跑马灯（速度、显示文本）
实现一个跑马灯效果的程序：
一、定义一个类AutoScrollTextView,该类继承TextView并实现OnClickListener接口(目的是通过点击跑马灯滚动中的文本，可以实现停止和恢复滚动的功能)。
package org.caotao.lamp;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.Display;
import android.view.View;
import android.view.WindowManager;
import android.view.View.OnClickListener;
import android.widget.TextView;
public class AutoScrollTextView extends TextView implements OnClickListener {
public final static String TAG = AutoScrollTextView.class.getSimpleName();
private float textLength = 0f;//文本长度
private float viewWidth = 0f;//AutoScrollTextView控件的长度
private float step = 0f;//文字的横坐标
private float y = 0f;//文字的纵坐标
private float temp_view_plus_text_length = 0.0f;//用于计算的临时变量
private float temp_view_plus_two_text_length = 0.0f;//用于计算的临时变量
public boolean isStarting = false;//是否开始滚动
private Paint paint = null;//绘图样式
private String text = "";//文本内容
public AutoScrollTextView(Context context) {
super(context);
initView();
}
public AutoScrollTextView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
}
public AutoScrollTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView();
}
private void initView(){
setOnClickListener(this);
}
public void init(WindowManager windowManager){
paint = getPaint();
paint.setColor(MainActivity.updateFontColor);
text = getText().toString();
textLength = paint.measureText(text); //measure()方法获取text的长度
viewWidth = getWidth();
if(viewWidth == 0){
if(windowManager != null){
Display display = windowManager.getDefaultDisplay();
viewWidth = display.getWidth();
}
}
step = viewWidth + textLength;
temp_view_plus_text_length = viewWidth + textLength;
temp_view_plus_two_text_length = viewWidth + textLength * 2;
System.out.println(temp_view_plus_text_length);
y = getTextSize() + getPaddingTop();
}
public void startScroll(){
isStarting = true;
invalidate();
}
public void stopScroll(){
isStarting = false;
invalidate();
}
//覆写TextView的onDraw()方法，实现文本滚动显示的效果
@Override
public void onDraw(Canvas canvas) {
/**
* drawText()方法：
* 参数1:要显示的文本
* 参数2：文本显示的x坐标，TextView的最左端的x坐标是0，最右端的x坐标是TextView.getWidth();
* 参数3:文本显示的y坐标，TextView的顶端所在的y坐标。
* 参数4：描绘文本的画笔
*/
canvas.drawText(text, temp_view_plus_text_length - step, y, paint);
if(!isStarting){
return;
}
step += MainActivity.updateSpeed;//速度设置：1-10
if(step > temp_view_plus_two_text_length){
step = textLength;
}
invalidate();
}
/**
* 响应用户点击事件：点击则停止，再点击继续开始滚动
*/
public void onClick(View v) {
if(isStarting){
stopScroll();
}
else{
startScroll();
}
}
}
二、在auto.xml布局文件里进行如下布局：
android:layout_height="fill_parent"
android:orientation="vertical" >
android:layout_height="50dp"
android:layout_width="fill_parent"
android:layout_marginTop="10dp"
android:text="@string/defaultview"
android:textColor="#000"
android:inputType="text"
android:background="#555"
android:textSize="30dp" />
android:layout_height="fill_parent">
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingTop="10dp"
android:layout_marginLeft="10dp"
android:text="@string/setspeed" />
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingTop="8dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_below="@id/setSpeed"
android:max="10"
android:progress="1" />
android:layout_width="200dp"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:layout_marginLeft="10dp"
android:hint="@string/text"
android:layout_below="@id/speedSeekBar" />
三、主界面中的代码：
package org.caotao.lamp;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.Spinner;
import android.widget.TextView;
public class MainActivity extends Activity {
/** Called when the activity is first created. */
//声明一系列的布局控件
private AutoScrollTextView autoScrollTextView = null;
private TextView setSpeed = null;
private SeekBar speedSeekBar = null;
private Button contentBtn = null;
private EditText contentText = null;
private Spinner fontColorSpinner = null;
private Spinner backgroundColorSpinner = null;
public static float updateSpeed = 0f; //设置文字的滚动速度，数字越大，速度越快。
public static String updateText = null;
public static int updateFontColor = 0;
public static int updateBackgroundColor = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//提示速度设置的TextView
setSpeed = (TextView)findViewById(R.id.setSpeed);
//设置速度的SeekBar进度条
speedSeekBar = (SeekBar)findViewById(R.id.speedSeekBar);
speedSeekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
updateSpeed = seekBar.getProgress();
setSpeed.setText("速度" + updateSpeed);
}
public void onStopTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub
}
public void onStartTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub
}
});
//根据ID获得设置显示文本的控件
contentText = (EditText)findViewById(R.id.contentText);
contentBtn = (Button)findViewById(R.id.contentSure);
contentBtn.setOnClickListener(new contentBtnListener());
//设置字体颜色的spinner
fontColorSpinner = (Spinner)findViewById(R.id.fontColorSpinner);
ArrayAdapter
this, R.array.fontcolor_array, android.R.layout.simple_spinner_item);
fontColorAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
fontColorSpinner.setAdapter(fontColorAdapter);
fontColorSpinner.setOnItemSelectedListener(new fontColorListener());
//设置背景颜色的spinner
backgroundColorSpinner = (Spinner)findViewById(R.id.backgroundColorSpinner);
ArrayAdapter
this, R.array.fontcolor_array, android.R.layout.simple_spinner_item);
backgroundColorAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
backgroundColorSpinner.setAdapter(fontColorAdapter);
backgroundColorSpinner.setOnItemSelectedListener(new backgroundColorListener());
//根据ID获取自定义AutoScrollTextView类的对象
autoScrollTextView = (AutoScrollTextView)findViewById(R.id.TextViewNotice);
autoScrollTextView.init(getWindowManager());
autoScrollTextView.startScroll();
}
class contentBtnListener implements OnClickListener{
public void onClick(View v) {
// TODO Auto-generated method stub
updateText = contentText.getText().toString();
autoScrollTextView.setText(updateText);
autoScrollTextView.init(getWindowManager());
}
}
//设置字体颜色的spinner的选项监听器
class fontColorListener implements OnItemSelectedListener{
public void onItemSelected(AdapterView parent, View v, int pos,
long id) {
// TODO Auto-generated method stub
System.out.println(id);
switch((int)id) {
case 0:
updateFontColor = Color.BLACK;
break;
case 1:
updateFontColor = Color.GREEN;
break;
case 2:
updateFontColor = Color.RED;
break;
case 3:
updateFontColor = Color.YELLOW;
break;
case 4:
updateFontColor = Color.GRAY;
break;
case 5:
updateFontColor = Color.MAGENTA;
break;
case 6:
updateFontColor = Color.BLUE;
break;
default:break;
}
//重新初始化autoScrollTextView对象，更新画笔Paint的颜色
autoScrollTextView.init(getWindowManager());
}
public void onNothingSelected(AdapterView arg0) {
// TODO Auto-generated method stub
}
}
//设置背景颜色的spinner的选项监听器
class backgroundColorListener implements OnItemSelectedListener{
public void onItemSelected(AdapterView parent, View v, int pos,
long id) {
// TODO Auto-generated method stub
System.out.println(id);
switch((int)id){
case 0:
updateBackgroundColor = Color.BLACK; break;
case 1:
updateBackgroundColor = Color.GREEN; break;
case 2:
updateBackgroundColor = Color.RED; break;
case 3:
updateBackgroundColor = Color.YELLOW; break;
case 4:
updateBackgroundColor = Color.GRAY; break;
case 5:
updateBackgroundColor = Color.MAGENTA; break;
case 6:
updateBackgroundColor = Color.BLUE; break;
default:break;
}
//重新初始化autoScrollTextView对象，更新画笔Paint的颜色
autoScrollTextView.setBackgroundColor(updateBackgroundColor);
autoScrollTextView.init(getWindowManager());
}
public void onNothingSelected(AdapterView arg0) {
// TODO Auto-generated method stub
}
}
}