2种不同形式的跑马灯的实现

普通的TextView可以实现跑马灯，但是只有当焦点在它上面时才有效。
如何做一个自动的跑马灯呢？
第一种：继承TextView，然后重写isFocused()方法就可以了，简单！

import android.content.Context;import android.util.AttributeSet;import android.widget.TextView;/** * 单行文本跑马灯控件 * @author admin * */public class ScrollForeverTextView extends TextView {public ScrollForeverTextView(Context context) {super(context);// TODO Auto-generated constructor stub}public ScrollForeverTextView(Context context, AttributeSet attrs) {super(context, attrs);}public ScrollForeverTextView(Context context, AttributeSet attrs,int defStyle) {super(context, attrs, defStyle);}@Overridepublic boolean isFocused() {return true;}}

使用时同TextView一样：

<com.ql.view.ScrollForeverTextView  android:layout_width="fill_parent" android:layout_height="wrap_content" android:textSize="30px"android:singleLine="true"android:ellipsize="marquee"android:marqueeRepeatLimit="marquee_forever"android:textColor="@color/red" android:text="1234567890wwwwwwwwwwwwwwwwwwwwww1234567890"android:focusable="true"/>

第2种：还是继承TextView，重写onDraw()，在onDraw中不停的重绘。

import android.content.Context;import android.graphics.Canvas;import android.graphics.Paint;import android.os.Parcel;import android.os.Parcelable;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;/** * 单行文本跑马灯控件 * @author admin * */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;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 CharSequence text = "";// 文本内容private float speed = 0.5f;private int textColor=0xFF000000;public int getTextColor() {return textColor;}public void setTextColor(int color) {this.textColor = color;}public float getSpeed() {return speed;}public void setSpeed(float speed) {this.speed = speed;}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();}/** *//** * 初始化控件 */private void initView() {setOnClickListener(this);}/** *//** * 文本初始化，每次更改文本内容或者文本效果等之后都需要重新初始化一下! */public void init(float width/*WindowManager windowManager*/) {text=super.getText();paint = super.getPaint();//Paint paint=new Paint();text = getText().toString();textLength = paint.measureText(text.toString());//viewWidth = getWidth();//if (viewWidth == 0) {//if (windowManager != null) {//Display display = windowManager.getDefaultDisplay();//viewWidth = display.getWidth();//}//}viewWidth=width;step = textLength;temp_view_plus_text_length = viewWidth + textLength;temp_view_plus_two_text_length = viewWidth + textLength * 2;y = getTextSize() + getPaddingTop();paint.setColor(textColor);}@Overridepublic Parcelable onSaveInstanceState() {Parcelable superState = super.onSaveInstanceState();SavedState ss = new SavedState(superState);ss.step = step;ss.isStarting = isStarting;return ss;}@Overridepublic void onRestoreInstanceState(Parcelable state) {if (!(state instanceof SavedState)) {super.onRestoreInstanceState(state);return;}SavedState ss = (SavedState) state;super.onRestoreInstanceState(ss.getSuperState());step = ss.step;isStarting = ss.isStarting;}public static class SavedState extends BaseSavedState {public boolean isStarting = false;public float step = 0.0f;SavedState(Parcelable superState) {super(superState);}@Overridepublic void writeToParcel(Parcel out, int flags) {super.writeToParcel(out, flags);out.writeBooleanArray(new boolean[] { isStarting });out.writeFloat(step);}public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() {public SavedState[] newArray(int size) {return new SavedState[size];}@Overridepublic SavedState createFromParcel(Parcel in) {return new SavedState(in);}};private SavedState(Parcel in) {super(in);boolean[] b = null;in.readBooleanArray(b);if (b != null && b.length > 0)isStarting = b[0];step = in.readFloat();}}/** *//** * 开始滚动 */public void startScroll() {isStarting = true;invalidate();}/** *//** * 停止滚动 */public void stopScroll() {isStarting = false;invalidate();}@Overridepublic void onDraw(Canvas canvas) {//super.onDraw(canvas);canvas.drawText(text,0,text.length(), temp_view_plus_text_length - step, y, paint);if (!isStarting) {return;}step += speed;if (step > temp_view_plus_two_text_length)step = textLength;invalidate();}@Overridepublic void onClick(View v) {if (isStarting)stopScroll();elsestartScroll();}}

使用：

marquee = (AutoScrollTextView) findViewById(R.id.marquee);//marquee.setText(String.format(getResources().getString(R.string.marquee0),Consts.termno,"2010-12-28"));marquee.setText("上证指数3000.15 6.81(0.37%)深圳成指3000.15 6.81(0.37%)");//marquee.setTextColor(0xffff0000);//注意：颜色必须在这里设置，xml中设置无效！默认黑色。//如果想改变跑马灯的文字内容或者文字效果，则在调用完setText方法之后，需要再调用一下init(width)方法，重新进行初始化和相关参数的计算。marquee.setSpeed(1.5f);marquee.init(width);//width通常就是屏幕宽！marquee.startScroll();

这2种跑马灯稍微有点区别，需要掂量着使用。
第1种跑马灯不能设置速度，并且要超过一行才会滚动。
第2种跑马灯只能设置单一颜色，且需要在代码中设置，不能同时设置多种颜色。速度设的不要过大(<= 2.0f)，否则停顿现象比较明显。
想知道同时设置多种颜色？
http://gundumw100.iteye.com/admin/blogs/904107