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package com.android.launcher3.allapps;
import android.annotation.TargetApi;
import android.content.res.Resources;
import android.graphics.Outline;
import android.graphics.Rect;
import android.graphics.drawable.GradientDrawable;
import android.os.Build;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewOutlineProvider;
import android.widget.FrameLayout;
import com.android.launcher3.BaseRecyclerView;
import com.android.launcher3.R;
/**
* Helper class for controlling the header elevation in response to RecyclerView scroll.
*/
public abstract class HeaderElevationController extends RecyclerView.OnScrollListener {
private int mCurrentY = 0;
public void reset() {
mCurrentY = 0;
onScroll(mCurrentY);
}
@Override
public final void onScrolled(RecyclerView recyclerView, int dx, int dy) {
mCurrentY = ((BaseRecyclerView) recyclerView).getCurrentScrollY();
onScroll(mCurrentY);
}
public void updateBackgroundPadding(Rect bgPadding) { }
abstract void onScroll(int scrollY);
public static class ControllerV16 extends HeaderElevationController {
private final View mShadow;
private final float mScrollToElevation;
public ControllerV16(View header) {
Resources res = header.getContext().getResources();
mScrollToElevation = res.getDimension(R.dimen.all_apps_header_scroll_to_elevation);
mShadow = new View(header.getContext());
mShadow.setBackground(new GradientDrawable(
GradientDrawable.Orientation.TOP_BOTTOM, new int[] {0x1E000000, 0x00000000}));
mShadow.setAlpha(0);
FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(
FrameLayout.LayoutParams.MATCH_PARENT,
res.getDimensionPixelSize(R.dimen.all_apps_header_shadow_height));
lp.topMargin = ((FrameLayout.LayoutParams) header.getLayoutParams()).height;
((ViewGroup) header.getParent()).addView(mShadow, lp);
}
@Override
public void onScroll(int scrollY) {
float elevationPct = (float) Math.min(scrollY, mScrollToElevation) /
mScrollToElevation;
mShadow.setAlpha(elevationPct);
}
@Override
public void updateBackgroundPadding(Rect bgPadding) {
FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) mShadow.getLayoutParams();
lp.leftMargin = bgPadding.left;
lp.rightMargin = bgPadding.right;
mShadow.requestLayout();
}
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public static class ControllerVL extends HeaderElevationController {
private final View mHeader;
private final float mMaxElevation;
private final float mScrollToElevation;
public ControllerVL(View header) {
mHeader = header;
Resources res = mHeader.getContext().getResources();
mMaxElevation = res.getDimension(R.dimen.all_apps_header_max_elevation);
mScrollToElevation = res.getDimension(R.dimen.all_apps_header_scroll_to_elevation);
// We need to provide a custom outline so the shadow only appears on the bottom edge.
// The top, left and right edges are all extended out, and the shadow is clipped
// by the parent.
final ViewOutlineProvider vop = new ViewOutlineProvider() {
@Override
public void getOutline(View view, Outline outline) {
final View parent = (View) mHeader.getParent();
final int left = parent.getLeft(); // Use the parent to account for offsets
final int top = view.getTop();
final int right = left + view.getWidth();
final int bottom = view.getBottom();
outline.setRect(
left - (int) mMaxElevation,
top - (int) mMaxElevation,
right + (int) mMaxElevation,
bottom);
}
};
mHeader.setOutlineProvider(vop);
}
@Override
public void onScroll(int scrollY) {
float elevationPct = Math.min(scrollY, mScrollToElevation) / mScrollToElevation;
float newElevation = mMaxElevation * elevationPct;
if (Float.compare(mHeader.getElevation(), newElevation) != 0) {
mHeader.setElevation(newElevation);
}
}
}
}
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