1package com.android.launcher3.allapps;
2
3import android.annotation.TargetApi;
4import android.content.res.Resources;
5import android.graphics.Outline;
6import android.graphics.Rect;
7import android.graphics.drawable.GradientDrawable;
8import android.os.Build;
9import android.support.v7.widget.RecyclerView;
10import android.view.View;
11import android.view.ViewGroup;
12import android.view.ViewOutlineProvider;
13import android.widget.FrameLayout;
14
15import com.android.launcher3.BaseRecyclerView;
16import com.android.launcher3.R;
17
18/**
19 * Helper class for controlling the header elevation in response to RecyclerView scroll.
20 */
21public abstract class HeaderElevationController extends RecyclerView.OnScrollListener {
22
23    private int mCurrentY = 0;
24
25    public void reset() {
26        mCurrentY = 0;
27        onScroll(mCurrentY);
28    }
29
30    @Override
31    public final void onScrolled(RecyclerView recyclerView, int dx, int dy) {
32        mCurrentY = ((BaseRecyclerView) recyclerView).getCurrentScrollY();
33        onScroll(mCurrentY);
34    }
35
36    public void updateBackgroundPadding(Rect bgPadding) { }
37
38    abstract void onScroll(int scrollY);
39
40    public static class ControllerV16 extends HeaderElevationController {
41
42        private final View mShadow;
43        private final float mScrollToElevation;
44
45        public ControllerV16(View header) {
46            Resources res = header.getContext().getResources();
47            mScrollToElevation = res.getDimension(R.dimen.all_apps_header_scroll_to_elevation);
48
49            mShadow = new View(header.getContext());
50            mShadow.setBackground(new GradientDrawable(
51                    GradientDrawable.Orientation.TOP_BOTTOM, new int[] {0x1E000000, 0x00000000}));
52            mShadow.setAlpha(0);
53
54            FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(
55                    FrameLayout.LayoutParams.MATCH_PARENT,
56                    res.getDimensionPixelSize(R.dimen.all_apps_header_shadow_height));
57            lp.topMargin = ((FrameLayout.LayoutParams) header.getLayoutParams()).height;
58
59            ((ViewGroup) header.getParent()).addView(mShadow, lp);
60        }
61
62        @Override
63        public void onScroll(int scrollY) {
64            float elevationPct = (float) Math.min(scrollY, mScrollToElevation) /
65                    mScrollToElevation;
66            mShadow.setAlpha(elevationPct);
67        }
68
69        @Override
70        public void updateBackgroundPadding(Rect bgPadding) {
71            FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) mShadow.getLayoutParams();
72            lp.leftMargin = bgPadding.left;
73            lp.rightMargin = bgPadding.right;
74            mShadow.requestLayout();
75        }
76    }
77
78    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
79    public static class ControllerVL extends HeaderElevationController {
80
81        private final View mHeader;
82        private final float mMaxElevation;
83        private final float mScrollToElevation;
84
85        public ControllerVL(View header) {
86            mHeader = header;
87            Resources res = mHeader.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            // We need to provide a custom outline so the shadow only appears on the bottom edge.
92            // The top, left and right edges are all extended out, and the shadow is clipped
93            // by the parent.
94            final ViewOutlineProvider vop = new ViewOutlineProvider() {
95                @Override
96                public void getOutline(View view, Outline outline) {
97                    final View parent = (View) mHeader.getParent();
98
99                    final int left = parent.getLeft(); // Use the parent to account for offsets
100                    final int top = view.getTop();
101                    final int right = left + view.getWidth();
102                    final int bottom = view.getBottom();
103
104                    outline.setRect(
105                            left - (int) mMaxElevation,
106                            top - (int) mMaxElevation,
107                            right + (int) mMaxElevation,
108                            bottom);
109                }
110            };
111            mHeader.setOutlineProvider(vop);
112        }
113
114        @Override
115        public void onScroll(int scrollY) {
116            float elevationPct = Math.min(scrollY, mScrollToElevation) / mScrollToElevation;
117            float newElevation = mMaxElevation * elevationPct;
118            if (Float.compare(mHeader.getElevation(), newElevation) != 0) {
119                mHeader.setElevation(newElevation);
120            }
121        }
122    }
123}
124