Render a single UIImage and rotation has to be applied - objective-c

Question

I have rendered few UIImage objects using CGContextDrawImage. But when i apply rotation to the image, it is not applied and the view disappears.
code here
-(void )renderImage: (ItemView *)array
{
NSArray *selectedImages = self.slideView.selectedView.subviews;
CGSize combinedSize = CGSizeMake(0, 0);
for (int i = 0; i < [selectedImages count]; ++i) {
CGSize sourceSize = [selectedImages[i] size];
NSLog(#"sdfsd %f %f ", sourceSize.width, sourceSize.height);
combinedSize.width = MAX(combinedSize.width, sourceSize.width);
combinedSize.height += sourceSize.height;
}
UIGraphicsBeginImageContextWithOptions(self.view.frame.size, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
{
CGContextTranslateCTM(context, 0, 768);
CGContextScaleCTM(context, 1,-1);
for (int i = 0; i < [selectedImages count]; ++i) {
UIImageView *imageview = selectedImages[i];
UIImage *sourceImage = imageview.image;
CGContextSaveGState(context);
float radians1 = atan2(imageview.transform.a, imageview.transform.b);
CGFloat angle = [(NSNumber *)[imageview valueForKeyPath:#"layer.transform.rotation.z"] floatValue];
printf("\n radians %f",radians1);
printf("\n angle %f",angle);
CGContextRotateCTM(context, radians(angle));
CGContextDrawImage(context, imageview.frame, imageview.image.CGImage);
CGContextRestoreGState(context);
//CGContextDrawImage(context, imageview.frame, imageview.image);
}
}
UIImage *combinedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(combinedImage, nil, nil, nil);
}
Thanks,
Any help would be appreciated

Answer 1

Let's say you have an array of source images:
NSArray *sourceImages = ...;
// each element of sourceImages is a UIImage
Now you want to take the first count images from the array and concatenate them vertically into a new image. Start by figuring out the size of the combined image:
CGSize combinedSize = CGSizeMake(0, 0);
for (int i = 0; i < count; ++i) {
CGSize sourceSize = [sourceImages[i] size];
combinedSize.width = MAX(combinedSize.width, sourceSize.width);
combinedSize.height += sourceSize.height;
}
Next, create a graphics context of that size:
UIGraphicsBeginImageContextWithOptions(combinedSize, NO, 0); {
Now draw each component image into the graphics context at the appropriate position:
CGFloat y = 0;
for (int i = 0; i < count; ++i) {
UIImage *sourceImage = sourceImages[i];
[sourceImage drawAtPoint:CGPointMake(0, y)];
y += sourceImage.size.height;
}
Finally, create the combined image from the context and dispose of the context:
}
UIImage *combinedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Read Drawing and Printing Guide for iOS - Drawing and Creating Images for more information.

Answer 2

I cracked the answer . # rob mayoff : Thanks much who helped me out.
code here
//code to render group of images excluding the image which has been selected in a particular view
-(void )renderImage: (ItemView *)selectedItem
{
NSArray *selectedImages = self.slideView.selectedView.subviews;
int selectedItemIndex = [selectedImages indexOfObject:selectedItem];
if(selectedItem.image==nil){
[selectedItem loadImageFromFile];
}
// first set
UIGraphicsBeginImageContextWithOptions(self.slideView.selectedView.frame.size, NO, 0);
for (int i = 0; i < selectedItemIndex; ++i) {
if([selectedImages[i] isKindOfClass:[ItemView class]]){
ItemView *imageview = (ItemView *)selectedImages[i];
CGAffineTransform transform = imageview.transform;
imageview.transform = CGAffineTransformIdentity;
UIImage *image = [[UIImage alloc] initWithContentsOfFile:imageview.filename];
UIImageView *renderImageView = [[UIImageView alloc] initWithImage:image]; //[imageview copy];
renderImageView.frame = imageview.frame;
renderImageView.bounds = imageview.bounds;
imageview.transform = transform;
renderImageView.transform = transform;
renderImageView.center = CGPointMake(imageview.frame.size.width/2,imageview.frame.size.height/2);
UIView *view = [[UIView alloc] initWithFrame:renderImageView.frame];
view.backgroundColor = [UIColor clearColor];
[view addSubview:renderImageView];
[renderImageView release];
[image release];
imageview.image = nil;
UIGraphicsBeginImageContext(imageview.frame.size);
CGContextRef context1 = UIGraphicsGetCurrentContext();
[view.layer renderInContext:context1];
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[view release];
[result drawAtPoint:imageview.frame.origin];
}
}
UIImage *combinedImage1 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
//UIImageWriteToSavedPhotosAlbum(combinedImage1, nil, nil, nil);
if (groupBgImage1) {
[groupBgImage1 removeFromSuperview];
[groupBgImage1 release];
groupBgImage1 = nil;
}
groupBgImage1 = [[UIImageView alloc] initWithImage:combinedImage1];
[self.slideView.selectedView insertSubview:groupBgImage1 belowSubview:selectedItem ];
// second set
UIGraphicsBeginImageContextWithOptions(self.slideView.selectedView.frame.size, NO, 0);
for (int i = selectedItemIndex+1; i < [selectedImages count]; ++i) {
if([selectedImages[i] isKindOfClass:[ItemView class]]){
ItemView *imageview = (ItemView *)selectedImages[i];
CGAffineTransform transform = imageview.transform;
imageview.transform = CGAffineTransformIdentity;
UIImage *image = [[UIImage alloc] initWithContentsOfFile:imageview.filename];
UIImageView *renderImageView = [[UIImageView alloc] initWithImage:image]; //[imageview copy];
renderImageView.frame = imageview.frame;
renderImageView.bounds = imageview.bounds;
imageview.transform = transform;
renderImageView.transform = transform;
renderImageView.center = CGPointMake(imageview.frame.size.width/2,imageview.frame.size.height/2);
UIView *view = [[UIView alloc] initWithFrame:renderImageView.frame];
view.backgroundColor = [UIColor clearColor];
[view addSubview:renderImageView];
[renderImageView release];
[image release];
imageview.image = nil;
UIGraphicsBeginImageContext(imageview.frame.size);
CGContextRef context1 = UIGraphicsGetCurrentContext();
[view.layer renderInContext:context1];
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[view release];
[result drawAtPoint:imageview.frame.origin];
}
}
UIImage *combinedImage2 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(combinedImage2, nil, nil, nil);
if (groupBgImage2) {
[groupBgImage2 removeFromSuperview];
[groupBgImage2 release];
groupBgImage2 = nil;
}
groupBgImage2 = [[UIImageView alloc] initWithImage:combinedImage2];
[self.slideView.selectedView insertSubview:groupBgImage2 aboveSubview:selectedItem ];
}