怎么在Android中点击overlay弹出带尾巴的气泡

1.在res/layout目录下建立pop view的xml文件:overlay_pop.xml

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<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"	android:orientation="vertical" android:background="@drawable/bubble_background"	android:layout_width="wrap_content" android:layout_height="wrap_content"	android:paddingLeft="5px" android:paddingTop="5px"	android:paddingRight="5px" android:paddingBottom="20px">	<TextView android:id="@+id/map_bubbleTitle" android:ellipsize="marquee"		style="@style/map_BubblePrimary" android:layout_width="fill_parent"		android:layout_height="wrap_content" android:gravity="center_horizontal"		android:singleLine="true" />	<TextView android:id="@+id/map_bubbleText" style="@style/map_BubbleSecondary"		android:layout_width="fill_parent" android:layout_height="wrap_content"		android:singleLine="false" /></LinearLayout>

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?其中用到的style是放在res/values中的style.xml

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<?xml version="1.0" encoding="utf-8"?><resources>	<style name="map_BubblePrimary">		<item name="android:textStyle">bold</item>		<item name="android:typeface">monospace</item>		<item name="android:textColor">#000</item>	</style>	<style name="map_BubbleSecondary">		<item name="android:textStyle">italic</item>		<item name="android:textColor">#000</item>	</style></resources>

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?另外，作为背景的bubble_background图片是采用采用9.png的格式：

在onCreate中：

MapView是继承自ViewGroup?的,因此,MapView有addView()方法,同时还有MapView.LayoutParams
MapView.LayoutParams 可以根据GeoPoint来定位,我就是利用这个特性来定位弹出的popView的.

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View popView = View.inflate(this, R.layout.overlay_pop, null);mapView.addView(popView, new MapView.LayoutParams(MapView.LayoutParams.WRAP_CONTENT,		MapView.LayoutParams.WRAP_CONTENT, null, MapView.LayoutParams.BOTTOM_CENTER));popView.setVisibility(View.GONE);

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?2.实现点击某个Overlay弹出popView。

overlay有onTap()方法,你可以实现自己的overlay onTap()方法,弹出popView,
也可以使用setOnFocusChangeListener(),在listener中实现弹出popView,.
我是用的listener,因为setOnFocusChangeListener在失去焦点也会触发,我可以再失去焦点的时候隐藏popView.

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/**	 * 气泡窗口监听器	 */	private final ItemizedOverlay.OnFocusChangeListener onFocusChangeListener = new ItemizedOverlay.OnFocusChangeListener() {		@Override		public void onFocusChanged(ItemizedOverlay overlay, OverlayItem newFocus) {			// 创建气泡窗口			if (popView != null) {				popView.setVisibility(View.GONE);			}			if (newFocus != null) {				MapView.LayoutParams geoLP = (MapView.LayoutParams) popView.getLayoutParams();				geoLP.point = newFocus.getPoint();// 这行用于popView的定位				TextView title = (TextView) popView.findViewById(R.id.map_bubbleTitle);				title.setText(newFocus.getTitle());				TextView desc = (TextView) popView.findViewById(R.id.map_bubbleText);				if (newFocus.getSnippet() == null || newFocus.getSnippet().length() == 0) {					desc.setVisibility(View.GONE);				} else {					desc.setVisibility(View.VISIBLE);					desc.setText(newFocus.getSnippet());				}				mapView.updateViewLayout(popView, geoLP);				popView.setVisibility(View.VISIBLE);			}		}	};

?3.自己实现一个继承自ItemizedOverlay的Overlay，

Overlay中有一个

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private static final int LAYER_FLAGS = Canvas.MATRIX_SAVE_FLAG | Canvas.CLIP_SAVE_FLAG			| Canvas.HAS_ALPHA_LAYER_SAVE_FLAG | Canvas.FULL_COLOR_LAYER_SAVE_FLAG | Canvas.CLIP_TO_LAYER_SAVE_FLAG;

private final ArrayList<OverlayItem> overlayItems = new ArrayList<OverlayItem>();

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?和用于向overlayItems中添加OverlayItem的方法

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public void addOverlay(OverlayItem overlay) {	overlayItems.add(overlay);	populate();}

在override的draw方法中

@Override	public void draw(Canvas canvas, MapView mapView, boolean shadow) {		if (!shadow) {			canvas.save(LAYER_FLAGS);			Projection projection = mapView.getProjection();			int size = overlayItems.size();			Point point = new Point();			Paint paint = new Paint();			paint.setAntiAlias(true);			OverlayItem overLayItem;			for (int i = 0; i < size; i++) {				overLayItem = overlayItems.get(i);				Drawable marker = overLayItem.getMarker(0);				// marker.getBounds()				/* 象素点取得转换 */				projection.toPixels(overLayItem.getPoint(), point);				if (marker != null) {					boundCenterBottom(marker);				}				/* 圆圈 */				paint.setColor(Color.RED);				canvas.drawCircle(point.x, point.y, 5, paint);				/* 标题 */				String title = overLayItem.getTitle();				if (title != null && title.length() > 0) {					paint.setColor(Color.BLACK);					paint.setTextSize(15);					canvas.drawText(title, point.x, point.y, paint);				}			}			canvas.restore();		}		super.draw(canvas, mapView, shadow);	}

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在onCreate中初始化

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overlay.addOverlay(new OverlayItem(pointQSH, "清水河", "清水河校区"));overlay.addOverlay(new OverlayItem(pointSH, "沙河", "沙河校区"));overlay.setOnFocusChangeListener(onFocusChangeListener);mapView.getOverlays().add(overlay);

?OK，实现效果：

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注：本文参加“第二届 Google 暑期大学生博客分享大赛 - 2011 Android 成长篇?”