Java tutorial
/* * Copyright (C) 2011 Patrik Akerfeldt * Copyright (C) 2011 Francisco Figueiredo Jr. * Copyright (C) 2011 Jake Wharton * * 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.jakewharton.android.viewpagerindicator; import java.util.ArrayList; import android.content.Context; import android.content.res.Resources; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.Path; import android.graphics.RectF; import android.os.Parcel; import android.os.Parcelable; import android.support.v4.view.ViewPager; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; /** * 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; 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; } } private ViewPager mViewPager; private ViewPager.OnPageChangeListener mListener; private TitleProvider mTitleProvider; private int mCurrentPage; private int mCurrentOffset; private final Paint mPaintText; private boolean mBoldText; private int mColorText; private int mColorSelected; private Path mPath; private final Paint mPaintFooterLine; private IndicatorStyle mFooterIndicatorStyle; private final Paint mPaintFooterIndicator; private float mFooterIndicatorHeight; private float mFooterIndicatorUnderlinePadding; private float mFooterPadding; private float mTitlePadding; /** Left and right side padding for not active view titles. */ private float mClipPadding; private float mFooterLineHeight; public TitlePageIndicator(Context context) { this(context, null); } public TitlePageIndicator(Context context, AttributeSet attrs) { this(context, attrs, R.attr.titlePageIndicatorStyle); } public TitlePageIndicator(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); //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 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); //Retrieve styles attributes TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TitlePageIndicator, defStyle, R.style.Widget_TitlePageIndicator); //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); 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_textColor, defaultTextColor); mBoldText = a.getBoolean(R.styleable.TitlePageIndicator_selectedBold, defaultSelectedBold); final float textSize = a.getDimension(R.styleable.TitlePageIndicator_textSize, defaultTextSize); final int footerColor = a.getColor(R.styleable.TitlePageIndicator_footerColor, defaultFooterColor); mPaintText = new Paint(); mPaintText.setTextSize(textSize); mPaintText.setAntiAlias(true); mPaintFooterLine = new Paint(); mPaintFooterLine.setStyle(Paint.Style.FILL_AND_STROKE); mPaintFooterLine.setStrokeWidth(mFooterLineHeight); mPaintFooterLine.setColor(footerColor); mPaintFooterIndicator = new Paint(); mPaintFooterIndicator.setStyle(Paint.Style.FILL_AND_STROKE); mPaintFooterIndicator.setColor(footerColor); a.recycle(); } 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 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 getClipPadding() { return this.mClipPadding; } public void setClipPadding(float clipPadding) { mClipPadding = clipPadding; invalidate(); } /* * (non-Javadoc) * * @see android.view.View#onDraw(android.graphics.Canvas) */ @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //Calculate views bounds ArrayList<RectF> bounds = calculateAllBounds(mPaintText); final int count = mViewPager.getAdapter().getCount(); final int countMinusOne = count - 1; final float halfWidth = getWidth() / 2f; final int left = getLeft(); final float leftClip = left + mClipPadding; final int width = getWidth(); final int height = getHeight(); final int right = left + width; final float rightClip = right - mClipPadding; int page = mCurrentPage; float offsetPercent; if (mCurrentOffset <= halfWidth) { offsetPercent = 1.0f * mCurrentOffset / width; } else { page += 1; offsetPercent = 1.0f * (width - mCurrentOffset) / width; } 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 RectF 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--) { RectF bound = bounds.get(i); //Is left side is outside the screen if (bound.left < leftClip) { float 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 RectF rightBound = bounds.get(i + 1); //Intersection if (bound.right + mTitlePadding > rightBound.left) { bound.left = 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++) { RectF bound = bounds.get(i); //If right side is outside the screen if (bound.right > rightClip) { float 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 RectF leftBound = bounds.get(i - 1); //Intersection if (bound.left - mTitlePadding < leftBound.right) { bound.left = leftBound.right + mTitlePadding; bound.right = bound.left + w; } } } } //Now draw views for (int i = 0; i < count; i++) { //Get the title RectF 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); //Only set bold if we are within bounds mPaintText.setFakeBoldText(currentPage && currentBold && mBoldText); //Draw text as unselected mPaintText.setColor(mColorText); canvas.drawText(mTitleProvider.getTitle(i), bound.left, bound.bottom, mPaintText); //If we are within the selected bounds draw the selected text if (currentPage && currentSelected) { mPaintText.setColor(mColorSelected); mPaintText.setAlpha((int) ((mColorSelected >>> 24) * selectedPercent)); canvas.drawText(mTitleProvider.getTitle(i), bound.left, bound.bottom, mPaintText); } } } //Draw the footer line mPath = new Path(); mPath.moveTo(0, height - mFooterLineHeight); mPath.lineTo(width, height - mFooterLineHeight); mPath.close(); canvas.drawPath(mPath, mPaintFooterLine); switch (mFooterIndicatorStyle) { case Triangle: mPath = new Path(); mPath.moveTo(halfWidth, height - mFooterLineHeight - mFooterIndicatorHeight); mPath.lineTo(halfWidth + mFooterIndicatorHeight, height - mFooterLineHeight); mPath.lineTo(halfWidth - mFooterIndicatorHeight, height - mFooterLineHeight); mPath.close(); canvas.drawPath(mPath, mPaintFooterIndicator); break; case Underline: if (!currentSelected) { break; } RectF underlineBounds = bounds.get(page); mPath = new Path(); mPath.moveTo(underlineBounds.left - mFooterIndicatorUnderlinePadding, height - mFooterLineHeight); mPath.lineTo(underlineBounds.right + mFooterIndicatorUnderlinePadding, height - mFooterLineHeight); mPath.lineTo(underlineBounds.right + mFooterIndicatorUnderlinePadding, height - mFooterLineHeight - mFooterIndicatorHeight); mPath.lineTo(underlineBounds.left - mFooterIndicatorUnderlinePadding, height - mFooterLineHeight - mFooterIndicatorHeight); mPath.close(); mPaintFooterIndicator.setAlpha((int) (0xFF * selectedPercent)); canvas.drawPath(mPath, mPaintFooterIndicator); mPaintFooterIndicator.setAlpha(0xFF); break; } } @Override public boolean onTouchEvent(MotionEvent event) { if (event.getAction() == MotionEvent.ACTION_DOWN) { final int count = mViewPager.getAdapter().getCount(); final int width = getWidth(); final float halfWidth = width / 2f; final float sixthWidth = width / 6f; if ((mCurrentPage > 0) && (event.getX() < halfWidth - sixthWidth)) { mViewPager.setCurrentItem(mCurrentPage - 1); return true; } else if ((mCurrentPage < count - 1) && (event.getX() > halfWidth + sixthWidth)) { mViewPager.setCurrentItem(mCurrentPage + 1); return true; } } return super.onTouchEvent(event); } /** * Set bounds for the right textView including clip padding. * * @param curViewBound * current bounds. * @param curViewWidth * width of the view. */ private void clipViewOnTheRight(RectF curViewBound, float curViewWidth, int right) { curViewBound.right = right - mClipPadding; curViewBound.left = 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(RectF curViewBound, float curViewWidth, int left) { curViewBound.left = left + mClipPadding; curViewBound.right = mClipPadding + curViewWidth; } /** * Calculate views bounds and scroll them according to the current index * * @param paint * @param currentIndex * @return */ private ArrayList<RectF> calculateAllBounds(Paint paint) { ArrayList<RectF> list = new ArrayList<RectF>(); //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++) { RectF bounds = calcBounds(i, paint); float w = (bounds.right - bounds.left); float h = (bounds.bottom - bounds.top); bounds.left = (halfWidth) - (w / 2) - mCurrentOffset + ((i - mCurrentPage) * 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 RectF calcBounds(int index, Paint paint) { //Calculate the text bounds RectF bounds = new RectF(); bounds.right = paint.measureText(mTitleProvider.getTitle(index)); bounds.bottom = paint.descent() - paint.ascent(); return bounds; } @Override public void setViewPager(ViewPager view) { if (view.getAdapter() == null) { throw new IllegalStateException("ViewPager does not have adapter instance."); } if (!(view.getAdapter() instanceof TitleProvider)) { throw new IllegalStateException( "ViewPager adapter must implement TitleProvider to be used with TitlePageIndicator."); } mViewPager = view; mViewPager.setOnPageChangeListener(this); mTitleProvider = (TitleProvider) mViewPager.getAdapter(); invalidate(); } @Override public void setViewPager(ViewPager view, int initialPosition) { setViewPager(view); setCurrentItem(initialPosition); } @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) { if (mListener != null) { mListener.onPageScrollStateChanged(state); } } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { mCurrentPage = position; mCurrentOffset = positionOffsetPixels; invalidate(); if (mListener != null) { mListener.onPageScrolled(position, positionOffset, positionOffsetPixels); } } @Override public void onPageSelected(int position) { if (mListener != null) { mListener.onPageSelected(position); } } @Override public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) { mListener = listener; } /* * (non-Javadoc) * * @see android.view.View#onMeasure(int, int) */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { setMeasuredDimension(measureWidth(widthMeasureSpec), measureHeight(heightMeasureSpec)); } /** * Determines the width of this view * * @param measureSpec * A measureSpec packed into an int * @return The width of the view, honoring constraints from measureSpec */ private int measureWidth(int measureSpec) { int result = 0; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); if (specMode != MeasureSpec.EXACTLY) { throw new IllegalStateException(getClass().getSimpleName() + " can only be used in EXACTLY mode."); } result = specSize; return result; } /** * Determines the height of this view * * @param measureSpec * A measureSpec packed into an int * @return The height of the view, honoring constraints from measureSpec */ private int measureHeight(int measureSpec) { float result = 0; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); if (specMode == MeasureSpec.EXACTLY) { //We were told how big to be result = specSize; } else { //Calculate the text bounds RectF bounds = new RectF(); bounds.bottom = mPaintText.descent() - mPaintText.ascent(); result = bounds.bottom - bounds.top + mFooterLineHeight + mFooterPadding; if (mFooterIndicatorStyle != IndicatorStyle.None) { result += mFooterIndicatorHeight; } } return (int) result; } @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); } public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() { @Override public SavedState createFromParcel(Parcel in) { return new SavedState(in); } @Override public SavedState[] newArray(int size) { return new SavedState[size]; } }; } }