3回答

• 

  atwal

  2015-12-24 14:15:40

  private int getSectionByPoint(float y) {
      if (mSections == null || mSections.length == 0) {
          return 0;
      }
      if (y <= mIndexbarRect.top + mIndexbarMargin) {
          return 0;
      }
      if (y >= mIndexbarRect.top + mIndexbarRect.height() - mIndexbarMargin) {
          return mSections.length - 1;
      }
      return (int) ((y - mIndexbarRect.top - mIndexbarMargin) / ((mIndexbarRect.height() - 2 * mIndexbarMargin) / mSections.length));
  }

  
  

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• 

  浩子灬Android

  2015-12-24 11:43:09

  http://blog.csdn.net/wwj_748/article/details/17305195

  0 1
• 

  豪了没

  2015-12-18 16:49:20

  /*

   * Copyright 2011 woozzu

   *

   * 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.woozzu.android.widget;

  
  

  import android.content.Context;

  import android.graphics.Canvas;

  import android.graphics.Color;

  import android.graphics.Paint;

  import android.graphics.RectF;

  import android.os.Handler;

  import android.os.Message;

  import android.os.SystemClock;

  import android.view.MotionEvent;

  import android.widget.Adapter;

  import android.widget.ListView;

  import android.widget.SectionIndexer;

  
  

  public class IndexScroller {

  private float mIndexbarWidth;

  private float mIndexbarMargin;

  private float mPreviewPadding;

  private float mDensity;

  private float mScaledDensity;

  private float mAlphaRate;

  private int mState = STATE_HIDDEN;

  private int mListViewWidth;

  private int mListViewHeight;

  private int mCurrentSection = -1;

  private boolean mIsIndexing = false;

  private ListView mListView = null;

  private SectionIndexer mIndexer = null;

  private String[] mSections = null;

  private RectF mIndexbarRect;

  private static final int STATE_HIDDEN = 0;

  private static final int STATE_SHOWING = 1;

  private static final int STATE_SHOWN = 2;

  private static final int STATE_HIDING = 3;

  public IndexScroller(Context context, ListView lv) {

  mDensity = context.getResources().getDisplayMetrics().density;

  mScaledDensity = context.getResources().getDisplayMetrics().scaledDensity;

  mListView = lv;

  setAdapter(mListView.getAdapter());

  mIndexbarWidth = 20 * mDensity;

  mIndexbarMargin = 10 * mDensity;

  mPreviewPadding = 5 * mDensity;

  }

  
  

  public void draw(Canvas canvas) {

  if (mState == STATE_HIDDEN)

  return;

  // mAlphaRate determines the rate of opacity

  Paint indexbarPaint = new Paint();

  indexbarPaint.setColor(Color.BLACK);

  indexbarPaint.setAlpha((int) (64 * mAlphaRate));

  indexbarPaint.setAntiAlias(true);

  canvas.drawRoundRect(mIndexbarRect, 5 * mDensity, 5 * mDensity, indexbarPaint);

  if (mSections != null && mSections.length > 0) {

  // Preview is shown when mCurrentSection is set

  if (mCurrentSection >= 0) {

  Paint previewPaint = new Paint();

  previewPaint.setColor(Color.BLACK);

  previewPaint.setAlpha(96);

  previewPaint.setAntiAlias(true);

  previewPaint.setShadowLayer(3, 0, 0, Color.argb(64, 0, 0, 0));

  Paint previewTextPaint = new Paint();

  previewTextPaint.setColor(Color.WHITE);

  previewTextPaint.setAntiAlias(true);

  previewTextPaint.setTextSize(50 * mScaledDensity);

  float previewTextWidth = previewTextPaint.measureText(mSections[mCurrentSection]);

  float previewSize = 2 * mPreviewPadding + previewTextPaint.descent() - previewTextPaint.ascent();

  RectF previewRect = new RectF((mListViewWidth - previewSize) / 2

  , (mListViewHeight - previewSize) / 2

  , (mListViewWidth - previewSize) / 2 + previewSize

  , (mListViewHeight - previewSize) / 2 + previewSize);

  canvas.drawRoundRect(previewRect, 5 * mDensity, 5 * mDensity, previewPaint);

  canvas.drawText(mSections[mCurrentSection], previewRect.left + (previewSize - previewTextWidth) / 2 - 1

  , previewRect.top + mPreviewPadding - previewTextPaint.ascent() + 1, previewTextPaint);

  }

  Paint indexPaint = new Paint();

  indexPaint.setColor(Color.WHITE);

  indexPaint.setAlpha((int) (255 * mAlphaRate));

  indexPaint.setAntiAlias(true);

  indexPaint.setTextSize(12 * mScaledDensity);

  float sectionHeight = (mIndexbarRect.height() - 2 * mIndexbarMargin) / mSections.length;

  float paddingTop = (sectionHeight - (indexPaint.descent() - indexPaint.ascent())) / 2;

  for (int i = 0; i < mSections.length; i++) {

  float paddingLeft = (mIndexbarWidth - indexPaint.measureText(mSections[i])) / 2;

  canvas.drawText(mSections[i], mIndexbarRect.left + paddingLeft

  , mIndexbarRect.top + mIndexbarMargin + sectionHeight * i + paddingTop - indexPaint.ascent(), indexPaint);

  }

  }

  }

  public boolean onTouchEvent(MotionEvent ev) {

  switch (ev.getAction()) {

  case MotionEvent.ACTION_DOWN:

  // If down event occurs inside index bar region, start indexing

  if (mState != STATE_HIDDEN && contains(ev.getX(), ev.getY())) {

  setState(STATE_SHOWN);

  // It demonstrates that the motion event started from index bar

  mIsIndexing = true;

  // Determine which section the point is in, and move the list to that section

  mCurrentSection = getSectionByPoint(ev.getY());

  mListView.setSelection(mIndexer.getPositionForSection(mCurrentSection));

  return true;

  }

  break;

  case MotionEvent.ACTION_MOVE:

  if (mIsIndexing) {

  // If this event moves inside index bar

  if (contains(ev.getX(), ev.getY())) {

  // Determine which section the point is in, and move the list to that section

  mCurrentSection = getSectionByPoint(ev.getY());

  mListView.setSelection(mIndexer.getPositionForSection(mCurrentSection));

  }

  return true;

  }

  break;

  case MotionEvent.ACTION_UP:

  if (mIsIndexing) {

  mIsIndexing = false;

  mCurrentSection = -1;

  }

  if (mState == STATE_SHOWN)

  setState(STATE_HIDING);

  break;

  }

  return false;

  }

  public void onSizeChanged(int w, int h, int oldw, int oldh) {

  mListViewWidth = w;

  mListViewHeight = h;

  mIndexbarRect = new RectF(w - mIndexbarMargin - mIndexbarWidth

  , mIndexbarMargin

  , w - mIndexbarMargin

  , h - mIndexbarMargin);

  }

  public void show() {

  if (mState == STATE_HIDDEN)

  setState(STATE_SHOWING);

  else if (mState == STATE_HIDING)

  setState(STATE_HIDING);

  }

  public void hide() {

  if (mState == STATE_SHOWN)

  setState(STATE_HIDING);

  }

  public void setAdapter(Adapter adapter) {

  if (adapter instanceof SectionIndexer) {

  mIndexer = (SectionIndexer) adapter;

  mSections = (String[]) mIndexer.getSections();

  }

  }

  private void setState(int state) {

  if (state < STATE_HIDDEN || state > STATE_HIDING)

  return;

  mState = state;

  switch (mState) {

  case STATE_HIDDEN:

  // Cancel any fade effect

  mHandler.removeMessages(0);

  break;

  case STATE_SHOWING:

  // Start to fade in

  mAlphaRate = 0;

  fade(0);

  break;

  case STATE_SHOWN:

  // Cancel any fade effect

  mHandler.removeMessages(0);

  break;

  case STATE_HIDING:

  // Start to fade out after three seconds

  mAlphaRate = 1;

  fade(3000);

  break;

  }

  }

  public boolean contains(float x, float y) {

  // Determine if the point is in index bar region, which includes the right margin of the bar

  return (x >= mIndexbarRect.left && y >= mIndexbarRect.top && y <= mIndexbarRect.top + mIndexbarRect.height());

  }

  private int getSectionByPoint(float y) {

  if (mSections == null || mSections.length == 0)

  return 0;

  if (y < mIndexbarRect.top + mIndexbarMargin)

  return 0;

  if (y >= mIndexbarRect.top + mIndexbarRect.height() - mIndexbarMargin)

  return mSections.length - 1;

  return (int) ((y - mIndexbarRect.top - mIndexbarMargin) / ((mIndexbarRect.height() - 2 * mIndexbarMargin) / mSections.length));

  }

  private void fade(long delay) {

  mHandler.removeMessages(0);

  mHandler.sendEmptyMessageAtTime(0, SystemClock.uptimeMillis() + delay);

  }

  private Handler mHandler = new Handler() {

  
  

  @Override

  public void handleMessage(Message msg) {

  super.handleMessage(msg);

  switch (mState) {

  case STATE_SHOWING:

  // Fade in effect

  mAlphaRate += (1 - mAlphaRate) * 0.2;

  if (mAlphaRate > 0.9) {

  mAlphaRate = 1;

  setState(STATE_SHOWN);

  }

  mListView.invalidate();

  fade(10);

  break;

  case STATE_SHOWN:

  // If no action, hide automatically

  setState(STATE_HIDING);

  break;

  case STATE_HIDING:

  // Fade out effect

  mAlphaRate -= mAlphaRate * 0.2;

  if (mAlphaRate < 0.1) {

  mAlphaRate = 0;

  setState(STATE_HIDDEN);

  }

  mListView.invalidate();

  fade(10);

  break;

  }

  }

  };

  }

  
  

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