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android 自定义文字跑马灯 支持拖拽，按住停止滚动，自定义速度

2024-07-07 07:35:25   220人阅读

android的textview自带跑马灯效果，一般使用足够了。不过也有不一般的情况，所以我实现了一个自定义textview控件，用来针对这种不一般情况下的跑马灯效果实现。

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import android.content.Context;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.GestureDetector.OnGestureListener;
import android.view.View.OnTouchListener;
import android.widget.TextView;
 
/**
 * 自定义跑马灯文本框，支持拖拽查看文本内容，点击暂停文字 先设置要显示文本，然后调用Start()方法运行跑马灯
 *
 * @author sy
 */
public class MarqueeTextView extends TextView implements Runnable,
        OnTouchListener {
    public MarqueeTextView(Context context) {
        super(context);
    }
 
    /** 是否停止滚动 */
    private boolean mStopMarquee;
    private String mText;
    public int mCoordinateX;
    int xOffset;
    private int mTextWidth;
    GestureDetector gestureDetector;
 
    public MarqueeTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
 
    public MarqueeTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }
 
    /**
     * 开始滚动
     *
     * @param text
     */
    public void Start() {
        this.setOnTouchListener(this);
 
        gestureDetector = new GestureDetector(getContext(),
                new OnGestureListener() {
                    @Override
                    public boolean onSingleTapUp(MotionEvent e) {
                        // TODO Auto-generated method stub
                        return false;
                    }
 
                    @Override
                    public void onShowPress(MotionEvent e) {
                        // TODO Auto-generated method stub
 
                    }
 
                    @Override
                    public boolean onScroll(MotionEvent e1, MotionEvent e2,
                            float distanceX, float distanceY) {
                        mCoordinateX += (int) distanceX;
                        scrollTo(mCoordinateX, 0);
                        // TODO:设置偏移量，distanceX为滑动距离
                        return true;
                    }
 
                    @Override
                    public void onLongPress(MotionEvent e) {
                        // TODO Auto-generated method stub
 
                    }
 
                    @Override
                    public boolean onFling(MotionEvent e1, MotionEvent e2,
                            float velocityX, float velocityY) {
                        return false;
                    }
 
                    @Override
                    public boolean onDown(MotionEvent e) {
                        // TODO Auto-generated method stub
                        return false;
                    }
                });
 
        xOffset = 0;
        mStopMarquee = false;
        mText = this.getText().toString();// 获取文本框文本
        mCoordinateX = 0;
        mTextWidth = (int) Math.abs(getPaint().measureText(mText));
        post(this);
    }
 
    @Override
    public void run() {
 
        if (!mStopMarquee) {
            mCoordinateX += 3;// 滚动速度
            scrollTo(mCoordinateX, 0);
            if (mCoordinateX > mTextWidth) {
                scrollTo(0, 0);
                mCoordinateX = 0;
            }
            postDelayed(this, 50);
        }
 
    }
 
    // 继续滚动
    public void Continue() {
        if (mStopMarquee) {
            mStopMarquee = false;
            post(this);
        }
    }
 
    // 暂停滚动
    public void Paush() {
        mStopMarquee = true;
    }
 
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
        case MotionEvent.ACTION_MOVE:
        case MotionEvent.ACTION_SCROLL:
            Paush();
            break;
        default:
            Continue();
            break;
        }
 
        gestureDetector.onTouchEvent(event);
        return true;
    }
 
}

　　首先调用setText设置文本内容，然后调用start()开始滚动。滚动速度为每50毫米移动3像素，这是我调试之后感觉比较平滑的一个速度。如果代码有什么错误或者可以改进的地方，希望你们能在评论中指出。谢谢！


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