android maps: How to Long Click a Map?

Question

How do I long click on a mapview so that a place marker appears at that point on the map?

I tried a couple ways without success:

1) Using setOnLongCl

Answer 1

This works with your MapActivity and will allow you to:

1. Set your own time threshold for what constitutes a long press on the map (0.8 seconds is good for me).
2. Not interpret a scroll, multi-touch, or non-multi-touch event as a long press. It also let's you set a tolerance for someone's finger to ever so slightly move on the screen as they are holding down a long press.

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This solution is based on Roger Kristiansen's solution. I added x and y point detection so that scrolling is not seen as a long press. This solution is not as elegant as Roger's because I use class variables and put the code in my existing MapActivity instead of extending MapView and creating a listener like he did. But if you want to stick with his code but have better non-multi-touch support, just take the x and y point stuff out of mine and add it to his.

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Class variables set at the top of my MapActivity:

//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

Add this function in your MapActivity:

    @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);
    }

Answer 2

There's an implementation for handling long press on maps here:

http://www.kind-kristiansen.no/2011/android-handling-longpresslongclick-on-map-revisited/