Question

我使用可滚动静态卡作为项目选择器（滚动直到找到一个，然后使用onItemSelected事件来捕获点击）。它可以工作，但它不会像菜单项和所有标准系统卡一样显示底部的滚动条。有没有办法启用它？

这是适配器代码：

private class FooCardScrollAdapter extends CardScrollAdapter {
    @Override
    public int findIdPosition(Object id) {
        return -1;
    }

    @Override
    public int findItemPosition(Object item) {
        return mCards.indexOf(item);
    }

    @Override
    public int getCount() {
        return mCards.size();
    }

    @Override
    public Object getItem(int position) {
        return mCards.get(position);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        return mCards.get(position).toView();
    }
}

Answer 1

从XE16开始，现在可以通过设置

来实现

mCardScrollView.setHorizontalScrollBarEnabled(true);

Answer 2

这是一个已知问题;目前无法在GDK上CardScrollView获取滚动指示器。请关注我们的问题跟踪器上的issue 256，以便随着GDK的发展而更新！

Answer 3

所以我遇到了和你一样的问题。要解决它，我必须创建自己的滚动条视图。它不如Mirror API的内置版本好，因为它不能处理滚动滚动，但它是我们可以做的最好的，直到谷歌发布它们自己。

首先我们创建一个自定义视图SimulatedScrollBar：

public class SimulatedScrollBar extends View {

private static final String TAG = SimulatedScrollBar.class.getSimpleName();
private static final boolean DEBUG = false;
private static final int WHITE_SCROLLBAR_COLOR = 0xfffefefe;

private int mScrollPosition;
private int mNumItems;
private Paint mPaint;
private float mInnerWidth;
private float mInnerHeight;
private int mOffsetX;
private int mWidth;
private int mHeight;

public SimulatedScrollBar(Context context, AttributeSet attrs) {
    super(context, attrs);
    TypedArray a = context.getTheme().obtainStyledAttributes(
            attrs,
            R.styleable.SimulatedScrollBar,
            0, 0);

    try {
        mScrollPosition = a.getInteger(R.styleable.SimulatedScrollBar_scrollPosition, 0);
        mNumItems = a.getInteger(R.styleable.SimulatedScrollBar_numItems, 0);
    } finally {
        a.recycle();
    }
    init();
}

private void init() {
    mPaint = new Paint();
    mPaint.setColor(WHITE_SCROLLBAR_COLOR);
    mPaint.setStyle(Paint.Style.FILL);
}

public int getScrollPosition() {
    return mScrollPosition;
}

public void setScrollPosition(int scrollPosition) {
    mScrollPosition = scrollPosition;
    invalidate();
    requestLayout();
}

public int getNumItems() {
    return mNumItems;
}

public void setNumItems(int numItems) {
    mNumItems = numItems;
    invalidate();
    requestLayout();
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    float xpad = (float)(getPaddingLeft() + getPaddingRight());
    float ypad = (float)(getPaddingTop() + getPaddingBottom());
    mInnerWidth = (float)w - xpad;
    mInnerHeight = (float)h - ypad;
    if (DEBUG) Log.i(TAG, "onSizeChanged() mInnerWidth=" + mInnerWidth + " mInnerHeight=" + mInnerHeight);
}

@Override
public void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    float widthFraction = mNumItems > 0 ? 1.0f / (float)mNumItems : 0;
    float scrollFraction = mNumItems > 0 ? (float)mScrollPosition / (float)mNumItems : 0;
    mOffsetX = (int)(mInnerWidth * scrollFraction);
    mWidth = (int)(mInnerWidth * widthFraction);
    mHeight = (int)mInnerHeight;
    Rect rect = new Rect(mOffsetX, 0, mOffsetX + mWidth, mHeight);
    if (DEBUG) Log.i(TAG, "onDraw() mOffsetX=" + mOffsetX + " mWidth=" + mWidth + " mHeight=" + mHeight
            + " mScrollPosition=" + mScrollPosition + " mNumItems=" + mNumItems);
    canvas.drawRect(rect, mPaint);
}

}

我们需要一个属性文件`attrs.xml'来支持配置视图：

<resources>
    <declare-styleable name="SimulatedScrollBar">
        <attr name="scrollPosition" format="integer"/>
        <attr name="numItems" format="integer"/>
    </declare-styleable>
</resources>

现在我们制作一个布局card_scroll_layout.xml，其中包含卡片滚动视图和我们的滚动条覆盖：

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:custom="http://schemas.android.com/apk/res/com.chanapps.glass.chan"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/black">

<com.google.android.glass.widget.CardScrollView
        android:id="@+id/card_scroll_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />

<ProgressBar
        android:id="@+id/progress_bar"
        style="?android:attr/progressBarStyleHorizontal"
        android:indeterminate="true"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        />

<com.chanapps.glass.chan.view.SimulatedScrollBar
        android:id="@+id/simulated_scroll_bar"
        android:layout_width="match_parent"
        android:layout_height="10px"
        android:layout_gravity="bottom"
        custom:numItems="0"
        custom:scrollPosition="0"
        />

</FrameLayout>

以下是您在onCreate()中放置的内容：

mSimulatedScrollBar = (SimulatedScrollBar)rootLayout.findViewById(R.id.simulated_scroll_bar);
mSimulatedScrollBar.setScrollPosition(0);
mSimulatedScrollBar.setNumItems(mAdapter.getCount());

mCardScrollView = (CardScrollView)rootLayout.findViewById(R.id.card_scroll_view);
mCardScrollView.setAdapter(mAdapter);
mCardScrollView.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        if (mSimulatedScrollBar != null)
            mSimulatedScrollBar.setScrollPosition(position);
    }
    @Override
    public void onNothingSelected(AdapterView<?> parent) {
    }
});
mCardScrollView.activate();

现在，当您在列表中滑动时，您会看到底部的滚动条跟踪列表位置。如果适配器更改大小，请更新适配器或onLoadFinished()加载程序回调中的项目数和滚动位置。

在可滚动静态卡上显示标准玻璃滚动条

3 个答案: