Android:水平居中 gridview [英] Android: center gridview horizontally

问题描述

我需要在我的 android layout.xml 中水平居中网格视图.我已经在谷歌上搜索了一段时间，但没有成功找到答案.

I need to center grid view horizontally in my android layout.xml. I have searched google for quite a while but didnt succeed in finding an answer.

我只能通过更改 strechMode 来更改 gridview 的水平位置，但是我的项目彼此并不靠近.我需要的是项目彼此靠近(没有空格)并水平居中.我选择 strechmode = none，所以现在我的项目彼此靠近，但它们位于屏幕左侧，我只希望它们水平居中.

I can only change gridview horizontal position by changing strechMode, but then my items are not near one another. that i need is items be one near another (without spaces) and centered horizontally. I choose strechmode = none, so now my items are near one another, but they are on the left of the screen, i just want them to be centered horizontally.

这是我的布局 xml:

Here is my layout xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="fill_parent" 
          android:layout_height="fill_parent"
          android:background="@drawable/background" 
          android:gravity="center">

<GridView android:id="@+id/lw_gridview" 
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:numColumns="3" 
          android:columnWidth="48dp"
          android:horizontalSpacing="0dp"
          android:verticalSpacing="0dp"
          android:stretchMode="none"
          />


</LinearLayout>

这是由图像适配器在 gridview 上设置的图像片段:

Here is fragment of an image which is set on gridview by image adapter:

imageView = new ImageView(context);
imageView.setLayoutParams(new GridView.LayoutParams(48,48)); //on medium density
imageView.setScaleType(ImageView.ScaleType.CENTER);
imageView.setPadding(0, 0, 0, 0);

我怎样才能成功?

推荐答案

我通过计算和设置其填充手动将网格视图居中.这是我的 onCreate 所做的:

I centered my grid view manually, by calculating and setting its padding. Here's what my onCreate does:

• 找出屏幕的宽度和屏幕密度
• 将项目宽度和间距的常量值从 DIP 转换为像素
• 计算我可以容纳的列数.

方程看起来像这样，numColumns 是唯一未知的:

Equation looks like this, numColumns is the only unknown:

numColumns * itemWidth + (numColumns - 1) * spatialBetweenItems + selectorPadding <= sreenWidth

• 有 numColumns，计算我的网格视图实际需要多少水平空间
• 具有网格视图的实际宽度，设置填充以使其位于屏幕中央

• having numColumns, calculate how much horizontal space my grid view will actually need
• having actual width of grid view, set padding so that it ends up in the center of screen

好的，这是一些代码:

// Convert DIPs to pixels
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
mSizePx = (int) Math.floor(SIZE_DIP * metrics.scaledDensity);
mSpacingPx = (int) Math.floor(SPACING_DIP * metrics.scaledDensity);

GridView gridview = (GridView) findViewById(R.id.gridview);
// Find out the extra space gridview uses for selector on its sides.
Rect p = new Rect();
gridview.getSelector().getPadding(p);
int selectorPadding = p.left + p.right;

// Determine the number of columns we can fit, given screen width,
// thumbnail width, and spacing between thumbnails.
int numColumns = (int) Math.floor(1f * (metrics.widthPixels - selectorPadding + mSpacingPx)
        / (mSizePx + mSpacingPx));

int contentWidth = numColumns * mSizePx; // Width of items
contentWidth += (numColumns - 1) * mSpacingPx; // Plus spaces between items
contentWidth += selectorPadding; // Plus extra space for selector on sides

// Now calculate amount of left and right margin so the grid gets
// centered. This is what we
// unfortunately cannot do with layout_width="wrap_content"
// and layout_gravity="center_horizontal"
int slack = metrics.widthPixels - contentWidth;

gridview.setNumColumns(numColumns);
gridview.setPadding(slack / 2, slack / 2, slack / 2, slack / 2);

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