java - 如何在谷歌地图上的标记上方添加文字？

Question

    try
    {
            JSONArray jArray = new JSONArray(result);
            for(int i=0;i<jArray.length();i++)
            {
                    JSONObject json_data = jArray.getJSONObject(i);                       
                    //Retrieve data from db. lat & long = double / name = String
                    latMarker = json_data.getDouble("latitude");
                    lonMarker = json_data.getDouble("longitude");
                    nameMarker = json_data.getString("name");
                    List<Overlay> mapOverlays = mapView.getOverlays();
                    Drawable drawable = this.getResources().getDrawable(R.drawable.ic_launcher);
                    CustomItemizedOverlay itemizedOverlay = 
                         new CustomItemizedOverlay(drawable, this);

                    markers = new GeoPoint (
                            (int) (latMarker * 1E6),
                            (int) (lonMarker * 1E6));

                    //Happens when a marker is clicked
                    OverlayItem overlayitem = new OverlayItem(markers, "Tapped", "Name: " + nameMarker);
                    itemizedOverlay.addOverlay(overlayitem);
                    mapOverlays.add(itemizedOverlay);           
            }
    }
    catch(JSONException e)
    {
            Log.e("log_tag", "Error parsing data. " + e.toString());
    }        
}

我制作了一个安卓应用程序并将谷歌地图集成到其中。我还在我所在城市周围的地方添加了标记。我的问题是，我不知道如何在这些标记上方添加文本。任何人都可以帮助我吗？

Answer 1

package com.labs;

import java.util.ArrayList;

import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.text.TextPaint;

import com.google.android.maps.GeoPoint;
import com.google.android.maps.ItemizedOverlay;
import com.google.android.maps.MapView;
import com.google.android.maps.OverlayItem;

public class ResoucesOverlay extends ItemizedOverlay
{

    public ResoucesOverlay(Drawable defaultMarker)
    {
        /*Calling boundCenterBottom() on defaultMarker makes the marker image connect
          at its Bottom center to the latitude and longitude of this Overlay Item*/
        super(boundCenterBottom(defaultMarker));

        markerHeight = ((BitmapDrawable) defaultMarker).getBitmap().getHeight();

        /* This call to populate is important. Although this does not appear in the MapView tutorial
         * on Google's Android developer site, the mapview some times crashes without this call.
         */
        populate();
    }

    @Override
    protected OverlayItem createItem(int i)
    {
        return mOverlays.get(i);
    }

    @Override
    public int size()
    {
        return mOverlays.size();
    }

    @Override
    public void draw(android.graphics.Canvas canvas, MapView mapView,
            boolean shadow)
    {
        super.draw(canvas, mapView, shadow);

        // go through all OverlayItems and draw title for each of them
        for (OverlayItem item:mOverlays)
        {
            /* Converts latitude & longitude of this overlay item to coordinates on screen.
             * As we have called boundCenterBottom() in constructor, so these coordinates
             * will be of the bottom center position of the displayed marker.
             */
            GeoPoint point = item.getPoint();
            Point markerBottomCenterCoords = new Point();
            mapView.getProjection().toPixels(point, markerBottomCenterCoords);

            /* Find the width and height of the title*/
            TextPaint paintText = new TextPaint();
            Paint paintRect = new Paint();

            Rect rect = new Rect();
            paintText.setTextSize(FONT_SIZE);
            paintText.getTextBounds(item.getTitle(), 0, item.getTitle().length(), rect);

            rect.inset(-TITLE_MARGIN, -TITLE_MARGIN);
            rect.offsetTo(markerBottomCenterCoords.x - rect.width()/2, markerBottomCenterCoords.y - markerHeight - rect.height());

            paintText.setTextAlign(Paint.Align.CENTER);
            paintText.setTextSize(FONT_SIZE);
            paintText.setARGB(255, 255, 255, 255);
            paintRect.setARGB(130, 0, 0, 0);

            canvas.drawRoundRect( new RectF(rect), 2, 2, paintRect);
            canvas.drawText(item.getTitle(), rect.left + rect.width() / 2,
                    rect.bottom - TITLE_MARGIN, paintText);
        }
    }

    public void addOverlay(int latitude, int longitude, String title,
            String snippet)
    {
        OverlayItem item;

        GeoPoint geopoint = new GeoPoint(latitude, longitude);
        item = new OverlayItem(geopoint, title, snippet);
        mOverlays.add(item);
        populate();

    }

    public void addOverlay(OverlayItem overlayItem)
    {
        mOverlays.add(overlayItem);
        populate();
    }

    private int markerHeight;
    private ArrayList<OverlayItem> mOverlays = new ArrayList<OverlayItem>();

    private static final int FONT_SIZE = 12;
    private static final int TITLE_MARGIN = 3;
}