当Android滚动时添加视差效果：ParallaxPager

jopen 9年前

ParallaxPager实现当页面滚动切换时产生视差效果。

There are 4 important steps:

  1. Use a ParallaxContainer in layout XML

  2. Create a layout XML file for each page

  3. Wrap the Activity Context

  4. Add the attachment code to onCreate of your Activity

1. Use a ParallaxContainer in layout XML

Use the class com.prolificinteractive.parallaxpager.ParallaxContainer in your layout XML, sizing it however you like.

Ex:

<com.prolificinteractive.parallaxpager.ParallaxContainer        android:id="@+id/parallax_container_1"        android:layout_width="match_parent"        android:layout_height="match_parent"/>

2. Create a layout XML file for each page

Each page must have its own layout XML file. Use whichever Layouts or Views you like, as usual.

Ensure this line is added to the Root Element:

xmlns:app="http://schemas.android.com/apk/res-auto"

Assign any combination of the following attributes (all floats):

  • x_in: as the View enters the screen, it will translate in the horizontal direction along with user swiping, at a rate multiplied by this value. Default is 0.

  • x_out: as the View leaves the screen, it will translate in the horizontal direction along with user swiping, at a rate multiplied by this value. Default is 0.

  • y_in: as the View enters the screen, it will translate downward as the user swipes right to left, at a rate multiplied by this value. Default is 0.

  • y_out: as the View leaves the screen, it will translate upward as the user swipes right to left, at a rate multiplied by this value. Default is 0.

  • a_in: as the View enters the screen, it will fade in as the user swipes right to left, at a rate multiplied by this value. Default is 0.

  • a_out: as the View leaves the screen, it will fade out as the user swipes right to left, at a rate multiplied by this value. Default is 0.

Ex:

<?xml version="1.0" encoding="utf-8"?>  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"      xmlns:app="http://schemas.android.com/apk/res-auto"      android:layout_width="match_parent"      android:layout_height="match_parent"      android:orientation="vertical">      <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        app:x_in="@dimen/parallax_speed_medium"        app:x_out="@dimen/parallax_speed_fast"        app:y_in="@dimen/parallax_speed_medium_rev"        app:y_out="@dimen/parallax_speed_fast"        app:a_in="@dimen/parallax_speed_very_fast"        app:a_out="@dimen/parallax_speed_very_fast"        android:text="@string/text_1"        />      <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        app:x_in="@dimen/parallax_speed_medium_rev"        app:x_out="@dimen/parallax_speed_fast"        app:y_in="@dimen/parallax_speed_medium"        app:y_out="@dimen/parallax_speed_fast_rev"        app:a_in="@dimen/parallax_speed_very_fast"        app:a_out="@dimen/parallax_speed_very_fast"        android:text="@string/text_2"        />  </LinearLayout>

Keep in mind that negative values mean a change in direction for translation effects, and have no effect for alpha. For translation effects, values between 0 and 1 will result in a high level of funkiness.

3. Wrap the Activity Context

Wrap the activity context using com.prolificinteractive.parallaxpager.ParallaxContextWrapper in your activity.

Ex:

  @Override    protected void attachBaseContext(Context newBase) {      super.attachBaseContext(new ParallaxContextWrapper(newBase));    }

4. Add the attachment code to onCreate of your Activity

Important steps in onCreate:

  • Find the parallax container by ID

  • Specify whether the pager should loop (true means it will loop)

  • Submit a Layout Inflater and list the layouts for each page (in order). Currently there must be at least 2 in this list (repeats allowed).

Ex:

// find the parallax container  ParallaxContainer parallaxContainer = (ParallaxContainer) findViewById(R.id.parallax_container);    // specify whether pager will loop  parallaxContainer.setLooping(true);    // wrap the inflater and inflate children with custom attributes  parallaxContainer.setupChildren(getLayoutInflater(),      R.layout.parallax_view_1,      R.layout.parallax_view_2,      R.layout.parallax_view_3,      R.layout.parallax_view_4);

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