版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/specialshoot/article/details/50786358
上一篇android通讯录实例（一）地址：http://blog.csdn.net/specialshoot/article/details/50651080
这一此我们把UI上最重要的部分IndexableListView说明，这个项目可以在github上找到。https://github.com/woozzu/IndexableListView
源码下载下来我们发现核心代码有两片，IndexableListView和IndexScroller这两个文件。其中IndexScroller是右侧字母滚动条的代码，IndexableListView是继承自ListView将滚动条整合到ListView的代码。
IndexScroller
IndexScroller.java源代码：
/*
* 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;//索引条宽度
private float mIndexbarMargin; //索引条外边距
private float mPreviewPadding; //索引条内边距
private float mDensity; //颜色密度(用于控制颜色透明度)
private float mScaledDensity; //缩放密度
private float mAlphaRate;//透明度
private int mState = STATE_HIDDEN; //索引条状态，默认为隐藏
private int mListViewWidth; //listview宽度
private int mListViewHeight;//listview高度
private int mCurrentSection = -1; //当前索引
private boolean mIsIndexing = false;//是否正在索引
private ListView mListView = null;//listview实例
private SectionIndexer mIndexer = null;//列表适配器
private String[] mSections = null;//存放索引字符的数组
private RectF mIndexbarRect;//索引条背景图形
//索引条状态
private static final int STATE_HIDDEN = 0; //隐藏
private static final int STATE_SHOWING = 1; //正在显示
private static final int STATE_SHOWN = 2; //已显示
private static final int STATE_HIDING = 3; //正在隐藏
public IndexScroller(Context context, ListView lv) {
mDensity = context.getResources().getDisplayMetrics().density;//获取密度值
mScaledDensity = context.getResources().getDisplayMetrics().scaledDensity;//获得缩放密度值
mListView = lv;//listview实例
setAdapter(mListView.getAdapter()); //设置适配器
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();//用于显示当前滑动到字母的背景画笔(屏幕中间大字)
indexbarPaint.setColor(Color.BLACK);
indexbarPaint.setAlpha((int) (64 * mAlphaRate));
indexbarPaint.setAntiAlias(true);//抗锯齿
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(); //预览图中背景画笔(右侧滚动条)
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(); //预览图中文字画笔(滚动条上的文字)
previewTextPaint.setColor(Color.WHITE);
previewTextPaint.setAntiAlias(true);
previewTextPaint.setTextSize(50 * mScaledDensity);
float previewTextWidth = previewTextPaint.measureText(mSections[mCurrentSection]);//字符宽度
float previewSize = 2 * mPreviewPadding + previewTextPaint.descent() - previewTextPaint.ascent();//背景宽度/高度
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;//索引条中每个字符空间的高度
float paddingTop = (sectionHeight - (indexPaint.descent() - indexPaint.ascent())) / 2;//索引条中每个字符的上下边距,indexPaint.descent() - indexPaint.ascent()得到的是字符的高度
for (int i = 0; i < mSections.length; i++) {
//索引条中各个字符的左右边距,其中indexPaint.measureText(mSections[i])为字符的宽度
float paddingLeft = (mIndexbarWidth - indexPaint.measureText(mSections[i])) / 2;
canvas.drawText(mSections[i], mIndexbarRect.left + paddingLeft
, mIndexbarRect.top + mIndexbarMargin + sectionHeight * i + paddingTop - indexPaint.ascent(), indexPaint);
}
}
}
/**
* 索引条的触摸事件
*
* @param ev
* @return
*/
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
// If down event occurs inside index bar region, start indexing
// 索引条可见,且按下事件发生在索引条范围内
if (mState != STATE_HIDDEN && contains(ev.getX(), ev.getY())) {
setState(STATE_SHOWN); //索引条设置为显示状态
// It demonstrates that the motion event started from index bar
mIsIndexing = true; //正在索引
// Determine which section the point is in, and move the list to that section
mCurrentSection = getSectionByPoint(ev.getY());//获取当前点击的索引条中字符的位置
mListView.setSelection(mIndexer.getPositionForSection(mCurrentSection));//列表定位到指定位置
return true;
}
break;
case MotionEvent.ACTION_MOVE:
if (mIsIndexing) {
// If this event moves inside index bar
// 在索引条上滑动
if (contains(ev.getX(), ev.getY())) {
// Determine which section the point is in, and move the list to that section
mCurrentSection = getSectionByPoint(ev.getY());// 获取当前手指触摸点对应的索引条中字符的位置
mListView.setSelection(mIndexer.getPositionForSection(mCurrentSection));// 列表定位到指定位置
}
return true;
}
break;
case MotionEvent.ACTION_UP:
if (mIsIndexing) {
mIsIndexing = false;// 设置mIsIndexing为false,表示正在索引取消
mCurrentSection = -1;// 将当前索引字符位置设置为-1,隐藏预览图
}
if (mState == STATE_SHOWN)
setState(STATE_HIDING);// 渐退索引条
break;
}
return false;
}
/**
* 索引条位置重定位
*
* @param w
* @param h
* @param oldw
* @param oldh
*/
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);
}
/**
* 显示索引条
*/
public void show() {
if (mState == STATE_HIDDEN)
setState(STATE_SHOWING);
else if (mState == STATE_HIDING)
setState(STATE_HIDING);
}
/**
* 隐藏索引条
*/
public void hide() {
if (mState == STATE_SHOWN)
setState(STATE_HIDING);
}
/**
* 设置监听器
*
* @param adapter
*/
public void setAdapter(Adapter adapter) {
if (adapter instanceof SectionIndexer) {
mIndexer = (SectionIndexer) adapter;
mSections = (String[]) mIndexer.getSections();
}
}
/**
* 设置索引条状态
*
* @param state
*/
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;
}
}
/**
* 判断该点是否在索引条范围内,包括索引条右边距
*
* @param x
* @param y
* @return
*/
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());
}
/**
* 根据手指触摸位置返回对应索引字符位置
*
* @param y
* @return
*/
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:
// 开始渐进显示索引条
// 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:
// 取消渐进效果
// If no action, hide automatically
setState(STATE_HIDING);
break;
case STATE_HIDING:
// 3秒后开始渐退
// Fade out effect
mAlphaRate -= mAlphaRate * 0.2;
if (mAlphaRate < 0.1) {
mAlphaRate = 0;
setState(STATE_HIDDEN);
}
mListView.invalidate();
fade(10);
break;
}
}
};
}
IndexableListView
IndexableListView.java代码：
/*
* 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.util.AttributeSet;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.widget.ListAdapter;
import android.widget.ListView;
public class IndexableListView extends ListView {
private boolean mIsFastScrollEnabled = false;//快速滚动设置
private IndexScroller mScroller = null;//索引条实例
private GestureDetector mGestureDetector = null; //手势监听
public IndexableListView(Context context) {
super(context);
}
public IndexableListView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public IndexableListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
public boolean isFastScrollEnabled() {
return mIsFastScrollEnabled;
}
@Override
public void setFastScrollEnabled(boolean enabled) {
mIsFastScrollEnabled = enabled;
if (mIsFastScrollEnabled) {
if (mScroller == null)
mScroller = new IndexScroller(getContext(), this); //设置快速滚动,初始化索引条
} else {
//否则隐藏索引条
if (mScroller != null) {
mScroller.hide();
mScroller = null;
}
}
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
// Overlay index bar
if (mScroller != null)
mScroller.draw(canvas); //绘制索引条(在索引条不为null时)
}
/**
* 触摸事件
*
* @param ev
* @return
*/
@Override
public boolean onTouchEvent(MotionEvent ev) {
// Intercept ListView's touch event
if (mScroller != null && mScroller.onTouchEvent(ev)) {
//若1.索引条类不为null 2.索引条可见且触摸事件发生在索引条范围内,则if语句中为true,onTouchEvent不再向下执行
return true;
}
if (mGestureDetector == null) {
//若索引条不可见或触摸事件不是发生在索引条范围内
mGestureDetector = new GestureDetector(getContext(), new GestureDetector.SimpleOnGestureListener() {
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2,
float velocityX, float velocityY) {
// If fling happens, index bar shows
if (mScroller != null)
mScroller.show(); //显示索引条
return super.onFling(e1, e2, velocityX, velocityY);
}
});
}
mGestureDetector.onTouchEvent(ev);
return super.onTouchEvent(ev);
}
/**
* 拦截触摸事件
*
* @param ev
* @return
*/
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
if (mScroller.contains(ev.getX(), ev.getY()))
return true;
return super.onInterceptTouchEvent(ev);
}
/**
* 设置adapter
*
* @param adapter
*/
@Override
public void setAdapter(ListAdapter adapter) {
super.setAdapter(adapter);
if (mScroller != null)
mScroller.setAdapter(adapter);
}
/**
* View大小改变时触发
*
* @param w
* @param h
* @param oldw
* @param oldh
*/
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if (mScroller != null)
mScroller.onSizeChanged(w, h, oldw, oldh);
}
}
onInterceptTouchEvent及onTouchEvent的详细用法可以见http://blog.csdn.net/lvxiangan/article/details/9309927
1、onInterceptTouchEvent()是用于处理事件（类似于预处理，当然也可以不处理）并改变事件的传递方向，也就是决定是否允许Touch事件继续向下（子控件）传递，一但返回True（代表事件在当前的viewGroup中会被处理），则向下传递之路被截断（所有子控件将没有机会参与Touch事件），同时把事件传递给当前的控件的onTouchEvent()处理；返回false，则把事件交给子控件的onInterceptTouchEvent()
2、onTouchEvent()用于处理事件，返回值决定当前控件是否消费（consume）了这个事件，也就是说在当前控件在处理完Touch事件后，是否还允许Touch事件继续向上（父控件）传递，一但返回True，则父控件不用操心自己来处理Touch事件。返回true，则向上传递给父控件（注：可能你会觉得是否消费了有关系吗，反正我已经针对事件编写了处理代码？答案是有区别！比如ACTION_MOVE或者ACTION_UP发生的前提是一定曾经发生了ACTION_DOWN，如果你没有消费ACTION_DOWN，那么系统会认为ACTION_DOWN没有发生过，所以ACTION_MOVE或者ACTION_UP就不能被捕获。）
对于此控件
- 首先如果捕获到手势，进入IndexableListView的onInterceptTouchEvent，若手势滑动到右边控制条，则进入IndexableListView的onTouchEvent事件中。如果此时索引条可见，则返回true不再向下执行，mScroll.onTouchEvent就可以执行IndexScroller中的动作了
- 如果此时滚动条不可见或触摸事件不是发生在索引条范围内，则将索引条显示出来
以上就是IndexableListView的代码分析，下篇将会讲解获取手机通讯录信息的相关知识。