Android实现文字滚动播放效果的示例代码

<!-- res/values/attrs.xml -->
<resources>
    <declare-styleable name="marqueetextview">
        <attr name="mtv_text" format="string" />
        <attr name="mtv_textcolor" format="color" />
        <attr name="mtv_textsize" format="dimension" />
        <attr name="mtv_speed" format="float" />
        <attr name="mtv_direction">
            <flag name="horizontal" value="0" />
            <flag name="vertical" value="1" />
        </attr>
        <attr name="mtv_repeatdelay" format="integer" />
        <attr name="mtv_repeatmode">
            <enum name="restart" value="1" />
            <enum name="reverse" value="2" />
        </attr>
        <attr name="mtvinterpolator" format="reference" />
        <attr name="mtv_loop" format="boolean" />
    </declare-styleable>
</resources>

<!-- res/layout/activity_main.xml -->
<framelayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp">
 
    <com.example.marquee.marqueetextview
        android:id="@+id/marqueeview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:mtv_text="欢迎使用android文字滚动播放控件"
        app:mtv_textcolor="#ff5722"
        app:mtv_textsize="18sp"
        app:mtv_speed="100"
        app:mtv_direction="horizontal"
        app:mtv_repeatdelay="500"
        app:mtv_repeatmode="restart"
        app:mtvinterpolator="@android:anim/linear_interpolator"
        app:mtv_loop="true"/>
</framelayout>

package com.example.marquee;
 
import android.animation.animator;
import android.animation.objectanimator;
import android.animation.timeinterpolator;
import android.content.context;
import android.content.res.typedarray;
import android.graphics.canvas;
import android.graphics.paint;
import android.text.textutils;
import android.util.attributeset;
import android.view.view;
import androidx.interpolator.view.animation.linearoutslowininterpolator;
import com.example.r;
 
public class marqueetextview extends view {
 
    // ========== 可配置属性 ==========
    private string text;
    private int textcolor;
    private float textsize;
    private float speed;               // px/s
    private int direction;             // 0: horizontal, 1: vertical
    private long repeatdelay;          // ms
    private int repeatmode;            // objectanimator.restart or reverse
    private boolean loop;              // 是否循环
    private timeinterpolator interpolator;
 
    // ========== 绘制相关 ==========
    private paint paint;
    private float textwidth, textheight;
    private float offset;              // 当前滚动偏移
 
    // ========== 动画 ==========
    private objectanimator animator;
 
    public marqueetextview(context context) {
        this(context, null);
    }
 
    public marqueetextview(context context, attributeset attrs) {
        this(context, attrs, 0);
    }
 
    public marqueetextview(context context, attributeset attrs, int defstyle) {
        super(context, attrs, defstyle);
        initattributes(context, attrs);
        initpaint();
    }
 
    private void initattributes(context context, attributeset attrs) {
        typedarray a = context.obtainstyledattributes(attrs, r.styleable.marqueetextview);
        text = a.getstring(r.styleable.marqueetextview_mtv_text);
        textcolor = a.getcolor(r.styleable.marqueetextview_mtv_textcolor, 0xff000000);
        textsize = a.getdimension(r.styleable.marqueetextview_mtv_textsize, 16 * getresources().getdisplaymetrics().scaleddensity);
        speed = a.getfloat(r.styleable.marqueetextview_mtv_speed, 50f);
        direction = a.getint(r.styleable.marqueetextview_mtv_direction, 0);
        repeatdelay = a.getint(r.styleable.marqueetextview_mtv_repeatdelay, 500);
        repeatmode = a.getint(r.styleable.marqueetextview_mtv_repeatmode, objectanimator.restart);
        loop = a.getboolean(r.styleable.marqueetextview_mtv_loop, true);
        int interpres = a.getresourceid(r.styleable.marqueetextview_mtvinterpolator, android.r.interpolator.linear);
        interpolator = android.view.animation.animationutils.loadinterpolator(context, interpres);
        a.recycle();
 
        if (textutils.isempty(text)) text = "";
    }
 
    private void initpaint() {
        paint = new paint(paint.anti_alias_flag);
        paint.setcolor(textcolor);
        paint.settextsize(textsize);
        paint.setstyle(paint.style.fill);
 
        // 计算文字尺寸
        textwidth = paint.measuretext(text);
        paint.fontmetrics fm = paint.getfontmetrics();
        textheight = fm.bottom - fm.top;
    }
 
    @override
    protected void onmeasure(int widthmeasurespec, int heightmeasurespec) {
        int desiredw = (int) (direction == 0 ? getsuggestedminimumwidth() : textwidth + getpaddingleft() + getpaddingright());
        int desiredh = (int) (direction == 1 ? getsuggestedminimumheight() : textheight + getpaddingtop() + getpaddingbottom());
 
        int width = resolvesize(desiredw, widthmeasurespec);
        int height = resolvesize(desiredh, heightmeasurespec);
        setmeasureddimension(width, height);
    }
 
    @override
    protected void onattachedtowindow() {
        super.onattachedtowindow();
        startscroll();
    }
 
    @override
    protected void ondetachedfromwindow() {
        super.ondetachedfromwindow();
        if (animator != null) animator.cancel();
    }
 
    private void startscroll() {
        if (animator != null && animator.isrunning()) return;
 
        float start, end, distance;
        if (direction == 0) {
            // 水平滚动：从右侧外开始，到左侧外结束
            start = getwidth();
            end = -textwidth;
            distance = start - end;
        } else {
            // 垂直滚动：从底部外开始，到顶部外结束
            start = getheight();
            end = -textheight;
            distance = start - end;
        }
        long duration = (long) (distance / speed * 1000);
 
        animator = objectanimator.offloat(this, "offset", start, end);
        animator.setinterpolator(interpolator);
        animator.setduration(duration);
        animator.setrepeatcount(loop ? objectanimator.infinite : 0);
        animator.setrepeatmode(repeatmode);
        animator.setstartdelay(repeatdelay);
        animator.addlistener(new animator.animatorlistener() {
            @override public void onanimationstart(animator animation) { }
            @override public void onanimationend(animator animation) { }
            @override public void onanimationcancel(animator animation) { }
            @override public void onanimationrepeat(animator animation) { }
        });
        animator.start();
    }
 
    public void setoffset(float value) {
        this.offset = value;
        invalidate();
    }
 
    public float getoffset() { return offset; }
 
    @override
    protected void ondraw(canvas canvas) {
        super.ondraw(canvas);
        if (direction == 0) {
            // 水平
            float y = getpaddingtop() - paint.getfontmetrics().top;
            canvas.drawtext(text, offset, y, paint);
        } else {
            // 垂直
            float x = getpaddingleft();
            canvas.drawtext(text, x, offset - paint.getfontmetrics().top, paint);
        }
    }
 
    // ==== 可添加更多 api：pause(), resume(), settext(), setspeed() 等 ====
}