Android 實(shí)現(xiàn)跑馬燈效果

Android中實(shí)現(xiàn)跑馬燈效果有多種方式,本篇簡(jiǎn)單介紹下:

1: TextView屬性實(shí)現(xiàn)

    <TextView
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:background="#77000000"
        android:padding="5dp"
        android:singleLine="true"
        android:ellipsize="marquee"
        android:scrollHorizontally="true"
        android:focusable="true"
        android:focusableInTouchMode="true"
        android:marqueeRepeatLimit="marquee_forever"
        android:text="這是textview的跑馬燈效果"
        android:id="@+id/tv1"
        />

這里需要注意下:

1. 需要限制textview的寬度,不能設(shè)置為wrap_content
2. 啟動(dòng)跑馬燈效果需要獲取焦點(diǎn)requestFocus().

2: 代碼實(shí)現(xiàn)

tv2.setSingleLine();
tv2.setHorizontallyScrolling(true);
tv2.setEllipsize(TextUtils.TruncateAt.MARQUEE);
tv2.setMarqueeRepeatLimit(-1);
tv2.setFocusable(true);
tv2.setFocusableInTouchMode(true);
tv2.requestFocus();

3: 自定義 view實(shí)現(xiàn)

這里可以使用動(dòng)畫(huà)的效果實(shí)現(xiàn).文章來(lái)源地址http://www.zghlxwxcb.cn/news/detail-800775.html

package com.test.marquee;

import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.LinearInterpolator;

import androidx.annotation.Nullable;

public class MarqueeView extends View {
    private String text;
    private Paint paint;
    private float textWidth;
    private float textX;
    private float viewWidth;
    private ValueAnimator animator;

    public MarqueeView(Context context) {
        super(context);
        init();
    }

    public MarqueeView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public MarqueeView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        text = "This is a marquee";
        paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setTextSize(50);
        paint.setColor(Color.BLACK);
        textWidth = paint.measureText(text);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        viewWidth = w;
        textX = viewWidth;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawText(text, textX, getHeight() / 2, paint);
    }

    public void startMarquee() {
        animator= ValueAnimator.ofFloat(viewWidth, -textWidth);
        animator.setDuration(5000);
        animator.setInterpolator(new LinearInterpolator());
        animator.setRepeatCount(ValueAnimator.INFINITE);
        animator.addUpdateListener(animation -> {
            textX = (float) animation.getAnimatedValue();
            invalidate();
        });
        animator.start();
    }

    public void stopMarquee() {
        // 停止動(dòng)畫(huà)
        if (animator!=null) animator.cancel();
    }
}

4: 實(shí)現(xiàn)豎直效果的跑馬燈

package com.test.marquee;

import android.content.Context;
import android.graphics.Canvas;
import android.text.TextUtils;
import android.text.method.ScrollingMovementMethod;
import android.util.AttributeSet;

import androidx.annotation.Nullable;
import androidx.appcompat.widget.AppCompatTextView;

public class VerticalMarqueeTextView extends AppCompatTextView {
    private float offsetY;

    public VerticalMarqueeTextView(Context context) {
        super(context);
        init();
    }

    public VerticalMarqueeTextView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        setSingleLine();
        setEllipsize(TextUtils.TruncateAt.MARQUEE);
        setMarqueeRepeatLimit(-1);
        setFocusable(true);
        setFocusableInTouchMode(true);
        setHorizontallyScrolling(true);
        setMovementMethod(ScrollingMovementMethod.getInstance());
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.translate(0, offsetY);
        super.onDraw(canvas);
    }

    @Override
    public boolean isFocused() {
        return true;
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        post(new Runnable() {
            @Override
            public void run() {
                offsetY -= 1;
                if (offsetY <= -getHeight()) {
                    offsetY = 0;
                }
                invalidate();
                postDelayed(this, 20);
            }
        });
    }
}

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