Android的:如何GridView的auto_fit找到列数? [英] Android: How does GridView auto_fit find the number of columns?
问题描述
我想更好地了解如何的GridView
的作品,特别是 auto_fit
。
下面是XML布局:
I would like to understand better how Gridview
works, in particular auto_fit
.
Here is the XML layout:
<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/gridview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:columnWidth="60dp"
android:numColumns="auto_fit"
/>
和它工作正常了一系列的六个缩略图(48 * 48像素)。在纵向模式下,它会显示一排,六列。
And it works fine with a series of six thumbnails (48*48 pixels). In portrait mode, it displays one row, six columns.
我不明白的是为什么行安卓columnWidth中=60dp
是必要的,因为<一href="http://developer.android.com/reference/android/widget/GridView.html#attr_android%3anumColumns">auto_fit预计将发现列的正确数量。
如果没有行安卓columnWidth中=60dp
,它会显示一个网格3行2列
What I don't understand is why the line android:columnWidth="60dp"
is necessary, because auto_fit is expected to find the right number of columns.
Without the line android:columnWidth="60dp"
, it displays a grid 3 rows and 2 columns.
下面是 ImageAdapter
类:
package com.examples.HelloGridView;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
public class ImageAdapter extends BaseAdapter {
private Context mContext;
public ImageAdapter(Context c) {
mContext = c;
}
public int getCount() {
return mThumbIds.length;
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) { // if it's not recycled, initialize some attributes
imageView = new ImageView(mContext);
imageView.setPadding(0, 0, 0, 0);
} else {
imageView = (ImageView) convertView;
}
imageView.setImageResource(mThumbIds[position]);
return imageView;
}
// references to our images
private Integer[] mThumbIds = {
R.drawable.ic_1, R.drawable.ic_2,
R.drawable.ic_3, R.drawable.ic_4,
R.drawable.ic_5, R.drawable.ic_6
};
}
感谢您的帮助。
推荐答案
看着GridView的来源,很显然,设置填充和您的ImageView的高度不会帮你的。如果未指定列的宽度,它只是选择列的preSET数(2):
Looking at the GridView source, it is clear that setting the padding and the height on your ImageView will not help you at all. When a column width is not specified, it just chooses a preset number of columns (2):
private void determineColumns(int availableSpace) {
...
if (mRequestedNumColumns == AUTO_FIT) {
if (requestedColumnWidth > 0) {
// Client told us to pick the number of columns
mNumColumns = (availableSpace + requestedHorizontalSpacing) /
(requestedColumnWidth + requestedHorizontalSpacing);
} else {
// Just make up a number if we don't have enough info
mNumColumns = 2;
}
} else {
// We picked the columns
mNumColumns = mRequestedNumColumns;
}
if (mNumColumns <= 0) {
mNumColumns = 1;
}
...
解决的办法是设置GridView的列宽之前来衡量你的列大小。这里是一个快速的方法来测量屏外浏览次数:
The solution is to measure your column size before setting the GridView's column width. Here is a quick way to measure Views offscreen:
public int measureCellWidth( Context context, View cell )
{
// We need a fake parent
FrameLayout buffer = new FrameLayout( context );
android.widget.AbsListView.LayoutParams layoutParams = new android.widget.AbsListView.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
buffer.addView( cell, layoutParams);
cell.forceLayout();
cell.measure(1000, 1000);
int width = cell.getMeasuredWidth();
buffer.removeAllViews();
return width;
}
然后你只需设置GridView的列宽:
And then you just set the GridView's column width:
gridView.setColumnWidth( width );
这篇关于Android的:如何GridView的auto_fit找到列数?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!