Iphone – Rotation and resizing the image + iPhone

iphone

I am trying to resize and rotate an image over the iPhone.
i picked the image and displayed it using UIImageView

and rotation of the image is done by two buttons (for clockwise & counterclockwise)

resizing of image works fine while rotation button not pressed
but when i pressed to rotate image into clockwise direction and the resize the image, width of the image increases rapidly even i am trying to decrease the width.

and when i pressed to rotate image into counterclockwise direction and the resize the image, height of the image increases rapidly even i am trying to decrease it.

i found that there is some sign changed while rotating the image along with the value, coz once press the clockwise button and then counterclockwise button, and then resizing works fine.

i used the following code for rotating the image.

CGAffineTransform transformRotate = CGAffineTransformMakeRotation(movingAngle);
imageViewRotation.transform = transformRotate;

where movingAngle is in Radians
and imageViewRotation is the UIImageView which contains the image.

waiting for your reply

Best Answer

You can make this happen smoother by making it an animation:

[UIView beginAnimations:nil contextNULL];
[UIView setAnimationDuration:.5;

CGAffineTransform transformRotate = CGAffineTransformMakeRotation(movingAngle); 
imageViewRotation.transform = transformRotate;

CGRect frame = /*make the new frame or set it to -->*/self.view.frame;
imageViewRotation.frame = newFrame;

[UIView commitAnimations];

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Ios – How to develop for iPhone using a Windows development machine

It's certainly possible to develop on a Windows machine, in fact, my first application was exclusively developed on the old Dell Precision I had at the time :)

There are three routes;

Install OSx86 (aka iATKOS / Kalyway) on a second partition/disk and dual boot.
Run Mac OS X Server under VMWare (Mac OS X 10.7 (Lion) onwards, read the update below).
Use Delphi XE4 and the macincloud service. This is a commercial toolset, but the component and lib support is growing.

The first route requires modifying (or using a pre-modified) image of Leopard that can be installed on a regular PC. This is not as hard as you would think, although your success/effort ratio will depend upon how closely the hardware in your PC matches that in Mac hardware - e.g. if you're running a Core 2 Duo on an Intel Motherboard, with an NVidia graphics card you are laughing. If you're running an AMD machine or something without SSE3 it gets a little more involved.

If you purchase (or already own) a version of Leopard then this is a gray area since the Leopard EULA states you may only run it on an "Apple Labeled" machine. As many point out if you stick an Apple sticker on your PC you're probably covered.

The second option is more costly. The EULA for the workstation version of Leopard prevents it from being run under emulation and as a result, there's no support in VMWare for this. Leopard server, however, CAN be run under emulation and can be used for desktop purposes. Leopard server and VMWare are expensive, however.

If you're interested in option 1) I would suggest starting at Insanelymac and reading the OSx86 sections.

I do think you should consider whether the time you will invest is going to be worth the money you will save though. It was for me because I enjoy tinkering with this type of stuff and I started during the early iPhone betas, months before their App Store became available.

Alternatively, you could pick up a low-spec Mac Mini from eBay. You don't need much horsepower to run the SDK and you can always sell it on later if you decide to stop development or buy a better Mac.

Update: You cannot create a Mac OS X Client virtual machine for OS X 10.6 and earlier. Apple does not allow these Client OSes to be virtualized. With Mac OS X 10.7 (Lion) onwards, Apple has changed its licensing agreement in regards to virtualization. Source: VMWare KnowledgeBase

Iphone – Resizing UIimages pulled from the Camera also ROTATES the UIimage

The reason your code doesn't work is because the imageOrientation on the code that you have is not being taken into account. Specifically, if the imageOrientation is right/left, then you need to both rotate the image and swap width/height. Here is some code to do this:

-(UIImage*)imageByScalingToSize:(CGSize)targetSize
{
    UIImage* sourceImage = self; 
    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;

    CGImageRef imageRef = [sourceImage CGImage];
    CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
    CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);

    if (bitmapInfo == kCGImageAlphaNone) {
        bitmapInfo = kCGImageAlphaNoneSkipLast;
    }

    CGContextRef bitmap;

    if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {
        bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    } else {
        bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    }   

    if (sourceImage.imageOrientation == UIImageOrientationLeft) {
        CGContextRotateCTM (bitmap, radians(90));
        CGContextTranslateCTM (bitmap, 0, -targetHeight);

    } else if (sourceImage.imageOrientation == UIImageOrientationRight) {
        CGContextRotateCTM (bitmap, radians(-90));
        CGContextTranslateCTM (bitmap, -targetWidth, 0);

    } else if (sourceImage.imageOrientation == UIImageOrientationUp) {
        // NOTHING
    } else if (sourceImage.imageOrientation == UIImageOrientationDown) {
        CGContextTranslateCTM (bitmap, targetWidth, targetHeight);
        CGContextRotateCTM (bitmap, radians(-180.));
    }

    CGContextDrawImage(bitmap, CGRectMake(0, 0, targetWidth, targetHeight), imageRef);
    CGImageRef ref = CGBitmapContextCreateImage(bitmap);
    UIImage* newImage = [UIImage imageWithCGImage:ref];

    CGContextRelease(bitmap);
    CGImageRelease(ref);

    return newImage; 
}

This will resize your image and rotate it to the correct orientation. If you need the definition for radians, it is:

static inline double radians (double degrees) {return degrees * M_PI/180;}

The answer Daniel gave is also correct, but it suffers from the problem that it is not thread-safe, since you're using UIGraphicsBeginImageContext(). Since the above code only uses CG functions, you're all set. I also have a similar function to resize and do proper aspect fill on images - let me know if that's what you're looking for.

Note: I got the original function from this post, and did some modifications to make it work on JPEGs.

Best Answer

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Ios – How to develop for iPhone using a Windows development machine

Iphone – Resizing UIimages pulled from the Camera also ROTATES the UIimage

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