Monday, April 2, 2012

Which direction is `UIImageOrientationUp`

UIImage has a good property named imageOrientation, all the images taken by iPhone/iPad is stored in physical orientation, when draw it on the view, most of the UIKit API and CoreGraphic API can recognize the orientation and render it it correct orientation. But if you need to resize the image or do some effect on the image by yourself, you need to calculate the image orientation by yourself. Thus you MUST understand which direction is UIImageOrientationUp.

The possible orientations

The UIImage header file defined the orientations as:

 typedef enum {     UIImageOrientationUp,            // default orientation     UIImageOrientationDown,          // 180 deg rotation     UIImageOrientationLeft,          // 90 deg CCW     UIImageOrientationRight,         // 90 deg CW     UIImageOrientationUpMirrored,    // as above but image mirrored along other axis. horizontal flip     UIImageOrientationDownMirrored,  // horizontal flip     UIImageOrientationLeftMirrored,  // vertical flip     UIImageOrientationRightMirrored, // vertical flip } UIImageOrientation;  

Fine, it is commented, but, hmm, no so well. Could you tell me which direction is the UIImageOrientationUp?

The UP orientation

It’s not the orientation when you hold your iPhone in the normal mode. Make a guess!

OK, I know your guys are not so patient, so,

Here is the correct answer: this orientation is the UP!

The UP orientation when you take a photo on iPhone

Via Tonny Xu iPhone Dev, Tips

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