[Author: caseyho]

UIImage rotate method plus tests.

R=altse
APPROVED=altse
DELTA=152  (152 added, 0 deleted, 0 changed)

5 files changed, 137 insertions, 0 deletions

diff --git a/iPhone/GTMUIImage+Resize.h b/iPhone/GTMUIImage+Resize.h
index 25e2125..a1d4ed3 100644
--- a/iPhone/GTMUIImage+Resize.h
+++ b/iPhone/GTMUIImage+Resize.h
@@ -37,4 +37,15 @@
 - (UIImage *)gtm_imageByResizingToSize:(CGSize)targetSize
                    preserveAspectRatio:(BOOL)preserveAspectRatio
                              trimToFit:(BOOL)trimToFit;
+
+// Returns an image rotated by |orientation| where the current orientation is
+// taken as UIImageOrientationUp. Nil if |orientation| is invalid.
+//
+// For example, UIImageOrientationRight is a 90 degree rotation clockwise,
+// UIImageOrientationDown is a 180 degree rotation closewise.
+//
+// Supplying UIImageOrientationUp to |orientation| will return a copy of the
+// image.
+- (UIImage *)gtm_imageByRotating:(UIImageOrientation)orientation;
+
 @end
diff --git a/iPhone/GTMUIImage+Resize.m b/iPhone/GTMUIImage+Resize.m
index 9dd2144..49b82c8 100644
--- a/iPhone/GTMUIImage+Resize.m
+++ b/iPhone/GTMUIImage+Resize.m
@@ -17,6 +17,16 @@
 //
 
 #import "GTMUIImage+Resize.h"
+#import "GTMDefines.h"
+
+GTM_INLINE CGSize swapWidthAndHeight(CGSize size) {
+  CGFloat  tempWidth = size.width;
+
+  size.width  = size.height;
+  size.height = tempWidth;
+
+  return size;
+}
 
 @implementation UIImage (GTMUIImageResizeAdditions)
 
@@ -83,4 +93,94 @@
   UIGraphicsEndImageContext();
   return resizedPhoto;
 }
+
+// Based on code by Trevor Harmon:
+// http://vocaro.com/trevor/blog/wp-content/uploads/2009/10/UIImage+Resize.h
+// http://vocaro.com/trevor/blog/wp-content/uploads/2009/10/UIImage+Resize.m
+- (UIImage *)gtm_imageByRotating:(UIImageOrientation)orientation {
+  CGRect bounds = CGRectZero;
+  CGRect rect = CGRectZero;
+  CGAffineTransform transform = CGAffineTransformIdentity;
+
+  bounds.size = [self size];
+  rect.size = [self size];
+
+  switch (orientation) {
+    case UIImageOrientationUp:
+      return [UIImage imageWithCGImage:[self CGImage]];
+
+    case UIImageOrientationUpMirrored:
+      transform = CGAffineTransformMakeTranslation(rect.size.width, 0.0);
+      transform = CGAffineTransformScale(transform, -1.0, 1.0);
+      break;
+
+    case UIImageOrientationDown:
+      transform = CGAffineTransformMakeTranslation(rect.size.width,
+                                                   rect.size.height);
+      transform = CGAffineTransformRotate(transform, M_PI);
+      break;
+
+    case UIImageOrientationDownMirrored:
+      transform = CGAffineTransformMakeTranslation(0.0, rect.size.height);
+      transform = CGAffineTransformScale(transform, 1.0, -1.0);
+      break;
+
+    case UIImageOrientationLeft:
+      bounds.size = swapWidthAndHeight(bounds.size);
+      transform = CGAffineTransformMakeTranslation(0.0, rect.size.width);
+      transform = CGAffineTransformRotate(transform, -M_PI_2);
+      break;
+
+    case UIImageOrientationLeftMirrored:
+      bounds.size = swapWidthAndHeight(bounds.size);
+      transform = CGAffineTransformMakeTranslation(rect.size.height,
+                                                   rect.size.width);
+      transform = CGAffineTransformScale(transform, -1.0, 1.0);
+      transform = CGAffineTransformRotate(transform, -M_PI_2);
+      break;
+
+    case UIImageOrientationRight:
+      bounds.size = swapWidthAndHeight(bounds.size);
+      transform = CGAffineTransformMakeTranslation(rect.size.height, 0.0);
+      transform = CGAffineTransformRotate(transform, M_PI_2);
+      break;
+
+    case UIImageOrientationRightMirrored:
+      bounds.size = swapWidthAndHeight(bounds.size);
+      transform = CGAffineTransformMakeScale(-1.0, 1.0);
+      transform = CGAffineTransformRotate(transform, M_PI_2);
+      break;
+
+    default:
+      _GTMDevAssert(false, @"Invalid orientation %d", orientation);
+      return nil;
+  }
+
+  UIGraphicsBeginImageContext(bounds.size);
+  CGContextRef context = UIGraphicsGetCurrentContext();
+
+  switch (orientation) {
+    case UIImageOrientationLeft:
+    case UIImageOrientationLeftMirrored:
+    case UIImageOrientationRight:
+    case UIImageOrientationRightMirrored:
+      CGContextScaleCTM(context, -1.0, 1.0);
+      CGContextTranslateCTM(context, -rect.size.height, 0.0);
+      break;
+
+    default:
+      CGContextScaleCTM(context, 1.0, -1.0);
+      CGContextTranslateCTM(context, 0.0, -rect.size.height);
+      break;
+  }
+
+  CGContextConcatCTM(context, transform);
+  CGContextDrawImage(context, rect, [self CGImage]);
+
+  UIImage *rotatedImage = UIGraphicsGetImageFromCurrentImageContext();
+  UIGraphicsEndImageContext();
+
+  return rotatedImage;
+}
+
 @end
diff --git a/iPhone/GTMUIImage+ResizeTest.m b/iPhone/GTMUIImage+ResizeTest.m
index 4678511..8318104 100644
--- a/iPhone/GTMUIImage+ResizeTest.m
+++ b/iPhone/GTMUIImage+ResizeTest.m
@@ -253,4 +253,30 @@
   GTMUIImageResizeAssertImageEqual(actual, @"50x100_to_40x60_clip");
 }
 
+- (void)testImageByRotating {
+  UIImage *actual = nil;
+  UIImage *landscapeImage =
+      [UIImage imageNamed:@"GTMUIImage+Resize_100x50.png"];
+  STAssertNotNil(landscapeImage, @"Unable to read image.");
+
+  // Rotate 90 degrees.
+  actual = [landscapeImage gtm_imageByRotating:UIImageOrientationRight];
+  GTMUIImageResizeAssertImageEqual(actual, @"50x100");
+
+  // Rotate 180 degrees.
+  actual = [landscapeImage gtm_imageByRotating:UIImageOrientationDown];
+  GTMUIImageResizeAssertImageEqual(actual,
+                                   @"100x50_flipped");
+
+
+  // Rotate 270 degrees.
+  actual = [landscapeImage gtm_imageByRotating:UIImageOrientationLeft];
+  GTMUIImageResizeAssertImageEqual(actual,
+                                   @"50x100_flipped");
+
+  // Rotate 360 degrees.
+  actual = [landscapeImage gtm_imageByRotating:UIImageOrientationUp];
+  GTMUIImageResizeAssertImageEqual(actual, @"100x50");
+}
+
 @end
diff --git a/iPhone/TestData/GTMUIImage+Resize_100x50_flipped.png b/iPhone/TestData/GTMUIImage+Resize_100x50_flipped.png
new file mode 100644
index 0000000..c6b1d8f
--- /dev/null
+++ b/iPhone/TestData/GTMUIImage+Resize_100x50_flipped.png
diff --git a/iPhone/TestData/GTMUIImage+Resize_50x100_flipped.png b/iPhone/TestData/GTMUIImage+Resize_50x100_flipped.png
new file mode 100644
index 0000000..bdce5a2
--- /dev/null
+++ b/iPhone/TestData/GTMUIImage+Resize_50x100_flipped.png