EdgeEffectCompat

public final class EdgeEffectCompat
extends Object

java.lang.Object
   ↳ androidx.core.widget.EdgeEffectCompat


Helper for accessing EdgeEffect. This class is used to access EdgeEffect on platform versions that support it. When running on older platforms it will result in no-ops. It should be used by views that wish to use the standard Android visual effects at the edges of scrolling containers.

Summary

Public constructors

EdgeEffectCompat(Context context)

This constructor is deprecated. Use EdgeEffect constructor directly or create(Context, AttributeSet).

Public methods

static EdgeEffect create(Context context, AttributeSet attrs)

Constructs and returns a new EdgeEffect themed using the given context, allowing support for the view attributes.

boolean draw(Canvas canvas)

This method is deprecated. Use EdgeEffect.draw(Canvas) directly.

void finish()

This method is deprecated. Use EdgeEffect.finish() directly.

static float getDistance(EdgeEffect edgeEffect)

Returns the pull distance needed to be released to remove the showing effect.

boolean isFinished()

This method is deprecated. Use EdgeEffect.isFinished() directly.

boolean onAbsorb(int velocity)

This method is deprecated. Use EdgeEffect.onAbsorb(int) directly.

boolean onPull(float deltaDistance)

This method is deprecated. Use onPull(EdgeEffect, float, float).

boolean onPull(float deltaDistance, float displacement)

This method is deprecated. Use EdgeEffect.onPull(float) directly.

static void onPull(EdgeEffect edgeEffect, float deltaDistance, float displacement)

A view should call this when content is pulled away from an edge by the user.

static float onPullDistance(EdgeEffect edgeEffect, float deltaDistance, float displacement)

A view should call this when content is pulled away from an edge by the user.

boolean onRelease()

This method is deprecated. Use EdgeEffect.onRelease() directly.

void setSize(int width, int height)

This method is deprecated. Use EdgeEffect.setSize(int, int) directly.

Inherited methods

Public constructors

EdgeEffectCompat

public EdgeEffectCompat (Context context)

This constructor is deprecated.
Use EdgeEffect constructor directly or create(Context, AttributeSet).

Construct a new EdgeEffect themed using the given context.

Note: On platform versions that do not support EdgeEffect, all operations on the newly constructed object will be mocked/no-ops.

Parameters
context Context: Context to use for theming the effect

Public methods

create

public static EdgeEffect create (Context context, 
                AttributeSet attrs)

Constructs and returns a new EdgeEffect themed using the given context, allowing support for the view attributes.

Parameters
context Context: Context to use for theming the effect

attrs AttributeSet: The attributes of the XML tag that is inflating the view

Returns
EdgeEffect

draw

public boolean draw (Canvas canvas)

This method is deprecated.
Use EdgeEffect.draw(Canvas) directly.

Draw into the provided canvas. Assumes that the canvas has been rotated accordingly and the size has been set. The effect will be drawn the full width of X=0 to X=width, beginning from Y=0 and extending to some factor < 1.f of height.

Parameters
canvas Canvas: Canvas to draw into

Returns
boolean true if drawing should continue beyond this frame to continue the animation

finish

public void finish ()

This method is deprecated.
Use EdgeEffect.finish() directly.

Immediately finish the current animation. After this call isFinished() will return true.

getDistance

public static float getDistance (EdgeEffect edgeEffect)

Returns the pull distance needed to be released to remove the showing effect. It is determined by the onPull(float, float) deltaDistance and any animating values, including from onAbsorb(int) and onRelease(). This can be used in conjunction with onPullDistance(EdgeEffect, float, float) to release the currently showing effect. On Build.VERSION_CODES.R and earlier, this will return 0.

Parameters
edgeEffect EdgeEffect

Returns
float The pull distance that must be released to remove the showing effect or 0 for versions Build.VERSION_CODES.R and earlier.

isFinished

public boolean isFinished ()

This method is deprecated.
Use EdgeEffect.isFinished() directly.

Reports if this EdgeEffectCompat's animation is finished. If this method returns false after a call to draw(Canvas) the host widget should schedule another drawing pass to continue the animation.

Returns
boolean true if animation is finished, false if drawing should continue on the next frame.

onAbsorb

public boolean onAbsorb (int velocity)

This method is deprecated.
Use EdgeEffect.onAbsorb(int) directly.

Call when the effect absorbs an impact at the given velocity. Used when a fling reaches the scroll boundary.

When using a Scroller or OverScroller, the method getCurrVelocity will provide a reasonable approximation to use here.

Parameters
velocity int: Velocity at impact in pixels per second.

Returns
boolean true if the host view should invalidate, false if it should not.

onPull

public boolean onPull (float deltaDistance)

This method is deprecated.
Use onPull(EdgeEffect, float, float).

A view should call this when content is pulled away from an edge by the user. This will update the state of the current visual effect and its associated animation. The host view should always View.invalidate() if this method returns true and draw the results accordingly.

Parameters
deltaDistance float: Change in distance since the last call. Values may be 0 (no change) to 1.f (full length of the view) or negative values to express change back toward the edge reached to initiate the effect.

Returns
boolean true if the host view should call invalidate, false if it should not.

onPull

public boolean onPull (float deltaDistance, 
                float displacement)

This method is deprecated.
Use EdgeEffect.onPull(float) directly.

A view should call this when content is pulled away from an edge by the user. This will update the state of the current visual effect and its associated animation. The host view should always View.invalidate() if this method returns true and draw the results accordingly. Views using EdgeEffect should favor EdgeEffect.onPull(float, float) when the displacement of the pull point is known.

Parameters
deltaDistance float: Change in distance since the last call. Values may be 0 (no change) to 1.f (full length of the view) or negative values to express change back toward the edge reached to initiate the effect.

displacement float: The displacement from the starting side of the effect of the point initiating the pull. In the case of touch this is the finger position. Values may be from 0-1.

Returns
boolean true if the host view should call invalidate, false if it should not.

onPull

public static void onPull (EdgeEffect edgeEffect, 
                float deltaDistance, 
                float displacement)

A view should call this when content is pulled away from an edge by the user. This will update the state of the current visual effect and its associated animation. The host view should always View.invalidate() after call this method and draw the results accordingly.

Parameters
edgeEffect EdgeEffect: The EdgeEffect that is attached to the view that is getting pulled away from an edge by the user.

deltaDistance float: Change in distance since the last call. Values may be 0 (no change) to 1.f (full length of the view) or negative values to express change back toward the edge reached to initiate the effect.

displacement float: The displacement from the starting side of the effect of the point initiating the pull. In the case of touch this is the finger position. Values may be from 0-1.

onPullDistance

public static float onPullDistance (EdgeEffect edgeEffect, 
                float deltaDistance, 
                float displacement)

A view should call this when content is pulled away from an edge by the user. This will update the state of the current visual effect and its associated animation. The host view should always View.invalidate() after this and draw the results accordingly. This works similarly to onPull(float, float), but returns the amount of deltaDistance that has been consumed. For versions Build.VERSION_CODES.S and above, if the getDistance(EdgeEffect) is currently 0 and deltaDistance is negative, this function will return 0 and the drawn value will remain unchanged. For versions Build.VERSION_CODES.R and below, this will consume all of the provided value and return deltaDistance. This method can be used to reverse the effect from a pull or absorb and partially consume some of a motion:

     if (deltaY < 0 && EdgeEffectCompat.getDistance(edgeEffect) != 0) {
         float displacement = x / getWidth();
         float dist = deltaY / getHeight();
         float consumed = EdgeEffectCompat.onPullDistance(edgeEffect, dist, displacement);
         deltaY -= consumed * getHeight();
         if (edgeEffect.getDistance() == 0f) edgeEffect.onRelease();
     }
 

Parameters
edgeEffect EdgeEffect

deltaDistance float: Change in distance since the last call. Values may be 0 (no change) to 1.f (full length of the view) or negative values to express change back toward the edge reached to initiate the effect.

displacement float: The displacement from the starting side of the effect of the point initiating the pull. In the case of touch this is the finger position. Values may be from 0-1.

Returns
float The amount of deltaDistance that was consumed, a number between 0 and deltaDistance.

onRelease

public boolean onRelease ()

This method is deprecated.
Use EdgeEffect.onRelease() directly.

Call when the object is released after being pulled. This will begin the "decay" phase of the effect. After calling this method the host view should View.invalidate() if this method returns true and thereby draw the results accordingly.

Returns
boolean true if the host view should invalidate, false if it should not.

setSize

public void setSize (int width, 
                int height)

This method is deprecated.
Use EdgeEffect.setSize(int, int) directly.

Set the size of this edge effect in pixels.

Parameters
width int: Effect width in pixels

height int: Effect height in pixels