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Diffstat (limited to 'core-ui/src/main/kotlin/ca/allanwang/kau/ui/widgets/InkPageIndicator.java')
-rw-r--r-- | core-ui/src/main/kotlin/ca/allanwang/kau/ui/widgets/InkPageIndicator.java | 859 |
1 files changed, 859 insertions, 0 deletions
diff --git a/core-ui/src/main/kotlin/ca/allanwang/kau/ui/widgets/InkPageIndicator.java b/core-ui/src/main/kotlin/ca/allanwang/kau/ui/widgets/InkPageIndicator.java new file mode 100644 index 0000000..cc90cb2 --- /dev/null +++ b/core-ui/src/main/kotlin/ca/allanwang/kau/ui/widgets/InkPageIndicator.java @@ -0,0 +1,859 @@ +/* + * Copyright 2015 Google Inc. + * + * 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 ca.allanwang.kau.ui.widgets; + +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.support.annotation.ColorInt; +import android.support.v4.view.ViewPager; +import android.util.AttributeSet; +import android.util.Log; +import android.view.View; +import android.view.animation.Interpolator; + +import java.util.Arrays; + +import ca.allanwang.kau.R; +import ca.allanwang.kau.utils.AnimHolder; +import ca.allanwang.kau.utils.ColorUtilsKt; + +/** + * An ink inspired widget for indicating pages in a {@link ViewPager}. + */ +public class InkPageIndicator extends View implements ViewPager.OnPageChangeListener, + View.OnAttachStateChangeListener { + + // 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; + + public void setColour(@ColorInt int color) { + selectedColour = color; + unselectedColour = ColorUtilsKt.adjustAlpha(color, 0.5f); + selectedPaint.setColor(selectedColour); + unselectedPaint.setColor(unselectedColour); + } + + // 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; + + // state + private int pageCount; + private int currentPage; + private int previousPage; + private float selectedDotX; + private boolean selectedDotInPosition; + private float[] dotCenterX; + private float[] joiningFractions; + private float retreatingJoinX1; + private float retreatingJoinX2; + private float[] dotRevealFractions; + private boolean isAttachedToWindow; + private boolean pageChanging; + + // 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 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 InkPageIndicator(Context context) { + this(context, null, 0); + } + + public InkPageIndicator(Context context, AttributeSet attrs) { + this(context, attrs, 0); + } + + public InkPageIndicator(Context context, AttributeSet attrs, int defStyle) { + super(context, attrs, defStyle); + + final int density = (int) context.getResources().getDisplayMetrics().density; + + // Load attributes + final TypedArray a = getContext().obtainStyledAttributes( + attrs, R.styleable.InkPageIndicator, defStyle, 0); + + dotDiameter = a.getDimensionPixelSize(R.styleable.InkPageIndicator_dotDiameter, + DEFAULT_DOT_SIZE * density); + dotRadius = dotDiameter / 2; + halfDotRadius = dotRadius / 2; + gap = a.getDimensionPixelSize(R.styleable.InkPageIndicator_dotGap, + DEFAULT_GAP * density); + animDuration = (long) a.getInteger(R.styleable.InkPageIndicator_animationDuration, + DEFAULT_ANIM_DURATION); + animHalfDuration = animDuration / 2; + unselectedColour = a.getColor(R.styleable.InkPageIndicator_pageIndicatorColor, + DEFAULT_UNSELECTED_COLOUR); + selectedColour = a.getColor(R.styleable.InkPageIndicator_currentPageIndicatorColor, + DEFAULT_SELECTED_COLOUR); + + a.recycle(); + + unselectedPaint = new Paint(Paint.ANTI_ALIAS_FLAG); + unselectedPaint.setColor(unselectedColour); + selectedPaint = new Paint(Paint.ANTI_ALIAS_FLAG); + selectedPaint.setColor(selectedColour); + interpolator = AnimHolder.INSTANCE.getFastOutSlowInInterpolator().invoke(context); + + // create paths & rect now – reuse & rewind later + combinedUnselectedPath = new Path(); + unselectedDotPath = new Path(); + unselectedDotLeftPath = new Path(); + unselectedDotRightPath = new Path(); + rectF = new RectF(); + + addOnAttachStateChangeListener(this); + } + + public void setViewPager(ViewPager viewPager) { + this.viewPager = viewPager; + viewPager.addOnPageChangeListener(this); + setPageCount(viewPager.getAdapter().getCount()); + viewPager.getAdapter().registerDataSetObserver(new DataSetObserver() { + @Override + public void onChanged() { + setPageCount(InkPageIndicator.this.viewPager.getAdapter().getCount()); + } + }); + setCurrentPageImmediate(); + } + + @Override + public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { + if (isAttachedToWindow) { + float fraction = positionOffset; + int currentPosition = pageChanging ? previousPage : currentPage; + int leftDotPosition = position; + // when swiping from #2 to #1 ViewPager reports position as 1 and a descending offset + // need to convert this into our left-dot-based 'coordinate space' + if (currentPosition != position) { + fraction = 1f - positionOffset; + + // if user scrolls completely to next page then the position param updates to that + // new page but we're not ready to switch our 'current' page yet so adjust for that + if (fraction == 1f) { + leftDotPosition = Math.min(currentPosition, position); + } + } + setJoiningFraction(leftDotPosition, fraction); + } + } + + @Override + public void onPageSelected(int position) { + if (isAttachedToWindow) { + // this is the main event we're interested in! + setSelectedPage(position); + } else { + // when not attached, don't animate the move, just store immediately + setCurrentPageImmediate(); + } + } + + @Override + public void onPageScrollStateChanged(int state) { + // nothing to do + } + + private void setPageCount(int pages) { + pageCount = pages; + resetState(); + requestLayout(); + } + + private void calculateDotPositions(int width, int height) { + int left = getPaddingLeft(); + int top = getPaddingTop(); + int right = width - getPaddingRight(); + int bottom = height - getPaddingBottom(); + + 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 (dotCenterX != null) { + selectedDotX = dotCenterX[currentPage]; + } + } + + private void resetState() { + 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; + case MeasureSpec.UNSPECIFIED: + default: + 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; + case MeasureSpec.UNSPECIFIED: + default: + width = desiredWidth; + break; + } + setMeasuredDimension(width, height); + calculateDotPositions(width, height); + } + + private int getDesiredHeight() { + return getPaddingTop() + dotDiameter + getPaddingBottom(); + } + + private int getRequiredWidth() { + return pageCount * dotDiameter + (pageCount - 1) * gap; + } + + private int getDesiredWidth() { + return getPaddingLeft() + getRequiredWidth() + getPaddingRight(); + } + + @Override + public void onViewAttachedToWindow(View view) { + isAttachedToWindow = true; + } + + @Override + public void onViewDetachedFromWindow(View view) { + isAttachedToWindow = false; + } + + @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; + combinedUnselectedPath.op(getUnselectedPath(page, + dotCenterX[page], + dotCenterX[nextXIndex], + page == pageCount - 1 ? INVALID_FRACTION : joiningFractions[page], + dotRevealFractions[page]), Path.Op.UNION); + } + // draw any retreating joins + if (retreatingJoinX1 != INVALID_FRACTION) { + combinedUnselectedPath.op(getRetreatingJoinPath(), Path.Op.UNION); + } + canvas.drawPath(combinedUnselectedPath, unselectedPaint); + } + + /** + * Unselected dots can be in 6 states: + * <p> + * #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 + * <p> + * 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. + * <p> + * 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 + * @return + */ + 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); + + 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); + unselectedDotPath.op(unselectedDotRightPath, Path.Op.UNION); + } + + if (joiningFraction > 0.5f && joiningFraction < 1f + && retreatingJoinX1 == INVALID_FRACTION) { + + // case #3 – Joining neighbour, combined curved + + // adjust the fraction so that it goes from 0.3 -> 1 to produce a more realistic 'join' + float adjustedFraction = (joiningFraction - 0.2f) * 1.25f; + + // 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 - (adjustedFraction * dotRadius); + controlX1 = endX1 - (adjustedFraction * dotRadius); + controlY1 = dotTopY; + controlX2 = endX1 - ((1 - adjustedFraction) * 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 - adjustedFraction) * dotRadius); + controlY1 = endY1; + controlX2 = endX1 + (adjustedFraction * 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 + (adjustedFraction * dotRadius); + controlX1 = endX1 + (adjustedFraction * dotRadius); + controlY1 = dotBottomY; + controlX2 = endX1 + ((1 - adjustedFraction) * 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 - adjustedFraction) * dotRadius); + controlY1 = endY1; + controlX2 = endX1 - (adjustedFraction * 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) return; + + pageChanging = true; + previousPage = currentPage; + currentPage = now; + final int steps = Math.abs(now - previousPage); + + if (steps > 1) { + if (now > previousPage) { + for (int i = 0; i < steps; i++) { + setJoiningFraction(previousPage + i, 1f); + } + } else { + for (int i = -1; i > -steps; i--) { + setJoiningFraction(previousPage + i, 1f); + } + } + } + + // 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 + moveAnimation = createMoveSelectedAnimator(dotCenterX[now], previousPage, now, steps); + moveAnimation.start(); + } + + 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))); + retreatAnimation.addListener(new AnimatorListenerAdapter() { + @Override + public void onAnimationEnd(Animator animation) { + resetState(); + pageChanging = false; + } + }); + 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 void setJoiningFraction(int leftDot, float fraction) { + if (leftDot < joiningFractions.length) { + + if (leftDot == 1) { + Log.d("PageIndicator", "dot 1 fraction:\t" + 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 cancelJoiningAnimations() { + if (joiningAnimationSet != null && joiningAnimationSet.isRunning()) { + joiningAnimationSet.cancel(); + } + } + + /** + * A {@link 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 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 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 int dot; + + public PendingRevealAnimator(int dot, StartPredicate predicate) { + super(predicate); + setFloatValues(MINIMAL_REVEAL, 1f); + this.dot = dot; + 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; + } + } +} |