also see: http://developer.apple.com/documentation/Cocoa/Conceptual/DrawBasic/index.html
An NSBezierPath object allows you to create paths using PostScript-style commands. Paths consist of straight and curved line segments joined together. Paths can form recognizable shapes such as rectangles, ovals, arcs, and glyphs; they can also form complex polygons using either straight or curved line segments. A single path can be closed by connecting its two endpoints or it can be left open.
Is it possible to somehow turn off antialiasing when using NSBezierPath objects?
Yep, just use [[NSGraphicsContext currentContext] setShouldAntialias:NO] before drawing a path to turn antialiasing off and the same call with YES after drawing to turn it back on (if you want).
Apple might have spent a lot of time making their antialiasing algorithm, but they seem to have ignored aliased (not antialiased) drawing. A 1 pixel wide bezier path looks more like 2 pixels.
Well, I tried [[NSGraphicsContext currentContext] setShouldAntialias:NO], and even [NSBezierPath setLineWidth:0.0], no satisfying result. I still get rectangles with two pixels wide borders.
You need to move your rect over 0.5 pixels. Use NSOffsetRect(myRect, 0.5, 0.5) to move it over before drawing it. You can use an NSAffineTransform to translate an NSBezierPath. – Bo
It’s probably worth mentioning that the reason for the 0.5 pixel offset is that Apple are viewing the screen as a grid, where the lines fall between the pixels (not on them), and when you draw a line, you specify the coordinates of the centre of the line. For example, the bottom-left pixel of the screen is a rectangle between the coordinates (0, 0) and (1, 1), with its centre at (0.5, 0.5).
If you specify an integer co-ordinate, you’re trying to draw your line down between two pixels, so the best Quartz can do is to render half of it in each of them.
Here is a little method I ran into once for this.
– Johan Kool
I’m working on a program that needs to trace the paths taken by objects on screen. Currently I have it set up so that each object has a bezier path, and calls [path lineToPoint:[self location]]; once per frame, and [path stroke]; once per frame. This gets VERY slow after a few minutes (several thousand segments being stroked every frame, plus some being added every frame). Can anyone think of a way of speeding this up? I would do something like draw the path into an NSImage so that I didn’t need to redraw all the time, but the path can be arbitrarily long, so an image big enough to fit any path would be arbitrarily large.
Could you not limit the image to screen resolution?
I could, but I’d be losing some major functionality of my program. I think I’d prefer to limit trail length rather than working area (which is what I’ll do if I can’t think of something better)
Why is NSBezierPath so slow? Why do plotting, clipping, stroking, and filling all take so long? Am I doing something wrong? —- It seems to me that you are drawing the WHOLE path for each object at each frame. Why don’t you just draw the last line with something like:
[NSBezierPath strokeLineFromPoint:[self previousLocation] toPoint:[self location]]
I may be missing something in what you are doing but at least, I tried ;-) –CharlesParnot
NSBezierPath / Quartz are slow with paths that self-intersect, since it has to handle the intersections specially (antialiasing, not making the overlaps draw darker with transparent, etc). Sometimes you can get a speedup by have a bunch of little paths rather than a single big honkin’ path