the screen image link , the savePic image link ,You can find the different between screenImg and savePic. I set the backgroundImageView a very small png. and i want save the backgroundimageview to a Picture。 In the iPhone Simulator Screen, the edge of image is normal, but the edge of savePic is not clear. Anybody can tell me how to save a high definition picture.
- (void)viewDidLoad
{
[super viewDidLoad];
//_backImgView 320*480
self.backImgView.image = [UIImage imageNamed:@"Purple.png"];
[self performSelector:@selector(savePic) withObject:nil afterDelay:0.1];
}
- (void)savePic
{
BOOL isDir;
NSString *dirPath = [NSHomeDirectory() stringByAppendingPathComponent:@"/Documents/Pic"];
NSFileManager *fm = [NSFileManager defaultManager];
if(![fm fileExistsAtPath:dirPath isDirectory:&isDir]){
BOOL bo = [fm createDirectoryAtPath:dirPath withIntermediateDirectories:YES attributes:nil error:nil];
if(!bo){
NSLog(@"-->Create CardSlide Dir Fail!!!");
return;
}
}
UIGraphicsBeginImageContext(_backImgView.bounds.size);
//UIGraphicsBeginImageContextWithOptions(_backImgView.bounds.size, _backImgView.opaque, 2.0);
CGContextSetAllowsAntialiasing(UIGraphicsGetCurrentContext(), YES);
[_backImgView drawRect:_backImgView.bounds];
//[_backImgView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *bgImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSString *path = [NSString stringWithFormat:@"save_%@.jpg", @"demo"];
NSString *jpgPath = [dirPath stringByAppendingPathComponent:path];
BOOL isSucc = [UIImageJPEGRepresentation(bgImg, 1.0) writeToFile:jpgPath atomically:YES];
NSLog(@"%@ write photo %@!", jpgPath, isSucc?@"SUCC":@"FAIL");
}
Using a small image, is impossible to scale it the correct way to a bigger image, you will always go through blurry, noisy images BUT if you image could have stretchable repetitive parts, you can stretch the interior of the image without creating a new one. There are two API in UIImage called:
– resizableImageWithCapInsets:
(Only ios5)
– stretchableImageWithLeftCapWidth:topCapHeight:
(Deprecated in iOS 5.0)
If you find the correct inset you can avoid to create a new image, basically is the same system used to create the bubble in message application. The balloon is really small but it has a stretchable area that maintain the aspect ratio.
Since the image is really simple you could also think to draw it using Quartz functions creating a rect path, paths are "almost" res independent just need to scale them the correct size.
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