经常有这样的需求，你的功能图标要像一个个物品，摆放在书架上，像这样：
我的思路比较简单，重载GridView，在他绘制子视图前，先把背景绘制完成
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public class RowGridView extends GridView { private static String NAMESPACE_ANDROID = "http://schemas.android.com/apk/res/android"; private Bitmap rowBackground; private int rowBgHeight; private int columnNum; public RowGridView(Context context, AttributeSet attrs){ super(context,attrs); //获得列数 columnNum = attrs.getAttributeIntValue(NAMESPACE_ANDROID,"numColumns",3); //获取自定义属性 TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.row_bg_grid_view); rowBgHeight = a.getDimensionPixelSize(R.styleable.row_bg_grid_view_row_bg_height,50); int row_bg_resource = a.getResourceId(R.styleable.row_bg_grid_view_row_background,-1); rowBackground = BitmapFactory.decodeResource(getResources(),row_bg_resource); } @Override protected void dispatchDraw(Canvas canvas){ //行高 int rHeight = getChildAt(0).getHeight(); int width = getWidth(); int rowNum = (int)Math.ceil(getChildCount()/(double)columnNum); //源绘制矩形 Rect src = new Rect(0,0,rowBackground.getWidth(),rowBackground.getHeight()); for(int i=0,y=rHeight-(rowBgHeight/2); i<rowNum; i++,y += rHeight){ //目的绘制矩形 Rect dst = new Rect(0,y,width,y+rowBgHeight); canvas.drawBitmap(rowBackground,src,dst,null); } super.dispatchDraw(canvas); }} |
上面第11行有这样一句
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columnNum = attrs.getAttributeIntValue(NAMESPACE_ANDROID,"numColumns",3); |
为什么不用getNumColumns？因为这个函数需要api level 11（即Android 3.0以上），而且有可能返回-1
两个自定义属性：背景和背景高度，在values/attrs.xml定义如下
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<?xml version="1.0" encoding="utf-8"?><resources> <declare-styleable name="row_bg_grid_view"> <attr name="row_background" format="reference"/> <attr name="row_bg_height" format="dimension" /> </declare-styleable></resources> |
最后使用的方法
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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical"> <com.best.oa.common.base.RowGridView android:id="@+id/functions" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_marginTop="20dip" android:layout_weight="1" android:numColumns="2" oa:row_background="@drawable/grid_row_bg" oa:row_bg_height="60dip" android:stretchMode="columnWidth"> </com.best.oa.common.base.RowGridView></LinearLayout> |