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Straighten and Scale UIImage

/ Published in: Objective C
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Usage: [self straightenAndScaleImage:imageView.image andTheMaxDimension:100];

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  1. - (UIImage*)straightenAndScaleImage:(UIImage *)theFullImage andTheMaxDimension:(int)maxDimension
  2. {
  3.  
  4. 	CGImageRef img = [theFullImage CGImage];
  5. 	CGFloat width = CGImageGetWidth(img);
  6. 	CGFloat height = CGImageGetHeight(img);
  7. 	CGRect bounds = CGRectMake(0, 0, width, height);
  8. 	CGSize size = bounds.size;
  9. 	if (width > maxDimension || height > maxDimension) {
  10.     CGFloat ratio = width/height;
  11.     if (ratio > 1.0f) {
  12. 			size.width = maxDimension;
  13. 			size.height = size.width / ratio;
  14.     }
  15.     else {
  16. 			size.height = maxDimension;
  17. 			size.width = size.height * ratio;
  18.     }
  19. 	} 
  20.  
  21. 	CGFloat scale = size.width/width;
  22. 	CGAffineTransform transform = orientationTransformForImage(theFullImage, &size);
  23.  
  24. 	//CGAffineTransform transform = orientationTransformForImage(theFullImage, &size);
  25. 	UIGraphicsBeginImageContext(size);
  26. 	CGContextRef context = UIGraphicsGetCurrentContext();
  27. 	// Flip 
  28. 	UIImageOrientation orientation = [theFullImage imageOrientation];
  29. 	if (orientation == UIImageOrientationRight || orientation == UIImageOrientationLeft) {
  30.  
  31.     CGContextScaleCTM(context, -scale, scale);
  32.     CGContextTranslateCTM(context, -height, 0);
  33. 	}else {
  34.     CGContextScaleCTM(context, scale, -scale);
  35.     CGContextTranslateCTM(context, 0, -height);
  36. 	}
  37. 	CGContextConcatCTM(context, transform);
  38. 	CGContextDrawImage(context, bounds, img);
  39. 	UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
  40. 	UIGraphicsEndImageContext();
  41. 	return newImage;
  42. }
  43.  
  44. CGAffineTransform orientationTransformForImage(UIImage *image, CGSize *newSize) {
  45. 	CGImageRef img = [image CGImage];
  46. 	CGFloat width = CGImageGetWidth(img);
  47. 	CGFloat height = CGImageGetHeight(img);
  48. 	CGSize size = CGSizeMake(width, height);
  49. 	CGAffineTransform transform = CGAffineTransformIdentity;
  50. 	CGFloat origHeight = size.height;
  51. 	UIImageOrientation orient = image.imageOrientation;
  52. 	switch(orient) { /* EXIF 1 to 8 */
  53. 		case UIImageOrientationUp:
  54. 			break;
  55. 		case UIImageOrientationUpMirrored:
  56. 			transform = CGAffineTransformMakeTranslation(width, 0.0f);
  57. 			transform = CGAffineTransformScale(transform, -1.0f, 1.0f);
  58. 			break;
  59. 		case UIImageOrientationDown:
  60. 			transform = CGAffineTransformMakeTranslation(width, height);
  61. 			transform = CGAffineTransformRotate(transform, M_PI);
  62. 			break;
  63. 		case UIImageOrientationDownMirrored:
  64. 			transform = CGAffineTransformMakeTranslation(0.0f, height);
  65. 			transform = CGAffineTransformScale(transform, 1.0f, -1.0f);
  66. 			break;
  67. 		case UIImageOrientationLeftMirrored:
  68. 			size.height = size.width;
  69. 			size.width = origHeight;
  70. 			transform = CGAffineTransformMakeTranslation(height, width);
  71. 			transform = CGAffineTransformScale(transform, -1.0f, 1.0f);
  72. 			transform = CGAffineTransformRotate(transform, 3.0f * M_PI / 2.0f);
  73. 			break;
  74. 		case UIImageOrientationLeft:
  75. 			size.height = size.width;
  76. 			size.width = origHeight;
  77. 			transform = CGAffineTransformMakeTranslation(0.0f, width);
  78. 			transform = CGAffineTransformRotate(transform, 3.0f * M_PI / 2.0f);
  79. 			break;
  80. 		case UIImageOrientationRightMirrored:
  81. 			size.height = size.width;
  82. 			size.width = origHeight;
  83. 			transform = CGAffineTransformMakeScale(-1.0f, 1.0f);
  84. 			transform = CGAffineTransformRotate(transform, M_PI / 2.0f);
  85. 			break;
  86. 		case UIImageOrientationRight:
  87. 			size.height = size.width;
  88. 			size.width = origHeight;
  89. 			transform = CGAffineTransformMakeTranslation(height, 0.0f);
  90. 			transform = CGAffineTransformRotate(transform, M_PI / 2.0f);
  91. 			break;
  92. 		default:
  93. 			;
  94. 	}
  95. 	*newSize = size;
  96. 	return transform;
  97. }

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