nsimage画入rect，但是图像模糊吗？

Question

designer give me picture like this

But when I use drawInRect API draw the picture in context, the picture is like this

The size of the rect is just the size of the image.And the image is @1x and @2x.

the difference is very clear, the picture is blurry and there is a gray line in the right of image, and My imac is retina resolution.

================================================ I have found the reason,

[self.headLeftImage drawInRect:NSMakeRect(100,
                                        100,
                                        self.headLeftImage.size.width,
                                        self.headLeftImage.size.height)];




CGContextRef context = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
CGContextSaveGState(context);
CGContextTranslateCTM(context, self.center.x , self.center.y);

[self.headLeftImage drawInRect:NSMakeRect(100,
                                        100,
                                        self.headLeftImage.size.width,
                                        self.headLeftImage.size.height)];
CGContextRestoreGState(context);

And in the first draw the image will not blur, but after translate the image is blurry. Just like the picture:

Answer 1

The problem is that you're translating the context to a non-integral pixel location. Then, the draw is honoring your request to put the image at a non-integral position, which causes it to be anti-aliased and color in some pixels partially.

You should convert the center point to device space, integral-ize it (eg by using floor() ), and then convert it back. Use CGContextConvertPointToDeviceSpace() and CGContextConvertPointToUserSpace() to do the conversions. That does the right thing for Retina and non-Retina displays.