Android custom Animation for an ArcShape

Question

First let me explain my goal. I am trying to make an Animation that changes the properties of an ArcShape. An ArcShape\'s constructor

Answer 1

I think you might be better off extending Drawable and override the draw() function to modify the sweep angle on each call and draw the corresponding arc. Draw is typically called every time the object is updated, which will mean that you'll have to make a new ArcShape every time it's drawn Animation is more for performing transformations on Views and other UI components.

Something like:

public class OpenPacman  
{

public OpenPacman(float startAngle, float sweepAngle) {  
    this.mStartAngle = startAngle;  
    this.mSweepAngle = sweepAngle;  
    this.wakaWaka = new ArcShape(this.startAngle, this.mSweepAngle);  
} 

public void draw(Canvas c){  
  //Do drawing stuff here with the canvas
}

//Your other functions for calculating angle, etc and making the ArcShape changes
//Can call these from inside draw function so that when the view that contains your
//object calls draw, it updates correctly.

public float mStartAngle;  
public float msweepAngle;  
private ArcShape wakaWaka;  
}

Hope this gets you on the right track.

Answer 2

I have found a solution. I have a class that extends View We'll call this Pacman I nested my custom Animation within this Pacman class. This allowed me to access the member variables of the Pacman class.

public class Pacman extends View {
  float mSweepAngle;
  ...
  //include constructors
  //override onMeasure
  ...

  /* Here we override onDraw */
  @Override
  protected void onDraw(final Canvas canvas) {
    Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
    RectF oval = new RectF(canvas.getClipBounds());
    canvas.drawArc(oval, 0, mCurrAngle, true, p);
  }

  /* Here we define our nested custom animation */
  public class OpenPacman extends Animation {
    float mStartAngle;
    float mSweepAngle;

    public OpenPacman (int startAngle, int sweepAngle, long duration) {
      mStartAngle = startAngle;
      mSweepAngle = sweepAngle;
      setDuration(duration);
      setInterpolator(new LinearInterpolator());
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
      float currAngle = mStartAngle + ((mSweepAngle - mStartAngle) * interpolatedTime);
      Pacman.this.mCurrAngle = -currAngle; //negative for counterclockwise animation.
    }
  }
}

Now when the custom animation updates the container classes mCurrAngle, onDraw is automatically called, which draws the appropriate ArcShape.