android 裡面跑馬燈效果一般都是當行顯示不全的情況下才會有跑馬燈效果，當一行能顯示全的情況下，跑馬燈是沒有效果的。前幾天ui要一效果，希望一行能顯示全的情況下也能出現跑馬燈效果，這樣更醒目。

public class RunTextView extends TextView implements OnClickListener {
public final static String TAG = CustomTextView.class.getSimpleName();

private float textLength = 0f;// 文字長度
private float viewWidth = 0f;
private float step = 0f;// 文字的橫座標
private final float SPEED = 1.5f; // 跑馬燈速度 值越大，越快
private float y = 0f;// 文字的縱座標
private float temp_view_plus_text_length = 0.0f;// 用於計算的臨時變數
private float temp_view_plus_two_text_length = 0.0f;// 用於計算的臨時變數
public boolean isStarting = false;// 是否開始滾動
private Paint paint = null;// 繪圖樣式
private String text = "";// 文字內容
private Context context;
public RunTextView (Context context) {
super(context);
this.context = context;
initView();
}
public RunTextView (Context context, AttributeSet attrs) {
super(context, attrs);
this.context = context;
initView();
}
public RunTextView (Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.context = context;
initView();
}
/**
* 初始化控制元件
*/
private void initView() {
setOnClickListener(this);
}
/**
* 文字初始化，每次更改文字內容或者文字效果等之後都需要重新初始化一下
*/
public void init(WindowManager windowManager) {
paint = getPaint();
paint.setColor(context.getResources().getColor(R.color.notice_text_color));  //設定文字顏色
text = getText().toString();
textLength = paint.measureText(text);
viewWidth = getWidth();
if (viewWidth == 0) {
if (windowManager != null) {
Display display = windowManager.getDefaultDisplay();
viewWidth = display.getWidth();
}
}
step = textLength;
temp_view_plus_text_length = viewWidth + textLength;
temp_view_plus_two_text_length = viewWidth + textLength * 2;
y = getTextSize() + getPaddingTop();
}

@Override
public Parcelable onSaveInstanceState() {
Parcelable superState = super.onSaveInstanceState();
SavedState ss = new SavedState(superState);
ss.step = step;
ss.isStarting = isStarting;
return ss;
}

@Override
public 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);
}

@Override
public 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];
}

@Override
public 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();
}
}
/**
* 開始滾動
*/
public void startScroll() {
isStarting = true;
invalidate();
}
/**
* 停止滾動
*/
public void stopScroll() {
isStarting = false;
invalidate();
}

@Override
public void onDraw(Canvas canvas) {
if (text != null) {
canvas.drawText(text, temp_view_plus_text_length - step, y, paint);
} 
if (!isStarting) {
return;
}
step += SPEED;
if (step > temp_view_plus_two_text_length){
step = textLength;
invalidate();
}
@Override
public void onClick(View v) {
if (isStarting){
startScroll();
}
}

}

}
stopScroll();
}else{
}

呼叫方式：
RunTextView noticeText;
..... // findViewById
noticeText.setText(result.getNotice());
//每次重新設定文字都需要重新呼叫一下下面的這些程式碼
noticeText.init(getActivity().getWindowManager());
noticeText.startScroll();
noticeText.setEnabled(false);