the pointer data if pointing to some image generated by an iphone application. Does anybody now if using CGBitmapContextCreate make a copy of this data or does it use the image "in place"?
Ideally, I'd like to reuse the information in data* and not create any additional copy of this image.
void* data = <my data>; CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef imageContext = CGBitmapContextCreate(data, w, h, 8, w*8, colorSpace, kCGBitmapByteOrder32Big|kCGImageAlphaPremultipliedLast); CGImageRef imageRef = CGBitmapContextCreateImage(imageContext); UIImage* image =[[UIImage alloc] initWithCGImage:imageRef];
More generally, this method of creating image seems rather convoluted to me. Does anybody knows what's going on here? Is there any easier way to create UIImage?
How do you duplicate a file in XCode?
Unit testing an iPhone static library with XCode 3
Image getting pixelated when used as part of an animation in iPhone animation
But the data may be copied by the call to CGBitmapContextCreateImage, .
UITableView Animation Headache
iPhone OpenGL ES incorrect alpha blending
Discussion The CGImage object returned by CGBitmapContextCreateImage is created by a copy operation.
Does a NSURLConnection retain its delegate?
Subsequent changes to the bitmap graphics context do not affect the contents of the returned image.
Which button was tapped… iPhone and Obj-C question
In some cases the copy operation actually follows copy-on-write semantics, so that the actual physical copy of the bits occur only if the underlying data in the bitmap graphics context is modified.
As a consequence, you may want to use the resulting image and release it before you perform additional drawing into the bitmap graphics context.
In this way, you can avoid the actual physical copy of the data..
void * data = <my data>; NSData * newData = [NSData dataWithBytesNoCopy:data length:lengthOfData]; UIImage * image = [[UIImage alloc] initWithData:newData];