CODEWITHSUNDEEP
android
Caleb Bramwell
Caleb Bramwell

Reputation: 1342

Android Save Canvas

I am creating a drawing app. I have a custom view with a Canvas which draws lines based on user input:

class Line {
  float startX, startY, stopX, stopY;
  public Line(float startX, float startY, float stopX, float stopY) {
    this.startX = startX;
    this.startY = startY;
    this.stopX = stopX;
    this.stopY = stopY;
  }
  public Line(float startX, float startY) { // for convenience
    this(startX, startY, startX, startY);
  }
}

public class DrawView extends View {
  Paint paint = new Paint();
  ArrayList<Line> lines = new ArrayList<Line>();

  public DrawView(Context context, AttributeSet attrs) {
    super(context, attrs);

    paint.setAntiAlias(true);
    paint.setStrokeWidth(6f);
    paint.setColor(Color.BLACK);
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeJoin(Paint.Join.ROUND);
  }

  @Override
  protected void onDraw(Canvas canvas) {
    for (Line l : lines) {
      canvas.drawLine(l.startX, l.startY, l.stopX, l.stopY, paint);
    }
  }

  @Override
  public boolean onTouchEvent(MotionEvent event) {

    if (event.getAction() == MotionEvent.ACTION_DOWN) {
      lines.add(new Line(event.getX(), event.getY()));
      return true;
    }
    else if ((event.getAction() == MotionEvent.ACTION_MOVE ||
        event.getAction() == MotionEvent.ACTION_UP) &&
        lines.size() > 0) {
      Line current = lines.get(lines.size() - 1);
      current.stopX = event.getX();
      current.stopY = event.getY();
      Invalidate();
      return true;
    }
    else {
      return false;
    }
  }
}

What I want to do is save the lines to a text file so that the user can load them later. How do I save them and then load them?

Upvotes: 1

Views: 168

Answers (1)

GreyBeardedGeek
GreyBeardedGeek

Reputation: 30088

I'd suggest serializing JSON to a file using the GSON library. There's a good tutorial at https://sites.google.com/site/gson/gson-user-guide

Upvotes: 2

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