Android 实现谷歌日历图像视图”；视差；影响

也许你们中的一些人在材料设计方面尝试了新的谷歌日历。我要寻找的是“效果”或使ImageView跟随您的滚动的方法。它看起来像是视差效果，但我能找到的只是标题视图上有视差效果的库。有人能给我指一下正确的方向吗？谢谢

AFAIK没有这样的库，但是我在几个月前做了类似的事情，但它非常简单，根本没有动态性

首先，您需要扩展

ScrollView

，以便获得仅对ScrollView类可用的所有滚动位置

像这样的

    public class TestScrollView extends ScrollView {

        private ScrollViewListener scrollViewListener = null;

        public interface ScrollViewListener {

            public void onScrollChanged(TestScrollView scrollView, int x, int y, int oldx, int oldy);

        }

        public TestScrollView(Context context) {
            super(context);
        }

        public TestScrollView(Context context, AttributeSet attrs) {
            super(context, attrs);
        }

        public TestScrollView(Context context, AttributeSet attrs, int defStyle) {
            super(context, attrs, defStyle);
        }

        public void setScrollViewListener(ScrollViewListener scrollViewListener) {
            this.scrollViewListener = scrollViewListener;
        }

        @Override
        protected void onScrollChanged(int x, int y, int oldx, int oldy) {
            super.onScrollChanged(x, y, oldx, oldy);
            if(scrollViewListener != null) {
                scrollViewListener.onScrollChanged(this, x, y, oldx, oldy);
            }
        }
    }

<com.example.parallaximageview.app.TestScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/scroll">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

         //other views

        <com.example.parallaximageview.app.ParallaxImageView
            android:layout_width="match_parent"
            android:layout_height="300dp"
            android:src="@drawable/camera_phone"
            android:scaleType="centerCrop"
            android:id="@+id/image2"/>

        //other views

    </LinearLayout>

</com.example.parallaximageview.app.TestScrollView>

接下来，您必须扩展ImageView来执行所有视差操作。这可能对你有用也可能不有用我不知道这是为一个特定的案例而做的

public class ParallaxImageView extends ImageView {

    public static final float PARALLAX_COEFFICIENT = 0.65F;
    public static final float PROPERTY_IMAGE_INV_RATIO = 0.6666667F;
    private int intrinsicHeight = -1;
    Context context;

    public ParallaxImageView(Context context) {
        super(context);
        this.context = context;
        init();
    }

    public ParallaxImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        init();
    }

    public ParallaxImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        this.context = context;
        init();
    }

    private void init(){
        post(new Runnable(){

            @Override
            public void run() {
                int i = (int)(PARALLAX_COEFFICIENT * (PROPERTY_IMAGE_INV_RATIO * getWidth()));
                getLayoutParams().height = i;
            }
        });
    }

    public void updateParallaxState()
    {
        int i = this.intrinsicHeight - getHeight();

        if (i == 0){
            return;
        }

        Rect localRect = getScreenLocation(this);
        int height = getHeight();
//        int j = getScreenSize().y + height;
//        float min = Math.min(1.0F, (localRect.top + height) / j);
//        float max = Math.max(min, 0.0F);
//        setScrollY((int)((max - 0.5F) * i));

        setScrollY((localRect.top-height-380)/8);
    }

    private Rect getScreenLocation(View paramView)
    {
        Rect localRect = new Rect();
        int[] arrayOfInt = new int[2];
        paramView.getLocationOnScreen(arrayOfInt);
        int i = getStatusbarHeight(paramView);
        localRect.set(arrayOfInt[0], arrayOfInt[1], arrayOfInt[0] + paramView.getWidth(), arrayOfInt[1] + paramView.getHeight());
        return localRect;
    }

    private int getStatusbarHeight(View paramView)
    {
        Rect localRect = new Rect();
        ((Activity)paramView.getContext()).getWindow().getDecorView().getWindowVisibleDisplayFrame(localRect);
        return localRect.top;
    }
}

然后在活动中实现scrolllistener和视图

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    TestScrollView scroll = (TestScrollView)findViewById(R.id.scroll);
    scroll.setScrollViewListener(this);

    i1 = (ParallaxImageView)findViewById(R.id.image1);
    i2 = (ParallaxImageView)findViewById(R.id.image2);
}

@Override
public void onScrollChanged(TestScrollView scrollView, int x, int y, int oldx, int oldy) {
    i1.updateParallaxState();
    i2.updateParallaxState();
}

然后你的布局会像这样

    public class TestScrollView extends ScrollView {

        private ScrollViewListener scrollViewListener = null;

        public interface ScrollViewListener {

            public void onScrollChanged(TestScrollView scrollView, int x, int y, int oldx, int oldy);

        }

        public TestScrollView(Context context) {
            super(context);
        }

        public TestScrollView(Context context, AttributeSet attrs) {
            super(context, attrs);
        }

        public TestScrollView(Context context, AttributeSet attrs, int defStyle) {
            super(context, attrs, defStyle);
        }

        public void setScrollViewListener(ScrollViewListener scrollViewListener) {
            this.scrollViewListener = scrollViewListener;
        }

        @Override
        protected void onScrollChanged(int x, int y, int oldx, int oldy) {
            super.onScrollChanged(x, y, oldx, oldy);
            if(scrollViewListener != null) {
                scrollViewListener.onScrollChanged(this, x, y, oldx, oldy);
            }
        }
    }

<com.example.parallaximageview.app.TestScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/scroll">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

         //other views

        <com.example.parallaximageview.app.ParallaxImageView
            android:layout_width="match_parent"
            android:layout_height="300dp"
            android:src="@drawable/camera_phone"
            android:scaleType="centerCrop"
            android:id="@+id/image2"/>

        //other views

    </LinearLayout>

</com.example.parallaximageview.app.TestScrollView>

//其他观点
//其他观点

这是运动！只要滚动一下就行了吗？看这篇文章：你好，谢谢你的方法！你知道使用recyclerviews或listviews是否有可能达到同样的效果吗？我确信这是可能的，但这会困难得多