ScrollHelper

java.lang.Object
- ohos.agp.components.ScrollHelper

```
public class ScrollHelper
extends Object
```
Provides methods of obtaining animation values of a scrolling or sliding component.
The animation values include the scrolling distance, whether the scrolling ends, speed of throwing the animation, and speed of accelerating and decelerating the animation.

从以下版本开始:

3

字段概要

字段
限定符和类型字段说明

static int AXIS_X
Indicates that the x coordinate axis.

static int AXIS_Y
Indicates that the y coordinate axis.

字段
限定符和类型	字段	说明
`static int`	`AXIS_X`	Indicates that the x coordinate axis.
`static int`	`AXIS_Y`	Indicates that the y coordinate axis.

构造器概要

构造器
构造器说明

ScrollHelper()
Default constructor used to create a ScrollHelper instance.

构造器
构造器	说明
`ScrollHelper()`	Default constructor used to create a `ScrollHelper` instance.

方法概要

所有方法实例方法具体方法
限定符和类型	方法	说明
`void`	`abortAnimation()`	Stops an animation by stopping the calculation of the animation position.
`void`	`doFling(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY)`	Starts flinging the content.
`void`	`doFlingX(int startX, int velocityX, int minX, int maxX)`	Starts flinging along the x axis.
`void`	`doFlingY(int startY, int velocityY, int minY, int maxY)`	Starts flinging along the y axis.
`int`	`getCurrValue(int direction)`	Obtains the X/Y-axis coordinate during scrolling or flinging.
`float`	`getCurrVelocity()`	Obtains the current velocity.
`int`	`getFlingDistanceX(int velocityX)`	Obtains the flinging distance on the x axis.
`int`	`getFlingDistanceY(int velocityY)`	Obtains the flinging distance on the y axis.
`int`	`getFlingVelocityX()`	Obtains the flinging velocity on the x axis.
`int`	`getFlingVelocityY()`	Obtains the flinging velocity on the y axis.
`float`	`getFriction()`	Obtains the amount of friction.
`int`	`getHorizontalBeginPosition()`	Obtains the x coordinate where scrolling starts.
`int`	`getScrollDistanceX()`	Obtains the scrolling distance on the x axis.
`int`	`getScrollDistanceY()`	Obtains the scrolling distance on the y axis.
`boolean`	`isFinished()`	Determines whether scrolling or flinging is finished.
`boolean`	`isOverScrolled()`	Checks whether the content has scrolled to a valid position.
`void`	`setFriction(float friction)`	Sets the amount of simulated friction to calculate the current speed.
`void`	`startScroll(int startX, int startY, int dx, int dy)`	Starts scrolling the content a component.
`void`	`startScrollX(int startX, int dx)`	Starts scrolling along the x axis.
`void`	`startScrollY(int startY, int dy)`	Starts scrolling along the y axis.
`boolean`	`updateScroll()`	Updates the position of a flinging or scrolling animation.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 字段详细资料
  - AXIS_X
```
public static final int AXIS_X
```
    Indicates that the x coordinate axis.
    
    从以下版本开始:
    
    3
    
    另请参阅:
    
    常量字段值
  - AXIS_Y
```
public static final int AXIS_Y
```
    Indicates that the y coordinate axis.
    
    从以下版本开始:
    
    3
    
    另请参阅:
    
    常量字段值
- 构造器详细资料
  - ScrollHelper
```
public ScrollHelper()
```
    Default constructor used to create a ScrollHelper instance.
- 方法详细资料
  - doFling
```
public void doFling(int startX,
                    int startY,
                    int velocityX,
                    int velocityY,
                    int minX,
                    int maxX,
                    int minY,
                    int maxY)
```
    Starts flinging the content.
    This method is also used to set the fling speed and distance.
    
    参数:
    
    startX - Indicates the X-axis coordinate of the start point to fling.
    
    startY - Indicates the Y-axis coordinate of the start point to fling.
    
    velocityX - Indicates the initial velocity on X-axis, in unit of pixels per second. The value can be negative, indicating that the component is slowing down.
    
    velocityY - Indicates the initial velocity on the Y-axis, in unit of pixels per second. The value can be negative, indicating that the component is slowing down.
    
    minX - Indicates the minimum fling distance on X-axis.
    
    maxX - Indicates the maximum fling distance on X-axis.
    
    minY - Indicates the minimum fling distance on Y-axis.
    
    maxY - Indicates the maximum fling distance on Y-axis.
    
    从以下版本开始:
    
    4
  - doFlingX
```
public void doFlingX(int startX,
                     int velocityX,
                     int minX,
                     int maxX)
```
    Starts flinging along the x axis.
    You can also use this method to set the fling velocity and distance.
    
    参数:
    
    startX - Indicates the x coordinate where flinging starts.
    
    velocityX - Indicates the number of pixels moved on the x axis per second.
    
    minX - Indicates the minimum flinging distance on the x axis.
    
    maxX - Indicates the maximum flinging distance on the x axis.
    
    从以下版本开始:
    
    4
  - doFlingY
```
public void doFlingY(int startY,
                     int velocityY,
                     int minY,
                     int maxY)
```
    Starts flinging along the y axis.
    You can also use this method to set the fling velocity and distance.
    
    参数:
    
    startY - Indicates the y coordinate where flinging starts.
    
    velocityY - Indicates the number of pixels moved on the y axis per second.
    
    minY - Indicates the minimum flinging distance on the y axis.
    
    maxY - Indicates the maximum flinging distance on the y axis.
    
    从以下版本开始:
    
    4
  - startScrollX
```
public void startScrollX(int startX,
                         int dx)
```
    Starts scrolling along the x axis.
    
    参数:
    
    startX - Indicates the x coordinate where scrolling starts.
    
    dx - Indicates the scrolling distance on the x axis. A positive value indicates scrolling leftwards, and a negative value indicates scrolling rightwards.
    
    从以下版本开始:
    
    4
  - startScrollY
```
public void startScrollY(int startY,
                         int dy)
```
    Starts scrolling along the y axis.
    
    参数:
    
    startY - Indicates the y coordinate where scrolling starts.
    
    dy - Indicates the scrolling distance on the y axis. A positive value indicates scrolling upwards, and a negative value indicates scrolling downwards.
    
    从以下版本开始:
    
    4
  - getFlingDistanceX
```
public int getFlingDistanceX(int velocityX)
```
    Obtains the flinging distance on the x axis.
    
    参数:
    
    velocityX - Indicates the number of pixels per second (px/s) on the x axis.
    
    返回:
    
    Returns the flinging distance.
    
    从以下版本开始:
    
    4
  - getFlingDistanceY
```
public int getFlingDistanceY(int velocityY)
```
    Obtains the flinging distance on the y axis.
    
    参数:
    
    velocityY - Indicates the number of pixels per second (px/s) on the y axis.
    
    返回:
    
    Returns the flinging distance.
    
    从以下版本开始:
    
    4
  - getFlingVelocityX
```
public int getFlingVelocityX()
```
    Obtains the flinging velocity on the x axis.
    
    返回:
    
    Returns the flinging velocity (unit: px/s).
    
    从以下版本开始:
    
    4
  - getFlingVelocityY
```
public int getFlingVelocityY()
```
    Obtains the flinging velocity on the y axis.
    
    返回:
    
    Returns the flinging velocity (unit: px/s).
    
    从以下版本开始:
    
    4
  - startScroll
```
public void startScroll(int startX,
                        int startY,
                        int dx,
                        int dy)
```
    Starts scrolling the content a component.
    
    参数:
    
    startX - Indicates the X-axis coordinate of the start point to scroll.
    
    startY - Indicates the Y-axis coordinate of the start point to scroll.
    
    dx - Indicates the scrolling distance on X-axis. If the value is positive, the content scrolls to the left. If the value is negative, the content scrolls to the right.
    
    dy - Indicates the scrolling distance on Y-axis. If the value is positive, the content scrolls up. If the value is negative, the content scrolls down.
  - getHorizontalBeginPosition
```
public int getHorizontalBeginPosition()
```
    Obtains the x coordinate where scrolling starts.
    
    返回:
    
    Returns the x coordinate.
    
    从以下版本开始:
    
    4
  - getScrollDistanceX
```
public int getScrollDistanceX()
```
    Obtains the scrolling distance on the x axis.
    
    返回:
    
    Returns the scrolling distance.
    
    从以下版本开始:
    
    4
  - getScrollDistanceY
```
public int getScrollDistanceY()
```
    Obtains the scrolling distance on the y axis.
    
    返回:
    
    Returns the scrolling distance.
    
    从以下版本开始:
    
    4
  - getCurrValue
```
public int getCurrValue(int direction)
```
    Obtains the X/Y-axis coordinate during scrolling or flinging.
    
    参数:
    
    direction - Indicate x-axis or y-axis.
    
    返回:
    
    Returns the current X/Y-axis coordinate.
    
    从以下版本开始:
    
    4
  - isFinished
```
public boolean isFinished()
```
    Determines whether scrolling or flinging is finished.
    
    返回:
    
    Returns true if scrolling or flinging is finished; returns false otherwise.
  - setFriction
```
public void setFriction(float friction)
```
    Sets the amount of simulated friction to calculate the current speed. A greater amount of friction indicates faster speed deceleration.
    
    参数:
    
    friction - Indicates the amount of friction.
  - getFriction
```
public float getFriction()
```
    Obtains the amount of friction. The friction is used to calculate the current speed. A greater amount of friction indicates faster speed deceleration.
    
    返回:
    
    Returns the set or default friction.
  - abortAnimation
```
public void abortAnimation()
```
    Stops an animation by stopping the calculation of the animation position.
  - updateScroll
```
public boolean updateScroll()
```
    Updates the position of a flinging or scrolling animation.
    After the animation position is updated, the animation update result is returned.
    
    返回:
    
    Returns true if the animation is updated; returns false otherwise.
    
    从以下版本开始:
    
    4
  - getCurrVelocity
```
public float getCurrVelocity()
```
    Obtains the current velocity.
    
    返回:
    
    Returns the current velocity.
  - isOverScrolled
```
public boolean isOverScrolled()
```
    Checks whether the content has scrolled to a valid position.
    
    返回:
    
    Returns true if the content has scrolled to a valid position; returns false otherwise.

类 ScrollHelper

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

AXIS_X

AXIS_Y

构造器详细资料

ScrollHelper

方法详细资料

doFling

doFlingX

doFlingY

startScrollX

startScrollY

getFlingDistanceX

getFlingDistanceY

getFlingVelocityX

getFlingVelocityY

startScroll

getHorizontalBeginPosition

getScrollDistanceX

getScrollDistanceY

getCurrValue

isFinished

setFriction

getFriction

abortAnimation

updateScroll

getCurrVelocity

isOverScrolled