Question

I want to rotate a image with UIslider control.

I have done that with the below function

- (void)rotateImage:(UIImageView *)image duration:(NSTimeInterval)duration 
              curve:(int)curve degrees:(CGFloat)degrees
{
    // Setup the animation
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:duration];
    [UIView setAnimationCurve:curve];
    [UIView setAnimationBeginsFromCurrentState:YES];


// The transform matrix
CGAffineTransform transform = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(degrees));
image.transform = transform;

// Commit the changes
[UIView commitAnimations];}

by using this function it will work perfect
but the problem is that i can not save the image reference that is rotated.
i have to use that rotated image for further processing.

So how can i save the image that is in Rotated position?

please Help me over this issue

Thanks

Answer 1

i found the solution of my question

use This below method for This

- (UIImage*)upsideDownBunny:(CGFloat)radians withImage:(UIImage*)testImage {
    __block CGImageRef cgImg;
    __block CGSize imgSize;
    __block UIImageOrientation orientation;
    dispatch_block_t createStartImgBlock = ^(void) {
        // UIImages should only be accessed from the main thread

        UIImage *img =testImage
        imgSize = [img size]; // this size will be pre rotated
        orientation = [img imageOrientation];
        cgImg = CGImageRetain([img CGImage]); // this data is not rotated
    };
    if([NSThread isMainThread]) {
        createStartImgBlock();
    } else {
        dispatch_sync(dispatch_get_main_queue(), createStartImgBlock);
    }
    CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
    // in iOS4+ you can let the context allocate memory by passing NULL
    CGContextRef context = CGBitmapContextCreate( NULL,
                                                 imgSize.width,
                                                 imgSize.height,
                                                 8,
                                                 imgSize.width * 4,
                                                 colorspace,
                                                 kCGImageAlphaPremultipliedLast);
    // rotate so the image respects the original UIImage's orientation
    switch (orientation) {
        case UIImageOrientationDown:
            CGContextTranslateCTM(context, imgSize.width, imgSize.height);
            CGContextRotateCTM(context, -radians);
            break;
        case UIImageOrientationLeft:
            CGContextTranslateCTM(context, 0.0, imgSize.height);
            CGContextRotateCTM(context, 3.0 * -radians / 2.0);
            break;
        case UIImageOrientationRight:
            CGContextTranslateCTM(context,imgSize.width, 0.0);
            CGContextRotateCTM(context, -radians / 2.0);
            break;
        default:
            // there are mirrored modes possible
            // but they aren't generated by the iPhone's camera
            break;
    }
    // rotate the image upside down

    CGContextTranslateCTM(context, +(imgSize.width * 0.5f), +(imgSize.height * 0.5f));
    CGContextRotateCTM(context, -radians);
    //CGContextDrawImage( context, CGRectMake(0.0, 0.0, imgSize.width, imgSize.height), cgImg );
    CGContextDrawImage(context, (CGRect){.origin.x = -imgSize.width* 0.5f , .origin.y = -imgSize.width* 0.5f , .size.width = imgSize.width, .size.height = imgSize.width}, cgImg);
    // grab the new rotated image
    CGContextFlush(context);
    CGImageRef newCgImg = CGBitmapContextCreateImage(context);
    __block UIImage *newImage;
    dispatch_block_t createRotatedImgBlock = ^(void) {
        // UIImages should only be accessed from the main thread
        newImage = [UIImage imageWithCGImage:newCgImg];
    };
    if([NSThread isMainThread]) {
        createRotatedImgBlock();
    } else {
        dispatch_sync(dispatch_get_main_queue(), createRotatedImgBlock);
    }
    CGColorSpaceRelease(colorspace);
    CGImageRelease(newCgImg);
    CGContextRelease(context);
    return newImage;
}

call this method with

 UIImage  *rotated2 = [self upsideDownBunny:rotation];

where rotation is sliderValue between 0 to 360.

now we can save the rotated state.