如何向GridView添加页脚?

我试图从这里找到的一个示例对gridview进行反向工程: https://github.com/liaohuqiu/android-GridViewWithHeaderAndFooter

使用他在这里找到的源代码:

https://github.com/liaohuqiu/android-cube-app/blob/master/src/in/srain/cube/demo/ui/fragment/GridViewWithHeaderAndFooterFragment.java#L89

但当我试图在其中显示图像时,会出现一个投射错误。 我想学习如何自己做,因为当我尝试使用glide加载图像时,他的代码崩溃了。

这是我的gridview代码:

package customgridapp.customgridview;

import android.annotation.SuppressLint;
import android.content.Context;
import android.database.DataSetObservable;
import android.database.DataSetObserver;
import android.os.Build;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.Filter;
import android.widget.Filterable;
import android.widget.FrameLayout;
import android.widget.GridView;
import android.widget.ListAdapter;
import android.widget.WrapperListAdapter;

import java.util.ArrayList;

public class TestFooterGridView extends GridView{

private static final String TAG = "TestFooterGridView";

/**
 * A class that represents a fixed view in a list, for example a header at the top
 * or a footer at the bottom.
 */
private static class FixedViewInfo {
    /**
     * The view to add to the grid
     */
    public View view;
    public ViewGroup viewContainer;
    /**
     * The data backing the view. This is returned from {@link ListAdapter#getItem(int)}.
     */
    public Object data;
    /**
     * <code>true</code> if the fixed view should be selectable in the grid
     */
    public boolean isSelectable;
}

private ArrayList<FixedViewInfo> mHeaderViewInfos = new ArrayList<FixedViewInfo>();

private ArrayList<FixedViewInfo> mFooterViewInfos = new ArrayList<FixedViewInfo>();

private int mRequestedNumColumns;

private int mNumColmuns = 1;

private void initHeaderGridView() {
    super.setClipChildren(false);
}

public TestFooterGridView(Context context) {
    super(context);
    initHeaderGridView();
}

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

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

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

    if (mRequestedNumColumns != AUTO_FIT) {
        mNumColmuns = mRequestedNumColumns;
    }
    if (mNumColmuns <= 0) {
        mNumColmuns = 1;
    }

    ListAdapter adapter = getAdapter();
    if (adapter != null && adapter instanceof FooterViewGridAdapter) {
        ((FooterViewGridAdapter) adapter).setNumColumns(getNumColumns());
    }
}

@Override
public void setClipChildren(boolean clipChildren) {
    // Ignore, since the header rows depend on not being clipped
}

/**
 * Add a fixed view to appear at the top of the grid. If addHeaderView is
 * called more than once, the views will appear in the order they were
 * added. Views added using this call can take focus if they want.
 * <p>
 * NOTE: Call this before calling setAdapter. This is so HeaderFooterGridView can wrap
 * the supplied cursor with one that will also account for header views.
 *
 * @param v            The view to add.
 * @param data         Data to associate with this view
 * @param isSelectable whether the item is selectable
 */
public void addHeaderView(View v, Object data, boolean isSelectable) {
    ListAdapter adapter = getAdapter();

    if (adapter != null && !(adapter instanceof FooterViewGridAdapter)) {
        throw new IllegalStateException(
                "Cannot add header view to grid -- setAdapter has already been called.");
    }

    FixedViewInfo info = new FixedViewInfo();
  //  FrameLayout fl = new FullWidthFixedViewLayout(getContext());
  //  fl.addView(v);
    info.view = v;
  //  info.viewContainer = fl;
    info.data = data;
    info.isSelectable = isSelectable;
    mHeaderViewInfos.add(info);

    // in the case of re-adding a header view, or adding one later on,
    // we need to notify the observer
    if (adapter != null) {
        ((FooterViewGridAdapter) adapter).notifyDataSetChanged();
    }
}
/**
 * Add a fixed view to appear at the bottom of the grid. If addFooterView is
 * called more than once, the views will appear in the order they were
 * added. Views added using this call can take focus if they want.
 * <p>
 * NOTE: Call this before calling setAdapter. This is so HeaderFooterGridView can wrap
 * the supplied cursor with one that will also account for header views.
 *
 * @param v            The view to add.
 * @param data         Data to associate with this view
 * @param isSelectable whether the item is selectable
 */
public void addFooterView(View v, Object data, boolean isSelectable) {
    ListAdapter adapter = getAdapter();

    if (adapter != null && !(adapter instanceof FooterViewGridAdapter)) {
        throw new IllegalStateException(
                "Cannot add footer view to grid -- setAdapter has already been called.");
    }

    FixedViewInfo info = new FixedViewInfo();
    FrameLayout fl = new FullWidthFixedViewLayout(getContext());
    fl.addView(v);
    info.view = v;
    info.viewContainer = fl;
    info.data = data;
    info.isSelectable = isSelectable;
    mFooterViewInfos.add(info);

    // in the case of re-adding a header view, or adding one later on,
    // we need to notify the observer
    if (adapter != null) {
        ((FooterViewGridAdapter) adapter).notifyDataSetChanged();

    }
}

/**
 * Add a fixed view to appear at the bottom of the grid. If addFooterView is
 * called more than once, the views will appear in the order they were
 * added. Views added using this call can take focus if they want.
 * <p>
 * NOTE: Call this before calling setAdapter. This is so HeaderFooterGridView can wrap
 * the supplied cursor with one that will also account for header views.
 *
 * @param v The view to add.
 */
public void addFooterView(View v) {
    addFooterView(v, null, false);
}

private void removeFixedViewInfo(View v, ArrayList<FixedViewInfo> where) {
    int len = where.size();
    for (int i = 0; i < len; ++i) {
        FixedViewInfo info = where.get(i);
        if (info.view == v) {
            where.remove(i);
            break;
        }
    }
}

@Override
public void setAdapter(ListAdapter adapter) {
    if (mHeaderViewInfos.size() > 0 || mFooterViewInfos.size() > 0) {
        FooterViewGridAdapter hadapter = new FooterViewGridAdapter(mFooterViewInfos, adapter);
        int numColumns = getNumColumns();
        if (numColumns > 1) {
            hadapter.setNumColumns(numColumns);
        }
        super.setAdapter(hadapter);
    } else {
        super.setAdapter(adapter);
    }
}

private class FullWidthFixedViewLayout extends FrameLayout {
    public FullWidthFixedViewLayout(Context context) {
        super(context);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int targetWidth = TestFooterGridView.this.getMeasuredWidth()
                - TestFooterGridView.this.getPaddingLeft()
                - TestFooterGridView.this.getPaddingRight();
        widthMeasureSpec = MeasureSpec.makeMeasureSpec(targetWidth,
                MeasureSpec.getMode(widthMeasureSpec));
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
}

@Override
public void setNumColumns(int numColumns) {
    super.setNumColumns(numColumns);
    // Store specified value for less than Honeycomb.
    mRequestedNumColumns = numColumns;
}

@Override
@SuppressLint("NewApi")
public int getNumColumns() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        return super.getNumColumns();
    }

    // Return value for less than Honeycomb.
    return mNumColmuns;
}

/**
 * ListAdapter used when a HeaderFooterGridView has header views. This ListAdapter
 * wraps another one and also keeps track of the header views and their
 * associated data objects.
 * <p>This is intended as a base class; you will probably not need to
 * use this class directly in your own code.
 */
private static class FooterViewGridAdapter implements WrapperListAdapter, Filterable {

    // This is used to notify the container of updates relating to number of columns
    // or headers changing, which changes the number of placeholders needed
    private final DataSetObservable mDataSetObservable = new DataSetObservable();

    private final ListAdapter mAdapter;
    private int mNumColumns = 1;

    // This ArrayList is assumed to NOT be null.


    ArrayList<FixedViewInfo> mFooterViewInfos;

    boolean mAreAllFixedViewsSelectable;

    private final boolean mIsFilterable;

    public FooterViewGridAdapter(ArrayList<FixedViewInfo> footerViewInfos, ListAdapter adapter) {
        mAdapter = adapter;
        mIsFilterable = adapter instanceof Filterable;

        if (footerViewInfos == null) {
            throw new IllegalArgumentException("footerViewInfos cannot be null");
        }
        mFooterViewInfos = footerViewInfos;

        mAreAllFixedViewsSelectable = areAllListInfosSelectable(mFooterViewInfos);
    }

    public int getHeadersCount() {
        return 0;
    }

    public int getFootersCount() {
        return mFooterViewInfos.size();
    }

    @Override
    public boolean isEmpty() {
        return (mAdapter == null || mAdapter.isEmpty()) && getHeadersCount() == 0 && getFootersCount() == 0;
    }

    public void setNumColumns(int numColumns) {
        if (numColumns < 1) {
            throw new IllegalArgumentException("Number of columns must be 1 or more");
        }
        if (mNumColumns != numColumns) {
            mNumColumns = numColumns;
            notifyDataSetChanged();
        }
    }

    private boolean areAllListInfosSelectable(ArrayList<FixedViewInfo> infos) {
        if (infos != null) {
            for (FixedViewInfo info : infos) {
                if (!info.isSelectable) {
                    return false;
                }
            }
        }
        return true;
    }


    public boolean removeFooter(View v) {
        for (int i = 0; i < mFooterViewInfos.size(); i++) {
            FixedViewInfo info = mFooterViewInfos.get(i);
            if (info.view == v) {
                mFooterViewInfos.remove(i);

                mAreAllFixedViewsSelectable = areAllListInfosSelectable(mFooterViewInfos);

                mDataSetObservable.notifyChanged();
                return true;
            }
        }

        return false;
    }

    @Override
    public int getCount() {
        if (mAdapter != null) {
            final int lastRowItemCount = (mAdapter.getCount() % mNumColumns);
            final int emptyItemCount = ((lastRowItemCount == 0) ? 0 : mNumColumns - lastRowItemCount);
            return (getHeadersCount() * mNumColumns) + mAdapter.getCount() + emptyItemCount + (getFootersCount() * mNumColumns);
        } else {
            return (getHeadersCount() * mNumColumns) + (getFootersCount() * mNumColumns);
        }
    }

    @Override
    public boolean areAllItemsEnabled() {
        if (mAdapter != null) {
            return mAreAllFixedViewsSelectable && mAdapter.areAllItemsEnabled();
        } else {
            return true;
        }
    }

    @Override
    public boolean isEnabled(int position) {
        // Header (negative positions will throw an ArrayIndexOutOfBoundsException)
        int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
        if (position < numHeadersAndPlaceholders) {

            return (position % mNumColumns == 0);
                   // && mHeaderViewInfos.get(position / mNumColumns).isSelectable;
        }

        // Adapter
        if (position < numHeadersAndPlaceholders + mAdapter.getCount()) {


            final int adjPosition = position - numHeadersAndPlaceholders;
            int adapterCount = 0;
            if (mAdapter != null) {
                adapterCount = mAdapter.getCount();
                if (adjPosition < adapterCount) {
                     return mAdapter.isEnabled(adjPosition);
                }
            }
        }

        // Empty item
        final int lastRowItemCount = (mAdapter.getCount() % mNumColumns);
        final int emptyItemCount = ((lastRowItemCount == 0) ? 0 : mNumColumns - lastRowItemCount);
        if (position < numHeadersAndPlaceholders + mAdapter.getCount() + emptyItemCount) {

           // return false;
            return (position % mNumColumns == 0)
                    && mFooterViewInfos.get((position - numHeadersAndPlaceholders - mAdapter.getCount() - emptyItemCount) / mNumColumns).isSelectable;
        }

        // Footer
        int numFootersAndPlaceholders = getFootersCount() * mNumColumns;
        if (position < numHeadersAndPlaceholders + mAdapter.getCount() + emptyItemCount + numFootersAndPlaceholders) {

            return (position % mNumColumns == 0)
                    && mFooterViewInfos.get((position - numHeadersAndPlaceholders - mAdapter.getCount() - emptyItemCount) / mNumColumns).isSelectable;
        }

        throw new ArrayIndexOutOfBoundsException(position);
    }

    @Override
    public Object getItem(int position) {
        // Header (negative positions will throw an ArrayIndexOutOfBoundsException)
        int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
        if (position < numHeadersAndPlaceholders) {


            if (position % mNumColumns == 0) {

                return 0; //mHeaderViewInfos.get(position / mNumColumns).data;
            }
            return null;
        }

        // Adapter
        if (position < numHeadersAndPlaceholders + mAdapter.getCount()) {


            final int adjPosition = position - numHeadersAndPlaceholders;
            int adapterCount = 0;
            if (mAdapter != null) {
                adapterCount = mAdapter.getCount();
                if (adjPosition < adapterCount) {


                    return mAdapter.getItem(adjPosition);
                }
            }
        }

        // Empty item
        final int lastRowItemCount = (mAdapter.getCount() % mNumColumns);
        Log.e(TAG, "Lastrowitemcount:" + lastRowItemCount);
        final int emptyItemCount = ((lastRowItemCount == 0) ? 0 : mNumColumns - lastRowItemCount);
        Log.e(TAG, "emptyitemcount:" + emptyItemCount);
        if (position < numHeadersAndPlaceholders + mAdapter.getCount() + emptyItemCount) {

            /*return null;*/
            return mFooterViewInfos.get((position - numHeadersAndPlaceholders - mAdapter.getCount() - emptyItemCount) / mNumColumns).data;
        }

        // Footer
        int numFootersAndPlaceholders = getFootersCount() * mNumColumns;
        if (position < numHeadersAndPlaceholders + mAdapter.getCount() + emptyItemCount + numFootersAndPlaceholders) {


            if (position % mNumColumns == 0) {


                return mFooterViewInfos.get((position - numHeadersAndPlaceholders - mAdapter.getCount() - emptyItemCount) / mNumColumns).data;
            }
        }

        throw new ArrayIndexOutOfBoundsException(position);
    }

    @Override
    public long getItemId(int position) {
        int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
        if (mAdapter != null) {
            if (position >= numHeadersAndPlaceholders && position < numHeadersAndPlaceholders + mAdapter.getCount()) {

                int adjPosition = position - numHeadersAndPlaceholders;
                int adapterCount = mAdapter.getCount();
                if (adjPosition < adapterCount) {

                    return mAdapter.getItemId(adjPosition);
                }
            }
        }
        return -1;
    }
    @Override
    public boolean hasStableIds() {
        if (mAdapter != null) {
            return mAdapter.hasStableIds();
        }
        return false;
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Header (negative positions will throw an ArrayIndexOutOfBoundsException)
        int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
        if (position < numHeadersAndPlaceholders) {
            /*View headerViewContainer = mHeaderViewInfos
                    .get(position / mNumColumns).viewContainer;*/
            if (position % mNumColumns == 0) {

                return null; //headerViewContainer;
            } else {

                convertView = new View(parent.getContext());
                // We need to do this because GridView uses the height of the last item
                // in a row to determine the height for the entire row.
                convertView.setVisibility(View.INVISIBLE);
             //   convertView.setMinimumHeight(headerViewContainer.getHeight());
                return convertView;
            }
        }
        // Adapter
      //  TODO Current implementation may not be enough in the case of 3 or more column. May need to be careful on the INVISIBLE View height.
        if (position < numHeadersAndPlaceholders + mAdapter.getCount()) {

            final int adjPosition = position - numHeadersAndPlaceholders;
            int adapterCount = 0;
            if (mAdapter != null) {
                adapterCount = mAdapter.getCount();
                if (adjPosition < adapterCount) {

                    convertView = mAdapter.getView(adjPosition, convertView, parent);
                    convertView.setVisibility(View.VISIBLE);
                    return convertView;
                }
            }
        }
        // Empty item
        final int lastRowItemCount = (mAdapter.getCount() % mNumColumns);
        Log.e(TAG, "Lastrowitemcount:" + lastRowItemCount);
        final int emptyItemCount = ((lastRowItemCount == 0) ? 0 : mNumColumns - lastRowItemCount);
        Log.e(TAG, "Emptyitemcount:" + emptyItemCount);
        if (position < numHeadersAndPlaceholders + mAdapter.getCount() + emptyItemCount) {

            // We need to do this because GridView uses the height of the last item
            // in a row to determine the height for the entire row.
            // TODO Current implementation may not be enough in the case of 3 or more column. May need to be careful on the INVISIBLE View height.
            convertView = mAdapter.getView(mAdapter.getCount() - 1, convertView, parent);
            convertView.setVisibility(View.INVISIBLE);
            return convertView;
        }
        // Footer
        int numFootersAndPlaceholders = getFootersCount() * mNumColumns;
        if (position < numHeadersAndPlaceholders + mAdapter.getCount()  + emptyItemCount + numFootersAndPlaceholders) {


            View footerViewContainer = mFooterViewInfos
                    .get((position - numHeadersAndPlaceholders - mAdapter.getCount() - emptyItemCount) / mNumColumns).viewContainer;
            if (position % mNumColumns == 0) {

                return footerViewContainer;
            } else {

                convertView = new View(parent.getContext());
                // We need to do this because GridView uses the height of the last item
                // in a row to determine the height for the entire row.
                convertView.setVisibility(View.INVISIBLE);
                convertView.setMinimumHeight(footerViewContainer.getHeight());
                return convertView;
            }
        }
        throw new ArrayIndexOutOfBoundsException(position);
    }
    @Override
    public int getItemViewType(int position) {
        int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
        if (position < numHeadersAndPlaceholders && (position % mNumColumns != 0)) {

            // Placeholders get the last view type number
            return mAdapter != null ? mAdapter.getViewTypeCount() : 1;
        }
        if (mAdapter != null && position >= numHeadersAndPlaceholders && position < numHeadersAndPlaceholders + mAdapter.getCount() + (mNumColumns - (mAdapter.getCount() % mNumColumns))) {
            int adjPosition = position - numHeadersAndPlaceholders;
            int adapterCount = mAdapter.getCount();
            if (adjPosition < adapterCount) {
                return mAdapter.getItemViewType(adjPosition);
            } else if (adapterCount != 0 && mNumColumns != 1) {
                return mAdapter.getItemViewType(adapterCount - 1);
            }
        }
        int numFootersAndPlaceholders = getFootersCount() * mNumColumns;
        if (mAdapter != null && position < numHeadersAndPlaceholders + mAdapter.getCount() + numFootersAndPlaceholders) {

            return mAdapter != null ? mAdapter.getViewTypeCount() : 1;
        }
        return AdapterView.ITEM_VIEW_TYPE_HEADER_OR_FOOTER;
    }
    @Override
    public int getViewTypeCount() {
        if (mAdapter != null) {
            return mAdapter.getViewTypeCount() + 1;
        }
        return 2;
    }
    @Override
    public void registerDataSetObserver(DataSetObserver observer) {
        mDataSetObservable.registerObserver(observer);
        if (mAdapter != null) {
            mAdapter.registerDataSetObserver(observer);
        }
    }
    @Override
    public void unregisterDataSetObserver(DataSetObserver observer) {
        mDataSetObservable.unregisterObserver(observer);
        if (mAdapter != null) {
            mAdapter.unregisterDataSetObserver(observer);
        }
    }
    @Override
    public Filter getFilter() {
        if (mIsFilterable) {
            return ((Filterable) mAdapter).getFilter();
        }
        return null;
    }
    @Override
    public ListAdapter getWrappedAdapter() {
        return mAdapter;
    }
    public void notifyDataSetChanged() {
        mDataSetObservable.notifyChanged();
    }
}

}

我试着通过删除任何与页眉相关的代码来理解他的代码,只看他对页脚的处理。

简而言之:如何向三列网格视图添加页脚? 我需要什么?