/*
* Copyright 2018 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 androidx.viewpager.widget;
import android.content.Context;
import android.content.res.TypedArray;
import android.database.DataSetObserver;
import android.graphics.drawable.Drawable;
import android.text.TextUtils.TruncateAt;
import android.text.method.SingleLineTransformationMethod;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.widget.TextView;
import androidx.annotation.ColorInt;
import androidx.annotation.FloatRange;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.widget.TextViewCompat;
import java.lang.ref.WeakReference;
import java.util.Locale;
/**
* PagerTitleStrip is a non-interactive indicator of the current, next,
* and previous pages of a {@link ViewPager}. It is intended to be used as a
* child view of a ViewPager widget in your XML layout.
* Add it as a child of a ViewPager in your layout file and set its
* android:layout_gravity to TOP or BOTTOM to pin it to the top or bottom
* of the ViewPager. The title from each page is supplied by the method
* {@link PagerAdapter#getPageTitle(int)} in the adapter supplied to
* the ViewPager.
*
* <p>For an interactive indicator, see {@link PagerTabStrip}.</p>
*/
@ViewPager.DecorView
public class PagerTitleStrip extends ViewGroup {
ViewPager mPager;
TextView mPrevText;
TextView mCurrText;
TextView mNextText;
private int mLastKnownCurrentPage = -1;
float mLastKnownPositionOffset = -1;
private int mScaledTextSpacing;
private int mGravity;
private boolean mUpdatingText;
private boolean mUpdatingPositions;
private final PageListener mPageListener = new PageListener();
private WeakReference<PagerAdapter> mWatchingAdapter;
private static final int[] ATTRS = new int[] {
android.R.attr.textAppearance,
android.R.attr.textSize,
android.R.attr.textColor,
android.R.attr.gravity
};
private static final int[] TEXT_ATTRS = new int[] {
0x0101038c // android.R.attr.textAllCaps
};
private static final float SIDE_ALPHA = 0.6f;
private static final int TEXT_SPACING = 16; // dip
private int mNonPrimaryAlpha;
int mTextColor;
private static class SingleLineAllCapsTransform extends SingleLineTransformationMethod {
private Locale mLocale;
SingleLineAllCapsTransform(Context context) {
mLocale = context.getResources().getConfiguration().locale;
}
@Override
public CharSequence getTransformation(CharSequence source, View view) {
source = super.getTransformation(source, view);
return source != null ? source.toString().toUpperCase(mLocale) : null;
}
}
private static void setSingleLineAllCaps(TextView text) {
text.setTransformationMethod(new SingleLineAllCapsTransform(text.getContext()));
}
public PagerTitleStrip(@NonNull Context context) {
this(context, null);
}
public PagerTitleStrip(@NonNull Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
addView(mPrevText = new TextView(context));
addView(mCurrText = new TextView(context));
addView(mNextText = new TextView(context));
final TypedArray a = context.obtainStyledAttributes(attrs, ATTRS);
final int textAppearance = a.getResourceId(0, 0);
if (textAppearance != 0) {
TextViewCompat.setTextAppearance(mPrevText, textAppearance);
TextViewCompat.setTextAppearance(mCurrText, textAppearance);
TextViewCompat.setTextAppearance(mNextText, textAppearance);
}
final int textSize = a.getDimensionPixelSize(1, 0);
if (textSize != 0) {
setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize);
}
if (a.hasValue(2)) {
final int textColor = a.getColor(2, 0);
mPrevText.setTextColor(textColor);
mCurrText.setTextColor(textColor);
mNextText.setTextColor(textColor);
}
mGravity = a.getInteger(3, Gravity.BOTTOM);
a.recycle();
mTextColor = mCurrText.getTextColors().getDefaultColor();
setNonPrimaryAlpha(SIDE_ALPHA);
mPrevText.setEllipsize(TruncateAt.END);
mCurrText.setEllipsize(TruncateAt.END);
mNextText.setEllipsize(TruncateAt.END);
boolean allCaps = false;
if (textAppearance != 0) {
final TypedArray ta = context.obtainStyledAttributes(textAppearance, TEXT_ATTRS);
allCaps = ta.getBoolean(0, false);
ta.recycle();
}
if (allCaps) {
setSingleLineAllCaps(mPrevText);
setSingleLineAllCaps(mCurrText);
setSingleLineAllCaps(mNextText);
} else {
mPrevText.setSingleLine();
mCurrText.setSingleLine();
mNextText.setSingleLine();
}
final float density = context.getResources().getDisplayMetrics().density;
mScaledTextSpacing = (int) (TEXT_SPACING * density);
}
/**
* Set the required spacing between title segments.
*
* @param spacingPixels Spacing between each title displayed in pixels
*/
public void setTextSpacing(int spacingPixels) {
mScaledTextSpacing = spacingPixels;
requestLayout();
}
/**
* @return The required spacing between title segments in pixels
*/
public int getTextSpacing() {
return mScaledTextSpacing;
}
/**
* Set the alpha value used for non-primary page titles.
*
* @param alpha Opacity value in the range 0-1f
*/
public void setNonPrimaryAlpha(@FloatRange(from = 0.0, to = 1.0) float alpha) {
mNonPrimaryAlpha = (int) (alpha * 255) & 0xFF;
final int transparentColor = (mNonPrimaryAlpha << 24) | (mTextColor & 0xFFFFFF);
mPrevText.setTextColor(transparentColor);
mNextText.setTextColor(transparentColor);
}
/**
* Set the color value used as the base color for all displayed page titles.
* Alpha will be ignored for non-primary page titles. See {@link #setNonPrimaryAlpha(float)}.
*
* @param color Color hex code in 0xAARRGGBB format
*/
public void setTextColor(@ColorInt int color) {
mTextColor = color;
mCurrText.setTextColor(color);
final int transparentColor = (mNonPrimaryAlpha << 24) | (mTextColor & 0xFFFFFF);
mPrevText.setTextColor(transparentColor);
mNextText.setTextColor(transparentColor);
}
/**
* Set the default text size to a given unit and value.
* See {@link TypedValue} for the possible dimension units.
*
* <p>Example: to set the text size to 14px, use
* setTextSize(TypedValue.COMPLEX_UNIT_PX, 14);</p>
*
* @param unit The desired dimension unit
* @param size The desired size in the given units
*/
public void setTextSize(int unit, float size) {
mPrevText.setTextSize(unit, size);
mCurrText.setTextSize(unit, size);
mNextText.setTextSize(unit, size);
}
/**
* Set the {@link Gravity} used to position text within the title strip.
* Only the vertical gravity component is used.
*
* @param gravity {@link Gravity} constant for positioning title text
*/
public void setGravity(int gravity) {
mGravity = gravity;
requestLayout();
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
final ViewParent parent = getParent();
if (!(parent instanceof ViewPager)) {
throw new IllegalStateException(
"PagerTitleStrip must be a direct child of a ViewPager.");
}
final ViewPager pager = (ViewPager) parent;
final PagerAdapter adapter = pager.getAdapter();
pager.setInternalPageChangeListener(mPageListener);
pager.addOnAdapterChangeListener(mPageListener);
mPager = pager;
updateAdapter(mWatchingAdapter != null ? mWatchingAdapter.get() : null, adapter);
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
if (mPager != null) {
updateAdapter(mPager.getAdapter(), null);
mPager.setInternalPageChangeListener(null);
mPager.removeOnAdapterChangeListener(mPageListener);
mPager = null;
}
}
void updateText(int currentItem, PagerAdapter adapter) {
final int itemCount = adapter != null ? adapter.getCount() : 0;
mUpdatingText = true;
CharSequence text = null;
if (currentItem >= 1 && adapter != null) {
text = adapter.getPageTitle(currentItem - 1);
}
mPrevText.setText(text);
mCurrText.setText(adapter != null && currentItem < itemCount
? adapter.getPageTitle(currentItem) : null);
text = null;
if (currentItem + 1 < itemCount && adapter != null) {
text = adapter.getPageTitle(currentItem + 1);
}
mNextText.setText(text);
// Measure everything
final int width = getWidth() - getPaddingLeft() - getPaddingRight();
final int maxWidth = Math.max(0, (int) (width * 0.8f));
final int childWidthSpec = MeasureSpec.makeMeasureSpec(maxWidth, MeasureSpec.AT_MOST);
final int childHeight = getHeight() - getPaddingTop() - getPaddingBottom();
final int maxHeight = Math.max(0, childHeight);
final int childHeightSpec = MeasureSpec.makeMeasureSpec(maxHeight, MeasureSpec.AT_MOST);
mPrevText.measure(childWidthSpec, childHeightSpec);
mCurrText.measure(childWidthSpec, childHeightSpec);
mNextText.measure(childWidthSpec, childHeightSpec);
mLastKnownCurrentPage = currentItem;
if (!mUpdatingPositions) {
updateTextPositions(currentItem, mLastKnownPositionOffset, false);
}
mUpdatingText = false;
}
@Override
public void requestLayout() {
if (!mUpdatingText) {
super.requestLayout();
}
}
void updateAdapter(PagerAdapter oldAdapter, PagerAdapter newAdapter) {
if (oldAdapter != null) {
oldAdapter.unregisterDataSetObserver(mPageListener);
mWatchingAdapter = null;
}
if (newAdapter != null) {
newAdapter.registerDataSetObserver(mPageListener);
mWatchingAdapter = new WeakReference<PagerAdapter>(newAdapter);
}
if (mPager != null) {
mLastKnownCurrentPage = -1;
mLastKnownPositionOffset = -1;
updateText(mPager.getCurrentItem(), newAdapter);
requestLayout();
}
}
void updateTextPositions(int position, float positionOffset, boolean force) {
if (position != mLastKnownCurrentPage) {
updateText(position, mPager.getAdapter());
} else if (!force && positionOffset == mLastKnownPositionOffset) {
return;
}
mUpdatingPositions = true;
final int prevWidth = mPrevText.getMeasuredWidth();
final int currWidth = mCurrText.getMeasuredWidth();
final int nextWidth = mNextText.getMeasuredWidth();
final int halfCurrWidth = currWidth / 2;
final int stripWidth = getWidth();
final int stripHeight = getHeight();
final int paddingLeft = getPaddingLeft();
final int paddingRight = getPaddingRight();
final int paddingTop = getPaddingTop();
final int paddingBottom = getPaddingBottom();
final int textPaddedLeft = paddingLeft + halfCurrWidth;
final int textPaddedRight = paddingRight + halfCurrWidth;
final int contentWidth = stripWidth - textPaddedLeft - textPaddedRight;
float currOffset = positionOffset + 0.5f;
if (currOffset > 1.f) {
currOffset -= 1.f;
}
final int currCenter = stripWidth - textPaddedRight - (int) (contentWidth * currOffset);
final int currLeft = currCenter - currWidth / 2;
final int currRight = currLeft + currWidth;
final int prevBaseline = mPrevText.getBaseline();
final int currBaseline = mCurrText.getBaseline();
final int nextBaseline = mNextText.getBaseline();
final int maxBaseline = Math.max(Math.max(prevBaseline, currBaseline), nextBaseline);
final int prevTopOffset = maxBaseline - prevBaseline;
final int currTopOffset = maxBaseline - currBaseline;
final int nextTopOffset = maxBaseline - nextBaseline;
final int alignedPrevHeight = prevTopOffset + mPrevText.getMeasuredHeight();
final int alignedCurrHeight = currTopOffset + mCurrText.getMeasuredHeight();
final int alignedNextHeight = nextTopOffset + mNextText.getMeasuredHeight();
final int maxTextHeight = Math.max(Math.max(alignedPrevHeight, alignedCurrHeight),
alignedNextHeight);
final int vgrav = mGravity & Gravity.VERTICAL_GRAVITY_MASK;
int prevTop;
int currTop;
int nextTop;
switch (vgrav) {
default:
case Gravity.TOP:
prevTop = paddingTop + prevTopOffset;
currTop = paddingTop + currTopOffset;
nextTop = paddingTop + nextTopOffset;
break;
case Gravity.CENTER_VERTICAL:
final int paddedHeight = stripHeight - paddingTop - paddingBottom;
final int centeredTop = (paddedHeight - maxTextHeight) / 2;
prevTop = centeredTop + prevTopOffset;
currTop = centeredTop + currTopOffset;
nextTop = centeredTop + nextTopOffset;
break;
case Gravity.BOTTOM:
final int bottomGravTop = stripHeight - paddingBottom - maxTextHeight;
prevTop = bottomGravTop + prevTopOffset;
currTop = bottomGravTop + currTopOffset;
nextTop = bottomGravTop + nextTopOffset;
break;
}
mCurrText.layout(currLeft, currTop, currRight,
currTop + mCurrText.getMeasuredHeight());
final int prevLeft = Math.min(paddingLeft, currLeft - mScaledTextSpacing - prevWidth);
mPrevText.layout(prevLeft, prevTop, prevLeft + prevWidth,
prevTop + mPrevText.getMeasuredHeight());
final int nextLeft = Math.max(stripWidth - paddingRight - nextWidth,
currRight + mScaledTextSpacing);
mNextText.layout(nextLeft, nextTop, nextLeft + nextWidth,
nextTop + mNextText.getMeasuredHeight());
mLastKnownPositionOffset = positionOffset;
mUpdatingPositions = false;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
if (widthMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("Must measure with an exact width");
}
final int heightPadding = getPaddingTop() + getPaddingBottom();
final int childHeightSpec = getChildMeasureSpec(heightMeasureSpec,
heightPadding, LayoutParams.WRAP_CONTENT);
final int widthSize = MeasureSpec.getSize(widthMeasureSpec);
final int widthPadding = (int) (widthSize * 0.2f);
final int childWidthSpec = getChildMeasureSpec(widthMeasureSpec,
widthPadding, LayoutParams.WRAP_CONTENT);
mPrevText.measure(childWidthSpec, childHeightSpec);
mCurrText.measure(childWidthSpec, childHeightSpec);
mNextText.measure(childWidthSpec, childHeightSpec);
final int height;
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightMode == MeasureSpec.EXACTLY) {
height = MeasureSpec.getSize(heightMeasureSpec);
} else {
final int textHeight = mCurrText.getMeasuredHeight();
final int minHeight = getMinHeight();
height = Math.max(minHeight, textHeight + heightPadding);
}
final int childState = mCurrText.getMeasuredState();
final int measuredHeight = View.resolveSizeAndState(height, heightMeasureSpec,
childState << View.MEASURED_HEIGHT_STATE_SHIFT);
setMeasuredDimension(widthSize, measuredHeight);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if (mPager != null) {
final float offset = mLastKnownPositionOffset >= 0 ? mLastKnownPositionOffset : 0;
updateTextPositions(mLastKnownCurrentPage, offset, true);
}
}
int getMinHeight() {
int minHeight = 0;
final Drawable bg = getBackground();
if (bg != null) {
minHeight = bg.getIntrinsicHeight();
}
return minHeight;
}
private class PageListener extends DataSetObserver implements ViewPager.OnPageChangeListener,
ViewPager.OnAdapterChangeListener {
private int mScrollState;
PageListener() {
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
if (positionOffset > 0.5f) {
// Consider ourselves to be on the next page when we're 50% of the way there.
position++;
}
updateTextPositions(position, positionOffset, false);
}
@Override
public void onPageSelected(int position) {
if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {
// Only update the text here if we're not dragging or settling.
updateText(mPager.getCurrentItem(), mPager.getAdapter());
final float offset = mLastKnownPositionOffset >= 0 ? mLastKnownPositionOffset : 0;
updateTextPositions(mPager.getCurrentItem(), offset, true);
}
}
@Override
public void onPageScrollStateChanged(int state) {
mScrollState = state;
}
@Override
public void onAdapterChanged(ViewPager viewPager, PagerAdapter oldAdapter,
PagerAdapter newAdapter) {
updateAdapter(oldAdapter, newAdapter);
}
@Override
public void onChanged() {
updateText(mPager.getCurrentItem(), mPager.getAdapter());
final float offset = mLastKnownPositionOffset >= 0 ? mLastKnownPositionOffset : 0;
updateTextPositions(mPager.getCurrentItem(), offset, true);
}
}
}