IOS 拍照旋转修正

1. - (UIImage *)fixOrientation:(UIImage *)aImage {
2. // No-op if the orientation is already correct
3. if (aImage.imageOrientation == UIImageOrientationUp)
4. return aImage;
5. // We need to calculate the proper transformation to make the image upright.
6. // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
7. CGAffineTransform transform = CGAffineTransformIdentity;
8. switch (aImage.imageOrientation) {
9. case UIImageOrientationDown:
10. case UIImageOrientationDownMirrored:
11. transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height);
12. transform = CGAffineTransformRotate(transform, M_PI);
13. break;
14. case UIImageOrientationLeft:
15. case UIImageOrientationLeftMirrored:
16. transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
17. transform = CGAffineTransformRotate(transform, M_PI_2);
18. break;
19. case UIImageOrientationRight:
20. case UIImageOrientationRightMirrored:
21. transform = CGAffineTransformTranslate(transform, 0, aImage.size.height);
22. transform = CGAffineTransformRotate(transform, -M_PI_2);
23. break;
24. default:
25. break;
26. }
27. switch (aImage.imageOrientation) {
28. case UIImageOrientationUpMirrored:
29. case UIImageOrientationDownMirrored:
30. transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
31. transform = CGAffineTransformScale(transform, -1, 1);
32. break;
33. case UIImageOrientationLeftMirrored:
34. case UIImageOrientationRightMirrored:
35. transform = CGAffineTransformTranslate(transform, aImage.size.height, 0);
36. transform = CGAffineTransformScale(transform, -1, 1);
37. break;
38. default:
39. break;
40. }
41. // Now we draw the underlying CGImage into a new context, applying the transform
42. // calculated above.
43. CGContextRef ctx = CGBitmapContextCreate(NULL, aImage.size.width, aImage.size.height,
44. CGImageGetBitsPerComponent(aImage.CGImage), 0,
45. CGImageGetColorSpace(aImage.CGImage),
46. CGImageGetBitmapInfo(aImage.CGImage));
47. CGContextConcatCTM(ctx, transform);
48. switch (aImage.imageOrientation) {
49. case UIImageOrientationLeft:
50. case UIImageOrientationLeftMirrored:
51. case UIImageOrientationRight:
52. case UIImageOrientationRightMirrored:
53. // Grr...
54. CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.height,aImage.size.width), aImage.CGImage);
55. break;
56. default:
57. CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.width,aImage.size.height), aImage.CGImage);
58. break;
59. }
60. // And now we just create a new UIImage from the drawing context
61. CGImageRef cgimg = CGBitmapContextCreateImage(ctx);
62. UIImage *img = [UIImage imageWithCGImage:cgimg];
63. CGContextRelease(ctx);
64. CGImageRelease(cgimg);
65. return img;
66. }