How to draw a shape dynamically on map touched location in android

问题

I want to draw a shape, wherever the user touches the map, the should be drawn dynamically. I don't have any idea about drawing these shapes. How could I achieve this? Can I get this done through canvas? I am using MapFragment.

Please see the image,

Please give me any idea!! Any help is appreciated!!

回答1:

You can do that by adding a View overlaying the map.

have a Polyline object (initially empty) that will be your line
handle onTouchEvent on that View
translate x,y from events to LatLng using Projection
add new point to Polyline

And you are done.

Note that this consumes all the events that would otherwise make map pan or zoom. You will have to have some other way to interact with map or enable consuming events using some flag.

回答2:

Add a ImageView overlying on the map. You can't draw on map.
The ImageView should implement "OnTouchListener"

Add any button on map, so as to bring the ImageView to front and map will be visible on background. 4.when touched on ImageView, perform the below action

public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction();
Point p = new Point();
path = new Path();
float upX;
float upY;

switch (action) {
case MotionEvent.ACTION_DOWN:
    laArray = "";
    lnArray = "";
    canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
    downx = event.getX();
    downy = event.getY();
    eventX = downx;
    eventY = downy;
    Log.d("", "startx" + eventX);
    p.x = (int) downx;
    p.y = (int) downy;
    LatLng latlngpoint;
    latlngpoint = map.getProjection().fromScreenLocation(p);
    break;
case MotionEvent.ACTION_MOVE:
    upx = event.getX();
    upy = event.getY();
    canvas.drawLine(downx, downy, upx, upy, paint);
    drawable.invalidate();
    downx = upx;
    downy = upy;
    Log.d("", "Action_Move");
    Log.d("", "downx, downy: " + downx + "," + downy);
    Log.d("", "upx, upy: " + upx + "," + upy);
    p.x = (int) upx;
    p.y = (int) upy;
    LatLng latlngpoint1;
    latlngpoint1 = map.getProjection().fromScreenLocation(p);           
    break;
case MotionEvent.ACTION_UP:
    upX = event.getX();
    upY = event.getY();
    p.x = (int) upX;
    p.y = (int) upY;
    Log.d("", "Action Up");
    canvas.drawLine(eventX, eventY, upX, upY, paint);
    LatLng latlngpoint2;
    latlngpoint2 = map.getProjection().fromScreenLocation(p);           
    drawable.invalidate();

    // When finger is Up, Start UserSearch.

    StartUserSearch(); //user defined function
    return true;
case MotionEvent.ACTION_CANCEL:
    break;
default:
    break;
}

return true;

}

Add ImageView like this,

   <ImageView
    android:id="@+id/viewOnMap"
    style="@style/AppTheme"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" 
    >

  </ImageView>

so, when the draw button on map is clicked,

 ImageView drawable= (ImageView) findViewById(R.id.viewOnMap);
 drawable.setVisibility(View.VISIBLE);
 drawable.bringToFront();

Now, you should be able to draw on the imageView, but it seems that you are drawing on the map.

You can modify the code according to your requirement. Hope this will be helpfull.

回答3:

The answer is you can't.

As you can see the gesture will be consumed by the map for pan/scroll action.

But there is a trick.

You can place a marker on user action (Long press on map)
Set marker draggable and set the drag listener
Prompt user to drag the marker
Drag listener will consume the dragged points as user drags the marker.
on Drag ends create a path with the Lat-Long and draw the path
Remove the marker.

来源：https://stackoverflow.com/questions/16976761/how-to-draw-a-shape-dynamically-on-map-touched-location-in-android

标签

google-maps

drawing

android-maps-v2