All Implemented Interfaces:

com.otaliastudios.zoom.ZoomApi
```
public class ZoomEngine
 implements ZoomApi
                    
```
A low level class that listens to touch events and posts zoom and pan updates. The most useful output is a Matrix that can be used to do pretty much everything, from canvas drawing to View hierarchies translations.
Users are required to:
- Pass the container view in the constructor
- Notify the helper of the content size, using setContentSize
- Pass touch events to onInterceptTouchEvent and onTouchEvent

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`public interface`	`ZoomEngine.Listener`	An interface to listen for updates in the inner matrix. This will be called typically on animation frames.
`public abstract class`	`ZoomEngine.SimpleListener`	A simple implementation of Listener that will extract the translation and scale values from the output matrix.
`public class`	`ZoomEngine.Companion`

Field Summary

Fields
Modifier and Type	Field	Description
`private final Float`	`realZoom`
`private final AbsolutePoint`	`pan`
`private final Float`	`panX`
`private final Float`	`panY`
`private final ScaledPoint`	`scaledPan`
`private final Float`	`scaledPanX`
`private final Float`	`scaledPanY`
`private final Matrix`	`matrix`
`private final Float`	`contentWidth`
`private final Float`	`contentHeight`
`private final Float`	`containerWidth`
`private final Float`	`containerHeight`
`private final Float`	`zoom`

Constructor Summary

Constructors
Constructor	Description
`ZoomEngine(Context context, View container)`	Constructs an helper instance.
`ZoomEngine(Context context, View container, ZoomEngine.Listener listener)`	Constructs an helper instance.
`ZoomEngine(Context context)`

Method Summary

Modifier and Type	Method	Description
`Float`	`getRealZoom()`
`AbsolutePoint`	`getPan()`
`Float`	`getPanX()`
`Float`	`getPanY()`
`ScaledPoint`	`getScaledPan()`
`Float`	`getScaledPanX()`
`Float`	`getScaledPanY()`
`final Matrix`	`getMatrix()`
`final Float`	`getContentWidth()`
`final Float`	`getContentHeight()`
`final Float`	`getContainerWidth()`
`final Float`	`getContainerHeight()`
`Float`	`getZoom()`
`final Unit`	`addListener(ZoomEngine.Listener listener)`	Registers a new Listener to be notified of matrix updates.
`final Unit`	`removeListener(ZoomEngine.Listener listener)`	Removes a previously registered listener.
`Unit`	`setOverScrollHorizontal(Boolean overScroll)`	Controls whether the content should be over-scrollable horizontally.
`Unit`	`setOverScrollVertical(Boolean overScroll)`	Controls whether the content should be over-scrollable vertically.
`Unit`	`setOverPanRange(OverPanRangeProvider provider)`	Set the OverPanRangeProvider that specifies the amount of overpan to allow.
`Unit`	`setHorizontalPanEnabled(Boolean enabled)`	Controls whether horizontal panning using gestures is enabled.
`Unit`	`setVerticalPanEnabled(Boolean enabled)`	Controls whether vertical panning using gestures is enabled.
`Unit`	`setOverPinchable(Boolean overPinchable)`	Controls whether the content should be overPinchable.
`Unit`	`setOverZoomRange(OverZoomRangeProvider provider)`	Set the OverZoomRangeProvider that specifies the amount of overzoom to allow.
`Unit`	`setZoomEnabled(Boolean enabled)`	Controls whether zoom using pinch gesture is enabled or not.
`Unit`	`setFlingEnabled(Boolean enabled)`	Controls whether fling gesture is enabled or not.
`Unit`	`setScrollEnabled(Boolean enabled)`	Controls whether scroll gesture is enabled or not.
`Unit`	`setOneFingerScrollEnabled(Boolean enabled)`	Controls whether one finger scroll gesture is enabled or not.
`Unit`	`setTwoFingersScrollEnabled(Boolean enabled)`	Controls whether two fingers scroll gesture is enabled or not.
`Unit`	`setThreeFingersScrollEnabled(Boolean enabled)`	Controls whether three fingers scroll gesture is enabled or not.
`Unit`	`setAllowFlingInOverscroll(Boolean allow)`	Controls whether fling events are allowed when the view is in an overscrolled state.
`Unit`	`setTransformation(Integer transformation, Integer gravity)`	Sets the base transformation to be applied to the content.
`Unit`	`setAlignment(Integer alignment)`	Sets the content alignment.
`final Unit`	`setContainer(View container)`	Set a container to perform transformations on.
`final Unit`	`setContentSize(RectF rect)`	Notifies the helper of the content size (be it a child View, a Bitmap, or whatever else).
`final Unit`	`setContentSize(Float width, Float height, Boolean applyTransformation)`	Notifies the helper of the content size (be it a child View, a Bitmap, or whatever else).
`final Unit`	`setContentSize(Float width, Float height)`	Notifies the helper of the content size (be it a child View, a Bitmap, or whatever else).
`final Unit`	`setContainerSize(Float width, Float height, Boolean applyTransformation)`	Sets the size of the container view.
`final Unit`	`setContainerSize(Float width, Float height)`	Sets the size of the container view.
`final Unit`	`clear()`	Clears the current state, and stops dispatching matrix events until the view is laid out again and ZoomEngine.setContentSize is called.
`final Boolean`	`onInterceptTouchEvent(MotionEvent ev)`	This is required when the content is a View that has clickable hierarchies inside.
`final Boolean`	`onTouchEvent(MotionEvent ev)`	Process the given touch event.
`Unit`	`moveTo(Float zoom, Float x, Float y, Boolean animate)`	A low level API that can animate both zoom and pan at the same time.
`Unit`	`moveToCenter(Float zoom, Boolean animate)`	Moves to the center of the content.
`Unit`	`panTo(Float x, Float y, Boolean animate)`	Pans the content until the top-left coordinates match the given x-y values.
`Unit`	`panBy(Float dx, Float dy, Boolean animate)`	Pans the content by the given quantity in dx-dy values.
`Unit`	`zoomTo(Float zoom, Boolean animate)`	Zooms to the given scale.
`Unit`	`zoomBy(Float zoomFactor, Boolean animate)`	Applies the given factor to the current zoom.
`Unit`	`zoomIn()`	Applies a small, animated zoom-in.
`Unit`	`zoomOut()`	Applies a small, animated zoom-out.
`Unit`	`realZoomTo(Float realZoom, Boolean animate)`	Animates the actual matrix zoom to the given value.
`Float`	`getMaxZoom()`	Get the currently allowed max zoom.
`Integer`	`getMaxZoomType()`	Get the currently set max zoom type.
`Unit`	`setMaxZoom(Float maxZoom, Integer type)`	Which is the max zoom that should be allowed.
`Float`	`getMinZoom()`	Get the currently allowed min zoom.
`Integer`	`getMinZoomType()`	Get the currently set min zoom type.
`Unit`	`setMinZoom(Float minZoom, Integer type)`	Which is the min zoom that should be allowed.
`Unit`	`setAnimationDuration(Long duration)`	Sets the duration of animations triggered by zoom and pan APIs.
`Boolean`	`cancelAnimations()`	Cancels all currently active animations triggered by either API calls with `animate = true` or touch input flings.
`final Integer`	`computeHorizontalScrollOffset()`	Helper for implementing View.computeHorizontalScrollOffset in custom views.
`final Integer`	`computeHorizontalScrollRange()`	Helper for implementing View.computeHorizontalScrollRange in custom views.
`final Integer`	`computeVerticalScrollOffset()`	Helper for implementing View.computeVerticalScrollOffset in custom views.
`final Integer`	`computeVerticalScrollRange()`	Helper for implementing View.computeVerticalScrollRange in custom views.

Methods inherited from class com.otaliastudios.zoom.ZoomEngine
setMaxZoom, setMinZoom, setTransformation
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - ZoomEngine
```
ZoomEngine(Context context, View container)
```
    Constructs an helper instance.
    
    Parameters:
    
    context - a valid context
    
    container - the view hosting the zoomable content
  - ZoomEngine
```
ZoomEngine(Context context, View container, ZoomEngine.Listener listener)
```
    Constructs an helper instance.
    
    Parameters:
    
    context - a valid context
    
    container - the view hosting the zoomable content
    
    listener - a listener for events
  - ZoomEngine
```
ZoomEngine(Context context)
```
- Method Detail
  - getRealZoom
```
 Float getRealZoom()
```
  - getPan
```
 AbsolutePoint getPan()
```
  - getPanX
```
 Float getPanX()
```
  - getPanY
```
 Float getPanY()
```
  - getScaledPan
```
 ScaledPoint getScaledPan()
```
  - getScaledPanX
```
 Float getScaledPanX()
```
  - getScaledPanY
```
 Float getScaledPanY()
```
  - getMatrix
```
 final Matrix getMatrix()
```
  - getContentWidth
```
 final Float getContentWidth()
```
  - getContentHeight
```
 final Float getContentHeight()
```
  - getContainerWidth
```
 final Float getContainerWidth()
```
  - getContainerHeight
```
 final Float getContainerHeight()
```
  - getZoom
```
 Float getZoom()
```
  - addListener
```
 final Unit addListener(ZoomEngine.Listener listener)
```
    Registers a new Listener to be notified of matrix updates.
    
    Parameters:
    
    listener - the new listener
  - removeListener
```
 final Unit removeListener(ZoomEngine.Listener listener)
```
    Removes a previously registered listener.
    
    Parameters:
    
    listener - the listener to be removed
  - setOverScrollHorizontal
```
 Unit setOverScrollHorizontal(Boolean overScroll)
```
    Controls whether the content should be over-scrollable horizontally. If it is, drag and fling horizontal events can scroll the content outside the safe area, then return to safe values.
    
    Parameters:
    
    overScroll - whether to allow horizontal over scrolling
  - setOverScrollVertical
```
 Unit setOverScrollVertical(Boolean overScroll)
```
    Controls whether the content should be over-scrollable vertically. If it is, drag and fling vertical events can scroll the content outside the safe area, then return to safe values.
    
    Parameters:
    
    overScroll - whether to allow vertical over scrolling
  - setOverPanRange
```
 Unit setOverPanRange(OverPanRangeProvider provider)
```
    Set the OverPanRangeProvider that specifies the amount of overpan to allow.
  - setHorizontalPanEnabled
```
 Unit setHorizontalPanEnabled(Boolean enabled)
```
    Controls whether horizontal panning using gestures is enabled.
    
    Parameters:
    
    enabled - true enables horizontal panning, false disables it
  - setVerticalPanEnabled
```
 Unit setVerticalPanEnabled(Boolean enabled)
```
    Controls whether vertical panning using gestures is enabled.
    
    Parameters:
    
    enabled - true enables vertical panning, false disables it
  - setOverPinchable
```
 Unit setOverPinchable(Boolean overPinchable)
```
    Controls whether the content should be overPinchable. If it is, pinch events can change the zoom outside the safe bounds, than return to safe values.
    
    Parameters:
    
    overPinchable - whether to allow over pinching
  - setOverZoomRange
```
 Unit setOverZoomRange(OverZoomRangeProvider provider)
```
    Set the OverZoomRangeProvider that specifies the amount of overzoom to allow.
    
    Parameters:
    
    provider - the range provider
  - setZoomEnabled
```
 Unit setZoomEnabled(Boolean enabled)
```
    Controls whether zoom using pinch gesture is enabled or not.
    
    Parameters:
    
    enabled - true enables zooming, false disables it
  - setFlingEnabled
```
 Unit setFlingEnabled(Boolean enabled)
```
    Controls whether fling gesture is enabled or not.
    
    Parameters:
    
    enabled - true enables fling gesture, false disables it
  - setScrollEnabled
```
 Unit setScrollEnabled(Boolean enabled)
```
    Controls whether scroll gesture is enabled or not.
    
    Parameters:
    
    enabled - true enables scroll gesture, false disables it
  - setOneFingerScrollEnabled
```
 Unit setOneFingerScrollEnabled(Boolean enabled)
```
    Controls whether one finger scroll gesture is enabled or not.
    
    Parameters:
    
    enabled - true enables one finger scroll gesture, false disables it
  - setTwoFingersScrollEnabled
```
 Unit setTwoFingersScrollEnabled(Boolean enabled)
```
    Controls whether two fingers scroll gesture is enabled or not.
    
    Parameters:
    
    enabled - true enables two fingers scroll gesture, false disables it
  - setThreeFingersScrollEnabled
```
 Unit setThreeFingersScrollEnabled(Boolean enabled)
```
    Controls whether three fingers scroll gesture is enabled or not.
    
    Parameters:
    
    enabled - true enables three fingers scroll gesture, false disables it
  - setAllowFlingInOverscroll
```
 Unit setAllowFlingInOverscroll(Boolean allow)
```
    Controls whether fling events are allowed when the view is in an overscrolled state.
    
    Parameters:
    
    allow - true allows fling in overscroll, false disables it
  - setTransformation
```
 Unit setTransformation(Integer transformation, Integer gravity)
```
    Sets the base transformation to be applied to the content. Defaults to ZoomApi.TRANSFORMATION_CENTER_INSIDE with Gravity.CENTER, which means that the content will be zoomed so that it fits completely inside the container.
    
    Parameters:
    
    transformation - the transformation type
    
    gravity - the transformation gravity.
  - setAlignment
```
 Unit setAlignment(Integer alignment)
```
    Sets the content alignment. Can be any of the constants defined in Alignment. The content will be aligned and forced to the specified side of the container. Defaults to ZoomApi.ALIGNMENT_DEFAULT.
    Keep in mind that this is disabled when the content is larger than the container, because a forced alignment in this case would result in part of the content being unreachable.
    
    Parameters:
    
    alignment - the new alignment
  - setContainer
```
 final Unit setContainer(View container)
```
    Set a container to perform transformations on. This method can only be called once at initialization time. It throws an exception if it is called twice.
    
    Parameters:
    
    container - view
  - setContentSize
```
@Deprecated(message = Deprecated in favor of not using RectF class, replaceWith = @ReplaceWith(imports = {}, expression = setContentSize(width, height))) final Unit setContentSize(RectF rect)
```
    Notifies the helper of the content size (be it a child View, a Bitmap, or whatever else). This is needed for the helper to start working.
    
    Parameters:
    
    rect - the content rect
  - setContentSize
```
@JvmOverloads() final Unit setContentSize(Float width, Float height, Boolean applyTransformation)
```
    Notifies the helper of the content size (be it a child View, a Bitmap, or whatever else). This is needed for the helper to start working.
    
    Parameters:
    
    width - the content width
    
    height - the content height
    
    applyTransformation - whether to apply the transformation defined by setTransformation
  - setContentSize
```
@JvmOverloads() final Unit setContentSize(Float width, Float height)
```
    Notifies the helper of the content size (be it a child View, a Bitmap, or whatever else). This is needed for the helper to start working.
    
    Parameters:
    
    width - the content width
    
    height - the content height
  - setContainerSize
```
@JvmOverloads() final Unit setContainerSize(Float width, Float height, Boolean applyTransformation)
```
    Sets the size of the container view. Normally you don't need to call this because the size is detected from the container passed to the constructor using a global layout listener.
    However, there are cases where you might want to update it, for example during View.onSizeChanged (called during shared element transitions).
    
    Parameters:
    
    width - the container width
    
    height - the container height
    
    applyTransformation - whether to apply the transformation defined by setTransformation
  - setContainerSize
```
@JvmOverloads() final Unit setContainerSize(Float width, Float height)
```
    Sets the size of the container view. Normally you don't need to call this because the size is detected from the container passed to the constructor using a global layout listener.
    However, there are cases where you might want to update it, for example during View.onSizeChanged (called during shared element transitions).
    
    Parameters:
    
    width - the container width
    
    height - the container height
  - clear
```
 final Unit clear()
```
    Clears the current state, and stops dispatching matrix events until the view is laid out again and ZoomEngine.setContentSize is called.
  - onInterceptTouchEvent
```
 final Boolean onInterceptTouchEvent(MotionEvent ev)
```
    This is required when the content is a View that has clickable hierarchies inside. If true is returned, implementors should not pass the call to super.
    
    Parameters:
    
    ev - the motion event
  - onTouchEvent
```
 final Boolean onTouchEvent(MotionEvent ev)
```
    Process the given touch event. If true is returned, implementors should not pass the call to super.
    
    Parameters:
    
    ev - the motion event
  - moveTo
```
 Unit moveTo(Float zoom, Float x, Float y, Boolean animate)
```
    A low level API that can animate both zoom and pan at the same time. Zoom might not be the actual matrix scale, see ZoomApi.zoom and ZoomApi.realZoom. The coordinates are referred to the content size passed in setContentSize so they do not depend on current zoom.
    
    Parameters:
    
    zoom - the desired zoom value
    
    x - the desired left coordinate
    
    y - the desired top coordinate
    
    animate - whether to animate the transition
  - moveToCenter
```
 Unit moveToCenter(Float zoom, Boolean animate)
```
    Moves to the center of the content.
    
    Parameters:
    
    zoom - the desired zoom value
    
    animate - whether to animate the transition
  - panTo
```
 Unit panTo(Float x, Float y, Boolean animate)
```
    Pans the content until the top-left coordinates match the given x-y values. These are referred to the content size passed in setContentSize, so they do not depend on current zoom.
    
    Parameters:
    
    x - the desired left coordinate
    
    y - the desired top coordinate
    
    animate - whether to animate the transition
  - panBy
```
 Unit panBy(Float dx, Float dy, Boolean animate)
```
    Pans the content by the given quantity in dx-dy values. These are referred to the content size passed in setContentSize, so they do not depend on current zoom.
    In other words, asking to pan by 1 pixel might result in a bigger pan, if the content was zoomed in.
    
    Parameters:
    
    dx - the desired delta x
    
    dy - the desired delta y
    
    animate - whether to animate the transition
  - zoomTo
```
 Unit zoomTo(Float zoom, Boolean animate)
```
    Zooms to the given scale. This might not be the actual matrix zoom, see ZoomApi.zoom and ZoomApi.realZoom.
    
    Parameters:
    
    zoom - the new scale value
    
    animate - whether to animate the transition
  - zoomBy
```
 Unit zoomBy(Float zoomFactor, Boolean animate)
```
    Applies the given factor to the current zoom.
    
    Parameters:
    
    zoomFactor - a multiplicative factor
    
    animate - whether to animate the transition
  - zoomIn
```
 Unit zoomIn()
```
    Applies a small, animated zoom-in. Shorthand for zoomBy with factor 1.3.
  - zoomOut
```
 Unit zoomOut()
```
    Applies a small, animated zoom-out. Shorthand for zoomBy with factor 0.7.
  - realZoomTo
```
 Unit realZoomTo(Float realZoom, Boolean animate)
```
    Animates the actual matrix zoom to the given value.
    
    Parameters:
    
    realZoom - the new real zoom value
    
    animate - whether to animate the transition
  - getMaxZoom
```
 Float getMaxZoom()
```
    Get the currently allowed max zoom. If ZoomApi.setOverPinchable is set to true, this can be over-pinched for a brief time.
  - getMaxZoomType
```
 Integer getMaxZoomType()
```
    Get the currently set max zoom type.
  - setMaxZoom
```
 Unit setMaxZoom(Float maxZoom, Integer type)
```
    Which is the max zoom that should be allowed. If setOverPinchable is set to true, this can be over-pinched for a brief time.
    
    Parameters:
    
    maxZoom - the max zoom
    
    type - the constraint mode
  - getMinZoom
```
 Float getMinZoom()
```
    Get the currently allowed min zoom. If ZoomApi.setOverPinchable is set to true, this can be over-pinched for a brief time.
  - getMinZoomType
```
 Integer getMinZoomType()
```
    Get the currently set min zoom type.
  - setMinZoom
```
 Unit setMinZoom(Float minZoom, Integer type)
```
    Which is the min zoom that should be allowed. If setOverPinchable is set to true, this can be over-pinched for a brief time.
    
    Parameters:
    
    minZoom - the min zoom
    
    type - the constraint mode
  - setAnimationDuration
```
 Unit setAnimationDuration(Long duration)
```
    Sets the duration of animations triggered by zoom and pan APIs. Defaults to ZoomEngine.DEFAULT_ANIMATION_DURATION.
    
    Parameters:
    
    duration - new animation duration
  - cancelAnimations
```
 Boolean cancelAnimations()
```
    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.
  - computeHorizontalScrollOffset
```
 final Integer computeHorizontalScrollOffset()
```
    Helper for implementing View.computeHorizontalScrollOffset in custom views.
  - computeHorizontalScrollRange
```
 final Integer computeHorizontalScrollRange()
```
    Helper for implementing View.computeHorizontalScrollRange in custom views.
  - computeVerticalScrollOffset
```
 final Integer computeVerticalScrollOffset()
```
    Helper for implementing View.computeVerticalScrollOffset in custom views.
  - computeVerticalScrollRange
```
 final Integer computeVerticalScrollRange()
```
    Helper for implementing View.computeVerticalScrollRange in custom views.

Class ZoomEngine

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class com.otaliastudios.zoom.ZoomEngine

Methods inherited from class java.lang.Object

Constructor Detail

ZoomEngine

ZoomEngine

ZoomEngine

Method Detail

getRealZoom

getPan

getPanX

getPanY

getScaledPan

getScaledPanX

getScaledPanY

getMatrix

getContentWidth

getContentHeight

getContainerWidth

getContainerHeight

getZoom

addListener

removeListener

setOverScrollHorizontal

setOverScrollVertical

setOverPanRange

setHorizontalPanEnabled

setVerticalPanEnabled

setOverPinchable

setOverZoomRange

setZoomEnabled

setFlingEnabled

setScrollEnabled

setOneFingerScrollEnabled

setTwoFingersScrollEnabled

setThreeFingersScrollEnabled

setAllowFlingInOverscroll

setTransformation

setAlignment

setContainer

setContentSize

setContentSize

setContentSize

setContainerSize

setContainerSize

clear

onInterceptTouchEvent

onTouchEvent

moveTo

moveToCenter

panTo

panBy

zoomTo

zoomBy

zoomIn

zoomOut

realZoomTo

getMaxZoom

getMaxZoomType

setMaxZoom

getMinZoom

getMinZoomType

setMinZoom

setAnimationDuration

cancelAnimations

computeHorizontalScrollOffset

computeHorizontalScrollRange

computeVerticalScrollOffset

computeVerticalScrollRange