如何为ScrollView设置图像而不是渐弱边缘？

Question

我正在使用水平滚动视图,动态我将添加项目.如果不.项目不仅仅是在屏幕上显示项目我想在边缘显示图像(箭头)(如滚动视图显示渐变边缘).我该怎么做.

只要看下面的图像,我想创造那样的.

这是xml代码

<HorizontalScrollView 
   android:layout_width="wrap_content"
   android:scrollbars="none"
   android:id="@+id/app_category"
   android:layout_below="@+id/top_layout"   
   android:background="@drawable/minitopbar"
   android:layout_height="30dp">

   <LinearLayout 
     android:orientation="horizontal"
     android:id="@+id/app_category_scroll_layout"
     android:layout_width="wrap_content"                            
     android:layout_height="fill_parent"/>

</HorizontalScrollView>

Answer 1

答:你必须创建自己的类,扩展HorizontalScrollView:

public class ExtendedHorizontalScrollView extends HorizontalScrollView {

private IScrollStateListener scrollStateListener;

public HorizontalScrollViewForMenu(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
}

public HorizontalScrollViewForMenu(Context context, AttributeSet attrs) {
    super(context, attrs);
}

public HorizontalScrollViewForMenu(Context context) {
    super(context);
}

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

private void prepare() {
    if (scrollStateListener != null) {
        View content = this.getChildAt(0);
        if (content.getLeft() >= 0)
            scrollStateListener.onScrollMostLeft();
        if (content.getLeft() < 0)
            scrollStateListener.onScrollFromMostLeft();

        if (content.getRight() <= getWidth())
            scrollStateListener.onScrollMostRight();
        if (content.getLeft() > getWidth())
            scrollStateListener.onScrollFromMostRight();
    }
}

@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
    super.onScrollChanged(l, t, oldl, oldt);
    if (scrollStateListener != null) {
        if (l == 0)
            scrollStateListener.onScrollMostLeft();
        else if (oldl == 0)
            scrollStateListener.onScrollFromMostLeft();
        int mostRightL = this.getChildAt(0).getWidth() - getWidth();
        if (l >= mostRightL)
            scrollStateListener.onScrollMostRight();
        if (oldl >= mostRightL && l < mostRightL)
            scrollStateListener.onScrollFromMostRight();
    }
}

public void setScrollStateListener(IScrollStateListener listener) {
    scrollStateListener = listener;
}

public interface IScrollStateListener {
    void onScrollMostLeft();

    void onScrollFromMostLeft();

    void onScrollMostRight();

    void onScrollFromMostRight();
}
}

B.使用它来定义布局:

<LinearLayout
      .....>
    <ImageView
        android:id="@+id/navigation_left"
        ..... />

    <your.custom.view.package.ExtendedHorizontalScrollView
        android:id="@+id/scroller"
        android:layout_width="0px"
        android:layout_weight="1"
        android:fadingEdge="none"
                ....>
        <LinearLayout
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </your.custom.view.package.ExtendedHorizontalScrollView>

    <ImageView
        android:id="@+id/navigation_right"
        ..... />

</LinearLayout>

C.当您无法再滚动时,添加用于禁用箭头的逻辑.

((ExtendedHorizontalScrollView)findViewById(R.id.scroller)).setScrollStateListener(new IScrollStateListener() {
        public void onScrollMostRight() {
            ((View) scroller.getParent()).findViewById(R.id.navigation_right).setVisibility(View.INVISIBLE);
        }

        public void onScrollMostLeft() {
            ((View) scroller.getParent()).findViewById(R.id.navigation_left).setVisibility(View.INVISIBLE);
        }

        public void onScrollFromMostLeft() {
            ((View) scroller.getParent()).findViewById(R.id.navigation_left).setVisibility(View.VISIBLE);
        }

        public void onScrollFromMostRight() {
            ((View) scroller.getParent()).findViewById(R.id.navigation_right).setVisibility(View.VISIBLE);
        }

    });