AndroidScroller的使用方法

/**
 * Set the scrolled position of your view. This will cause a call to
 * {@link #onScrollChanged(int, int, int, int)} and the view will be
 * invalidated.
 * @param x the x position to scroll to
 * @param y the y position to scroll to
 */
public void scrollTo(int x, int y) {
    if (mScrollX != x || mScrollY != y) {
        int oldX = mScrollX;
        int oldY = mScrollY;
        mScrollX = x;
        mScrollY = y;
        invalidateParentCaches();
        onScrollChanged(mScrollX, mScrollY, oldX, oldY);
        if (!awakenScrollBars()) {
            postInvalidateOnAnimation();
        }
    }
}

/**
 * Move the scrolled position of your view. This will cause a call to
 * {@link #onScrollChanged(int, int, int, int)} and the view will be
 * invalidated.
 * @param x the amount of pixels to scroll by horizontally
 * @param y the amount of pixels to scroll by vertically
 */
public void scrollBy(int x, int y) {
    scrollTo(mScrollX + x, mScrollY + y);
}

int sx = 0;
int sy = 0;
if (!drawingWithRenderNode) {
    computeScroll();
    sx = mScrollX;
    sy = mScrollY;
}

...

if (offsetForScroll) {
    canvas.translate(mLeft - sx, mTop - sy);
}

/**
 * Called by a parent to request that a child update its values for mScrollX
 * and mScrollY if necessary. This will typically be done if the child is
 * animating a scroll using a {@link android.widget.Scroller Scroller}
 * object.
 */
public void computeScroll() {
}

class ScrollableLinearLayout @JvmOverloads constructor(
    context: Context, attrs: AttributeSet&＃63; = null, defStyleAttr: Int = 0
) : LinearLayout(context, attrs, defStyleAttr) {
    private val scroller = Scroller(context, BounceInterpolator())

    override fun computeScroll() {
        if(scroller.computeScrollOffset()) {
            // 真正实现滚动操作的地方
            scrollTo(scroller.currX, scroller.currY)

            // 刷新
            invalidate()
        }
    }

    fun scroll() {
        // 调用Scroller的startScroll
        if(scrollX == 0) {
            scroller.startScroll(scrollX, scrollY, /*dx*/ -500, /*dy*/ 0, /*duration*/ 300)
        } else {
            scroller.startScroll(scrollX, scrollY, 500, 0, 300)
        }

        // 刷新
        invalidate()
    }

}

<&＃63;xml version="1.0" encoding="utf-8"&＃63;>


    

        

    

class ScrollerSampleActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle&＃63;) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_scroller_sample)

        val btnScroll = findViewById(R.id.btnScroll)
        btnScroll.setOnClickListener {
            findViewById(R.id.sll).scroll()
        }
    }
}