Drawing 1 pixel line with zoom change
Drawing 1 pixel line with zoom change
- Subject: Drawing 1 pixel line with zoom change
- From: Sahana A <email@hidden>
- Date: Mon, 11 May 2009 20:14:27 +0530
Hi There,
We have a feature in our application wherein we have to draw a 1 pixel
line. This drawing also varies relative to the zoom factor of our
view. For example
if we are drawing at a zoom factor of 200% we draw 0.5 pixel line.
( basically: 1/zoomfactor width of line; 1 if the zoomfactor < 100 ).
For most of the times we succeed in drawing the 1 pixel line. However
after we change the zoom factor, our drawing fails. Our 1 pixel
line is now drawn in 2 pixels.
For example: On changing the zoom values from say 100% to 300% and
back to 100% again, the single pixel line sometimes draw in 2 pixels.
Even if the stroke width is set to 0.0 or 1.0, the stroked line will
draw 2 pixels.
We have referred to the earlier posts in the mailing list and tried
the alternatives mentioned there. We have used NSFrameRect of width or
height equal to 1.
But on changing to zoom value to 66.7%, the line again draws 2 pixels.
Following is how our code looks like:
[NSGraphicsContext saveGraphicsState];
[[NSGraphicsContext currentContext] setShouldAntialias: FALSE];
NSRect rect = NSMakeRect(100.0, 100.0, 1.0, 200.0); //hardcoded for
testing
NSFrameRect(rect);
[[NSGraphicsContext currentContext] setShouldAntialias: TRUE];//maybe
this is not required.
[NSGraphicsContext restoreGraphicsState];
Following is the code used to change the zoom factor of the view:
- (void)scaleUnitSquareToSize:(NSSize)newUnitSize
Can you please give some inputs on this?
Thanks in advance.
Regards,
Sahana A
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