Android 中的脉动按钮动画

Question

我正在使用语音识别应用程序，我想在录音时让我的 play/stop 按钮 "pulse"。像这样：

我尝试制作一个 ScaleAnimation，让按钮变大，但当然，它会使所有按钮变大。

   public static ObjectAnimator pulseAnimation(ImageView target){

    ObjectAnimator scaleDown = ObjectAnimator.ofPropertyValuesHolder(target,
            PropertyValuesHolder.ofFloat("scaleX", 1.1f),
            PropertyValuesHolder.ofFloat("scaleY", 1.1f));
    scaleDown.setDuration(310);
    scaleDown.setRepeatCount(ObjectAnimator.INFINITE);
    scaleDown.setRepeatMode(ObjectAnimator.REVERSE);

    return scaleDown;
}

所以这个想法是实现类似的东西，但只是在实际按钮后面有一个 alpha。我想知道在我的按钮后面添加第二个 "Alpha Button" 以使其增长并实现此效果之前，是否可以使用 alpha 动画或其他方式执行此操作。

Answer 1

终于找到解决办法了！我重写了 onDraw 方法并为我的按钮绘制了第一个圆圈，当我的布尔值为真时。我以 alpha 作为背景绘制了第二个圆圈。制作脉动效果：

 @Override
protected void onDraw(Canvas canvas) {

    int w = getMeasuredWidth();
    int h = getMeasuredHeight();
    mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mCirclePaint.setColor(mColor);
    mBackgroundPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mBackgroundPaint.setColor(Util.adjustAlpha(mColor, 0.4f));
    //Draw circle
    canvas.drawCircle(w/2, h/2, MIN_RADIUS_VALUE , mCirclePaint);        
    if (mAnimationOn) {
        if (mRadius >= MAX_RADIUS_VALUE)
            mPaintGoBack = true;
        else if(mRadius <= MIN_RADIUS_VALUE)
            mPaintGoBack = false;
        //Draw pulsating shadow
        canvas.drawCircle(w / 2, h / 2, mRadius, mBackgroundPaint);
        mRadius = mPaintGoBack ? (mRadius - 0.5f) : (mRadius + 0.5f);
        invalidate();
    }

    super.onDraw(canvas);
}
 public void animateButton(boolean animate){
    if (!animate)
        mRadius = MIN_RADIUS_VALUE;
    mAnimationOn = animate;
    invalidate();
}

Answer 2

使用 Jetpack Compose 更容易做到无需自定义视图或 canvas

@Composable
fun PulseLoading(
    durationMillis:Int = 1000,
    maxPulseSize:Float = 300f,
    minPulseSize:Float = 50f,
    pulseColor:Color = Color(234,240,246),
    centreColor:Color =  Color(66,133,244)
){
    val infiniteTransition = rememberInfiniteTransition()
    val size by infiniteTransition.animateFloat(
        initialValue = minPulseSize,
        targetValue = maxPulseSize,
        animationSpec = infiniteRepeatable(
            animation = tween(durationMillis, easing = LinearEasing),
            repeatMode = RepeatMode.Restart
        )
    )
    val alpha by infiniteTransition.animateFloat(
        initialValue = 1f,
        targetValue = 0f,
        animationSpec = infiniteRepeatable(
            animation = tween(durationMillis, easing = LinearEasing),
            repeatMode = RepeatMode.Restart
        )
    )
    Box(contentAlignment = Alignment.Center,modifier = Modifier.fillMaxSize()) {
//Card for Pulse Effect
        Card(
            shape = CircleShape,
            modifier = Modifier.size(size.dp).align(Alignment.Center).alpha(alpha),
            backgroundColor = pulseColor,
            elevation = 0.dp
        ) {}
//Card For inner circle
        Card(modifier = Modifier
            .size(minPulseSize.dp)
            .align(Alignment.Center),
            shape = CircleShape,
            backgroundColor = centreColor){}
    }
}

您可以根据自己的需要进行定制。在“内圈”卡片中，您可以添加文字或任何您想要的内容。

我已经为此创建了一个完整的分步教程你可以看看here.

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