Can UIimage change the size and resolution of pictures? - objective-c

Question

If I pick a 640*960 picture and put it into a 200*300 UIImage,then will that picture uploaded to services as a 200*300 picture .

Answer 1

You can use following methods to resize your image:
+ (UIImage *) imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
//UIGraphicsBeginImageContext(newSize);
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
+ (UIImage *) imageWithImage: (UIImage*) sourceImage scaledToWidth: (float) i_width {//method to scale image accordcing to width
float oldWidth = sourceImage.size.width;
float scaleFactor = i_width / oldWidth;
float newHeight = sourceImage.size.height * scaleFactor;
float newWidth = oldWidth * scaleFactor;
UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight));
[sourceImage drawInRect:CGRectMake(0, 0, newWidth, newHeight)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}

Answer 2

- (void)viewDidLoad
{
[super viewDidLoad];
// Create the image from a png file
imageOriginal = [UIImage imageNamed:#"bg-640by960.png"];
imageView =[[UIImageView alloc] initWithImage:imageOriginal];
imageView.tag=200;
// Get size of current image
size = [imageOriginal size];
// Frame location in view to show original image
[imageView setFrame:CGRectMake(0, 0, size.width, size.height)];
[[self view] addSubview:imageView];
[self.view bringSubviewToFront:btnCrop];
//To resize image call below method
[[self.view viewWithTag:200] removeFromSuperview];
[self squareImageWithImage:imageOriginal scaledToSize:CGSizeMake(200, 300)];
}
- (UIImage *)squareImageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize
{
double ratio;
double delta;
CGPoint offset;
//make a new square size, that is the resized imaged width
CGSize sz = CGSizeMake(newSize.width, newSize.width);
//figure out if the picture is landscape or portrait, then
//calculate scale factor and offset
if (image.size.width > image.size.height) {
ratio = newSize.width / image.size.width;
delta = (ratio*image.size.width - ratio*image.size.height);
offset = CGPointMake(delta/2, 0);
} else {
ratio = newSize.width / image.size.height;
delta = (ratio*image.size.height - ratio*image.size.width);
offset = CGPointMake(0, delta/2);
}
//make the final clipping rect based on the calculated values
CGRect clipRect = CGRectMake(-offset.x, -offset.y,
(ratio * image.size.width) + delta,
(ratio * image.size.height) + delta);
//start a new context, with scale factor 0.0 so retina displays get
//high quality image
if ([[UIScreen mainScreen] respondsToSelector:#selector(scale)]) {
UIGraphicsBeginImageContextWithOptions(sz, YES, 0.0);
} else {
UIGraphicsBeginImageContext(sz);
}
UIRectClip(clipRect);
[image drawInRect:clipRect];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
imageView =
[[UIImageView alloc] initWithImage:newImage];
[imageView setFrame:CGRectMake(60, 60, newSize.width, newSize.height)];
[self.view addSubview:imageView];
return newImage;
}