public class MyMapView  extends MapView

{

static PopupOverlay pop = null;// 弹出泡泡图层，点击图标使用

private View mScaleView = null;

private int mScaleMaxWidth;

private int mScaleMaxHeight;

private TextView mScaleTextView;

private ImageView mScaleImageView;

public MPCMapLocationMapView(Context context) {

super(context);

if (mScaleView == null) {

initScaleView();

}

}

public MPCMapLocationMapView(Context context, AttributeSet

attrs) {

super(context, attrs);

if (mScaleView == null) {

initScaleView();

}

}

public MPCMapLocationMapView(Context context, AttributeSet

attrs,

int defStyle) {

super(context, attrs, defStyle);

if (mScaleView == null) {

initScaleView();

}

}

private void initScaleView() {

mScaleView = View.inflate(this.getContext(),

R.layout.map_scale, null);

mScaleTextView = (TextView)

mScaleView.findViewById(R.id.scale_text);

mScaleImageView = (ImageView)

mScaleView.findViewById(R.id.scale_image);

regMapViewListener();

refreshScale();

}

public View getScaleView() {

return mScaleView;

}

private void regMapViewListener() {

// TODO Auto-generated method stub

super.regMapViewListener(

MPCCrashHandlerApplication.getInstance().mBMapManager,

new MKMapViewListener() {

@Override

public void onMapMoveFinish() {

// TODO Auto-generated method stub

refreshScale();

}

@Override

public void onMapLoadFinish() {

// TODO Auto-generated method stub

refreshScale();

}

@Override

public void onMapAnimationFinish() {

// TODO Auto-generated method stub

refreshScale();

}

@Override

public void onGetCurrentMap(Bitmap arg0) {

// TODO Auto-generated method stub

}

@Override

public void onClickMapPoi(MapPoi arg0) {

// TODO Auto-generated method stub

}

});

}

@Override

public boolean onTouchEvent(MotionEvent event) {

int action = event.getAction();

switch (action) {

case MotionEvent.ACTION_DOWN:

this.getParent().requestDisallowInterceptTouchEvent(true);

break;

case MotionEvent.ACTION_UP:

this.getParent().requestDisallowInterceptTouchEvent(false);

break;

}

if (mScaleView != null) {

refreshScale();

}

return super.onTouchEvent(event);

}

//计算两处经纬度的实际距离并换算成实际比例尺单位，这个是精华 /

private void refreshScale()

{

// 获取设置默认屏幕宽度480

int default_screen_width =

MPCBrowserUtils.getScreenWidthPixel(this

.getContext());

// 获取设置默认屏幕高度800

int default_screen_height =

MPCBrowserUtils.getScreenHeightPixel(this

.getContext());

// mScaleMaxWidth =

默认屏幕宽度四分之一

mScaleMaxWidth = default_screen_width

>> 2;

// mScaleMaxHeight =

默认屏幕高度二分之一

mScaleMaxHeight =

default_screen_height >> 1;

// 转换为起点的经纬度GeoPoint

GeoPoint fromGeopoint =

getProjection().fromPixels(0, mScaleMaxHeight);

// 转换为终点的经纬度GeoPoint

GeoPoint toGeopoint =

getProjection().fromPixels(mScaleMaxWidth,

mScaleMaxHeight);

//

通过getDistance函数得出两点间的真实距离

double distance =

DistanceUtil.getDistance(fromGeopoint,

toGeopoint);

String discripition =

null;

int dis = 0;

int width = 20;

//

出于百度地图缩放最小为世界地图时，以纸的形式展现，这里强制规定如果zoomlevel=最高级

//

比例尺数值恒定wie：2000公里，黑条宽度恒定为52像素，缩放最大时同样的道理，如果是google

// 地图，不需要if和 else if

if (getZoomLevel() == 19)

{

dis =

MPCMapConstants.SCALE[1];

width = 52;

} else if (getZoomLevel() == 3)

{

dis =

MPCMapConstants.SCALE[17];

width = 80;

} else {

//

真实距离和数组中相近的两个值循环比较，以小值为准，得出规定好的比例尺数值赋值给dis

for (int j = 1; j <

MPCMapConstants.SCALE.length; j++) {

if (MPCMapConstants.SCALE[j - 1]

<= distance

&& distance <

MPCMapConstants.SCALE[j]) {

dis = MPCMapConstants.SCALE[j -

1];

break;

}

}

// 比例尺黑条的宽度

=(dis*默认屏幕宽度四分之一)/真实的距离

width = (int) (dis * mScaleMaxWidth /

distance);

}

// 如果比例尺数值大于1000，则discripition = 2500

km(公里)，否则 为 900 m(米)

if (dis >= 1000)

{

discripition = dis /

1000

+

this.getContext().getString(R.string.units_km);

} else {

discripition = dis +

this.getContext().getString(R.string.units_m);

}

//

设置TextView组件要显示的比例尺数值

mScaleTextView.setText(discripition);

//

设置比例尺黑条ImageView的的长度

android.view.ViewGroup.LayoutParams

lp = mScaleImageView

.getLayoutParams();

lp.width = width;

mScaleImageView.setLayoutParams(lp);

}

}