ViewGroup可实现上下、各地跑马灯效果滚动

package com.example.scrolltextview;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Paint;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.Scroller;
import android.widget.SpinnerAdapter;
import android.widget.TextView;

public class ScrollTextView extends ViewGroup {

private static final int SCROLL = 0;
private static final int JUSTIFY = 1;
private static final int ANIMATION_DURATION = 3000;

private int mOrientation;
private int mSize;
private int mIndex;
private int mPosition;
private Scroller mScroller;
private Map<View, Integer> mViews;
private SpinnerAdapter mAdapter;
private int mPackedViews;
private int mAnimationDuration;

private float measuredWidth = 0;
private float textSize = 0;
private float measuredHeight = 0;
private String text= null;
private String[] data;
private boolean flag = true;
public ScrollTextView(Context context, AttributeSet attrs) {
super(context, attrs);

int[] linerarLayoutAttrs = {
android.R.attr.orientation,
};
TypedArray a = context.obtainStyledAttributes(attrs, linerarLayoutAttrs);
mOrientation = a.getInteger(0, LinearLayout.HORIZONTAL);
a.recycle();

mAnimationDuration = ANIMATION_DURATION;

mScroller = new Scroller(context);
mIndex = -1;
mPosition = -1;
mPackedViews = -1;
mViews = new HashMap<View, Integer>();

setFocusable(true);
setFocusableInTouchMode(true);

}

public float getCharacterWidth(String text, float size){
if(null == text || "".equals(text))
return 0;
float width = 0;
Paint paint = new Paint();
paint.setTextSize(size);
float text_width = paint.measureText(text);//得到整体长度
width = text_width/text.length();//字符的长度
return width;
}

public void setText(String text)
{
this.text = text;
data  = new String[]{this.text};
LayoutInflater inflater= (LayoutInflater) getContext().getSystemService(getContext().LAYOUT_INFLATER_SERVICE);
TextView view = (TextView) inflater.inflate(R.layout.scroll_text_view, null);
textSize = view.getTextSize();
measuredHeight = textSize;
textSize = getCharacterWidth(text,textSize);
}

public void beginScroll()
{
thread.start();
}
Thread thread = new Thread(new Runnable() {
boolean enabled = true;
@Override
public void run() {
// TODO Auto-generated method stub
while(enabled)
{
try {
Thread.sleep(4000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
setNextView();
enabled = mIndex + 1 < mAdapter.getCount();
}
}
});

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
measuredWidth = getMeasuredWidth();
mSize = mOrientation == LinearLayout.HORIZONTAL?

getMeasuredWidth() : getMeasuredHeight();
if(flag && text!=null)
{
int length = text.length();
Log.i("AAA", "length*textSize:"+length*textSize+" measuredWidth:"+measuredWidth);
if(length*textSize >= measuredWidth)
{
int textCountInOneLine = (int) (measuredWidth/textSize -1);
int lineCount =(int) ((length%textCountInOneLine==0)? (length/textCountInOneLine):(length/textCountInOneLine+1));
Log.i("AAA", "length:"+length+" textCountInOneLine:"+textCountInOneLine+" lineCount:"+lineCount);
data = new String[lineCount];
for(int i=0;i<lineCount;i++)
{
if((i+1)*textCountInOneLine<length)
data[i] =  text.substring(i*textCountInOneLine, (i+1)*textCountInOneLine);
else
data[i] =  text.substring(i*textCountInOneLine, length);
Log.i("AAA", "data:"+data[i]);
}
}
else
{
data = new String[]{text};
}

ArrayAdapter<String> adapter = new ArrayAdapter<String>(getContext(), R.layout.scroll_text_view, data);
setAdapter(adapter);
flag = false;
}
View view = getChildAt(0);
if(view!=null)
{
measureChild(view, widthMeasureSpec, widthMeasureSpec);
measuredHeight = view.getMeasuredHeight();
}

setMeasuredDimension((int)measuredWidth, (int)measuredHeight);
}

private int getPackedViews(int offset) {
int size = mSize;
int start = offset / size;
int numViews = offset % size != 0?

1 : 0;
return start << 1 | numViews;
}

Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
mScroller.computeScrollOffset();
int currX = mScroller.getCurrX();
int delta = mPosition - currX;
mPosition = currX;
int packed = getPackedViews(mPosition);
manageViews(packed);
scroll(delta);
if (!mScroller.isFinished()) {
handler.sendEmptyMessage(msg.what);
} else {
if (msg.what == SCROLL) {
justify();
} else {
mIndex = mPosition / mSize;

}
}
}
};

private void justify() {
int offset = mPosition % mSize;
if (offset != 0) {
int endPosition = mPosition - offset;
if (offset > mSize / 2) {
endPosition += mSize;
}
mScroller.startScroll(mPosition, 0, endPosition - mPosition, 0, mAnimationDuration);
handler.sendEmptyMessage(JUSTIFY);
} else {
mIndex = mPosition / mSize;

}
}

private void scroll(int offset) {
if (mOrientation == LinearLayout.HORIZONTAL) {
for (View view : mViews.keySet()) {
view.offsetLeftAndRight(offset);
}
} else {
for (View view : mViews.keySet()) {
view.offsetTopAndBottom(offset);
}
}
invalidate();
}

public void setSelection(int index, boolean animate) {
if (index == mIndex) {
return;
}
int endPosition = index * mSize;
int diff = Math.abs(index - mIndex);
int sign = index > mIndex?

1 : -1;
mIndex = index;
if (diff > 1) {
mPosition = endPosition - sign * mSize;
}
if (animate) {
mScroller.startScroll(mPosition, 0, endPosition - mPosition, 0, mAnimationDuration);
handler.removeMessages(JUSTIFY);
handler.removeMessages(SCROLL);
handler.sendEmptyMessage(JUSTIFY);
} else {
mPosition = endPosition;
manageViews(index << 1);

invalidate();
}
}

private void manageViews(int packedViews) {
if (packedViews == mPackedViews) {
return;
}

mPackedViews = packedViews;
int startIdx = packedViews >> 1;
int endIdx = startIdx + (packedViews & 1);
int viewIdx = startIdx;
while (viewIdx <= endIdx) {
if (!mViews.containsValue(viewIdx)) {
if (viewIdx >= 0 && viewIdx < mAdapter.getCount()) {
View view = mAdapter.getView(viewIdx, null, this);
mViews.put(view, viewIdx);
addView(view);
}
}
viewIdx++;
}

// remove not visible views
Iterator<View> iterator = mViews.keySet().iterator();
while (iterator.hasNext()) {
View view = iterator.next();
int idx = mViews.get(view);
if (idx < startIdx || idx > endIdx) {
iterator.remove();
removeView(view);
}
}
}

public int getSelection() {
return mIndex;
}

public void setPreviousView() {
if (mAdapter != null && mIndex > 0) {
setSelection(mIndex-1, true);

}
}

public void setNextView() {
if (mAdapter != null && mIndex + 1 < mAdapter.getCount()) {
setSelection(mIndex+1, true);
}
}

public void setAdapter(SpinnerAdapter adapter) {
mAdapter = adapter;
if (mAdapter != null) {
setSelection(0, false);
}
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
for (View view : mViews.keySet()) {
if (view.getWidth() == 0) {
// new View: not layout()ed
int idx = mViews.get(view);
if (mOrientation == LinearLayout.HORIZONTAL) {
int left = mSize * idx - mPosition;
view.layout(left, 0, left+r-l, b-t);
} else {
int top = mSize * idx - mPosition;
view.layout(0, top, r-l, top+b-t);
}
}
}
}

}

String temp = getResources().getString(R.string.info);
ScrollTextView switcher1 = (ScrollTextView) findViewById(R.id.switcher1);
switcher1.setText(temp);
switcher1.beginScroll();