android - 如何正确创建自定义动画可绘制对象？

Question

背景

我一直在很多地方搜索以了解如何不为 View 设置动画并且不使用内置的可绘制对象来设置可绘制对象的动画。

原因是我需要在drawable中准备一个自定义的动画，以后可能会有不同的需求。

目前，我正在制作一个基本的动画可绘制对象，它只会在其中旋转给定的位图。

我已经在 imageView 上设置了它，但我希望能够在任何类型的 View 上使用它，甚至是覆盖了 onDraw 函数的自定义 View 。

问题

无论 View 的大小如何，我都找不到如何在不剪切的情况下显示可绘制对象。这是我看到的:

代码

代码如下:

private class CircularAnimatedDrawable extends Drawable implements Animatable {
    private static final Interpolator ANGLE_INTERPOLATOR = new LinearInterpolator();
    private static final int ANGLE_ANIMATOR_DURATION = 2000;
    private final RectF fBounds = new RectF();
    private float angle = 0;
    private ObjectAnimator mObjectAnimatorAngle;
    private final Paint mPaint;
    private boolean mRunning;
    private final Bitmap mBitmap;

    public CircularAnimatedDrawable(final Bitmap bitmap) {
        this.mBitmap = bitmap;
        mPaint = new Paint();
        setupAnimations();
    }

    public float getAngle() {
        return this.angle;
    }

    public void setAngle(final float angle) {
        this.angle = angle;
        invalidateSelf();
    }

    @Override
    public Callback getCallback() {
        return mCallback;
    }

    @Override
    public void draw(final Canvas canvas) {
        canvas.save();
        canvas.rotate(angle);
        canvas.drawBitmap(mBitmap, 0, 0, mPaint);
        canvas.restore();
    }

    @Override
    public void setAlpha(final int alpha) {
        mPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(final ColorFilter cf) {
        mPaint.setColorFilter(cf);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSPARENT;
    }

    @Override
    protected void onBoundsChange(final Rect bounds) {
        super.onBoundsChange(bounds);
        fBounds.left = bounds.left;
        fBounds.right = bounds.right;
        fBounds.top = bounds.top;
        fBounds.bottom = bounds.bottom;
    }

    private void setupAnimations() {
        mObjectAnimatorAngle = ObjectAnimator.ofFloat(this, "angle", 360f);
        mObjectAnimatorAngle.setInterpolator(ANGLE_INTERPOLATOR);
        mObjectAnimatorAngle.setDuration(ANGLE_ANIMATOR_DURATION);
        mObjectAnimatorAngle.setRepeatMode(ValueAnimator.RESTART);
        mObjectAnimatorAngle.setRepeatCount(ValueAnimator.INFINITE);
    }

    @Override
    public void start() {
        if (isRunning())
            return;
        mRunning = true;
        mObjectAnimatorAngle.start();
        invalidateSelf();
    }

    @Override
    public void stop() {
        if (!isRunning())
            return;
        mRunning = false;
        mObjectAnimatorAngle.cancel();
        invalidateSelf();
    }

    @Override
    public boolean isRunning() {
        return mRunning;
    }

}

和用法:

    final ImageView imageView = (ImageView) findViewById(R.id.imageView);
    final Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.spinner_76_inner_holo);

    final CircularAnimatedDrawable circularAnimatedDrawable = new CircularAnimatedDrawable(bitmap);
    circularAnimatedDrawable.setCallback(imageView);
    circularAnimatedDrawable.start();
    imageView.setImageDrawable(circularAnimatedDrawable);

问题

如何设置它使可绘制对象适合 View ？

我应该使用位图大小吗？范围？两个都？还是别的什么？

Answer 1

试试你的 Drawable 的这个修改版本:

class CircularAnimatedDrawable extends Drawable implements Animatable, TimeAnimator.TimeListener {
    private static final float TURNS_PER_SECOND = 0.5f;
    private Bitmap mBitmap;
    private boolean mRunning;
    private TimeAnimator mTimeAnimator = new TimeAnimator();
    private Paint mPaint = new Paint();
    private Matrix mMatrix = new Matrix();

    public CircularAnimatedDrawable(final Bitmap bitmap) {
        mBitmap = bitmap;
        mTimeAnimator.setTimeListener(this);
    }
    @Override
    public void draw(final Canvas canvas) {
        canvas.drawBitmap(mBitmap, mMatrix, mPaint);
    }
    @Override
    protected void onBoundsChange(Rect bounds) {
        Log.d(TAG, "onBoundsChange " + bounds);
        mMatrix.setRectToRect(new RectF(0, 0, mBitmap.getWidth(), mBitmap.getHeight()),
                new RectF(bounds),
                Matrix.ScaleToFit.CENTER);
    }
    @Override
    public void onTimeUpdate(TimeAnimator animation, long totalTime, long deltaTime) {
        Rect b = getBounds();
        mMatrix.postRotate(360 * TURNS_PER_SECOND * deltaTime / 1000, b.centerX(), b.centerY());
        invalidateSelf();
    }
    @Override
    public void setAlpha(final int alpha) {
        mPaint.setAlpha(alpha);
    }
    @Override
    public void setColorFilter(final ColorFilter cf) {
        mPaint.setColorFilter(cf);
    }
    @Override
    public int getOpacity() {
        return PixelFormat.TRANSPARENT;
    }
    @Override
    public void start() {
        if (isRunning())
            return;
        mRunning = true;
        mTimeAnimator.start();
        invalidateSelf();
    }
    @Override
    public void stop() {
        if (!isRunning())
            return;
        mRunning = false;
        mTimeAnimator.cancel();
        invalidateSelf();
    }
    @Override
    public boolean isRunning() {
        return mRunning;
    }
}

编辑:没有 Animator 东西的版本(使用 [un]scheduleSelf)，注意它使用 View 的 Drawable.Callback 机制，所以它通常不能直接从 onCreate 启动，其中 View 还没有附加 Handler

class CircularAnimatedDrawable extends Drawable implements Animatable, Runnable {
    private static final float TURNS_PER_SECOND = 0.5f;
    private static final long DELAY = 50;
    private Bitmap mBitmap;
    private long mLastTime;
    private boolean mRunning;
    private Paint mPaint = new Paint();
    private Matrix mMatrix = new Matrix();

    public CircularAnimatedDrawable(final Bitmap bitmap) {
        mBitmap = bitmap;
    }
    @Override
    public void draw(final Canvas canvas) {
        canvas.drawBitmap(mBitmap, mMatrix, mPaint);
    }
    @Override
    protected void onBoundsChange(Rect bounds) {
        Log.d(TAG, "onBoundsChange " + bounds);
        mMatrix.setRectToRect(new RectF(0, 0, mBitmap.getWidth(), mBitmap.getHeight()),
                new RectF(bounds),
                Matrix.ScaleToFit.CENTER);
    }
    @Override
    public void setAlpha(final int alpha) {
        mPaint.setAlpha(alpha);
    }
    @Override
    public void setColorFilter(final ColorFilter cf) {
        mPaint.setColorFilter(cf);
    }
    @Override
    public int getOpacity() {
        return PixelFormat.TRANSPARENT;
    }
    @Override
    public void start() {
        if (isRunning())
            return;
        mRunning = true;
        mLastTime = SystemClock.uptimeMillis();
        scheduleSelf(this, 0);
        invalidateSelf();
    }
    @Override
    public void stop() {
        if (!isRunning())
            return;
        mRunning = false;
        unscheduleSelf(this);
        invalidateSelf();
    }
    @Override
    public boolean isRunning() {
        return mRunning;
    }
    @Override
    public void run() {
        long now = SystemClock.uptimeMillis();
        Rect b = getBounds();
        long deltaTime = now - mLastTime;
        mLastTime = now;
        mMatrix.postRotate(360 * TURNS_PER_SECOND * deltaTime / 1000, b.centerX(), b.centerY());
        scheduleSelf(this, now + DELAY);
        invalidateSelf();
    }
}