自定义跑马灯，可控制速度与方向

使用drawText方法不断重绘文字。
xml布局：
<com.ycq.myview.MarqueeText    android:id="@+id/test"    android:layout_width="match_parent"    android:layout_height="50dp"    android:background="#339320"    android:maxLines="1"    android:textColor="#FF00FF"    android:textSize="21sp"/>注意：需要设置为1行。可在XML中设置颜色，字号，不要设置文字内容。
Activity调用：
test = (MarqueeText) this.findViewById(R.id.test);test.setMyContext("11111112225555");test.setL2r(true);
test.setMySpeed(10);test.setOnClickListener(new OnClickListener() {    @Override    public void onClick(View view) {        start();    }});
setL2r设置方向，默认为从左向右；
setMySpeed设置速度，默认为5，说明：若速度设置<0，则默认为1，若>15，则默认15.
@OverridePRotected void onPause() {    super.onPause();    stop();}@Overrideprotected void onResume() {    super.onResume();    start();}@Overrideprotected void onDestroy() {    super.onDestroy();    stop();}public void start() {    test.startScroll();}public void stop() {    test.stopScroll();}销毁Activity，则不在执行。
具体实现：
package com.ycq.myview;import android.content.Context;import android.graphics.Canvas;import android.util.AttributeSet;import android.widget.TextView;/** * Created by yi on 2017/2/6. */public class MarqueeText extends TextView implements Runnable {    private int currentScrollX = 0;// 当前滚动的位置    private boolean isStop = false;    private int textWidth;    private boolean isMeasure = false;    private String myContext = "";    private int vWidth;    private int mySpeed = 5;    private Boolean l2r = true;    //getPaint()获取系统画笔    public MarqueeText(Context context) {        super(context);    }    public MarqueeText(Context context, AttributeSet attrs) {        super(context, attrs);    }    public MarqueeText(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        if (!isMeasure) {// 文字宽度只需获取一次就可以了            textWidth = (int) getPaint().measureText(myContext);            vWidth = getWidth();            isMeasure = true;        }        float baseline = getHeight() / 2 + getPaint().getTextSize() / 2 - getPaint().getFontMetrics().descent;        canvas.drawText(myContext, currentScrollX, baseline, getPaint());    }    @Override    public void run() {        if (!l2r) {//向左运动            currentScrollX -= mySpeed;// 滚动速度            if (currentScrollX < 0) {                if (Math.abs(currentScrollX) >= textWidth) {                    currentScrollX = vWidth;                }            }        }        if (l2r) {//由左向右运动            currentScrollX += mySpeed;// 滚动速度            if (currentScrollX >= vWidth) {                currentScrollX = -textWidth;            }        }        invalidate();        postDelayed(this, 5);        if (isStop) {            return;        }    }    // 开始滚动    public void startScroll() {        isStop = false;        this.removeCallbacks(this);        post(this);    }    // 停止滚动    public void stopScroll() {        isStop = true;    }    public String getMyContext() {        return myContext;    }    public void setMyContext(String myContext) {        this.myContext = myContext;        textWidth = (int) getPaint().measureText(myContext);    }    public int getMySpeed() {        return mySpeed;    }    public void setMySpeed(int mySpeed) {        this.mySpeed = mySpeed;        if (mySpeed <= 0) {            this.mySpeed = 1;        }        if (mySpeed >= 15) {            this.mySpeed = 15;        }    }    public Boolean getL2r() {        return l2r;    }    public void setL2r(Boolean l2r) {        this.l2r = l2r;    }}
float baseline = getHeight() / 2 + getPaint().getTextSize() / 2 - getPaint().getFontMetrics().descent;        canvas.drawText(myContext, currentScrollX, baseline, getPaint());保证绘制的文字在控件的竖直中线位置。