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/*
* Copyright (C) 2015 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.os.Build;
import android.util.AttributeSet;
import android.view.View;
import android.view.WindowInsets;
/**
* This class provides sticky header functionality in a scroll view, to use with
* SetupWizardIllustration. To use this, add a subview tagged with "sticky", or a subview tagged
* with "stickyContainer" and one of its child tagged as "sticky". The sticky container will be
* drawn when the sticky element hits the top of the view.
*
* <p>There are a few things to note:
*
* <ol>
* <li>The two supported scenarios are StickyHeaderScrollView -> subview (stickyContainer) ->
* sticky, and StickyHeaderScrollView -> container -> subview (sticky). The arrow (->)
* represents parent/child relationship and must be immediate child.
* <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.
* <li>For versions before Honeycomb, this will behave like a regular ScrollView.
* </ol>
*
* @see StickyHeaderListView
*/
public class StickyHeaderScrollView extends BottomScrollView {
private View sticky;
private View stickyContainer;
private int statusBarInset = 0;
public StickyHeaderScrollView(Context context) {
super(context);
}
public StickyHeaderScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public StickyHeaderScrollView(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();
}
updateStickyHeaderPosition();
}
public void updateStickyView() {
sticky = findViewWithTag("sticky");
stickyContainer = findViewWithTag("stickyContainer");
}
private void updateStickyHeaderPosition() {
// Note: for pre-Honeycomb the header will not be moved, so this ScrollView essentially
// behaves like a normal BottomScrollView.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
if (sticky != null) {
// The view to draw when sticking to the top
final View drawTarget = stickyContainer != null ? stickyContainer : sticky;
// The offset to draw the view at when sticky
final int drawOffset = stickyContainer != null ? sticky.getTop() : 0;
// Position of the draw target, relative to the outside of the scrollView
final int drawTop = drawTarget.getTop() - getScrollY();
if (drawTop + drawOffset < statusBarInset || !drawTarget.isShown()) {
// ScrollView translates the whole canvas so we have to compensate for that
drawTarget.setTranslationY(getScrollY() - drawOffset);
} else {
drawTarget.setTranslationY(0);
}
}
}
}
@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
updateStickyHeaderPosition();
}
@Override
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public WindowInsets onApplyWindowInsets(WindowInsets insets) {
if (getFitsSystemWindows()) {
statusBarInset = insets.getSystemWindowInsetTop();
insets =
insets.replaceSystemWindowInsets(
insets.getSystemWindowInsetLeft(),
0, /* top */
insets.getSystemWindowInsetRight(),
insets.getSystemWindowInsetBottom());
}
return insets;
}
}
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