Home | History | Annotate | Download | only in allapps 
      1 package com.android.launcher3.allapps;
      2 
      3 import android.annotation.TargetApi;
      4 import android.content.res.Resources;
      5 import android.graphics.Rect;
      6 import android.graphics.drawable.GradientDrawable;
      7 import android.os.Build;
      8 import android.support.v7.widget.RecyclerView;
      9 import android.view.View;
     10 import android.view.ViewGroup;
     11 import android.view.ViewOutlineProvider;
     12 import android.widget.FrameLayout;
     13 
     14 import com.android.launcher3.R;
     15 
     16 /**
     17  * Helper class for controlling the header elevation in response to RecyclerView scroll.
     18  */
     19 public abstract class HeaderElevationController extends RecyclerView.OnScrollListener {
     20 
     21     private int mCurrentY = 0;
     22 
     23     public void reset() {
     24         mCurrentY = 0;
     25         onScroll(mCurrentY);
     26     }
     27 
     28     @Override
     29     public final void onScrolled(RecyclerView recyclerView, int dx, int dy) {
     30         mCurrentY += dy;
     31         onScroll(mCurrentY);
     32     }
     33 
     34     public void updateBackgroundPadding(Rect bgPadding) { }
     35 
     36     abstract void onScroll(int scrollY);
     37 
     38     public static class ControllerV16 extends HeaderElevationController {
     39 
     40         private final View mShadow;
     41         private final float mScrollToElevation;
     42 
     43         public ControllerV16(View header) {
     44             Resources res = header.getContext().getResources();
     45             mScrollToElevation = res.getDimension(R.dimen.all_apps_header_scroll_to_elevation);
     46 
     47             mShadow = new View(header.getContext());
     48             mShadow.setBackground(new GradientDrawable(
     49                     GradientDrawable.Orientation.TOP_BOTTOM, new int[] {0x1E000000, 0x00000000}));
     50             mShadow.setAlpha(0);
     51 
     52             FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(
     53                     FrameLayout.LayoutParams.MATCH_PARENT,
     54                     res.getDimensionPixelSize(R.dimen.all_apps_header_shadow_height));
     55             lp.topMargin = ((FrameLayout.LayoutParams) header.getLayoutParams()).height;
     56 
     57             ((ViewGroup) header.getParent()).addView(mShadow, lp);
     58         }
     59 
     60         @Override
     61         public void onScroll(int scrollY) {
     62             float elevationPct = (float) Math.min(scrollY, mScrollToElevation) /
     63                     mScrollToElevation;
     64             mShadow.setAlpha(elevationPct);
     65         }
     66 
     67         @Override
     68         public void updateBackgroundPadding(Rect bgPadding) {
     69             FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) mShadow.getLayoutParams();
     70             lp.leftMargin = bgPadding.left;
     71             lp.rightMargin = bgPadding.right;
     72             mShadow.requestLayout();
     73         }
     74     }
     75 
     76     @TargetApi(Build.VERSION_CODES.LOLLIPOP)
     77     public static class ControllerVL extends HeaderElevationController {
     78 
     79         private final View mHeader;
     80         private final float mMaxElevation;
     81         private final float mScrollToElevation;
     82 
     83         public ControllerVL(View header) {
     84             mHeader = header;
     85             mHeader.setOutlineProvider(ViewOutlineProvider.BOUNDS);
     86 
     87             Resources res = header.getContext().getResources();
     88             mMaxElevation = res.getDimension(R.dimen.all_apps_header_max_elevation);
     89             mScrollToElevation = res.getDimension(R.dimen.all_apps_header_scroll_to_elevation);
     90         }
     91 
     92         @Override
     93         public void onScroll(int scrollY) {
     94             float elevationPct = Math.min(scrollY, mScrollToElevation) / mScrollToElevation;
     95             float newElevation = mMaxElevation * elevationPct;
     96             if (Float.compare(mHeader.getElevation(), newElevation) != 0) {
     97                 mHeader.setElevation(newElevation);
     98             }
     99         }
    100     }
    101 }
    102