title: Rotate bitmap on canvas in android
body: <p>I have a problem to rotate bitmap on canvas ,I am drawing bitmap on canvas by using canvas.drawline and use following code to rotate image</p>
  
  <p>It rotate but it shows two image now ?How to remove previous image from canvas? What to do?</p>
  
  <pre><code>bitmap = Bitmap.createBitmap((int) /*getWindowManager()
                          .getDefaultDisplay().getWidth()*/600, (int) /*getWindowManager()
                          .getDefaultDisplay().getHeight()*/600, Bitmap.Config.ARGB_8888 );
               Canvas canvas = new Canvas(bitmap);
               drawingImageView.setVisibility(View.VISIBLE);
  
                 drawingImageView.setImageBitmap(bitmap);
  
                // canvas.rotate(90);
                     for(int i=0;i&lt;SettingsStaticData.arrX1_crossPoint.size();i++)
                     {
  
                         canvas.drawLine(new Float(SettingsStaticData.arrX1_crossPoint.get(i)),new Float(SettingsStaticData.arrY1_crossPoint.get(i)),new Float(SettingsStaticData.arrX2_crossPoint.get(i)) ,new Float(SettingsStaticData.arrY2_crossPoint.get(i)), paint);
  
  
                     }
  
  
                      paint.setStrokeWidth((float) 0.9);
                     paint.setStyle(Paint.Style.FILL);
                   //  paint.setColor(Color.RED);
  
                     paint.setColor(Color.parseColor("#800080"));
                 for(int i=0;i&lt;arrXX.size()-1;i++)
                  {
  
                    if(i==arrXX.size()-2)
                    {
                        canvas.drawLine(new Float(arrXX.get(0)),new Float(arrYY.get(0)),new Float(arrXX.get(i+1)) ,new Float(arrYY.get(i+1)), paint);
                        canvas.drawLine(new Float(arrXX.get(i)),new Float(arrYY.get(i)),new Float(arrXX.get(i+1)) ,new Float(arrYY.get(i+1)), paint);
  
                    }
                    else
                    {
                        canvas.drawLine(new Float(arrXX.get(i)),new Float(arrYY.get(i)),new Float(arrXX.get(i+1)) ,new Float(arrYY.get(i+1)), paint);
  
                    }
                  }
  
  
          //     canvas.drawColor(0, Mode.CLEAR);
                 Matrix matrix = new Matrix();
  
                    matrix.reset();
                 matrix.postTranslate(-bitmap.getWidth() / 2-500, -bitmap.getHeight() / 2-500); // Centers image
                 matrix.postRotate(180);
                //matrix.postTranslate(px, py);
  
  
                 canvas.drawBitmap(bitmap, matrix, null);
  </code></pre>