I'm using a CATiledLayer for the visualisation of data. By default the drawLayer function gets a transposed and scaled context, which allow the drawing code to be agnostic of the zoom-level and the tile that's being requested.
However, I would like to use the zoom functionality to change the horizontal range of the data, without actual zooming occuring.
So far, I got this code:
(void)drawLayer:(CALayer*)layer inContext:(CGContextRef)context {
/* retrieve the transformation matrix from the context. */
CGAffineTransform contextTrans = CGContextGetCTM(context);
/* Scale the context back, so all items will still have the same size */
CGContextScaleCTM(context, 1.0/contextTrans.a, 1.0/contextTrans.d);
<.. loop through all datapoints ..> {
/* Transpose the point-centers to the new zoomed context */
xCoord = xCoord * contextTrans.a;
yCoord = yCoord * contextTrans.d;
}
<.. drawing code ..>
}
This works, but has the disadvantage that the elements get blurry when zoomed in. (only 1/zoomfactor pixels are rendered for each on-screen pixel)
Any methods to prevent this blurryness from happening?
Alternatively, is there any way to draw to the non-transformed context, rather than the transposed one?