com.matthewtamlin.sliding_intro_screen_library

Class MultiViewParallaxTransformer

java.lang.Object

com.matthewtamlin.sliding_intro_screen_library.MultiViewParallaxTransformer

public class MultiViewParallaxTransformer
extends java.lang.Object

A ViewPager transformer which allows custom parallax effects to be applied to some or all of the Views displayed in the pages. Parallax effects are assigned by mapping parallax factors to resource IDs. A parallax factor is a scale factor, which determines how Views are positioned compared to the drag position.

For example, if a parallax factor of 1.2 is provided for the resource ID R.id.myview, then all Views with that resource ID will have a 20% parallax effect. This means that when the page is scrolled in some direction by some number of pixels (call this variable x), then the affected views will be scrolled 1.2*x pixels in the same direction.

This class can safely be used with ViewPager instances where not all pages have the same views/layout.

Constructor Summary

Constructors

Constructor and Description
MultiViewParallaxTransformer()

Method Summary

Modifier and Type	Method and Description
android.view.View	getViewToTransform(android.view.View rootView, int id) Returns a reference to the child view of rootView with the resource ID of id.
static MultiViewParallaxTransformer	newInstance() Constructs a new MultiViewParallaxTransformer instance.
void	transformPage(android.view.View page, float position)
MultiViewParallaxTransformer	withoutParallaxView(int id) Removes a parallax effect from all Views with the provided resource id.
MultiViewParallaxTransformer	withParallaxView(int id, float parallaxFactor) Sets this MultiViewParallaxTransformer to apply a parallax effect to all Views with the provided resource id.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MultiViewParallaxTransformer

public MultiViewParallaxTransformer()

Method Detail

transformPage

public void transformPage(android.view.View page,
                          float position)

newInstance

public static MultiViewParallaxTransformer newInstance()

Constructs a new MultiViewParallaxTransformer instance.

Returns:

the new instance, not null

withParallaxView

public MultiViewParallaxTransformer withParallaxView(int id,
                                                     float parallaxFactor)

Sets this MultiViewParallaxTransformer to apply a parallax effect to all Views with the provided resource id. The parallax factor determines how fast the affected views are translated, relative to the normal scrolling speed. For example, consider a parallax factor of 1.2, and a ViewPager which has been dragged to the left by 100 pixels. Any views with this parallax factor will translate 120 pixels to the left.

It is strongly recommended that parallax factors less than 1 not be used. Most implementations of ViewPager will clip any affected Views since they will translate slower than the boundaries of the pages. This recommendation is not enforced.

Parameters:

id - the resource ID of the views to apply the parallax effect to

parallaxFactor - determines how fast

Returns:

this MultiViewParallaxTransformer

withoutParallaxView

public MultiViewParallaxTransformer withoutParallaxView(int id)

Removes a parallax effect from all Views with the provided resource id.

Parameters:

id - the resource if of the Views to remove the effect from

Returns:

this MultiViewParallaxTransformer

getViewToTransform

public android.view.View getViewToTransform(android.view.View rootView,
                                            int id)

Returns a reference to the child view of rootView with the resource ID of id. Using this method is more efficient that frequent calls to View.findViewById(int).

Parameters:

rootView - the view to get the child view from, not null

id - the resource ID of the child view

Returns:

the child view of rootView with the resource ID of id, or null if no such child view exists