Android 實作跑馬燈效果

方法一、

這裡用到了HorizontalScrollView嵌套TextView，上xml布局:

<HorizontalScrollView
        android:id="@+id/horiSv"
        android:layout_width="match_parent"
        android:layout_height="70px"
        android:background="@color/green"
        android:scrollbars="none">

        <TextView
            android:id="@+id/noticeTv"
            android:layout_width="wrap_content"
            android:layout_height="70px"
            android:gravity="center"
            android:singleLine="true"
            android:text=""
            android:textColor="@color/white"
            android:textSize="36sp" />
    </HorizontalScrollView>
           

java代碼中的實作:

private HorizontalScrollView mNoticeScrollView;
private TextView mNoticeTv;
private TranslateAnimation mRigthToLeftAnim;
private final static float SCOLL_V = 0.2f;



mNoticeScrollView = (HorizontalScrollView) findViewById(R.id.horiSv);
mNoticeTv = (TextView) findViewById(R.id.noticeTv);
mNoticeTv.setFocusable(true);




String value = "<font color='white' size='24'>" + "收費标準:4小時/元" + "</font>";
        mNoticeTv.setText(Html.fromHtml(value));
        mNoticeTv.post(new Runnable() {
            @Override
            public void run() {
                mRigthToLeftAnim = new TranslateAnimation(mNoticeScrollView.getWidth(), -mNoticeTv.getWidth(), 0, 0);
                mRigthToLeftAnim.setRepeatCount(Animation.INFINITE);
                mRigthToLeftAnim.setInterpolator(new LinearInterpolator());
                mRigthToLeftAnim.setDuration((long) ((mNoticeScrollView.getWidth() + mNoticeTv.getWidth()) / SCOLL_V));
                mNoticeTv.startAnimation(mRigthToLeftAnim);
            }
        });
           

方法二、

自定義TextView

public class FlashTextView extends TextView {
    private int mViewWidth = 0;
    private Paint mPaint;
    private LinearGradient mLinearGradient;
    private Matrix mGradientMatrix;
    private int mTranslate;

    public FlashTextView(Context context) {
        super(context);
    }

    public FlashTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        if (mViewWidth == 0) {
            mViewWidth = getMeasuredWidth();
            if (mViewWidth > 0) {
                mPaint = getPaint();
                mLinearGradient = new LinearGradient(0, 0, mViewWidth, 0, new int[]{Color.GREEN, 0xA020F0, Color.BLUE}, null, Shader.TileMode.CLAMP);
                mPaint.setShader(mLinearGradient);
                mGradientMatrix = new Matrix();
            }
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (mGradientMatrix != null) {
            mTranslate += mViewWidth / 5;
            if (mTranslate > 2 * mViewWidth) {
                mTranslate = -mViewWidth;
            }
            mGradientMatrix.setTranslate(mTranslate, 0);
            mLinearGradient.setLocalMatrix(mGradientMatrix);
            postInvalidateDelayed(50);
        }
    }

}