title: Android BlurMaskFilter Issues
body: <p>I'm creating a drawing app, and I want on of the brushes the user can draw with to have the following effect:</p>
  
  <p><a href="https://i.stack.imgur.com/9MKTB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9MKTB.png" alt="Example Effect"></a></p>
  
  <p>Currently, to achieve this effect, I'm drawing 5 separate Paths, each with the same X values but a small Y offset, and each with a BlurMaskFilter. Here's the code from the PaintBrush class:</p>
  
  <pre><code>public PaintBrush(int initColor, int initSize) {
      strokeRadius = ((10 * initSize) + 20) / 2;
      currentColor = initColor
      setupPaths();
  }
  
  private void setupPaths(){
      paths = new Path[5];
      paints = new Paint[5];
      for (int i = 0; i &lt; 5; i++){
          paths[i] = new Path();
          Paint curPaint =  new Paint();
          curPaint.setColor(currentColor);
          curPaint.setAntiAlias(true);
          curPaint.setDither(true);
          curPaint.setStyle(Paint.Style.STROKE);
          curPaint.setStrokeJoin(Paint.Join.ROUND);
          curPaint.setStrokeCap(Paint.Cap.ROUND);
          paints[i] = curPaint;
      }
      Paint paint1 = paints[0];
      paint1.setStrokeWidth(strokeRadius / 3);
      paint1.setMaskFilter(new BlurMaskFilter(Math.max(strokeRadius / 5, 1), BlurMaskFilter.Blur.NORMAL));
      Paint paint2 = paints[1];
      paint2.setStrokeWidth(strokeRadius / 6);
      paint2.setMaskFilter(new BlurMaskFilter(Math.max(strokeRadius / 7, 1), BlurMaskFilter.Blur.NORMAL));
      Paint paint3 = paints[2];
      paint3.setStrokeWidth(strokeRadius / 5);
      paint3.setMaskFilter(new BlurMaskFilter(Math.max(strokeRadius / 7, 1), BlurMaskFilter.Blur.NORMAL));
      Paint paint4 = paints[3];
      paint4.setStrokeWidth(strokeRadius / 3);
      paint4.setMaskFilter(new BlurMaskFilter(Math.max(strokeRadius / 4, 1), BlurMaskFilter.Blur.NORMAL));
      Paint paint5 = paints[4];
      paint5.setStrokeWidth(strokeRadius / 4);
      paint5.setMaskFilter(new BlurMaskFilter(Math.max(strokeRadius / 4, 1), BlurMaskFilter.Blur.NORMAL));
  }
  
  public void drawBrush(Canvas canvas){
      for (int i = 0; i &lt; 5; i++) {
          canvas.drawPath(paths[i], paints[i]);
      }
  }
  
  
  
  public void startStroke(float x, float y){
      paths[0].moveTo(x, y - (strokeRadius * 4 / 6));
      paths[1].moveTo(x, y - (strokeRadius / 3));
      paths[2].moveTo(x, y - (strokeRadius / 8));
      paths[3].moveTo(x, y + (strokeRadius / 3));
      paths[4].moveTo(x, y + (strokeRadius * 3 / 4));
      prevX = x;
      prevY = y;
  }
  
  public void moveStroke(float x, float y){
      float dx = Math.abs(x - prevX);
      float dy = Math.abs(y - prevY);
      if (dx &gt;= TOUCH_TOLERANCE || dy &gt;= TOUCH_TOLERANCE) {
          paths[0].quadTo(prevX, prevY - (strokeRadius * 4 / 6), (x + prevX) / 2, ((y + prevY) / 2) - (strokeRadius * 4 / 6));
          paths[1].quadTo(prevX, prevY - (strokeRadius / 3), (x + prevX) / 2, ((y + prevY) / 2) - (strokeRadius / 3));
          paths[2].quadTo(prevX, prevY - (strokeRadius / 8), (x + prevX) / 2, ((y + prevY) / 2) - (strokeRadius / 8));
          paths[3].quadTo(prevX, prevY + (strokeRadius / 3), (x + prevX) / 2, ((y + prevY) / 2) + (strokeRadius / 3));
          paths[4].quadTo(prevX, prevY + (strokeRadius * 3 / 4), (x + prevX) / 2, ((y + prevY) / 2) + (strokeRadius * 3 / 4));
      }
      prevX = x;
      prevY = y;
  }
  
  public void endStroke(Canvas canvas){
      drawBrush(canvas);
      paths[0].reset();
      paths[1].reset();
      paths[2].reset();
      paths[3].reset();
      paths[4].reset();
  }
  </code></pre>
  
  <p>And the code for the custom View:</p>
  
  <pre><code>@Override
  protected void onDraw(Canvas canvas) {
      canvas.drawBitmap(drawingCanvas, 0, 0, canvasPaint);
      currentBrush.drawBrush(canvas);
  }
  
  @Override
  public boolean onTouchEvent(MotionEvent event) {
      if (!activity.isPaused()) {
          float touchX = event.getX();
          float touchY = event.getY();
          switch (event.getAction()){
              case MotionEvent.ACTION_DOWN:
                  currentBrush.startStroke(touchX, touchY);
                  break;
              case MotionEvent.ACTION_MOVE:
                  currentBrush.moveStroke(touchX, touchY);
                  break;
              case MotionEvent.ACTION_UP:
                  currentBrush.endStroke(touchX, touchY, drawingCanvas);
                  break;
              default:
                  return false;
          }
          invalidate();
      }
      return true;
  }
  </code></pre>
  
  <p>I'm aware that BlurMaskFilter is not compatible with hardware accelerations, so in my main activity i have the following code:</p>
  
  <pre><code>drawingView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
  </code></pre>
  
  <p>This code works, however, with hardware acceleration disabled, my drawing activity took a massive (and unacceptable) performance hit; it draws with a extremely noticeable lag, especially as the paths get longer. My question is: is there a way I could increase the performance, without using hardware acceleration, enough to decrease the lag? If not, is there any way to emulate this same effect in ways that are compatible with hardware acceleration?</p>