public
final
class
EdgeEffectCompat
extends Object
| java.lang.Object | |
| ↳ | android.support.v4.widget.EdgeEffectCompat |
Helper for accessing EdgeEffect introduced after
API level 4 in a backwards compatible fashion.
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.
Public constructors | |
|---|---|
EdgeEffectCompat(Context context)
Construct a new EdgeEffect themed using the given context. |
|
Public methods | |
|---|---|
boolean
|
draw(Canvas canvas)
Draw into the provided canvas. |
void
|
finish()
Immediately finish the current animation. |
boolean
|
isFinished()
Reports if this EdgeEffectCompat's animation is finished. |
boolean
|
onAbsorb(int velocity)
Call when the effect absorbs an impact at the given velocity. |
boolean
|
onPull(float deltaDistance)
This method is deprecated.
use |
boolean
|
onPull(float deltaDistance, float displacement)
A view should call this when content is pulled away from an edge by the user. |
boolean
|
onRelease()
Call when the object is released after being pulled. |
void
|
setSize(int width, int height)
Set the size of this edge effect in pixels. |
Inherited methods | |
|---|---|
 From
class
java.lang.Object
| |
EdgeEffectCompat (Context context)
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
|
boolean draw (Canvas canvas)
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 |
void finish ()
Immediately finish the current animation.
After this call isFinished() will return true.
boolean isFinished ()
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. |
boolean onAbsorb (int velocity)
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. |
boolean onPull (float deltaDistance)
This method is deprecated.
use onPull(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 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. |
Developers
boolean onPull (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 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. |
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. |
boolean onRelease ()
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 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. |
void setSize (int width,
int height)
Set the size of this edge effect in pixels.
| Parameters | |
|---|---|
width |
int:
Effect width in pixels |
height |
int:
Effect height in pixels
|