Java tutorial
/* * Copyright (C) 2012 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.zzq.viewpagerindicator; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Rect; 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.util.AttributeSet; import android.view.MotionEvent; import android.view.View; import android.view.ViewConfiguration; import java.util.ArrayList; /** * Draws a line for each page. The current page line is colored differently than * the unselected page lines. */ public class TitlePageIndicator extends View implements PageIndicator { private static final int INVALID_POINTER = -1; private final Paint mPaintText = new Paint(Paint.ANTI_ALIAS_FLAG); private final Rect mBounds = new Rect(); private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG); private int mSelectedColor; private int mLineColor = Color.RED; private int mTextSize; private ViewPager mViewPager; private ViewPager.OnPageChangeListener mListener; private int mScrollState; private int mCurrentPage; private float mPositionOffset; private int mTouchSlop; private float mLastMotionX = -1; private int mActivePointerId = INVALID_POINTER; private boolean mIsDragging; private int mTextToTop = 0;// private int mIndicatorToText = 10; private int mIndicatorLineHeight = 15; private int mBaseIndicatorLineHeight = 5; private int mHorizontalSpace = 50; public TitlePageIndicator(Context context) { this(context, null); } public TitlePageIndicator(Context context, AttributeSet attrs) { this(context, attrs, -1); } public TitlePageIndicator(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); if (isInEditMode()) return; // Retrieve styles attributes TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TitlePageIndicator, defStyle, 0); mSelectedColor = a.getColor(R.styleable.TitlePageIndicator_indicator_selected_color, -1); mLineColor = a.getColor(R.styleable.TitlePageIndicator_indicator_line_color, -1); mTextSize = (int) a.getDimension(R.styleable.TitlePageIndicator_indicator_text_size, 80f); mPaintText.setTextSize(mTextSize); mTextToTop = (int) a.getDimension(R.styleable.TitlePageIndicator_indicator_text_to_top, 0); mIndicatorToText = (int) a.getDimension(R.styleable.TitlePageIndicator_indicator_to_text, 10); mIndicatorLineHeight = (int) a.getDimension(R.styleable.TitlePageIndicator_indicator_line_height, 15); mBaseIndicatorLineHeight = (int) a .getDimension(R.styleable.TitlePageIndicator_indicator_base_indicator_line_height, 5); mHorizontalSpace = (int) a.getDimension(R.styleable.TitlePageIndicator_indicator_horizontal_space, 50); a.recycle(); final ViewConfiguration configuration = ViewConfiguration.get(context); mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(configuration); } @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 + mIndicatorLineHeight + mBaseIndicatorLineHeight + mIndicatorToText; } final int measuredHeight = (int) height; setMeasuredDimension(measuredWidth, measuredHeight); } 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(); for (int i = 0; i < count; i++) { Rect bounds = calcBounds(i, paint); list.add(bounds); } return list; } 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; } private CharSequence getTitle(int i) { CharSequence title = mViewPager.getAdapter().getPageTitle(i); if (title == null) { title = ""; } return title; } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (mViewPager == null) { return; } final int count = mViewPager.getAdapter().getCount(); if (count == 0) { return; } ArrayList<Rect> bounds = calculateAllBounds(mPaintText); if (mCurrentPage >= count) { setCurrentItem(count - 1); return; } final int paddingLeft = getPaddingLeft(); final float bottom = getHeight() - getPaddingBottom(); // mPaintText.setColor(mSelectedColor); int textWidthCount = 0; int textheightCount = 0; for (int i = 0; i < bounds.size(); i++) { int textWidth = bounds.get(i).right - bounds.get(i).left; int textheight = bounds.get(i).bottom - bounds.get(i).top; textWidthCount += textWidth; textheightCount += textheight; } int textSpace = (getWidth() - getPaddingLeft() - getPaddingRight() - textWidthCount) / (bounds.size() + 1); for (int i = 0; i < bounds.size(); i++) { int textWidth = bounds.get(i).right - bounds.get(i).left; int textheight = bounds.get(i).bottom - bounds.get(i).top; canvas.drawText(getTitle(i).toString(), textSpace + (textSpace + textWidth) * i, textheight, mPaintText); } // mPaint.setColor(mLineColor); canvas.drawRect(getPaddingLeft(), bottom - mBaseIndicatorLineHeight, getWidth() - getPaddingRight(), bottom, mPaint); // int lineWidth = (getWidth() - getPaddingLeft() - getPaddingRight() - (bounds.size() * 2) * mHorizontalSpace) / (bounds.size()); mPaint.setColor(mSelectedColor); final float left = paddingLeft + mHorizontalSpace + (lineWidth + mHorizontalSpace) * (mCurrentPage + mPositionOffset); final float right = left + (lineWidth + mHorizontalSpace); canvas.drawRect(left, bottom - mIndicatorLineHeight, right, bottom, mPaint); } 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; if ((mCurrentPage > 0) && (ev.getX() < halfWidth)) { if (action != MotionEvent.ACTION_CANCEL) { mViewPager.setCurrentItem(mCurrentPage - 1); } return true; } else if ((mCurrentPage < count - 1) && (ev.getX() > halfWidth)) { if (action != MotionEvent.ACTION_CANCEL) { mViewPager.setCurrentItem(mCurrentPage + 1); } return true; } } 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; } @Override public void setViewPager(ViewPager viewPager) { if (mViewPager == viewPager) { return; } if (mViewPager != null) { // Clear us from the old pager. mViewPager.setOnPageChangeListener(null); } if (viewPager.getAdapter() == null) { throw new IllegalStateException("ViewPager does not have adapter instance."); } mViewPager = viewPager; mViewPager.setOnPageChangeListener(this); 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 notifyDataSetChanged() { 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; mPositionOffset = positionOffset; invalidate(); if (mListener != null) { mListener.onPageScrolled(position, positionOffset, positionOffsetPixels); } } @Override public void onPageSelected(int position) { if (mScrollState == ViewPager.SCROLL_STATE_IDLE) { mCurrentPage = position; mPositionOffset = 0; invalidate(); } if (mListener != null) { mListener.onPageSelected(position); } } @Override public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) { mListener = listener; } @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]; } }; } }