Alias + core graphics at retina display

Question

I wanted to use alias drawing capability of core graphics with Zooming in capablility so the pixels will be seen very clear at 1600% or up and everything works fine in ipad 1 (no retina display)

when i have the same code running on iphone4S / 4, I can't see alias drawing is on

follow the instructions from this post CoreGraphics for retina display but the image is still not "alias"

here's the screen cap of my question - http://farm8.staticflickr.com/7161/6634020573_19d8b3549f_o.jpg

here's how i do the screen capture below - (subclass a UIView and put the drawing code in drawRect:)

- (void)drawRect:(CGRect)rect
{
    //[self setNeedsDisplay];
    // Drawing code
    CGContextRef context = UIGraphicsGetCurrentContext();
    //
    CGContextSetLineWidth(context, 1.0);
    CGColorSpaceRef cs=CGColorSpaceCreateDeviceRGB();
    float cc[]={1.0,0.0,0.0,1.0};
    CGContextSetStrokeColorWithColor(context,CGColorCreate(cs, cc));
    CGContextSetShouldAntialias(context, FALSE);
    CGContextSetAllowsAntialiasing(context, FALSE);
    //
    CGContextMoveToPoint(context,10,0);
    CGContextAddLineToPoint(context, 266,256);
    CGContextStrokePath(context);

    CGContextSetShouldAntialias(context, TRUE);
    CGContextSetAllowsAntialiasing(context, TRUE);
    //
    CGContextMoveToPoint(context,-10,0);
    CGContextAddLineToPoint(context, 246,256);
    CGContextStrokePath(context);
}

and zoom in by double tap simply

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *t=[touches anyObject];
    if([t tapCount]==2) {
        paper *p=[paperStack objectAtIndex:0];
        CGAffineTransform transform = p.transform;
        p.transform = CGAffineTransformScale(transform, 16.0f, 16.0f);

    }
}

any helps / tips will be much appreciated, thank you in advance !

best, Kitdastudio

score 0 · Answer 1 · answered Jan 16 '12 at 19:42

to get the retina display a SHARP CRISP pixel

i need to give up

CGContextMoveToPoint(context,10,0);
CGContextAddLineToPoint(context, 266,256);

instead i need to use a loop to add rectangles (1x1 big each) along the line

and it will yield SHARP CRISP pixel in both retina display and older gen 1x display

Alias + core graphics at retina display

1 Answers1