set(nextCenterX - dotRadius, dotTopY, nextCenterX + dotRadius, dotBottomY);
unselectedDotRightPath.arcTo(rectF, 90, -180, true);
// cubic to the left middle
endX1 = nextCenterX - dotRadius - (joiningFraction * gap);
endY1 = dotCenterY;
controlX1 = nextCenterX - halfDotRadius;
controlY1 = dotTopY;
controlX2 = endX1;
controlY2 = endY1 - halfDotRadius;
unselectedDotRightPath.cubicTo(controlX1, controlY1, controlX2, controlY2, endX1, endY1);
// cubic back to the bottom center
endX2 = nextCenterX;
endY2 = dotBottomY;
controlX1 = endX1;
controlY1 = endY1 + halfDotRadius;
controlX2 = endX2 - halfDotRadius;
controlY2 = dotBottomY;
unselectedDotRightPath.cubicTo(controlX1, controlY1, controlX2, controlY2, endX2, endY2);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
unselectedDotPath.op(unselectedDotRightPath, Path.Op.UNION);
}
}
if (joiningFraction > 0.5f && joiningFraction < 1f && retreatingJoinX1 == INVALID_FRACTION) {
// case #3 – Joining neighbour, combined curved
// start in the bottom left
unselectedDotPath.moveTo(centerX, dotBottomY);
// semi-circle to the top left
rectF.set(centerX - dotRadius, dotTopY, centerX + dotRadius, dotBottomY);
unselectedDotPath.arcTo(rectF, 90, 180, true);
// bezier to the middle top of the join
endX1 = centerX + dotRadius + (gap / 2);
endY1 = dotCenterY - (joiningFraction * dotRadius);
controlX1 = endX1 - (joiningFraction * dotRadius);
controlY1 = dotTopY;
controlX2 = endX1 - ((1 - joiningFraction) * dotRadius);
controlY2 = endY1;
unselectedDotPath.cubicTo(controlX1, controlY1, controlX2, controlY2, endX1, endY1);
// bezier to the top right of the join
endX2 = nextCenterX;
endY2 = dotTopY;
controlX1 = endX1 + ((1 - joiningFraction) * dotRadius);
controlY1 = endY1;
controlX2 = endX1 + (joiningFraction * dotRadius);
controlY2 = dotTopY;
unselectedDotPath.cubicTo(controlX1, controlY1, controlX2, controlY2, endX2, endY2);
// semi-circle to the bottom right
rectF.set(nextCenterX - dotRadius, dotTopY, nextCenterX + dotRadius, dotBottomY);
unselectedDotPath.arcTo(rectF, 270, 180, true);
// bezier to the middle bottom of the join
// endX1 stays the same
endY1 = dotCenterY + (joiningFraction * dotRadius);
controlX1 = endX1 + (joiningFraction * dotRadius);
controlY1 = dotBottomY;
controlX2 = endX1 + ((1 - joiningFraction) * dotRadius);
controlY2 = endY1;
unselectedDotPath.cubicTo(controlX1, controlY1, controlX2, controlY2, endX1, endY1);
// bezier back to the start point in the bottom left
endX2 = centerX;
endY2 = dotBottomY;
controlX1 = endX1 - ((1 - joiningFraction) * dotRadius);
controlY1 = endY1;
controlX2 = endX1 - (joiningFraction * dotRadius);
controlY2 = endY2;
unselectedDotPath.cubicTo(controlX1, controlY1, controlX2, controlY2, endX2, endY2);
}
if (joiningFraction == 1 && retreatingJoinX1 == INVALID_FRACTION) {
// case #4 Joining neighbour, combined straight
// technically we could use case 3 for this situation as well
// but assume that this is an optimization rather than faffing around with beziers
// just to draw a rounded rect
rectF.set(centerX - dotRadius, dotTopY, nextCenterX + dotRadius, dotBottomY);
unselectedDotPath.addRoundRect(rectF, dotRadius, dotRadius, Path.Direction.CW);
}
// case #5 is handled by #getRetreatingJoinPath()
// this is done separately so that we can have a single retreating path spanning
// multiple dots and therefore animate it's movement smoothly
if (dotRevealFraction > MINIMAL_REVEAL) {
// case #6 – previously hidden dot revealing
unselectedDotPath.addCircle(centerX, dotCenterY, dotRevealFraction * dotRadius,
Path.Direction.CW);
}
return unselectedDotPath;
}
private Path getRetreatingJoinPath() {
unselectedDotPath.rewind();
rectF.set(retreatingJoinX1, dotTopY, retreatingJoinX2, dotBottomY);
unselectedDotPath.addRoundRect(rectF, dotRadius, dotRadius, Path.Direction.CW);
return unselectedDotPath;
}
private void drawSelected(Canvas canvas) {
canvas.drawCircle(selectedDotX, dotCenterY, dotRadius, selectedPaint);
}
private void setSelectedPage(int now) {
if (now == currentPage || pageCount == 0) {
return;
}
int was = currentPage;
currentPage = now;
// These animations are not supported in pre-JB versions.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
cancelRunningAnimations();
// create the anim to move the selected dot – this animator will kick off
// retreat animations when it has moved 75% of the way.
// The retreat animation in turn will kick of reveal anims when the
// retreat has passed any dots to be revealed
final int steps = Math.abs(now - was);
moveAnimation = createMoveSelectedAnimator(dotCenterX[now], was, now, steps);
// create animators for joining the dots. This runs independently of the above and relies
// on good timing. Like comedy.
// if joining multiple dots, each dot after the first is delayed by 1/8 of the duration
joiningAnimations = new ValueAnimator[steps];
for (int i = 0; i < steps; i++) {
joiningAnimations[i] = createJoiningAnimator(now > was ? was + i : was - 1 - i,
i * (animDuration / 8L));
}
moveAnimation.start();
startJoiningAnimations();
} else {
setCurrentPageImmediate();
invalidate();
}
}
private ValueAnimator createMoveSelectedAnimator(final float moveTo, int was, int now,
int steps) {
// create the actual move animator
ValueAnimator moveSelected = ValueAnimator.ofFloat(selectedDotX, moveTo);
// also set up a pending retreat anim – this starts when the move is 75% complete
retreatAnimation = new PendingRetreatAnimator(was, now, steps,
now > was
? new RightwardStartPredicate(moveTo - ((moveTo - selectedDotX) * 0.25f))
: new LeftwardStartPredicate(moveTo + ((selectedDotX - moveTo) * 0.25f)));
moveSelected.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
// todo avoid autoboxing
selectedDotX = (Float) valueAnimator.getAnimatedValue();
retreatAnimation.startIfNecessary(selectedDotX);
postInvalidateOnAnimation();
}
});
moveSelected.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationStart(Animator animation) {
// set a flag so that we continue to draw the unselected dot in the target position
// until the selected dot has finished moving into place
selectedDotInPosition = false;
}
@Override
public void onAnimationEnd(Animator animation) {
// set a flag when anim finishes so that we don't draw both selected & unselected
// page dots
selectedDotInPosition = true;
}
});
// slightly delay the start to give the joins a chance to run
// unless dot isn't in position yet – then don't delay!
moveSelected.setStartDelay(selectedDotInPosition ? animDuration / 4L : 0L);
moveSelected.setDuration(animDuration * 3L / 4L);
moveSelected.setInterpolator(interpolator);
return moveSelected;
}
private ValueAnimator createJoiningAnimator(final int leftJoiningDot, final long startDelay) {
// animate the joining fraction for the given dot
ValueAnimator joining = ValueAnimator.ofFloat(0f, 1.0f);
joining.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
setJoiningFraction(leftJoiningDot, valueAnimator.getAnimatedFraction());
}
});
joining.setDuration(animHalfDuration);
joining.setStartDelay(startDelay);
joining.setInterpolator(interpolator);
return joining;
}
private void setJoiningFraction(int leftDot, float fraction) {
joiningFractions[leftDot] = fraction;
postInvalidateOnAnimation();
}
private void clearJoiningFractions() {
Arrays.fill(joiningFractions, 0f);
postInvalidateOnAnimation();
}
private void setDotRevealFraction(int dot, float fraction) {
dotRevealFractions[dot] = fraction;
postInvalidateOnAnimation();
}
private void cancelRunningAnimations() {
cancelMoveAnimation();
cancelJoiningAnimations();
cancelRetreatAnimation();
cancelRevealAnimations();
resetState();
}
private void cancelMoveAnimation() {
if (moveAnimation != null && moveAnimation.isRunning()) {
moveAnimation.cancel();
}
}
private void startJoiningAnimations() {
joiningAnimationSet = new AnimatorSet();
joiningAnimationSet.playTogether(joiningAnimations);
joiningAnimationSet.start();
}
private void cancelJoiningAnimations() {
if (joiningAnimationSet != null && joiningAnimationSet.isRunning()) {
joiningAnimationSet.cancel();
}
}
private void cancelRetreatAnimation() {
if (retreatAnimation != null && retreatAnimation.isRunning()) {
retreatAnimation.cancel();
}
}
private void cancelRevealAnimations() {
if (revealAnimations != null) {
for (PendingRevealAnimator reveal : revealAnimations) {
reveal.cancel();
}
}
}
int getUnselectedColour() {
return unselectedColour;
}
int getSelectedColour() {
return selectedColour;
}
float getDotCenterY() {
return dotCenterY;
}
float getDotCenterX(int page) {
return dotCenterX[page];
}
float getSelectedDotX() {
return selectedDotX;
}
int getCurrentPage() {
return currentPage;
}
/**
* A {@link android.animation.ValueAnimator} that starts once a given predicate returns true.
*/
public abstract class PendingStartAnimator extends ValueAnimator {
protected boolean hasStarted;
protected StartPredicate predicate;
public PendingStartAnimator(StartPredicate predicate) {
super();
this.predicate = predicate;
hasStarted = false;
}
public void startIfNecessary(float currentValue) {
if (!hasStarted && predicate.shouldStart(currentValue)) {
start();
hasStarted = true;
}
}
}
/**
* An Animator that shows and then shrinks a retreating join between the previous and newly
* selected pages. This also sets up some pending dot reveals – to be started when the retreat
* has passed the dot to be revealed.
*/
public class PendingRetreatAnimator extends PendingStartAnimator {
public PendingRetreatAnimator(int was, int now, int steps, StartPredicate predicate) {
super(predicate);
setDuration(animHalfDuration);
setInterpolator(interpolator);
// work out the start/end values of the retreating join from the direction we're
// travelling in. Also look at the current selected dot position, i.e. we're moving on
// before a prior anim has finished.
final float initialX1 = now > was ? Math.min(dotCenterX[was], selectedDotX) - dotRadius
: dotCenterX[now] - dotRadius;
final float finalX1 = now > was ? dotCenterX[now] - dotRadius
: dotCenterX[now] - dotRadius;
final float initialX2 = now > was ? dotCenterX[now] + dotRadius
: Math.max(dotCenterX[was], selectedDotX) + dotRadius;
final float finalX2 = now > was ? dotCenterX[now] + dotRadius
: dotCenterX[now] + dotRadius;
revealAnimations = new PendingRevealAnimator[steps];
// hold on to the indexes of the dots that will be hidden by the retreat so that
// we can initialize their revealFraction's i.e. make sure they're hidden while the
// reveal animation runs
final int[] dotsToHide = new int[steps];
if (initialX1 != finalX1) { // rightward retreat
setFloatValues(initialX1, finalX1);
// create the reveal animations that will run when the retreat passes them
for (int i = 0; i < steps; i++) {
revealAnimations[i] = new PendingRevealAnimator(was + i,
new RightwardStartPredicate(dotCenterX[was + i]));
dotsToHide[i] = was + i;
}
addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
// todo avoid autoboxing
retreatingJoinX1 = (Float) valueAnimator.getAnimatedValue();
postInvalidateOnAnimation();
// start any reveal animations if we've passed them
for (PendingRevealAnimator pendingReveal : revealAnimations) {
pendingReveal.startIfNecessary(retreatingJoinX1);
}
}
});
} else { // (initialX2 != finalX2) leftward retreat
setFloatValues(initialX2, finalX2);
// create the reveal animations that will run when the retreat passes them
for (int i = 0; i < steps; i++) {
revealAnimations[i] = new PendingRevealAnimator(was - i,
new LeftwardStartPredicate(dotCenterX[was - i]));
dotsToHide[i] = was - i;
}
addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
// todo avoid autoboxing
retreatingJoinX2 = (Float) valueAnimator.getAnimatedValue();
postInvalidateOnAnimation();
// start any reveal animations if we've passed them
for (PendingRevealAnimator pendingReveal : revealAnimations) {
pendingReveal.startIfNecessary(retreatingJoinX2);
}
}
});
}
addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationStart(Animator animation) {
cancelJoiningAnimations();
clearJoiningFractions();
// we need to set this so that the dots are hidden until the reveal anim runs
for (int dot : dotsToHide) {
setDotRevealFraction(dot, MINIMAL_REVEAL);
}
retreatingJoinX1 = initialX1;
retreatingJoinX2 = initialX2;
postInvalidateOnAnimation();
}
@Override
public void onAnimationEnd(Animator animation) {
retreatingJoinX1 = INVALID_FRACTION;
retreatingJoinX2 = INVALID_FRACTION;
postInvalidateOnAnimation();
}
});
}
}
/**
* An Animator that animates a given dot's revealFraction i.e. scales it up
*/
public class PendingRevealAnimator extends PendingStartAnimator {
private final int dot;
public PendingRevealAnimator(int dot, StartPredicate predicate) {
super(predicate);
this.dot = dot;
setFloatValues(MINIMAL_REVEAL, 1f);
setDuration(animHalfDuration);
setInterpolator(interpolator);
addUpdateListener(new AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
// todo avoid autoboxing
setDotRevealFraction(PendingRevealAnimator.this.dot,
(Float) valueAnimator.getAnimatedValue());
}
});
addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
setDotRevealFraction(PendingRevealAnimator.this.dot, 0f);
postInvalidateOnAnimation();
}
});
}
}
/**
* A predicate used to start an animation when a test passes
*/
public abstract class StartPredicate {
protected float thresholdValue;
public StartPredicate(float thresholdValue) {
this.thresholdValue = thresholdValue;
}
abstract boolean shouldStart(float currentValue);
}
/**
* A predicate used to start an animation when a given value is greater than a threshold
*/
public class RightwardStartPredicate extends StartPredicate {
public RightwardStartPredicate(float thresholdValue) {
super(thresholdValue);
}
boolean shouldStart(float currentValue) {
return currentValue > thresholdValue;
}
}
/**
* A predicate used to start an animation then a given value is less than a threshold
*/
public class LeftwardStartPredicate extends StartPredicate {
public LeftwardStartPredicate(float thresholdValue) {
super(thresholdValue);
}
boolean shouldStart(float currentValue) {
return currentValue < thresholdValue;
}
}
}