在使用Canvas绘制文本的时候，如果要绘制的字符串含有\r\n,\n换行的时候，会识别不出来，当成空格绘制出来。
解决方案：
1.使用StaticLayout来实现，具体代码如下：
TextPaint mTextPaint=new TextPaint(); StaticLayout mTextLayout = new StaticLayout(mText, mTextPaint, canvas.getWidth(), Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false); canvas.save(); // calculate x and y position where your text will be placed textX = ... textY = ... canvas.translate(textX, textY); mTextLayout.draw(canvas); canvas.restore();
2.截取字符串，进行按行处理：
int x = 100, y = 100;
for (String line: text.split("\n")) {
canvas.drawText(line, x, y, mTextPaint);
y += mTextPaint.descent() - mTextPaint.ascent();
}
参考：http://stackoverflow.com/questions/6756975/draw-multi-line-text-to-canvas
遇见这个问题是在使用https://github.com/JakeWharton/ViewPagerIndicator，ViewPagerIndicator这个控件的时候，设置title竟然不能换行，只能设置单行的标题，很是蛋疼，只需要修改TitlePageIndicator这个类即可。
附代码：
/*
* Copyright (C) 2011 Jake Wharton
* Copyright (C) 2011 Patrik Akerfeldt
* Copyright (C) 2011 Francisco Figueiredo Jr.
*
* 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.viewpagerindicator;
import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Rect;
import android.graphics.Typeface;
import android.graphics.drawable.Drawable;
import android.os.Parcel;
import android.os.Parcelable;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.ViewConfigurationCompat;
import android.support.v4.view.ViewPager;
import android.text.Layout;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import com.edaixi.activity.R;
import com.edaixi.utils.LogUtil;
import java.util.ArrayList;
/**
* A TitlePageIndicator is a PageIndicator which displays the title of left view
* (if exist), the title of the current select view (centered) and the title of
* the right view (if exist). When the user scrolls the ViewPager then titles are
* also scrolled.
*/
public class TitlePageIndicator extends View implements PageIndicator {
/**
* Percentage indicating what percentage of the screen width away from
* center should the underline be fully faded. A value of 0.25 means that
* halfway between the center of the screen and an edge.
*/
private static final float SELECTION_FADE_PERCENTAGE = 0.25f;
/**
* Percentage indicating what percentage of the screen width away from
* center should the selected text bold turn off. A value of 0.05 means
* that 10% between the center and an edge.
*/
private static final float BOLD_FADE_PERCENTAGE = 0.05f;
/**
* Title text used when no title is provided by the adapter.
*/
private static final String EMPTY_TITLE = "";
/**
* Interface for a callback when the center item has been clicked.
*/
public interface OnCenterItemClickListener {
/**
* Callback when the center item has been clicked.
*
* @param position Position of the current center item.
*/
void onCenterItemClick(int position);
}
public enum IndicatorStyle {
None(0), Triangle(1), Underline(2);
public final int value;
private IndicatorStyle(int value) {
this.value = value;
}
public static IndicatorStyle fromValue(int value) {
for (IndicatorStyle style : IndicatorStyle.values()) {
if (style.value == value) {
return style;
}
}
return null;
}
}
public enum LinePosition {
Bottom(0), Top(1);
public final int value;
private LinePosition(int value) {
this.value = value;
}
public static LinePosition fromValue(int value) {
for (LinePosition position : LinePosition.values()) {
if (position.value == value) {
return position;
}
}
return null;
}
}
private ViewPager mViewPager;
private ViewPager.OnPageChangeListener mListener;
private int mCurrentPage = -1;
private float mPageOffset;
private int mScrollState;
private final TextPaint mPaintText = new TextPaint();
private boolean mBoldText;
private int mColorText;
private int mColorSelected;
private Path mPath = new Path();
private final Rect mBounds = new Rect();
private final Paint mPaintFooterLine = new Paint();
private IndicatorStyle mFooterIndicatorStyle;
private LinePosition mLinePosition;
private final Paint mPaintFooterIndicator = new Paint();
private float mFooterIndicatorHeight;
private float mFooterIndicatorUnderlinePadding;
private float mFooterPadding;
private float mTitlePadding;
private float mTopPadding;
/**
* Left and right side padding for not active view titles.
*/
private float mClipPadding;
private float mFooterLineHeight;
private static final int INVALID_POINTER = -1;
private int mTouchSlop;
private float mLastMotionX = -1;
private int mActivePointerId = INVALID_POINTER;
private boolean mIsDragging;
private OnCenterItemClickListener mCenterItemClickListener;
public TitlePageIndicator(Context context) {
this(context, null);
}
public TitlePageIndicator(Context context, AttributeSet attrs) {
this(context, attrs, R.attr.vpiTitlePageIndicatorStyle);
}
public TitlePageIndicator(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
if (isInEditMode()) return;
//Load defaults from resources
final Resources res = getResources();
final int defaultFooterColor = res.getColor(R.color.default_title_indicator_footer_color);
final float defaultFooterLineHeight = res.getDimension(R.dimen.default_title_indicator_footer_line_height);
final int defaultFooterIndicatorStyle = res.getInteger(R.integer.default_title_indicator_footer_indicator_style);
final float defaultFooterIndicatorHeight = res.getDimension(R.dimen.default_title_indicator_footer_indicator_height);
final float defaultFooterIndicatorUnderlinePadding = res.getDimension(R.dimen.default_title_indicator_footer_indicator_underline_padding);
final float defaultFooterPadding = res.getDimension(R.dimen.default_title_indicator_footer_padding);
final int defaultLinePosition = res.getInteger(R.integer.default_title_indicator_line_position);
final int defaultSelectedColor = res.getColor(R.color.default_title_indicator_selected_color);
final boolean defaultSelectedBold = res.getBoolean(R.bool.default_title_indicator_selected_bold);
final int defaultTextColor = res.getColor(R.color.default_title_indicator_text_color);
final float defaultTextSize = res.getDimension(R.dimen.default_title_indicator_text_size);
final float defaultTitlePadding = res.getDimension(R.dimen.default_title_indicator_title_padding);
final float defaultClipPadding = res.getDimension(R.dimen.default_title_indicator_clip_padding);
final float defaultTopPadding = res.getDimension(R.dimen.default_title_indicator_top_padding);
//Retrieve styles attributes
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TitlePageIndicator, defStyle, 0);
//Retrieve the colors to be used for this view and apply them.
mFooterLineHeight = a.getDimension(R.styleable.TitlePageIndicator_footerLineHeight, defaultFooterLineHeight);
mFooterIndicatorStyle = IndicatorStyle.fromValue(a.getInteger(R.styleable.TitlePageIndicator_footerIndicatorStyle, defaultFooterIndicatorStyle));
mFooterIndicatorHeight = a.getDimension(R.styleable.TitlePageIndicator_footerIndicatorHeight, defaultFooterIndicatorHeight);
mFooterIndicatorUnderlinePadding = a.getDimension(R.styleable.TitlePageIndicator_footerIndicatorUnderlinePadding, defaultFooterIndicatorUnderlinePadding);
mFooterPadding = a.getDimension(R.styleable.TitlePageIndicator_footerPadding, defaultFooterPadding);
mLinePosition = LinePosition.fromValue(a.getInteger(R.styleable.TitlePageIndicator_linePosition, defaultLinePosition));
mTopPadding = a.getDimension(R.styleable.TitlePageIndicator_topPadding, defaultTopPadding);
mTitlePadding = a.getDimension(R.styleable.TitlePageIndicator_titlePadding, defaultTitlePadding);
mClipPadding = a.getDimension(R.styleable.TitlePageIndicator_clipPadding, defaultClipPadding);
mColorSelected = a.getColor(R.styleable.TitlePageIndicator_selectedColor, defaultSelectedColor);
mColorText = a.getColor(R.styleable.TitlePageIndicator_android_textColor, defaultTextColor);
mBoldText = a.getBoolean(R.styleable.TitlePageIndicator_selectedBold, defaultSelectedBold);
final float textSize = a.getDimension(R.styleable.TitlePageIndicator_android_textSize, defaultTextSize);
final int footerColor = a.getColor(R.styleable.TitlePageIndicator_footerColor, defaultFooterColor);
mPaintText.setTextSize(textSize);
mPaintText.setAntiAlias(true);
mPaintFooterLine.setStyle(Paint.Style.FILL_AND_STROKE);
mPaintFooterLine.setStrokeWidth(mFooterLineHeight);
mPaintFooterLine.setColor(footerColor);
mPaintFooterIndicator.setStyle(Paint.Style.FILL_AND_STROKE);
mPaintFooterIndicator.setColor(footerColor);
Drawable background = a.getDrawable(R.styleable.TitlePageIndicator_android_background);
if (background != null) {
setBackgroundDrawable(background);
}
a.recycle();
final ViewConfiguration configuration = ViewConfiguration.get(context);
mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(configuration);
}
public int getFooterColor() {
return mPaintFooterLine.getColor();
}
public void setFooterColor(int footerColor) {
mPaintFooterLine.setColor(footerColor);
mPaintFooterIndicator.setColor(footerColor);
invalidate();
}
public float getFooterLineHeight() {
return mFooterLineHeight;
}
public void setFooterLineHeight(float footerLineHeight) {
mFooterLineHeight = footerLineHeight;
mPaintFooterLine.setStrokeWidth(mFooterLineHeight);
invalidate();
}
public float getFooterIndicatorHeight() {
return mFooterIndicatorHeight;
}
public void setFooterIndicatorHeight(float footerTriangleHeight) {
mFooterIndicatorHeight = footerTriangleHeight;
invalidate();
}
public float getFooterIndicatorPadding() {
return mFooterPadding;
}
public void setFooterIndicatorPadding(float footerIndicatorPadding) {
mFooterPadding = footerIndicatorPadding;
invalidate();
}
public IndicatorStyle getFooterIndicatorStyle() {
return mFooterIndicatorStyle;
}
public void setFooterIndicatorStyle(IndicatorStyle indicatorStyle) {
mFooterIndicatorStyle = indicatorStyle;
invalidate();
}
public LinePosition getLinePosition() {
return mLinePosition;
}
public void setLinePosition(LinePosition linePosition) {
mLinePosition = linePosition;
invalidate();
}
public int getSelectedColor() {
return mColorSelected;
}
public void setSelectedColor(int selectedColor) {
mColorSelected = selectedColor;
invalidate();
}
public boolean isSelectedBold() {
return mBoldText;
}
public void setSelectedBold(boolean selectedBold) {
mBoldText = selectedBold;
invalidate();
}
public int getTextColor() {
return mColorText;
}
public void setTextColor(int textColor) {
mPaintText.setColor(textColor);
mColorText = textColor;
invalidate();
}
public float getTextSize() {
return mPaintText.getTextSize();
}
public void setTextSize(float textSize) {
mPaintText.setTextSize(textSize);
invalidate();
}
public float getTitlePadding() {
return this.mTitlePadding;
}
public void setTitlePadding(float titlePadding) {
mTitlePadding = titlePadding;
invalidate();
}
public float getTopPadding() {
return this.mTopPadding;
}
public void setTopPadding(float topPadding) {
mTopPadding = topPadding;
invalidate();
}
public float getClipPadding() {
return this.mClipPadding;
}
public void setClipPadding(float clipPadding) {
mClipPadding = clipPadding;
invalidate();
}
public void setTypeface(Typeface typeface) {
mPaintText.setTypeface(typeface);
invalidate();
}
public Typeface getTypeface() {
return mPaintText.getTypeface();
}
/*
* (non-Javadoc)
*
* @see android.view.View#onDraw(android.graphics.Canvas)
*/
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (mViewPager == null) {
return;
}
final int count = mViewPager.getAdapter().getCount();
if (count == 0) {
return;
}
// mCurrentPage is -1 on first start and after orientation changed. If so, retrieve the correct index from viewpager.
if (mCurrentPage == -1 && mViewPager != null) {
mCurrentPage = mViewPager.getCurrentItem();
}
//Calculate views bounds
ArrayList<Rect> bounds = calculateAllBounds(mPaintText);
final int boundsSize = bounds.size();
//Make sure we‘re on a page that still exists
if (mCurrentPage >= boundsSize) {
setCurrentItem(boundsSize - 1);
return;
}
final int countMinusOne = count - 1;
final float halfWidth = getWidth() / 2f;
final int left = getLeft();
final float leftClip = left + mClipPadding;
final int width = getWidth();
int height = getHeight();
final int right = left + width;
final float rightClip = right - mClipPadding;
int page = mCurrentPage;
float offsetPercent;
if (mPageOffset <= 0.5) {
offsetPercent = mPageOffset;
} else {
page += 1;
offsetPercent = 1 - mPageOffset;
}
final boolean currentSelected = (offsetPercent <= SELECTION_FADE_PERCENTAGE);
final boolean currentBold = (offsetPercent <= BOLD_FADE_PERCENTAGE);
final float selectedPercent = (SELECTION_FADE_PERCENTAGE - offsetPercent) / SELECTION_FADE_PERCENTAGE;
//Verify if the current view must be clipped to the screen
Rect curPageBound = bounds.get(mCurrentPage);
float curPageWidth = curPageBound.right - curPageBound.left;
if (curPageBound.left < leftClip) {
//Try to clip to the screen (left side)
clipViewOnTheLeft(curPageBound, curPageWidth, left);
}
if (curPageBound.right > rightClip) {
//Try to clip to the screen (right side)
clipViewOnTheRight(curPageBound, curPageWidth, right);
}
//Left views starting from the current position
if (mCurrentPage > 0) {
for (int i = mCurrentPage - 1; i >= 0; i--) {
Rect bound = bounds.get(i);
//Is left side is outside the screen
if (bound.left < leftClip) {
int w = bound.right - bound.left;
//Try to clip to the screen (left side)
clipViewOnTheLeft(bound, w, left);
//Except if there‘s an intersection with the right view
Rect rightBound = bounds.get(i + 1);
//Intersection
if (bound.right + mTitlePadding > rightBound.left) {
bound.left = (int) (rightBound.left - w - mTitlePadding);
bound.right = bound.left + w;
}
}
}
}
//Right views starting from the current position
if (mCurrentPage < countMinusOne) {
for (int i = mCurrentPage + 1; i < count; i++) {
Rect bound = bounds.get(i);
//If right side is outside the screen
if (bound.right > rightClip) {
int w = bound.right - bound.left;
//Try to clip to the screen (right side)
clipViewOnTheRight(bound, w, right);
//Except if there‘s an intersection with the left view
Rect leftBound = bounds.get(i - 1);
//Intersection
if (bound.left - mTitlePadding < leftBound.right) {
bound.left = (int) (leftBound.right + mTitlePadding);
bound.right = bound.left + w;
}
}
}
}
//Now draw views
int colorTextAlpha = mColorText >>> 24;
for (int i = 0; i < count; i++) {
//Get the title
Rect bound = bounds.get(i);
//Only if one side is visible
if ((bound.left > left && bound.left < right) || (bound.right > left && bound.right < right)) {
final boolean currentPage = (i == page);
final CharSequence pageTitle = getTitle(i);
//Only set bold if we are within bounds
mPaintText.setFakeBoldText(currentPage && currentBold && mBoldText);
//Draw text as unselected
mPaintText.setColor(mColorText);
if (currentPage && currentSelected) {
//Fade out/in unselected text as the selected text fades in/out
mPaintText.setAlpha(colorTextAlpha - (int) (colorTextAlpha * selectedPercent));
}
//Except if there‘s an intersection with the right view
if (i < boundsSize - 1) {
Rect rightBound = bounds.get(i + 1);
//Intersection
if (bound.right + mTitlePadding > rightBound.left) {
int w = bound.right - bound.left;
bound.left = (int) (rightBound.left - w - mTitlePadding);
bound.right = bound.left + w;
}
}
//If we are within the selected bounds draw the selected text
if (currentPage && currentSelected) {
//canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
// canvas.drawText(pageTitle, 0, pageTitle.length(), bound.left, bound.bottom + mTopPadding, mPaintText);
mPaintText.setColor(mColorSelected);
mPaintText.setAlpha((int) ((mColorSelected >>> 24) * selectedPercent));
mPaintText.setTextSize(30.0F);
StaticLayout layout = new StaticLayout(pageTitle, mPaintText, canvas.getWidth(),
Layout.Alignment.ALIGN_CENTER, 1.0F, 0.0F, true);
canvas.save();
layout.draw(canvas);
canvas.restore();//别忘了restore
LogUtil.e(" select the length bound left is :" + bound.left);
LogUtil.e(" select the length bound top is :" + bound.top);
LogUtil.e(" select the index bound is :" + i);
} else {
// canvas.drawText(pageTitle, 0, pageTitle.length(), bound.left, bound.bottom + mTopPadding, mPaintText);
//canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
mPaintText.setColor(Color.parseColor("#098745"));
mPaintText.setTextSize(30.0F);
StaticLayout layoutss;
if (mCurrentPage < i) {
StaticLayout layoutButtom = new StaticLayout(pageTitle, mPaintText, (int) (canvas.getWidth() * 1.8),
Layout.Alignment.ALIGN_CENTER, 1.0F, 0.0F, true);
canvas.save();
layoutButtom.draw(canvas);
canvas.restore();//别忘了restore
} else {
StaticLayout layoutTop = new StaticLayout(pageTitle, mPaintText, (int) (canvas.getWidth() * 0.2),
Layout.Alignment.ALIGN_CENTER, 1.0F, 0.0F, true);
canvas.save();
layoutTop.draw(canvas);
canvas.restore();//别忘了restore
}
}
}
}
//If we want the line on the top change height to zero and invert the line height to trick the drawing code
float footerLineHeight = mFooterLineHeight;
float footerIndicatorLineHeight = mFooterIndicatorHeight;
if (mLinePosition == LinePosition.Top) {
height = 0;
footerLineHeight = -footerLineHeight;
footerIndicatorLineHeight = -footerIndicatorLineHeight;
}
//Draw the footer line
mPath.reset();
mPath.moveTo(0, height - footerLineHeight / 2f);
mPath.lineTo(width, height - footerLineHeight / 2f);
mPath.close();
canvas.drawPath(mPath, mPaintFooterLine);
float heightMinusLine = height - footerLineHeight;
switch (mFooterIndicatorStyle) {
case Triangle:
mPath.reset();
mPath.moveTo(halfWidth, heightMinusLine - footerIndicatorLineHeight);
mPath.lineTo(halfWidth + footerIndicatorLineHeight, heightMinusLine);
mPath.lineTo(halfWidth - footerIndicatorLineHeight, heightMinusLine);
mPath.close();
canvas.drawPath(mPath, mPaintFooterIndicator);
break;
case Underline:
if (!currentSelected || page >= boundsSize) {
break;
}
Rect underlineBounds = bounds.get(page);
final float rightPlusPadding = underlineBounds.right + mFooterIndicatorUnderlinePadding;
final float leftMinusPadding = underlineBounds.left - mFooterIndicatorUnderlinePadding;
final float heightMinusLineMinusIndicator = heightMinusLine - footerIndicatorLineHeight;
mPath.reset();
mPath.moveTo(leftMinusPadding, heightMinusLine);
mPath.lineTo(rightPlusPadding, heightMinusLine);
mPath.lineTo(rightPlusPadding, heightMinusLineMinusIndicator);
mPath.lineTo(leftMinusPadding, heightMinusLineMinusIndicator);
mPath.close();
mPaintFooterIndicator.setAlpha((int) (0xFF * selectedPercent));
canvas.drawPath(mPath, mPaintFooterIndicator);
mPaintFooterIndicator.setAlpha(0xFF);
break;
}
}
public boolean onTouchEvent(MotionEvent ev) {
if (super.onTouchEvent(ev)) {
return true;
}
if ((mViewPager == null) || (mViewPager.getAdapter().getCount() == 0)) {
return false;
}
final int action = ev.getAction() & MotionEventCompat.ACTION_MASK;
switch (action) {
case MotionEvent.ACTION_DOWN:
mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
mLastMotionX = ev.getX();
break;
case MotionEvent.ACTION_MOVE: {
final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
final float x = MotionEventCompat.getX(ev, activePointerIndex);
final float deltaX = x - mLastMotionX;
if (!mIsDragging) {
if (Math.abs(deltaX) > mTouchSlop) {
mIsDragging = true;
}
}
if (mIsDragging) {
mLastMotionX = x;
if (mViewPager.isFakeDragging() || mViewPager.beginFakeDrag()) {
mViewPager.fakeDragBy(deltaX);
}
}
break;
}
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
if (!mIsDragging) {
final int count = mViewPager.getAdapter().getCount();
final int width = getWidth();
final float halfWidth = width / 2f;
final float sixthWidth = width / 6f;
final float leftThird = halfWidth - sixthWidth;
final float rightThird = halfWidth + sixthWidth;
final float eventX = ev.getX();
if (eventX < leftThird) {
if (mCurrentPage > 0) {
if (action != MotionEvent.ACTION_CANCEL) {
mViewPager.setCurrentItem(mCurrentPage - 1);
}
return true;
}
} else if (eventX > rightThird) {
if (mCurrentPage < count - 1) {
if (action != MotionEvent.ACTION_CANCEL) {
mViewPager.setCurrentItem(mCurrentPage + 1);
}
return true;
}
} else {
//Middle third
if (mCenterItemClickListener != null && action != MotionEvent.ACTION_CANCEL) {
mCenterItemClickListener.onCenterItemClick(mCurrentPage);
}
}
}
mIsDragging = false;
mActivePointerId = INVALID_POINTER;
if (mViewPager.isFakeDragging()) mViewPager.endFakeDrag();
break;
case MotionEventCompat.ACTION_POINTER_DOWN: {
final int index = MotionEventCompat.getActionIndex(ev);
mLastMotionX = MotionEventCompat.getX(ev, index);
mActivePointerId = MotionEventCompat.getPointerId(ev, index);
break;
}
case MotionEventCompat.ACTION_POINTER_UP:
final int pointerIndex = MotionEventCompat.getActionIndex(ev);
final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex);
if (pointerId == mActivePointerId) {
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex);
}
mLastMotionX = MotionEventCompat.getX(ev, MotionEventCompat.findPointerIndex(ev, mActivePointerId));
break;
}
return true;
}
/**
* Set bounds for the right textView including clip padding.
*
* @param curViewBound current bounds.
* @param curViewWidth width of the view.
*/
private void clipViewOnTheRight(Rect curViewBound, float curViewWidth, int right) {
curViewBound.right = (int) (right - mClipPadding);
curViewBound.left = (int) (curViewBound.right - curViewWidth);
}
/**
* Set bounds for the left textView including clip padding.
*
* @param curViewBound current bounds.
* @param curViewWidth width of the view.
*/
private void clipViewOnTheLeft(Rect curViewBound, float curViewWidth, int left) {
curViewBound.left = (int) (left + mClipPadding);
curViewBound.right = (int) (mClipPadding + curViewWidth);
}
/**
* Calculate views bounds and scroll them according to the current index
*
* @param paint
* @return
*/
private ArrayList<Rect> calculateAllBounds(Paint paint) {
ArrayList<Rect> list = new ArrayList<Rect>();
//For each views (If no values then add a fake one)
final int count = mViewPager.getAdapter().getCount();
final int width = getWidth();
final int halfWidth = width / 2;
for (int i = 0; i < count; i++) {
Rect bounds = calcBounds(i, paint);
int w = bounds.right - bounds.left;
int h = bounds.bottom - bounds.top;
bounds.left = (int) (halfWidth - (w / 2f) + ((i - mCurrentPage - mPageOffset) * width));
bounds.right = bounds.left + w;
bounds.top = 0;
bounds.bottom = h;
list.add(bounds);
}
return list;
}
/**
* Calculate the bounds for a view‘s title
*
* @param index
* @param paint
* @return
*/
private Rect calcBounds(int index, Paint paint) {
//Calculate the text bounds
Rect bounds = new Rect();
CharSequence title = getTitle(index);
bounds.right = (int) paint.measureText(title, 0, title.length());
bounds.bottom = (int) (paint.descent() - paint.ascent());
return bounds;
}
@Override
public void setViewPager(ViewPager view) {
if (mViewPager == view) {
return;
}
if (mViewPager != null) {
mViewPager.setOnPageChangeListener(null);
}
if (view.getAdapter() == null) {
throw new IllegalStateException("ViewPager does not have adapter instance.");
}
mViewPager = view;
mViewPager.setOnPageChangeListener(this);
invalidate();
}
@Override
public void setViewPager(ViewPager view, int initialPosition) {
setViewPager(view);
setCurrentItem(initialPosition);
}
@Override
public void notifyDataSetChanged() {
invalidate();
}
/**
* Set a callback listener for the center item click.
*
* @param listener Callback instance.
*/
public void setOnCenterItemClickListener(OnCenterItemClickListener listener) {
mCenterItemClickListener = listener;
}
@Override
public void setCurrentItem(int item) {
if (mViewPager == null) {
throw new IllegalStateException("ViewPager has not been bound.");
}
mViewPager.setCurrentItem(item);
mCurrentPage = item;
invalidate();
}
@Override
public void onPageScrollStateChanged(int state) {
mScrollState = state;
if (mListener != null) {
mListener.onPageScrollStateChanged(state);
}
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
mCurrentPage = position;
mPageOffset = positionOffset;
invalidate();
if (mListener != null) {
mListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
}
}
@Override
public void onPageSelected(int position) {
if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {
mCurrentPage = position;
invalidate();
}
if (mListener != null) {
mListener.onPageSelected(position);
}
}
@Override
public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
mListener = listener;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
//Measure our width in whatever mode specified
final int measuredWidth = MeasureSpec.getSize(widthMeasureSpec);
//Determine our height
float height;
final int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightSpecMode == MeasureSpec.EXACTLY) {
//We were told how big to be
height = MeasureSpec.getSize(heightMeasureSpec);
} else {
//Calculate the text bounds
mBounds.setEmpty();
mBounds.bottom = (int) (mPaintText.descent() - mPaintText.ascent());
height = mBounds.bottom - mBounds.top + mFooterLineHeight + mFooterPadding + mTopPadding;
if (mFooterIndicatorStyle != IndicatorStyle.None) {
height += mFooterIndicatorHeight;
}
}
final int measuredHeight = (int) height;
setMeasuredDimension(measuredWidth, measuredHeight);
}
@Override
public void onRestoreInstanceState(Parcelable state) {
SavedState savedState = (SavedState) state;
super.onRestoreInstanceState(savedState.getSuperState());
mCurrentPage = savedState.currentPage;
requestLayout();
}
@Override
public Parcelable onSaveInstanceState() {
Parcelable superState = super.onSaveInstanceState();
SavedState savedState = new SavedState(superState);
savedState.currentPage = mCurrentPage;
return savedState;
}
static class SavedState extends BaseSavedState {
int currentPage;
public SavedState(Parcelable superState) {
super(superState);
}
private SavedState(Parcel in) {
super(in);
currentPage = in.readInt();
}
@Override
public void writeToParcel(Parcel dest, int flags) {
super.writeToParcel(dest, flags);
dest.writeInt(currentPage);
}
@SuppressWarnings("UnusedDeclaration")
public static final Creator<SavedState> CREATOR = new Creator<SavedState>() {
@Override
public SavedState createFromParcel(Parcel in) {
return new SavedState(in);
}
@Override
public SavedState[] newArray(int size) {
return new SavedState[size];
}
};
}
private CharSequence getTitle(int i) {
CharSequence title = mViewPager.getAdapter().getPageTitle(i);
if (title == null) {
title = EMPTY_TITLE;
}
return title;
}
}
时间： 2024-11-03 05:40:17