UIImagePickerController cameraViewTransform acts differently in iOS 4

Question

I upgraded both my iPhone and SDK to iOS 4.0.1 and now my App doesn\'t run the same way it was running in iOS 3.x.

My App uses the UIImagePickerController with a cus

Answer 1

ios 4.0 Magic number 1936/320= 6.05 , 2592/6.05 = 428 , 480-428 = 52 52/(428/2)=0.24299 +1=1.24299

ios 3.0 Magic number 1536/320=4.8 2048/4.8=427 480-427=53 53/427=0.121412 +1=1.12412

That is the relationship cameraresolution-screenresolution

For iOS 3.0 the cameraViewTransform is applied from the top so you have to use all the height. But in iOS4 it is applied from the center of the frame so you have to use the half of the height. And you have to move the frame down (52/2) to leave the frame in the center.

Answer 2

I'm finding the new scale transform for the iPhone 4 to be ~1.25 (instead of ~1.12).

I spent a few minutes trying to figure out where these magic numbers come from - I assume there's some sort of relationship between the screen resolution & the camera resolution, but I couldn't figure it out in a hurry...

If someone does, please post an answer - I hate magic numbers.

FYI the camera res of the iPhone 4 is 2592x1936, while the iPhone 3GS is 2048x1536.

Answer 3

CGAffineTransformMakeTranslation will not work directly on cameraViewTransform. So, use CGAffineTransformScale to apply CGAffineTransformMakeTranslation.

float yOffset = 44.0;
CGAffineTransform translate = CGAffineTransformMakeTranslation(0.0, yOffset);
self.cameraFeed.cameraViewTransform = CGAffineTransformScale(translate, 1, 1);

Answer 4

I am not sure about iOS 3.0 but for iOS 4.0 the cameraViewTransform is applied from the center of the frame. You can verify this by first applying a translation transform.

CGAffineTransform translate = CGAffineTransformMakeTranslation(0.0, 27.0);
imagePickerController.cameraViewTransform = translate;

You can see that this moves the view to the center. Next apply the scaling transform and you will see that it fills the screen.

CGAffineTransform scale = CGAffineTransformScale(translate, 1.125, 1.125);
imagePickerController.cameraViewTransform = scale;

If the scaling transform alone works for iOS 3 and company then the transform is applied to the a different anchor point like center top. You should always scale linearly in both directions or your image will be skewed.