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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.settings.widget;
import android.content.Context;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.TextView;
import androidx.viewpager.widget.PagerAdapter;
import com.android.settings.R;
/**
* To be used with ViewPager to provide a tab indicator component which give constant feedback as
* to the user's scroll progress.
*/
public final class SlidingTabLayout extends FrameLayout implements View.OnClickListener {
private final LinearLayout mTitleView;
private final View mIndicatorView;
private final LayoutInflater mLayoutInflater;
private RtlCompatibleViewPager mViewPager;
private int mSelectedPosition;
private float mSelectionOffset;
public SlidingTabLayout(Context context, AttributeSet attrs) {
super(context, attrs);
mLayoutInflater = LayoutInflater.from(context);
mTitleView = new LinearLayout(context);
mTitleView.setGravity(Gravity.CENTER_HORIZONTAL);
mIndicatorView = mLayoutInflater.inflate(R.layout.sliding_tab_indicator_view, this, false);
addView(mTitleView, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
addView(mIndicatorView, mIndicatorView.getLayoutParams());
}
/**
* Sets the associated view pager. Note that the assumption here is that the pager content
* (number of tabs and tab titles) does not change after this call has been made.
*/
public void setViewPager(RtlCompatibleViewPager viewPager) {
mTitleView.removeAllViews();
mViewPager = viewPager;
if (viewPager != null) {
viewPager.addOnPageChangeListener(new InternalViewPagerListener());
populateTabStrip();
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
final int titleCount = mTitleView.getChildCount();
if (titleCount > 0) {
final int width = MeasureSpec.makeMeasureSpec(
mTitleView.getMeasuredWidth() / titleCount, MeasureSpec.EXACTLY);
final int height = MeasureSpec.makeMeasureSpec(
mIndicatorView.getMeasuredHeight(), MeasureSpec.EXACTLY);
mIndicatorView.measure(width, height);
}
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
if (mTitleView.getChildCount() > 0) {
final int indicatorBottom = getMeasuredHeight();
final int indicatorHeight = mIndicatorView.getMeasuredHeight();
final int indicatorWidth = mIndicatorView.getMeasuredWidth();
final int totalWidth = getMeasuredWidth();
final int leftPadding = getPaddingLeft();
final int rightPadding = getPaddingRight();
mTitleView.layout(leftPadding, 0, mTitleView.getMeasuredWidth() + rightPadding,
mTitleView.getMeasuredHeight());
// IndicatorView should start on the right when RTL mode is enabled
if (isRtlMode()) {
mIndicatorView.layout(totalWidth - indicatorWidth,
indicatorBottom - indicatorHeight, totalWidth,
indicatorBottom);
} else {
mIndicatorView.layout(0, indicatorBottom - indicatorHeight,
indicatorWidth, indicatorBottom);
}
}
}
@Override
public void onClick(View v) {
final int titleCount = mTitleView.getChildCount();
for (int i = 0; i < titleCount; i++) {
if (v == mTitleView.getChildAt(i)) {
mViewPager.setCurrentItem(i);
return;
}
}
}
private void onViewPagerPageChanged(int position, float positionOffset) {
mSelectedPosition = position;
mSelectionOffset = positionOffset;
// Translation should be reversed in RTL mode
final int leftIndicator = isRtlMode() ? -getIndicatorLeft() : getIndicatorLeft();
mIndicatorView.setTranslationX(leftIndicator);
}
private void populateTabStrip() {
final PagerAdapter adapter = mViewPager.getAdapter();
for (int i = 0; i < adapter.getCount(); i++) {
final TextView tabTitleView = (TextView) mLayoutInflater.inflate(
R.layout.sliding_tab_title_view, mTitleView, false);
tabTitleView.setText(adapter.getPageTitle(i));
tabTitleView.setOnClickListener(this);
mTitleView.addView(tabTitleView);
tabTitleView.setSelected(i == mViewPager.getCurrentItem());
}
}
private int getIndicatorLeft() {
View selectedTitle = mTitleView.getChildAt(mSelectedPosition);
int left = selectedTitle.getLeft();
if (mSelectionOffset > 0f && mSelectedPosition < (getChildCount() - 1)) {
View nextTitle = mTitleView.getChildAt(mSelectedPosition + 1);
left = (int) (mSelectionOffset * nextTitle.getLeft()
+ (1.0f - mSelectionOffset) * left);
}
return left;
}
private boolean isRtlMode() {
return getLayoutDirection() == LAYOUT_DIRECTION_RTL;
}
private final class InternalViewPagerListener implements
RtlCompatibleViewPager.OnPageChangeListener {
private int mScrollState;
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
final int titleCount = mTitleView.getChildCount();
if ((titleCount == 0) || (position < 0) || (position >= titleCount)) {
return;
}
onViewPagerPageChanged(position, positionOffset);
}
@Override
public void onPageScrollStateChanged(int state) {
mScrollState = state;
}
@Override
public void onPageSelected(int position) {
position = mViewPager.getRtlAwareIndex(position);
if (mScrollState == RtlCompatibleViewPager.SCROLL_STATE_IDLE) {
onViewPagerPageChanged(position, 0f);
}
final int titleCount = mTitleView.getChildCount();
for (int i = 0; i < titleCount; i++) {
mTitleView.getChildAt(i).setSelected(position == i);
}
}
}
}
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