Android实现跑马灯效果的代码详解

tv2.setSingleLine();//设置TextView的文本内容是否可以水平滚动。

tv2.setHorizontallyScrolling(true);//设置当TextView的文本内容超出可显示范围时的省略方式，这里设置为跑马灯效果。

tv2.setEllipsize(TextUtils.TruncateAt.MARQUEE);//设置跑马灯效果重复的次数，-1表示无限重复。

tv2.setMarqueeRepeatLimit(-1);//设置TextView是否可以获取焦点。

tv2.setFocusable(true);//设置TextView在触摸模式下是否可以获取焦点。

tv2.setFocusableInTouchMode(true);//请求获取焦点。

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();}

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;}