環形ProgressBar動畫效果的自定義

要實現環形ProgressBar的動畫效果，可以借助ValueAnimator和Canvas來實現。以下是一個簡單的示例代碼：

public class CircleProgressBar extends View {

    private Paint mPaint;
    private int mProgress;
    private int mMaxProgress;
    private int mBackgroundColor;
    private int mProgressColor;
    private ValueAnimator mAnimator;

    public CircleProgressBar(Context context) {
        this(context, null);
    }

    public CircleProgressBar(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CircleProgressBar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        mPaint = new Paint();
        mPaint.setAntiAlias(true);

        mProgress = 0;
        mMaxProgress = 100;
        mBackgroundColor = Color.GRAY;
        mProgressColor = Color.BLUE;

        mAnimator = ValueAnimator.ofInt(0, mMaxProgress);
        mAnimator.setDuration(1000);
        mAnimator.addUpdateListener(animation -> {
            mProgress = (int) animation.getAnimatedValue();
            invalidate();
        });
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        int width = getWidth();
        int height = getHeight();

        float centerX = width / 2;
        float centerY = height / 2;
        float radius = Math.min(width, height) / 2 - 10;

        // 繪制背景圓環
        mPaint.setColor(mBackgroundColor);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(20);
        canvas.drawCircle(centerX, centerY, radius, mPaint);

        // 繪制進度圓環
        mPaint.setColor(mProgressColor);
        float sweepAngle = 360f * mProgress / mMaxProgress;
        canvas.drawArc(centerX - radius, centerY - radius, centerX + radius, centerY + radius, -90, sweepAngle, false, mPaint);
    }

    public void setProgress(int progress) {
        if (progress >= 0 && progress <= mMaxProgress) {
            mProgress = progress;
            invalidate();
        }
    }

    public void startAnimation() {
        mAnimator.start();
    }

    public void setMaxProgress(int maxProgress) {
        mMaxProgress = maxProgress;
    }

    public void setBackgroundColor(int color) {
        mBackgroundColor = color;
    }

    public void setProgressColor(int color) {
        mProgressColor = color;
    }
}

在布局文件中添加CircleProgressBar，并設置屬性：

<com.example.CircleProgressBar
    android:id="@+id/circleProgressBar"
    android:layout_width="100dp"
    android:layout_height="100dp"
    app:backgroundColor="@color/gray"
    app:progressColor="@color/blue" />

在代碼中可以通過調用setProgress方法更新進度，通過調用startAnimation方法啟動動畫效果。可以根據需要調整畫筆樣式、動畫時長等屬性來實現不同的環形ProgressBar動畫效果。