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程序没有讲完整，最后的contains和getSectionByPoint两个方法没有讲

谢谢分享，但是程序没有讲完整，最后的contains和getSectionByPoint两个方法没有讲

慕粉3170408

2016-04-15

源自：Android高级特效-索引 3-2

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慕无忌7233295
2022-04-01

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慕函数5881151
2016-08-05

package com.user.Widget;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.Rect;

import android.graphics.RectF;

import android.os.Handler;

import android.os.SystemClock;

import android.view.MotionEvent;

import android.widget.Adapter;

import android.widget.ListView;

import android.widget.SectionIndexer;

public class IndexScroller {

private Context mContext;

private ListView mListView = null;

private float mIndexbarWidth; // 索引条的宽度，

private float mIndexbarMargin; // 索引条离右侧边缘的距离

private float mPreviewPadding; // 点击中间显示的索引文本，距离四周的距离

private float mDensity; // 当前屏幕密度除以160

private float mScaledDensity; // 当前屏幕密度除以160（设置字体的尺寸）

private float mAlphaRate; // 索引条透明度（用来显示和隐藏索引条）0-1

private int mState = STATE_HIDDEN; // 索引条当前状态

private int mListViewWidth; // 屏幕的宽度

private int mListViewHeight; // 屏幕的高度

private int mCurrentSection = -1; // 当前所点击的索引值

private boolean mIsIndexing = false;

private SectionIndexer mIndexer = null;

private String[] mSections;

private RectF mIdexbarRect; // 绘制索引条区域

public static final int STATE_HIDDEN = 0;

public static final int STATE_SHOWING = 1;

public static final int STATE_SHOW = 2;

public static final int STATE_HIDDENING = 3;

public IndexScroller(Context mContext, ListView mListView) {

this.mContext = mContext;

this.mListView = mListView;

// 获取当前屏幕的密度比值

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

// 获取字体密度比值

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

setAdapter(mListView.getAdapter());

// 根据屏幕的密度比值来调整索引条的宽度（单位：像素）

mIndexbarWidth = 20 * mDensity;

mIndexbarMargin = 10 * mDensity;

mPreviewPadding = 5 * mDensity;

}

public void setAdapter(Adapter adapter) {

if (adapter instanceof SectionIndexer) {

mIndexer = (SectionIndexer) adapter;

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

}

/**

* 绘制索引条和预览文本

* @param mPaint

public void draw(Canvas mCanvas) {

// 1、绘制索引条和背景

// 2、绘制预览文本和背景

if (mState == STATE_HIDDEN) {

return;

}

/**

* 绘制索引条的区域

Paint mPaint = new Paint();

mPaint.setColor(Color.BLACK);

mPaint.setAlpha((int) (64 * mAlphaRate)); // 设置透明度，逐渐显示

// 绘制索引条(四个角都是圆角区域)

mCanvas.drawRoundRect(mIdexbarRect, 5 * mDensity, 5 * mDensity, mPaint);

/**

* 绘制预览文本背景和文字

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

// 绘制预览文本背景和文字 , 大于0则点击

if (mCurrentSection > 0) {

Paint previewPaint = new Paint(); // 绘制文本画笔

previewPaint.setColor(Color.BLACK);

previewPaint.setAlpha(96);

Paint previewTextPaint = new Paint(); // 绘制文字画笔

previewTextPaint.setColor(Color.WHITE);

previewTextPaint.setTextSize(50 * mScaledDensity);

// 获取文本字体的宽度

float previewTextWidth = previewTextPaint

.measureText(mSections[mCurrentSection]);

// 获得显示文本的区域宽高度 = 上下间距padding + 字母往下超过基准线的高度（正值） +

// 字母在基准线的上面的高度（负值，负负得正）

float previewSize = 2 * mPreviewPadding

+ previewTextPaint.descent()

- previewTextPaint.ascent();

// 预览文本区域所在位置

// 左=（屏幕宽度-显示文本区域宽度）/ 2 上= （屏幕高度-显示文本区域高度）/ 2

RectF previewRectF = new RectF(

(mListViewWidth - previewSize) / 2,

(mListViewHeight - previewSize) / 2,

(mListViewWidth - previewSize) / 2 + previewSize,

(mListViewHeight - previewSize) / 2 + previewSize);

// 绘制预览文本背景

mCanvas.drawRoundRect(previewRectF, 5 * mDensity, 5 * mDensity,

previewPaint);

// 绘制预览文本的字体

mCanvas.drawText(

mSections[mCurrentSection],

(previewRectF.left + (previewSize - previewTextWidth)

/ 2 + 1),

(previewRectF.top + mPreviewPadding

- previewTextPaint.ascent() + 1),

previewTextPaint);

}

/**

* 设置索引字母

// 设置绘制索引字母的属性

Paint indexPaint = new Paint();

indexPaint.setColor(Color.WHITE);

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

indexPaint.setTextSize(12 * mScaledDensity);

// 取得索引中每个字母的区域高度 = （索引区域高度 - 上下margin值）/索引的长度length

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

// 设置每个字母区域中的文字的padding值 = （每个字母区域 - 文字高度）/2

float sectionPaddingTop = ((sectionHeight - (indexPaint.descent() - indexPaint

.ascent())) / 2);

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

// 取得绘制的文字的paddingLeft值

float sectionPaddingLeft = (mIndexbarWidth - indexPaint

.measureText(mSections[i])) / 2;

// 开始绘制

mCanvas.drawText(mSections[i],

(mIdexbarRect.left + sectionPaddingLeft), mIdexbarRect.top

+ mIndexbarMargin + sectionPaddingTop * i/* 索引字母区域 */

+ sectionPaddingTop - indexPaint.ascent(),

indexPaint);

}

/**

* 保持最新的高度与宽度重新加载索引条的区域

* @param w

* @param h

* @param oldw

* @param oldh

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

mListViewWidth = w;

mListViewHeight = h;

mIdexbarRect = new RectF(w - mIndexbarMargin - mIndexbarWidth,

mIndexbarMargin, w - mIndexbarMargin, h - mIndexbarMargin);

}

private void fade(long delay) {

// 0立即执行，不延迟

// 清除消息

mHandler.removeMessages(0);

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

}

/**

* 判定状态来显示，并移除消息message

private Handler mHandler = new Handler() {

public void handleMessage(android.os.Message msg) {

super.handleMessage(msg);

switch (mState) {

case STATE_HIDDENING:

mAlphaRate -= mAlphaRate * 0.2;

if (mAlphaRate < 0.1) {

mAlphaRate = 0;

setState(STATE_HIDDEN);

}

mListView.invalidate();

fade(10);

break;

case STATE_HIDDEN:

setState(STATE_SHOWING);

break;

case STATE_SHOWING:

mAlphaRate += (1 - mAlphaRate) * 0.2;

if (mAlphaRate > 0.9) {

mAlphaRate = 1;

setState(STATE_SHOW);

}

mListView.invalidate(); // listview不断刷新，知道mAlphaRate > 0.9

fade(10);

break;

case STATE_SHOW:

setState(STATE_HIDDENING);

break;

}

};

/**

* 改变状态

* @param state

private void setState(int state) {

if (state < STATE_HIDDEN || state > STATE_HIDDENING) {

return;

}

mState = state;

switch (mState) {

case STATE_SHOWING:

mAlphaRate = 0;

fade(0);

break;

case STATE_SHOW:

mHandler.removeMessages(0);

break;

case STATE_HIDDENING:

mAlphaRate = 1;

fade(3000); // 显示的时间

break;

case STATE_HIDDEN:

mHandler.removeMessages(0);

break;

}

/**

* 管理触摸索引条

* @param ev

* @return

public boolean onTouchEvent(MotionEvent ev) {

switch (ev.getAction()) {

case MotionEvent.ACTION_DOWN:

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

setState(STATE_SHOW);

mIsIndexing = true;

mCurrentSection = getSectionByPoint(ev.getY());

mListView.setSelection(mIndexer

.getPositionForSection(mCurrentSection));

return true;

}

break;

case MotionEvent.ACTION_MOVE:

if (mIsIndexing) {

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

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_SHOW) {

setState(STATE_HIDDENING);

break;

}

return false;

}

/**

* @param x

* @param y

* @return

private boolean cantains(float x, float y) {

return (x >= mIdexbarRect.left && y >= mIdexbarRect.top && y <= mIdexbarRect.top

+ mIdexbarRect.height());

}

/**

* @param y

* @return

private int getSectionByPoint(float y) {

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

return 0;

if (y < mIdexbarRect.top + mIndexbarMargin)

return 0;

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

return mSections.length - 1;

return (int) ((y - mIdexbarRect.top - mIndexbarMargin) / ((mIdexbarRect

.height() - 2 * mIndexbarMargin) / mSections.length));

}

/**

* show()

public void show() {

if (mState == STATE_HIDDEN)

setState(STATE_SHOWING);

else if (mState == STATE_HIDDENING)

setState(STATE_HIDDENING);

}

/**

* hide()

public void hide() {

if (mState == STATE_SHOW)

setState(STATE_HIDDENING);

}

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程序没有讲完整，最后的contains和getSectionByPoint两个方法没有讲

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程序没有讲完整，最后的contains和getSectionByPoint两个方法没有讲