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Cancel active fling animation when appropriate (#85)
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* added cancelAnimations method to ZoomApi
removed mClearAnimation flag and replaced it with mActiveAnimators which holds a list of all active animators that will be cancelled if a new animation starts or the state changes for other reasons
updated readme

* only set state to none if all active animators are done

* cancelAnimations when using positioning or zoom API methods without animation

* remove unnecessary valueanimator parameter

* review fix

* review fix
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@markusressel
markusressel authored Feb 12, 2019
1 parent a2f9fb1 commit d814040
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Showing 3 changed files with 80 additions and 57 deletions.
2 changes: 2 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -243,6 +243,7 @@ will make more sense than the other - e. g., in a PDF viewer, you might want to
|`zoomOut()`|Applies a small, animated zoom-out.|`-`|
|`setZoomEnabled(boolean)`|If true, the content will be allowed to zoom in and out by user input.|`true`|


The `moveTo(float, float, float, boolean)` API will let you animate both zoom and [pan](#pan) at the same time.

### Pan
Expand All @@ -267,6 +268,7 @@ In any case the current scale is not considered, so your system won't change if
|`setAllowFlingInOverscroll(boolean)`|If true, fling gestures will be allowed even when detected while overscrolled. This might cause artifacts so it is disabled by default.|`false`|
|`panTo(float, float, boolean)`|Pans to the given values, animating if needed.|`-`|
|`panBy(float, float, boolean)`|Applies the given deltas to the current pan, animating if needed.|`-`|
|`cancelAnimations()`|Cancels all currently active animations triggered by either API calls with `animate = true` or touch input flings.|`-`|

The `moveTo(float, float, float, boolean)` API will let you animate both [zoom](#zoom) and pan at the same time.

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8 changes: 8 additions & 0 deletions library/src/main/java/com/otaliastudios/zoom/ZoomApi.kt
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Expand Up @@ -336,6 +336,14 @@ interface ZoomApi {
*/
fun setAnimationDuration(duration: Long)

/**
* Cancels all currently active animations triggered by either API calls with `animate = true`
* or touch input flings. If no animation is currently active this is a no-op.
*
* @return true if anything was cancelled, false otherwise
*/
fun cancelAnimations(): Boolean

companion object {

/**
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127 changes: 70 additions & 57 deletions library/src/main/java/com/otaliastudios/zoom/ZoomEngine.kt
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Expand Up @@ -85,7 +85,6 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener
private var mInitialized = false
private var mContentScaledRect = RectF()
private var mContentRect = RectF()
private var mClearAnimation = false
private var mAnimationDuration = DEFAULT_ANIMATION_DURATION

// Gestures
Expand Down Expand Up @@ -677,27 +676,31 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener

// Returns true if we should go to that mode.
@SuppressLint("SwitchIntDef")
private fun setState(@State state: Int): Boolean {
LOG.v("trySetState:", state.toStateName())
private fun setState(@State newState: Int): Boolean {
LOG.v("trySetState:", newState.toStateName())
if (!mInitialized) return false
if (state == mState) return true
val oldMode = mState

when (state) {
SCROLLING -> if (oldMode == PINCHING || oldMode == ANIMATING) return false
FLINGING -> if (oldMode == ANIMATING) return false
PINCHING -> if (oldMode == ANIMATING) return false
// we need to do some cleanup in case of ANIMATING so we can't return just yet
if (newState == mState && newState != ANIMATING) return true
val oldState = mState

when (newState) {
SCROLLING -> if (oldState == PINCHING || oldState == ANIMATING) return false
FLINGING -> if (oldState == ANIMATING) return false
PINCHING -> if (oldState == ANIMATING) return false
NONE -> dispatchOnIdle()
}

// Now that it succeeded, do some cleanup.
when (oldMode) {
when (oldState) {
ANIMATING -> {
mActiveAnimators.forEach { it.cancel() }
mActiveAnimators.clear()
}
FLINGING -> mFlingScroller.forceFinished(true)
ANIMATING -> mClearAnimation = true
}

LOG.i("setState:", state.toStateName())
mState = state
LOG.i("setState:", newState.toStateName())
mState = newState
return true
}

Expand Down Expand Up @@ -1131,6 +1134,7 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener
if (animate) {
animateZoomAndAbsolutePan(zoom, x, y, allowOverScroll = false)
} else {
cancelAnimations()
applyZoomAndAbsolutePan(zoom, x, y, allowOverScroll = false)
}
}
Expand Down Expand Up @@ -1166,6 +1170,7 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener
if (animate) {
animateZoomAndAbsolutePan(zoom, panX + dx, panY + dy, allowOverScroll = false)
} else {
cancelAnimations()
applyZoomAndAbsolutePan(zoom, panX + dx, panY + dy, allowOverScroll = false)
}
}
Expand All @@ -1182,6 +1187,7 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener
if (animate) {
animateZoom(zoom, allowOverPinch = false)
} else {
cancelAnimations()
applyZoom(zoom, allowOverPinch = false)
}
}
Expand All @@ -1202,17 +1208,13 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener
* Applies a small, animated zoom-in.
* Shorthand for [zoomBy] with factor 1.3.
*/
override fun zoomIn() {
zoomBy(1.3f, animate = true)
}
override fun zoomIn() = zoomBy(1.3f, animate = true)

/**
* Applies a small, animated zoom-out.
* Shorthand for [zoomBy] with factor 0.7.
*/
override fun zoomOut() {
zoomBy(0.7f, animate = true)
}
override fun zoomOut() = zoomBy(0.7f, animate = true)

/**
* Animates the actual matrix zoom to the given value.
Expand Down Expand Up @@ -1277,24 +1279,46 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener

//region Apply values

private val mActiveAnimators = mutableSetOf<ValueAnimator>()
private val mCancelAnimationListener = object : AnimatorListenerAdapter() {

override fun onAnimationEnd(animation: Animator?) {
setState(NONE)
override fun onAnimationEnd(animator: Animator) {
cleanup(animator)
}

override fun onAnimationCancel(animation: Animator?) {
setState(NONE)
override fun onAnimationCancel(animator: Animator) {
cleanup(animator)
}

private fun cleanup(animator: Animator) {
animator.removeListener(this)
mActiveAnimators.remove(animator)
if (mActiveAnimators.isEmpty()) setState(NONE)
}
}

/**
* Prepares a [ValueAnimator] for the first run
*
* @return itself (for chaining)
*/
private fun ValueAnimator.prepare() {
private fun ValueAnimator.prepare(): ValueAnimator {
this.duration = mAnimationDuration
this.addListener(mCancelAnimationListener)
this.interpolator = ANIMATION_INTERPOLATOR
return this
}

/**
* Starts a [ValueAnimator] with the given update function
*
* @return itself (for chaining)
*/
private fun ValueAnimator.start(onUpdate: (ValueAnimator) -> Unit): ValueAnimator {
this.addUpdateListener(onUpdate)
this.start()
mActiveAnimators.add(this)
return this
}

/**
Expand All @@ -1306,21 +1330,12 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener
*/
private fun animateZoom(@Zoom zoom: Float, allowOverPinch: Boolean) {
if (setState(ANIMATING)) {
mClearAnimation = false
@Zoom val startZoom = this.zoom
@Zoom val endZoom = checkZoomBounds(zoom, allowOverPinch)
val zoomAnimator = ValueAnimator.ofFloat(startZoom, endZoom)
zoomAnimator.prepare()
zoomAnimator.addUpdateListener {
ValueAnimator.ofFloat(startZoom, endZoom).prepare().start {
LOG.v("animateZoom:", "animationStep:", it.animatedFraction)
if (mClearAnimation) {
it.cancel()
return@addUpdateListener
}
applyZoom(it.animatedValue as Float, allowOverPinch)
}

zoomAnimator.start()
}
}

Expand All @@ -1336,23 +1351,22 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener
* @param zoomTargetX the x-axis zoom target
* @param zoomTargetY the y-axis zoom target
*/
@SuppressLint("ObjectAnimatorBinding")
private fun animateZoomAndAbsolutePan(@Zoom zoom: Float,
@AbsolutePan x: Float, @AbsolutePan y: Float,
allowOverScroll: Boolean,
allowOverPinch: Boolean = false,
zoomTargetX: Float? = null,
zoomTargetY: Float? = null) {
if (setState(ANIMATING)) {
mClearAnimation = false
@Zoom val startZoom = this.zoom
@Zoom val endZoom = checkZoomBounds(zoom, allowOverScroll)
val startPan = pan
val targetPan = AbsolutePoint(x, y)
LOG.i("animateZoomAndAbsolutePan:", "starting.", "startX:", startPan.x, "endX:", x, "startY:", startPan.y, "endY:", y)
LOG.i("animateZoomAndAbsolutePan:", "starting.", "startZoom:", startZoom, "endZoom:", endZoom)

@SuppressLint("ObjectAnimatorBinding")
val animator = ObjectAnimator.ofPropertyValuesHolder(mContainer,
ObjectAnimator.ofPropertyValuesHolder(
PropertyValuesHolder.ofObject(
"pan",
TypeEvaluator { fraction: Float, startValue: AbsolutePoint, endValue: AbsolutePoint ->
Expand All @@ -1362,20 +1376,13 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener
PropertyValuesHolder.ofFloat(
"zoom",
startZoom, endZoom)
)
animator.prepare()
animator.addUpdateListener {
if (mClearAnimation) {
it.cancel()
return@addUpdateListener
}
).prepare().start {
val newZoom = it.getAnimatedValue("zoom") as Float
val currentPan = it.getAnimatedValue("pan") as AbsolutePoint
applyZoomAndAbsolutePan(newZoom, currentPan.x, currentPan.y,
allowOverScroll, allowOverPinch,
zoomTargetX, zoomTargetY)
}
animator.start()
}
}

Expand All @@ -1390,25 +1397,16 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener
private fun animateScaledPan(@ScaledPan deltaX: Float, @ScaledPan deltaY: Float,
allowOverScroll: Boolean) {
if (setState(ANIMATING)) {
mClearAnimation = false
val startPan = scaledPan
val endPan = startPan + ScaledPoint(deltaX, deltaY)

val panAnimator = ValueAnimator.ofObject(TypeEvaluator { fraction, startValue: ScaledPoint, endValue: ScaledPoint ->
ValueAnimator.ofObject(TypeEvaluator { fraction, startValue: ScaledPoint, endValue: ScaledPoint ->
startValue + (endValue - startValue) * fraction - scaledPan
}, startPan, endPan)
panAnimator.prepare()
panAnimator.addUpdateListener {
}, startPan, endPan).prepare().start {
LOG.v("animateScaledPan:", "animationStep:", it.animatedFraction)
if (mClearAnimation) {
it.cancel()
return@addUpdateListener
}
val currentPan = it.animatedValue as ScaledPoint
applyScaledPan(currentPan.x, currentPan.y, allowOverScroll)
}

panAnimator.start()
}
}

Expand Down Expand Up @@ -1596,6 +1594,21 @@ internal constructor(context: Context) : ViewTreeObserver.OnGlobalLayoutListener
return true
}

/**
* Cancels all currently active animations triggered by either API calls with `animate = true`
* or touch input flings. If no animation is currently active this is a no-op.
*
* @return true if anything was cancelled, false otherwise
*/
override fun cancelAnimations(): Boolean {
if (mState == FLINGING || mState == ANIMATING) {
setState(NONE)
return true
}

return false
}

//endregion

//region scrollbars helpers
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