android - Horizo​​ntalScrollView 与 imageviews 作为一个孩子，而在屏幕中滚动图像的中心应该播放动画？

Question

我是新的android平台应用程序开发。我的问题是在不使用图库视图的情况下将图像居中锁定，并且我们播放动画的图像。滚动动画图像时应使用屏幕中心进行调整。目前我正在使用带有线性布局的 Horizo​​ntalScrollView 作为 HSV 的子元素。具有多个图像的线性布局。请给我建议如何实现它。在此先感谢。

Answer 1

继承 Horizo​​ntalScrollView 并覆盖/添加方法

已编辑

我的完整来源

public class HorizontalScrollSpinner extends HorizontalScrollView {

    private ListAdapter mAdapter;

    private int mCenterViewPosition = -1;

    private OnSelectedItemChanged onSelectedItemChanged = new OnSelectedItemChanged() {
        @Override
        public void onSelectedChanged(View view, int newPosition) {

        }
    };

    public HorizontalScrollSpinner(Context context, AttributeSet attrs) {
        super(context, attrs);

        this.setHorizontalFadingEdgeEnabled(true);
        this.setHorizontalScrollBarEnabled(false);
        this.setFadingEdgeLength(5);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        super.onLayout(changed, l, t, r, b);

        if(getChildCount() == 0)
            return;

        initCenterView();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        if(getChildCount() == 0)
            return;

        ViewGroup parent = (ViewGroup) getChildAt(0);

        if(parent.getChildCount() == 0)
            return;

        View FirstChild = parent.getChildAt(0);

        int LeftPadding = (getWidth() / 2) - (FirstChild.getMeasuredWidth() / 2);

        View LastChild = parent.getChildAt(getChildCount() - 1);

        int RightPadding = (getWidth() / 2) - (LastChild.getMeasuredWidth() / 2);

        if(parent.getPaddingLeft() != LeftPadding && parent.getPaddingRight() != RightPadding)
        {
            parent.setPadding(LeftPadding, parent.getPaddingTop(), RightPadding, parent.getPaddingBottom());
            requestLayout();
        }
    }

    private int getInternalCenterView()
    {
        if(getChildCount() == 0)
            return -1;

        int CenterView= 0;
        int CenterX = getScrollX() + (getWidth() / 2); 

        ViewGroup parent = (ViewGroup) getChildAt(0);

        if(parent.getChildCount() == 0)
            return -1;

        View child = parent.getChildAt(0);

        while(child != null && child.getRight() <= CenterX && CenterView < parent.getChildCount())
        {
            CenterView++;
            child = parent.getChildAt(CenterView);
        }

        if(CenterView >= parent.getChildCount())
            CenterView = parent.getChildCount() - 1;

        return CenterView;
    }

    private int getCenterPositionFromView()
    {
        int CenterView = getInternalCenterView();

        if(mCenterViewPosition != CenterView)
        {
            onSelectedItemChanged.onSelectedChanged(this, CenterView);
        }

        mCenterViewPosition = CenterView;

        return mCenterViewPosition;
    }

    public int getCenterViewPosition()
    {
        return mCenterViewPosition;
    }

    public ListAdapter getAdapter() {
        return mAdapter;
    }

    public void setAdapter(ListAdapter mAdapter) {

        this.mAdapter = mAdapter;
        fillViewWithAdapter();      
    }

    private void fillViewWithAdapter()
    {
        if(getChildCount() == 0 || mAdapter == null)
            return;

        ViewGroup parent = (ViewGroup) getChildAt(0);

        parent.removeAllViews();

        for (int i = 0; i < mAdapter.getCount(); i++) {
            parent.addView(mAdapter.getView(i, null, parent));          
        }
    }

    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);

        getCenterPositionFromView();

        initCenterView();
    }

    private void initCenterView()
    {
        if(getChildCount() == 0)
            return;

        ViewGroup parent = (ViewGroup) getChildAt(0);

        if(parent.getChildCount() == 0)
            return;

        int CenterView = getCenterViewPosition();

        if(CenterView == -1)
        {
            mCenterViewPosition = 0;
            CenterView = 0;
        }

        if(CenterView != -1 && CenterView != getInternalCenterView() && parent.getChildAt(0).getLeft() >= 0)
        {
            scrollToSelectedIndex();
        }

        if(CenterView < 0 || CenterView > parent.getChildCount())
            return;

        for (int i = 0; i <= parent.getChildCount(); i++) {

            if(!(parent.getChildAt(i) instanceof TextView))
                continue;

            if(i == CenterView)
            {
                // Start Animation
            }
            else
            {
                // Remove Animation for other Views
            }
        }


    }

    public int getSelectedIndex()
    {
        return getCenterViewPosition();
    }

    public void setSelectedIndex(int index)
    {
        if(getChildCount() == 0)
            return;

        ViewGroup parent = (ViewGroup) getChildAt(0);

        if(index < 0 || index > parent.getChildCount())
        {
            throw new ArrayIndexOutOfBoundsException(index);
        }

        mCenterViewPosition = index;

        onSelectedItemChanged.onSelectedChanged(this, mCenterViewPosition);

        requestLayout();
    }

    protected void scrollToSelectedIndex()
    {
        ViewGroup parent = (ViewGroup) getChildAt(0);

        View child = parent.getChildAt(mCenterViewPosition);

        int ChildCenterX = child.getLeft() + (child.getMeasuredWidth() / 2);

        int ScreenCenterX = getWidth() / 2;

        int ChildScrollToX = ChildCenterX - ScreenCenterX;


        scrollTo(ChildScrollToX, 0);
    }

    public interface OnSelectedItemChanged
    {
        public void onSelectedChanged(View view, int newPosition);
    }

    public OnSelectedItemChanged getOnSelectedItemChanged() {
        return onSelectedItemChanged;
    }

    public void setOnSelectedItemChanged(OnSelectedItemChanged onSelectedItemChanged) {
        this.onSelectedItemChanged = onSelectedItemChanged;
    }


}

这将向位于中心的视图显示动画

onMeasure 将 Padding 添加到 LinearLayout 以便 LinearLayout 中的 First Child 和 Last Child 将始终位于中心。