I have an Android application that I am working on with Android Studio. I have a custom view that gets rendered from another activity. Inside of the custom view's onDraw() function, I schedule a new timer task to redraw a part of the UI. Initially, when I did this I was getting a SIGSEGV error, but I was able to fix that by adding this: setLayerType(LAYER_TYPE_SOFTWARE, null)

However, after adding this, the Bitmap I drew inside of the Timer doesn't appear on the Canvas.

Here is some of the code for better understanding:

List<Person> people = new ArrayList<>(); 

public CustomView() {
   super(context);
   patch = BitmapFactory.decodeResource(this.getResources(), R.drawable.person);
   patch = Bitmap.createScaledBitmap(patch, 60, 60, true);
}

protected void onDraw() {
   if (drawPatch) {     // draw patch is a static boolean var that gets set to true 
                        // from the activity using this view

      timer.schedule(new TimerTask() {
         @Override
         public void run() {
            if (currentTime == timeBetweenSpawns) {
               people.add(new Person(x, y)); // x, y represents the location of the
                                             // person on the canvas
               currentTime = 0;
            } else {
               currentTime++;
            }
         }

         for (Person person : people) {
             person.movePerson(); // moves the person on the canvas
         }

         for (Person person : people) {
             canvas.drawBitmap(person.getBitmap(), person.getX(), person.getY(), null);
         }
      }, 0, 1000);
   } 
}

What I am trying to do:

CustomView represents a map for a game. I want to draw people moving on the map in the game and repetitively redraw the people to make it seem like they are moving smoothly. The issue is, I don't want to redraw the entire CustomView when I do this since the only thing changing in the CustomView is the location of the people (also for context there is a lot of other stuff being drawn in the onDraw() function in CustomView, I just omitted it for brevity). The timer logic I attempted above was an attempt to do this, but it didn't work.

Is there a better way to only redraw the Person objects in the people list without having to invalidate and redraw the entire view?

Extra Context

protected void onDraw(Canvas canvas) {
        for (Grass grassLocation : grassLocations) {
            canvas.drawBitmap(grassLocation.getBitMap(),
                    grassLocation.getX(),
                    grassLocation.getY(),
                    null);
        }

        for (Path pathLocation : pathLocations) {
            canvas.drawBitmap(pathLocation.getBitMap(),
                    pathLocation.getX(),
                    pathLocation.getY(),
                    null);
        }

        canvas.drawBitmap(monumentLocation.getBitMap(),
                monumentLocation.getX(),
                monumentLocation.getY(),
                null);

        for (Indicator indicatorLocation : indicatorLocations) {
            canvas.drawBitmap(indicatorLocation.getBitMap(),
                    indicatorLocation.getX(),
                    indicatorLocation.getY(),
                    null);
        }

        for (Turret turretLocation : turretLocations) {
            canvas.drawBitmap(turretLocation.getBitMap(),
                    turretLocation.getX(),
                    turretLocation.getY(),
                    null);
        }

        if (combatStarted) {
            if (currentTime == timeBetweenSpawns) {
                addPerson(); // add a new person
                currentTime = 0;
            } else {
                currentTime++;
            }

            // Move all enemies, check if person has reached monument
            for (Person person : people) {
             person.movePerson(); // moves the person on the canvas
            }

            for (Person person : people) {
             canvas.drawBitmap(person.getBitmap(), person.getX(), 
             person.getY(), null);
            }

            invalidate();
        }
}