一、item设置的高度和宽度不起作用
转自:http://www.cnblogs.com/0616--ataozhijia/p/6031875.html
[Android Pro] listView和GridView的item设置的高度和宽度不起作用
referece to : http://blog.csdn.net/beibeixiao/article/details/9032569
1. 在Android开发中会发现,有时listView和GridView的item顶层布局不起作用,即不能设置高度和宽度
原因是当用自定义的adapter时,如果使用convertView= mInflater.inflate(R.layout.material_grid_item, null)
方法就不会起作用,这个 方法的第二个参数是父View,传入为空,所以没有加载顶层布局,此时如果使用
convertView= mInflater.inflate(R.layout.material_grid_item, parent,false);传入parent设置的高度和宽度就会起作用了。
二、自动适配列数
转自:http://blog.csdn.net/archer_zoro/article/details/43500389
写了一个展示多张图片的gridview(几乎每个listview里面都有一个gridview)
之前用auto_fit和设置列宽来控制列数,以达到自适应的目的。
- this.setNumColumns(GridView.AUTO_FIT);
- this.setColumnWidth(getResources().getDimensionPixelSize(R.dimen.item_image_size));
- this.setHorizontalSpacing(getResources().getDimensionPixelSize(R.dimen.item_image_spacing));
- this.setVerticalSpacing(getResources().getDimensionPixelSize(R.dimen.item_image_spacing));
这样的效果就是图片宽度最小为item_image_size,会在接近这个大小的情况下,自动调整一些大小将gridview占满,间隔不变。3列。
而后来在720p以上的手机上运行时,变成了4列,但是要求是3列,于是我把列数从auto_fit改成了3,依然是上面的显示效果,
但是,在滑动listview的过程中明显比刚才卡顿了,所以有改回了auto_fit,转而把item_image_size增大了。
原理不清楚,留下这个坑待研究
转自:http://blog.csdn.net/maizangxiangwang/article/details/50913900
/**
* 获取屏幕宽度
*/
public static int getScreenWidth(Context context) {
WindowManager manager = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
Display display = manager.getDefaultDisplay();
return display.getWidth();
} public static int dipToPx(Context context, int dip) {
if(density <= 0.0F) {
density = context.getResources().getDisplayMetrics().density;
} return (int)((float)dip * density + 0.5F);
}
给gridview子项要屏幕适配,子项item宽度,高度与宽度相同
itemWidth = (getScreenWidth(this)-(3*dipToPx(this, 3)))/2;
在gridview的adapter中的getview中设置子项的参数
public View getView(int position, View convertView, ViewGroup parent) {
ViewHodler viewHodler;
String url = blogAlbumList.get(position).getAlbumUrl();
if (convertView == null) {
convertView = View.inflate(context, R.layout.celebrity_item, null);
viewHodler = new ViewHodler();
viewHodler.iv_image = (ImageView) convertView.findViewById(R.id.iv_image);
convertView.setTag(viewHodler);
} else {
viewHodler = (ViewHodler) convertView.getTag();
}
// if (viewHodler.iv_image.getTag()!=url ||viewHodler.iv_image.getTag()==null) {
ImageTools.getImageLoader().displayImage(blogAlbumList.get(position).getAlbumUrl(), viewHodler.iv_image, mDisplayImageOptions);
// viewHodler.iv_image.setTag(url);
// }
AbsListView.LayoutParams param = new AbsListView.LayoutParams(LeoApplication.itemWidth, LeoApplication.itemWidth);
convertView.setLayoutParams(param);
return convertView;
}
其实gridview有个属性.Android:stretchMode=”columnWidth"//缩放与列宽大小同步
GridView的一些特殊属性:
1.android:numColumns=”auto_fit” //GridView的列数设置为自动
2.android:columnWidth=”90dp " //每列的宽度,也就是Item的宽度
3.android:stretchMode=”columnWidth"//缩放与列宽大小同步
4.android:verticalSpacing=”10dp” //两行之间的边距
5.android:horizontalSpacing=”10dp” //两列之间的边距
6.android:cacheColorHint="#00000000" //去除拖动时默认的黑色背景
7.android:listSelector="#00000000" //去除选中时的黄色底色
8.android:scrollbars="none" //隐藏GridView的滚动条
9.android:fadeScrollbars="true" //设置为true就可以实现滚动条的自动隐藏和显示
10.android:fastScrollEnabled="true" //GridView出现快速滚动的按钮(至少滚动4页才会显示)
11.android:fadingEdge="none" //GridView衰落(褪去)边缘颜色为空,缺省值是vertical。(可以理解为上下边缘的提示色)
12.android:fadingEdgeLength="10dip" //定义的衰落(褪去)边缘的长度
13.android:stackFromBottom="true" //设置为true时,你做好的列表就会显示你列表的最下面
14.android:transcriptMode="alwaysScroll" //当你动态添加数据时,列表将自动往下滚动最新的条目可以自动滚动到可视范围内
15.android:drawSelectorOnTop="false" //点击某条记录不放,颜色会在记录的后面成为背景色,内容的文字可见(缺省为false)
三、添加Header和Footer
转自:http://blog.csdn.net/zhzhyang0313/article/details/39163735
实现这个功能一般有两种思路,一种思路是使用ScrollView+GridView,第二种思路是使用ListView来实现GridView的效果。
第一种思路的具体实现是把HeaderView和GridView都放到ScrollView里面,这里要解决的问题是ScrollView和GridView滑动手势的冲突问题,解决办法是让GridView充满ScrollView,不让GridView滑动而只让ScrollView滑动。具题做法是重载GridView的onMeasure()方法。
- public class MyGridView extends GridView {
- public MyGridView(Context context, AttributeSet attrs) {
- super(context, attrs);
- }
- public MyGridView(Context context) {
- super(context);
- }
- public MyGridView(Context context, AttributeSet attrs, int defStyle) {
- super(context, attrs, defStyle);
- }
- @Override
- public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
- int expandSpec = MeasureSpec.makeMeasureSpec(
- Integer.MAX_VALUE >> 2, MeasureSpec.AT_MOST);
- super.onMeasure(widthMeasureSpec, expandSpec);
- }
- }
这种方法的不足是GridView中的View没有复用,如果内容较多将比较消耗内存。
第二种思路的具体实现是使用ListView的addHeaderView()来添加HeaderView,而ListView的每一行都放一个LinearLayout来保存一行的item,这里要注意的是item的个数和ListView行数的关系。
后来在*上又看到了第三中方法。原来Google已经用GridView实现了,而且很巧妙,下面把代码贴出来
- /*
- * Copyright (C) 2013 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package com.android.photos.views;
- import android.content.Context;
- import android.database.DataSetObservable;
- import android.database.DataSetObserver;
- import android.util.AttributeSet;
- 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;
- /**
- * A {@link GridView} that supports adding header rows in a
- * very similar way to {@link ListView}.
- * See {@link HeaderGridView#addHeaderView(View, Object, boolean)}
- */
- public class HeaderGridView extends GridView {
- private static final String TAG = "HeaderGridView";
- /**
- * 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 void initHeaderGridView() {
- super.setClipChildren(false);
- }
- public HeaderGridView(Context context) {
- super(context);
- initHeaderGridView();
- }
- public HeaderGridView(Context context, AttributeSet attrs) {
- super(context, attrs);
- initHeaderGridView();
- }
- public HeaderGridView(Context context, AttributeSet attrs, int defStyle) {
- super(context, attrs, defStyle);
- initHeaderGridView();
- }
- @Override
- protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
- super.onMeasure(widthMeasureSpec, heightMeasureSpec);
- ListAdapter adapter = getAdapter();
- if (adapter != null && adapter instanceof HeaderViewGridAdapter) {
- ((HeaderViewGridAdapter) 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 HeaderGridView 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 HeaderViewGridAdapter)) {
- 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) {
- ((HeaderViewGridAdapter) adapter).notifyDataSetChanged();
- }
- }
- /**
- * 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 HeaderGridView can wrap
- * the supplied cursor with one that will also account for header views.
- *
- * @param v The view to add.
- */
- public void addHeaderView(View v) {
- addHeaderView(v, null, true);
- }
- public int getHeaderViewCount() {
- return mHeaderViewInfos.size();
- }
- /**
- * Removes a previously-added header view.
- *
- * @param v The view to remove
- * @return true if the view was removed, false if the view was not a header
- * view
- */
- public boolean removeHeaderView(View v) {
- if (mHeaderViewInfos.size() > 0) {
- boolean result = false;
- ListAdapter adapter = getAdapter();
- if (adapter != null && ((HeaderViewGridAdapter) adapter).removeHeader(v)) {
- result = true;
- }
- removeFixedViewInfo(v, mHeaderViewInfos);
- return result;
- }
- return 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) {
- HeaderViewGridAdapter hadapter = new HeaderViewGridAdapter(mHeaderViewInfos, 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 = HeaderGridView.this.getMeasuredWidth()
- - HeaderGridView.this.getPaddingLeft()
- - HeaderGridView.this.getPaddingRight();
- widthMeasureSpec = MeasureSpec.makeMeasureSpec(targetWidth,
- MeasureSpec.getMode(widthMeasureSpec));
- super.onMeasure(widthMeasureSpec, heightMeasureSpec);
- }
- }
- /**
- * ListAdapter used when a HeaderGridView 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 HeaderViewGridAdapter 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> mHeaderViewInfos;
- boolean mAreAllFixedViewsSelectable;
- private final boolean mIsFilterable;
- public HeaderViewGridAdapter(ArrayList<FixedViewInfo> headerViewInfos, ListAdapter adapter) {
- mAdapter = adapter;
- mIsFilterable = adapter instanceof Filterable;
- if (headerViewInfos == null) {
- throw new IllegalArgumentException("headerViewInfos cannot be null");
- }
- mHeaderViewInfos = headerViewInfos;
- mAreAllFixedViewsSelectable = areAllListInfosSelectable(mHeaderViewInfos);
- }
- public int getHeadersCount() {
- return mHeaderViewInfos.size();
- }
- @Override
- public boolean isEmpty() {
- return (mAdapter == null || mAdapter.isEmpty()) && getHeadersCount() == 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 removeHeader(View v) {
- for (int i = 0; i < mHeaderViewInfos.size(); i++) {
- FixedViewInfo info = mHeaderViewInfos.get(i);
- if (info.view == v) {
- mHeaderViewInfos.remove(i);
- mAreAllFixedViewsSelectable = areAllListInfosSelectable(mHeaderViewInfos);
- mDataSetObservable.notifyChanged();
- return true;
- }
- }
- return false;
- }
- @Override
- public int getCount() {
- if (mAdapter != null) {
- return getHeadersCount() * mNumColumns + mAdapter.getCount();
- } else {
- return getHeadersCount() * 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
- final int adjPosition = position - numHeadersAndPlaceholders;
- int adapterCount = 0;
- if (mAdapter != null) {
- adapterCount = mAdapter.getCount();
- if (adjPosition < adapterCount) {
- return mAdapter.isEnabled(adjPosition);
- }
- }
- 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 mHeaderViewInfos.get(position / mNumColumns).data;
- }
- return null;
- }
- // Adapter
- final int adjPosition = position - numHeadersAndPlaceholders;
- int adapterCount = 0;
- if (mAdapter != null) {
- adapterCount = mAdapter.getCount();
- if (adjPosition < adapterCount) {
- return mAdapter.getItem(adjPosition);
- }
- }
- throw new ArrayIndexOutOfBoundsException(position);
- }
- @Override
- public long getItemId(int position) {
- int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
- if (mAdapter != null && position >= numHeadersAndPlaceholders) {
- 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 headerViewContainer;
- } else {
- if (convertView == null) {
- 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
- final int adjPosition = position - numHeadersAndPlaceholders;
- int adapterCount = 0;
- if (mAdapter != null) {
- adapterCount = mAdapter.getCount();
- if (adjPosition < adapterCount) {
- return mAdapter.getView(adjPosition, convertView, parent);
- }
- }
- 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) {
- int adjPosition = position - numHeadersAndPlaceholders;
- int adapterCount = mAdapter.getCount();
- if (adjPosition < adapterCount) {
- return mAdapter.getItemViewType(adjPosition);
- }
- }
- 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();
- }
- }
- }
代码地址:https://android.googlesource.com/platform/packages/apps/Gallery2/+/idea133/src/com/android/photos/