将微调器宽度设置为当前项目宽度 [英] Set spinner width to current item width

问题描述

默认情况下，微调器的宽度设置为适合下拉菜单中最大的项目，但我希望它的宽度与所选项目的宽度相同.

By default the spinner width is set to fit the largest item in the dropdown but I want it to be the same width as the selected item.

<android.widget.Spinner
    android:id="@+id/tab_spinner"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:entries="@array/countries" />

如您在右侧图像中看到的那样，由于列表中的项目太长，微调器太长了.

As you can see in the right side image, the spinner is way too long, because of the long item in the list.

如何将其调整为所选项目的宽度?

How can I resize it to the selected item width ?

推荐答案

默认情况下， Spinner 将尝试测量您的某些下拉视图并使用找到的最大宽度.这发生在 Spinner#measureContentWidth()中，这是在 Spinner#onMeasure()中调用的，受 Spinner 保护的 Spinner 方法.

By default, Spinner will try to measure some of your dropdown views and use the max width found. This happens in Spinner#measureContentWidth(), a protected method of Spinner called in Spinner#onMeasure().

解决此问题的一种方法是确保您的 SpinnerAdapter#getView()方法始终将 Spinner#getSelectedItemPosition()用于其位置>论点.

One way to solve the issue is to make sure your SpinnerAdapter#getView() method always uses Spinner#getSelectedItemPosition() for its position argument.

我可以想到两种可能的解决方案:

I can think of two possible solutions:

1. 使用包装适配器创建自定义微调器(我更喜欢这种解决方案)
2. 或调整您的自定义适配器

1.使用包装器适配器创建自定义微调器

请确保在您的 xml 布局中使用它，而不是常规的< Spinner> .

Make sure to use this in your xml layout, instead of a normal <Spinner>.

请注意， DynamicWidthSpinner#getAdapter()将返回 WrapperSpinnerAdapter ；使用其 getBaseAdapter()方法访问您的适配器.

Be careful that DynamicWidthSpinner#getAdapter() will return a WrapperSpinnerAdapter; use its getBaseAdapter() method to access to your adapter.

public class DynamicWidthSpinner extends Spinner {

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

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

    public DynamicWidthSpinner(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }


    public void setAdapter(SpinnerAdapter adapter) {
        super.setAdapter(adapter != null ? new WrapperSpinnerAdapter(adapter) : null);
    }


    public final class WrapperSpinnerAdapter implements SpinnerAdapter {

        private final SpinnerAdapter mBaseAdapter;


        public WrapperSpinnerAdapter(SpinnerAdapter baseAdapter) {
            mBaseAdapter = baseAdapter;
        }


        public View getView(int position, View convertView, ViewGroup parent) {
            return mBaseAdapter.getView(getSelectedItemPosition(), convertView, parent);
        }

        public final SpinnerAdapter getBaseAdapter() {
            return mBaseAdapter;
        }

        public int getCount() {
            return mBaseAdapter.getCount();
        }

        public View getDropDownView(int position, View convertView, ViewGroup parent) {
            return mBaseAdapter.getDropDownView(position, convertView, parent);
        }

        public Object getItem(int position) {
            return mBaseAdapter.getItem(position);
        }

        public long getItemId(int position) {
            return mBaseAdapter.getItemId(position);
        }

        public int getItemViewType(int position) {
            return mBaseAdapter.getItemViewType(position);
        }

        public int getViewTypeCount() {
            return mBaseAdapter.getViewTypeCount();
        }

        public boolean hasStableIds() {
            return mBaseAdapter.hasStableIds();
        }

        public boolean isEmpty() {
            return mBaseAdapter.isEmpty();
        }

        public void registerDataSetObserver(DataSetObserver observer) {
            mBaseAdapter.registerDataSetObserver(observer);
        }

        public void unregisterDataSetObserver(DataSetObserver observer) {
            mBaseAdapter.unregisterDataSetObserver(observer);
        }
    }
}

2.调整您的自定义适配器

请注意， getView()中的 parent 不一定总是 Spinner .

Be careful that parent in getView() might not always be a Spinner.

private class SimpleSpinnerAdapter extends BaseAdapter {

    private LayoutInflater mInflater;
    private int mResource;


    public SimpleSpinnerAdapter(Context context, int resource) {
        mInflater = LayoutInflater.from(context);
        mResource = resource;
    }


    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        return createViewFromResource(
                mInflater,
                ((Spinner) parent).getSelectedItemPosition(),
                convertView,
                parent,
                mResource);
    }

    @Override
    public View getDropDownView(int position, View convertView, ViewGroup parent) {
        return createViewFromResource(
                mInflater,
                position,
                convertView,
                parent,
                mResource);
    }

    protected View createViewFromResource(LayoutInflater inflater, int position, 
                                          View convertView, ViewGroup parent,
                                          int resource) {
        View view;
        if (convertView == null) {
            view = inflater.inflate(resource, parent, false);
        } else {
            view = convertView;
        }

        bindView(position, view);

        return view;
    }

    protected void bindView(int position, View view) {
        // Bind your view.
    }

    // getCount(), getItem(), and getItemId() methods.
}

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