In working on an update to one of my applications on the Apple iPhone I thought I’d share another quick tip.
I found on a blog and it works brilliantly, to make rounded corners on any UIImage.
ImageManipulator.h
@interface ImageManipulator : NSObject {
}
+(UIImage *)makeRoundCornerImage:(UIImage*)img 
int) cornerWidth int) cornerHeight;
@end
ImageManipulator.m
#import "ImageManipulator.h"
@implementation ImageManipulator
static void addRoundedRectToPath(CGContextRef context, CGRect rect, float ovalWidth, float ovalHeight)
{
float fw, fh;
if (ovalWidth == 0 || ovalHeight == 0) {
CGContextAddRect(context, rect);
return;
}
CGContextSaveGState(context);
CGContextTranslateCTM (context, CGRectGetMinX(rect), CGRectGetMinY(rect));
CGContextScaleCTM (context, ovalWidth, ovalHeight);
fw = CGRectGetWidth (rect) / ovalWidth;
fh = CGRectGetHeight (rect) / ovalHeight;
CGContextMoveToPoint(context, fw, fh/2);
CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1);
CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1);
CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1);
CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1);
CGContextClosePath(context);
CGContextRestoreGState(context);
}
+(UIImage *)makeRoundCornerImage : (UIImage*) img : (int) cornerWidth : (int) cornerHeight
{
UIImage * newImage = nil;
if( nil != img)
{
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
int w = img.size.width;
int h = img.size.height;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextBeginPath(context);
CGRect rect = CGRectMake(0, 0, img.size.width, img.size.height);
addRoundedRectToPath(context, rect, cornerWidth, cornerHeight);
CGContextClosePath(context);
CGContextClip(context);
CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);
CGImageRef imageMasked = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
[img release];
newImage = [[UIImage imageWithCGImage:imageMasked] retain];
CGImageRelease(imageMasked);
[pool release];
}
return newImage;
}
@end
Just call the static method makeRoundCornerImage and pass your image to have the image rounded off the way you want.
For example
UIImage *imageFromFile = [UIImage imageNamed:@"myimage.png"]; imageFromFile = [ImageManipulator makeRoundCornerImage:imageFromFile : 20 : 20];
Note that you do need the CoreGraphics framework for this to compile.
More information can be found at the blog post link above.
The second tip is to load a remote image over the web and display it in a UIImageView object.
Create the following method in your interface
-(UIImage*) newUIImageWithURLString:(NSString*)urlString
{
return [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:urlString]]];
}
Then call the following
UIImage *myImage = [self newUIImageWithURLString:@"http://url.to/image.jpg"];
