<!-- 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="歡迎使用Android文字滾動播放控件"
        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 {
 
    // ========== 可配置屬性 ==========
    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;              // 是否循環(huán)
    private TimeInterpolator interpolator;
 
    // ========== 繪制相關(guān) ==========
    private Paint paint;
    private float textWidth, textHeight;
    private float offset;              // 當(dāng)前滾動偏移
 
    // ========== 動畫 ==========
    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);
 
        // 計算文字尺寸
        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) {
            // 水平滾動：從右側(cè)外開始，到左側(cè)外結(jié)束
            start = getWidth();
            end = -textWidth;
            distance = start - end;
        } else {
            // 垂直滾動：從底部外開始，到頂部外結(jié)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 ====
}