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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.setupwizardlib.view;
import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.RectF;
import android.os.Build;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowInsets;
/**
* This class provides sticky header functionality in a recycler view, to use with
* SetupWizardIllustration. To use this, add a header tagged with "sticky". The header will continue
* to be drawn when the sticky element hits the top of the view.
*
* <p>There are a few things to note:
*
* <ol>
* <li>The view does not work well with padding. b/16190933
* <li>If fitsSystemWindows is true, then this will offset the sticking position by the height of
* the system decorations at the top of the screen.
* </ol>
*/
public class StickyHeaderRecyclerView extends HeaderRecyclerView {
private View sticky;
private int statusBarInset = 0;
private final RectF stickyRect = new RectF();
public StickyHeaderRecyclerView(Context context) {
super(context);
}
public StickyHeaderRecyclerView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public StickyHeaderRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (sticky == null) {
updateStickyView();
}
if (sticky != null) {
final View headerView = getHeader();
if (headerView != null && headerView.getHeight() == 0) {
headerView.layout(0, -headerView.getMeasuredHeight(), headerView.getMeasuredWidth(), 0);
}
}
}
@Override
protected void onMeasure(int widthSpec, int heightSpec) {
super.onMeasure(widthSpec, heightSpec);
if (sticky != null) {
measureChild(getHeader(), widthSpec, heightSpec);
}
}
/**
* Call this method when the "sticky" view has changed, so this view can update its internal
* states as well.
*/
public void updateStickyView() {
final View header = getHeader();
if (header != null) {
sticky = header.findViewWithTag("sticky");
}
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
if (sticky != null) {
final View headerView = getHeader();
final int saveCount = canvas.save();
// The view to draw when sticking to the top
final View drawTarget = headerView != null ? headerView : sticky;
// The offset to draw the view at when sticky
final int drawOffset = headerView != null ? sticky.getTop() : 0;
// Position of the draw target, relative to the outside of the scrollView
final int drawTop = drawTarget.getTop();
if (drawTop + drawOffset < statusBarInset || !drawTarget.isShown()) {
// RecyclerView does not translate the canvas, so we can simply draw at the top
stickyRect.set(
0,
-drawOffset + statusBarInset,
drawTarget.getWidth(),
drawTarget.getHeight() - drawOffset + statusBarInset);
canvas.translate(0, stickyRect.top);
canvas.clipRect(0, 0, drawTarget.getWidth(), drawTarget.getHeight());
drawTarget.draw(canvas);
} else {
stickyRect.setEmpty();
}
canvas.restoreToCount(saveCount);
}
}
@Override
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public WindowInsets onApplyWindowInsets(WindowInsets insets) {
if (getFitsSystemWindows()) {
statusBarInset = insets.getSystemWindowInsetTop();
insets.replaceSystemWindowInsets(
insets.getSystemWindowInsetLeft(),
0, /* top */
insets.getSystemWindowInsetRight(),
insets.getSystemWindowInsetBottom());
}
return insets;
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
if (stickyRect.contains(ev.getX(), ev.getY())) {
ev.offsetLocation(-stickyRect.left, -stickyRect.top);
return getHeader().dispatchTouchEvent(ev);
} else {
return super.dispatchTouchEvent(ev);
}
}
}
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