title: Zoom image without scaling overlay annotations (CALayers)
body: <p>I'm implementing a view with an image that I can zoom, pan and rotate and where I can add some annotations (<strong>lines</strong>) using <code>CALayers</code>. My doubt is how can I perform zoom operations on the underlaying image only and keep the annotations size and position? with my first experiment I ended up with all the annotation lines zoomed too... is there a good library out there to handle this kind of needs? or which is in your opinion the best way to create something like this? </p>
  
  <p>This is what I have in mind: </p>
  
  <p><strong>1)</strong> The main structure is based on two sibling views (Image and Annotations)</p>
  
  <p><strong>2)</strong> When I apply zoom I apply it to Image only.</p>
  
  <p><strong>3)</strong> I keep track of all the rotations and scaling operations and I apply a transform matrix to the points that define the lines in the annotations view, so the point will just be drawn at the new positions keeping line width unscaled.  </p>
  
  <p>To me it sounds a little bit overcomplicated solution... there should be something easier :/ </p>