Android Open Source - app-gkplayer-android Volume Control

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License

The source code is released under:
Apache License
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Java Source Code

package com.roamtouch.gesturekit.gkplayer.graphics;
//from w w w .  ja  v a  2 s. co m
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PointF;
import android.graphics.RectF;
import android.media.AudioManager;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;

public class VolumeControl extends ImageView {
  private static final int START_ANGLE = 270;
  private static final int MAX_VOLUME_ANGLE = 340;
  private static final double MAX_VOLUME_ANGLE_RADIANS = Math.toRadians(MAX_VOLUME_ANGLE);
  
  private AudioManager audio;
  private int maxVolume = 0;
  private int currentVolume = 0;
  private int to = 0;
  private PointF buttonCenter = new PointF();
  private float buttonRadius = 0;
  
  private Paint paint = new Paint();
  private RectF rect = new RectF();
  private int halfStrokeWidth = 10;
  //auxiliar vars for efficiency
  PointF center = new PointF();
  float radius;
  
  private boolean dragging = false;
  

  public VolumeControl(Context context) {
    super(context);
    audio = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
    maxVolume = audio.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
    currentVolume = audio.getStreamVolume(AudioManager.STREAM_MUSIC);
    to = currentVolume * 340 / maxVolume;
    setBackgroundColor(0x00000000);
    paint.setStyle(Paint.Style.STROKE);
    paint.setAntiAlias(true);
    paint.setColor(0xDDDFDCD3);
        
    setOnTouchListener(new OnTouchListener() {
      @Override
      public boolean onTouch(View v, MotionEvent event) {
        switch(event.getAction()){
        case MotionEvent.ACTION_DOWN:
          return checkButton(event.getX(), event.getY());
        case MotionEvent.ACTION_MOVE:
          if(dragging)
            updateVolume(event.getX(), event.getY());
          return true;
        case MotionEvent.ACTION_UP:
          dragging = false;
          return true;
        }
        return false;
      }
    });
  }
  
  @Override
  public void onLayout(boolean changed, int left, int top, int right, int bottom){
    super.onLayout(changed, left, top, right, bottom);
    halfStrokeWidth = (int)((right-left)*0.018f);
    paint.setStrokeWidth(halfStrokeWidth*2);
    buttonRadius = paint.getStrokeWidth() * 2;
    rect.set(halfStrokeWidth*4, halfStrokeWidth*4, right - left - halfStrokeWidth*4, bottom - top - halfStrokeWidth*4);
    center.x = rect.width() / 2;
    center.y = rect.height() / 2;
    radius = rect.width() / 2;
    calculateButtonPosition();
  }
  
  @Override
  public void onDraw(Canvas canvas){
    super.onDraw(canvas);
    paint.setStyle(Paint.Style.STROKE);
    canvas.drawArc(rect, START_ANGLE, to, false, paint);
    drawButton(canvas, paint, to);
  }
  
  private void drawButton(Canvas canvas, Paint paint, int angle){
    paint.setStyle(Paint.Style.FILL);
    canvas.drawCircle(buttonCenter.x, buttonCenter.y, buttonRadius, paint);
    
  }
  
  private void calculateVolume(){
    currentVolume = audio.getStreamVolume(AudioManager.STREAM_MUSIC);
    to = currentVolume * MAX_VOLUME_ANGLE / maxVolume;
  }
  
  public void adjust(int direction){
    audio.adjustStreamVolume(AudioManager.STREAM_MUSIC, direction, 0);
    calculateVolume();
    calculateButtonPosition();
    postInvalidate();
  }
  
  public int getHalfStrokeWidth(){
    return halfStrokeWidth;
  }
  
  private void calculateButtonPosition(){
    calculateButtonPosition(Math.toRadians(to));
  }
  
  private void calculateButtonPosition(double radians){
    buttonCenter.x = (float)(center.x + Math.sin(radians) * center.x) + halfStrokeWidth*4;
    buttonCenter.y = (float)(center.y - Math.cos(radians) * center.y) + halfStrokeWidth*4;
    postInvalidate();
  }

  private boolean checkButton(float x, float y){
    //buttonRadius*2 because otherwise circle's area is too small
    if(Math.pow(x - buttonCenter.x, 2) + Math.pow(y - buttonCenter.y, 2) <= Math.pow(buttonRadius*2, 2)){ 
      dragging = true;
      return true;
    }else
      return false;
  }
  
  private void updateVolume(float x, float y){
    double angle;
    
    if(x >= center.x)
      if(y > center.y)
        angle = Math.PI / 2 + Math.atan((y - center.y) / (x - center.x) );
      else
        angle = Math.atan((x - center.x) / (center.y - y));
    else
      if(y > center.y)
        angle = Math.PI + Math.atan( (center.x - x) / (y - center.y) );
      else
        angle = Math.PI * 1.5d + Math.atan((y - center.y) / (x - center.x) );
    
    if(angle > MAX_VOLUME_ANGLE_RADIANS){
      if(to == 0)
        return;
      else if(to == MAX_VOLUME_ANGLE)
        return;
      else if(to > 270){
        to = MAX_VOLUME_ANGLE;
        calculateButtonPosition(MAX_VOLUME_ANGLE_RADIANS);
      }else{
        to = 0;
        calculateButtonPosition(0);
      }
      //dragging = false;
    }else{
      int degrees = (int)Math.toDegrees(angle);
      if(to == 0 && degrees > 90)
        return;
      else if(to == MAX_VOLUME_ANGLE && degrees < MAX_VOLUME_ANGLE - 90)
        return;
      else{
        to = degrees;
        calculateButtonPosition(angle);
      }
    }
    audio.setStreamVolume(AudioManager.STREAM_MUSIC, to*maxVolume/MAX_VOLUME_ANGLE, 0);
    
  }
}
Java Source Code List
