问题描述

如何给滚动视图设置成图像显示?

我使用水平滚动视图，并且在视图上动态的添加项目。如果项目的数量超过能在屏幕上能显示的数量，我想用如下图显示的，用箭头形式水平滚动来显示这些项目。怎么实现呢?
这是我使用的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>

解决方案

A.你应该创建自己的类，然后继承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);}@Overrideprotected 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();    }}@Overrideprotected 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.当不能水平滚动的时候，给箭头添加以下逻辑：

((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);        }    });

解决方案二：
一个简单的方法是让scrollview没有边缘然后在scrollview上面或下面添加带箭头的图像。

<FrameLayout        android:layout_width=""fill_parent""        android:layout_height=""fill_parent"">        <ListView            android:layout_width=""fill_parent""            android:layout_height=""fill_parent""            android:layout_alignParentTop=""true""            android:fadingEdge=""none""        />        <RelativeLayout             android:layout_width=""fill_parent""            android:layout_height=""fill_parent"">            <View                android:layout_height=""6dp""                android:layout_width=""fill_parent""                android:layout_alignParentBottom=""true""                android:background=""@drawable/background_effect""/>        </RelativeLayout>    </FrameLayout>