BarLineChartTouchListener.java 文件源码

public void computeScroll() {

        if (mDecelerationVelocity.x == 0.f && mDecelerationVelocity.y == 0.f)
            return; // There's no deceleration in progress

        final long currentTime = AnimationUtils.currentAnimationTimeMillis();

        mDecelerationVelocity.x *= mChart.getDragDecelerationFrictionCoef();
        mDecelerationVelocity.y *= mChart.getDragDecelerationFrictionCoef();

        final float timeInterval = (float) (currentTime - mDecelerationLastTime) / 1000.f;

        float distanceX = mDecelerationVelocity.x * timeInterval;
        float distanceY = mDecelerationVelocity.y * timeInterval;

        mDecelerationCurrentPoint.x += distanceX;
        mDecelerationCurrentPoint.y += distanceY;

        MotionEvent event = MotionEvent.obtain(currentTime, currentTime, MotionEvent.ACTION_MOVE, mDecelerationCurrentPoint.x,
                mDecelerationCurrentPoint.y, 0);
        performDrag(event);
        event.recycle();
        mMatrix = mChart.getViewPortHandler().refresh(mMatrix, mChart, false);

        mDecelerationLastTime = currentTime;

        if (Math.abs(mDecelerationVelocity.x) >= 0.01 || Math.abs(mDecelerationVelocity.y) >= 0.01)
            Utils.postInvalidateOnAnimation(mChart); // This causes computeScroll to fire, recommended for this by Google
        else {
            // Range might have changed, which means that Y-axis labels
            // could have changed in size, affecting Y-axis size.
            // So we need to recalculate offsets.
            mChart.calculateOffsets();
            mChart.postInvalidate();

            stopDeceleration();
        }
    }