如何在地图视图上进行长按操作，以便在地图上的该点显示一个地点标记？
我尝试了几种方法都没有成功：
1）在MapView上使用setOnLongClickListener始终无法检测到长按事件。
2）我的另一个想法是扩展MapView以覆盖dispatchTouchEvent...创建一个GestureDetector来响应长按回调。 但是我被卡住了，因为我无法获取对我的子类化后的Mapview的控制。即：
MyMapview mymapview; //MyMapView extends MapView
//results in a classcast exception
mymapView = (MyMapView) findViewById(R.id.map);
3) 我所知道的另外一种尝试方法是：检测一个 MotionEvent.ACTION_DOWN 事件，然后在处理程序中发布一个延迟的可运行对象，并检测长按是否发生，如果另外两个事件：acton_move 或 action_up 没有发生。
请问有人能对这些检测长按的方法提供想法吗？
我发现了一种更简单的方法。只需要在覆盖层列表中创建一个不绘制任何内容的覆盖层，并使用GestureDetector来识别手势。如果它处理了事件，则应返回true，以便事件不会传播到下一层。
List<Overlay> overlays = mapView.getOverlays();
overlays.clear();
overlays.add(new MapGestureDetectorOverlay(new MyOnGestureListener()));
以下是该类的代码：
public class MapGestureDetectorOverlay extends Overlay implements OnGestureListener {
private GestureDetector gestureDetector;
private OnGestureListener onGestureListener;
public MapGestureDetectorOverlay() {
gestureDetector = new GestureDetector(this);
}
public MapGestureDetectorOverlay(OnGestureListener onGestureListener) {
this();
setOnGestureListener(onGestureListener);
}
@Override
public boolean onTouchEvent(MotionEvent event, MapView mapView) {
if (gestureDetector.onTouchEvent(event)) {
return true;
}
return false;
}
@Override
public boolean onDown(MotionEvent e) {
if (onGestureListener != null) {
return onGestureListener.onDown(e);
}
return false;
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
if (onGestureListener != null) {
return onGestureListener.onFling(e1, e2, velocityX, velocityY);
}
return false;
}
@Override
public void onLongPress(MotionEvent e) {
if (onGestureListener != null) {
onGestureListener.onLongPress(e);
}
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
float distanceY) {
if (onGestureListener != null) {
onGestureListener.onScroll(e1, e2, distanceX, distanceY);
}
return false;
}
@Override
public void onShowPress(MotionEvent e) {
if (onGestureListener != null) {
onGestureListener.onShowPress(e);
}
}
@Override
public boolean onSingleTapUp(MotionEvent e) {
if (onGestureListener != null) {
onGestureListener.onSingleTapUp(e);
}
return false;
}
public boolean isLongpressEnabled() {
return gestureDetector.isLongpressEnabled();
}
public void setIsLongpressEnabled(boolean isLongpressEnabled) {
gestureDetector.setIsLongpressEnabled(isLongpressEnabled);
}
public OnGestureListener getOnGestureListener() {
return onGestureListener;
}
public void setOnGestureListener(OnGestureListener onGestureListener) {
this.onGestureListener = onGestureListener;
}
}
public void onLongPress(MotionEvent e, ManagedOverlay overlay)
此解决方案基于Roger Kristiansen的解决方案。 我添加了x和y点检测，以便滚动不被视为长按。 这个解决方案不如Roger的优雅，因为我使用类变量并将代码放在现有的MapActivity中，而不是扩展MapView并创建像他一样的监听器。 但是，如果您想坚持使用他的代码但具有更好的非多点触控支持，请将我的x和y点内容删除并将其添加到他的代码中。
在我的MapActivity顶部设置的类变量：
//variable for determining long press and then automatically adding a pin to the map
private int minMillisecondThresholdForLongClick = 800;
private long startTimeForLongClick = 0;
private float xScreenCoordinateForLongClick;
private float yScreenCoordinateForLongClick;
private float xtolerance=10;//x pixels that your finger can be off but still constitute a long press
private float ytolerance=10;//y pixels that your finger can be off but still constitute a long press
private float xlow; //actual screen coordinate when you subtract the tolerance
private float xhigh; //actual screen coordinate when you add the tolerance
private float ylow; //actual screen coordinate when you subtract the tolerance
private float yhigh; //actual screen coordinate when you add the tolerance
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
/* We want to capture the place the user long pressed on the map and add a marker (pin) on the map at that lat/long.
* This solution:
* 1. Allows you to set the time threshold for what constitutes a long press
* 2. Doesn't get fooled by scrolling, multi-touch, or non-multi-touch events
* Thank you Roger Kind Kristiansen for the main idea
*/
//get the action from the MotionEvent: down, move, or up
int actionType = ev.getAction();
if (actionType == MotionEvent.ACTION_DOWN) {
//user pressed the button down so let's initialize the main variables that we care about:
// later on when the "Action Up" event fires, the "DownTime" should match the "startTimeForLongClick" that we set here
// the coordinate on the screen should not change much during the long press
startTimeForLongClick=ev.getEventTime();
xScreenCoordinateForLongClick=ev.getX();
yScreenCoordinateForLongClick=ev.getY();
} else if (actionType == MotionEvent.ACTION_MOVE) {
//For non-long press actions, the move action can happen a lot between ACTION_DOWN and ACTION_UP
if (ev.getPointerCount()>1) {
//easiest way to detect a multi-touch even is if the pointer count is greater than 1
//next thing to look at is if the x and y coordinates of the person's finger change.
startTimeForLongClick=0; //instead of a timer, just reset this class variable and in our ACTION_UP event, the DownTime value will not match and so we can reset.
} else {
//I know that I am getting to the same action as above, startTimeForLongClick=0, but I want the processor
//to quickly skip over this step if it detects the pointer count > 1 above
float xmove = ev.getX(); //where is their finger now?
float ymove = ev.getY();
//these next four values allow you set a tiny box around their finger in case
//they don't perfectly keep their finger still on a long click.
xlow = xScreenCoordinateForLongClick - xtolerance;
xhigh= xScreenCoordinateForLongClick + xtolerance;
ylow = yScreenCoordinateForLongClick - ytolerance;
yhigh= yScreenCoordinateForLongClick + ytolerance;
if ((xmove<xlow || xmove> xhigh) || (ymove<ylow || ymove> yhigh)){
//out of the range of an acceptable long press, reset the whole process
startTimeForLongClick=0;
}
}
} else if (actionType == MotionEvent.ACTION_UP) {
//determine if this was a long click:
long eventTime = ev.getEventTime();
long downTime = ev.getDownTime(); //this value will match the startTimeForLongClick variable as long as we didn't reset the startTimeForLongClick variable because we detected nonsense that invalidated a long press in the ACTION_MOVE block
//make sure the start time for the original "down event" is the same as this event's "downTime"
if (startTimeForLongClick==downTime){
//see if the event time minus the start time is within the threshold
if ((eventTime-startTimeForLongClick)>minMillisecondThresholdForLongClick){
//make sure we are at the same spot where we started the long click
float xup = ev.getX();
float yup = ev.getY();
//I don't want the overhead of a function call:
xlow = xScreenCoordinateForLongClick - xtolerance;
xhigh= xScreenCoordinateForLongClick + xtolerance;
ylow = yScreenCoordinateForLongClick - ytolerance;
yhigh= yScreenCoordinateForLongClick + ytolerance;
if ((xup>xlow && xup<xhigh) && (yup>ylow && yup<yhigh)){
//**** safe to process your code for an actual long press ****
//comment out these next rows after you confirm in logcat that the long press works
long totaltime=eventTime-startTimeForLongClick;
String strtotaltime=Long.toString(totaltime);
Log.d("long press detected: ", strtotaltime);
/*
//Now get the latitude/longitude of where you clicked. Replace all the code below if you already know how to translate a screen coordinate to lat/long. I know it works though.
//*****************
//I have my map under a tab so I have to account for the tab height and the notification bar at the top of the phone.
// Maybe there are other ways so just ignore this if you already know how to get the lat/long of the pixels that were pressed.
int TabHeightAdjustmentPixels=tabHost.getTabWidget().getChildAt(0).getLayoutParams().height;
int EntireTabViewHeight = tabHost.getHeight();
Display display = getWindowManager().getDefaultDisplay();
int EntireScreenHeight = display.getHeight();
int NotificationBarHeight=EntireScreenHeight-EntireTabViewHeight;
//the projection is mapping pixels to where you touch on the screen.
Projection proj = mapView.getProjection();
GeoPoint loc = proj.fromPixels((int)(ev.getX(ev.getPointerCount()-1)), (int)(ev.getY(ev.getPointerCount()-1)-TabHeightAdjustmentPixels-NotificationBarHeight));
int longitude=loc.getLongitudeE6();
int latitude=loc.getLatitudeE6();
//*****************
//**** here's where you add code to:
// put a marker on the map, save the point to your SQLite database, etc
*/
}
}
}
}
return super.dispatchTouchEvent(ev);
}
这个地图视图覆盖管理库非常好用。由于该库没有考虑到多点触控，因此在“滚动”时会触发onLongPress事件。你可以通过以下方式解决这个问题：如果涉及到多个指针，请拒绝onLongPress事件：
public void onLongPress(MotionEvent motionEvent, ManagedOverlay arg1) {
if (motionEvent.getPointerCount() > 1) return;
... your logic here ...
}
ambrose，
我修改了mapview-overlay-manager库的演示代码，使它可以使用双击手势运行：
package de.android1.overlaymanager.demo;
import android.os.Bundle;
import android.widget.Toast;
import android.graphics.drawable.Drawable;
import android.view.MotionEvent;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapView;
import com.google.android.maps.MapController;
import com.google.android.maps.GeoPoint;
import de.android1.overlaymanager.*;
public class DemoView extends MapActivity {
MapView mapView;
MapController mapController;
OverlayManager overlayManager;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mapView = (MapView) findViewById(R.id.mapview);
mapView.setBuiltInZoomControls(true);
mapController = mapView.getController();
overlayManager = new OverlayManager(getApplication(), mapView);
}
@Override
public void onWindowFocusChanged(boolean b) {
createOverlayWithListener();
}
public void createOverlayWithListener() {
//This time we use our own marker
final ManagedOverlay managedOverlay = overlayManager.createOverlay("listenerOverlay", getResources().getDrawable(R.drawable.marker));
for (int i = 0; i < 40; i = i + 3) {
managedOverlay.createItem(GeoHelper.geopoint[i], "Item" + i);
}
managedOverlay.setOnOverlayGestureListener(new ManagedOverlayGestureDetector.OnOverlayGestureListener() {
public boolean onZoom(ZoomEvent zoom, ManagedOverlay overlay) {
return false;
}
public boolean onDoubleTap(MotionEvent e, ManagedOverlay overlay, GeoPoint point, ManagedOverlayItem item) {
Drawable defaultmarker = getResources().getDrawable(R.drawable.marker);
ManagedOverlay managedOverlay = overlayManager.createOverlay(defaultmarker);
//creating some marker:
managedOverlay.createItem(point);
//registers the ManagedOverlayer to the MapView
overlayManager.populate();
Toast.makeText(getApplicationContext(), "You created a Marker!", Toast.LENGTH_LONG).show();
return true;
}
public void onLongPress(MotionEvent arg0, ManagedOverlay arg1) {
// TODO Auto-generated method stub
}
public void onLongPressFinished(MotionEvent arg0,
ManagedOverlay arg1, GeoPoint arg2, ManagedOverlayItem arg3) {
// TODO Auto-generated method stub
}
public boolean onScrolled(MotionEvent arg0, MotionEvent arg1,
float arg2, float arg3, ManagedOverlay arg4) {
// TODO Auto-generated method stub
return false;
}
public boolean onSingleTap(MotionEvent arg0, ManagedOverlay arg1,
GeoPoint arg2, ManagedOverlayItem arg3) {
// TODO Auto-generated method stub
return false;
}
});
overlayManager.populate();
}
@Override
protected boolean isRouteDisplayed() {
return false;
}
}
当我尝试使用MyMapView时，我也遇到了ClassCastException。为了解决这个问题，我创建了一个MyMapView对象而不是一个MapView对象，并以编程方式将其添加到布局中，这样做非常好用。
MyMapView mapView = new MyMapView(this, this.getString(R.string.APIMapKey));
mapView.displayZoomControls(false);
mapView.setClickable(true);
FrameLayout item = (FrameLayout) findViewById(R.id.getlocationmap);
item.addView((MapView)mapView);
mapView.getMapCenter()、mapView.getLatitudeSpan()和mapView.getLongitudeSpan()返回与指针按下时相同的内容。