Question

我遇到rotating问题并保存JPEG NSImage。我翻了NSView

- (BOOL)isFlipped
{
  return YES;
}

然后我使用以下函数应用NSImage轮换：

- (NSImage*)imageRotatedByDegrees:(CGFloat)degrees
{
  // calculate the bounds for the rotated image
  NSRect imageBounds = {NSZeroPoint, [image size]};
  NSBezierPath* boundsPath = [NSBezierPath
                          bezierPathWithRect:imageBounds];
  NSAffineTransform* transform = [NSAffineTransform transform];

  [transform rotateByDegrees:degrees];
  [boundsPath transformUsingAffineTransform:transform];

  NSRect rotatedBounds = {NSZeroPoint, [boundsPath bounds].size};
  NSImage* rotatedImage = [[NSImage alloc]
                        initWithSize:rotatedBounds.size];

  // center the image within the rotated bounds
  imageBounds.origin.x = NSMidX(rotatedBounds) - (NSWidth
                                              (imageBounds) / 2);
  imageBounds.origin.y = NSMidY(rotatedBounds) - (NSHeight
                                              (imageBounds) / 2);

  // set up the rotation transform
  transform = [NSAffineTransform transform];
  [transform translateXBy:+(NSWidth(rotatedBounds) / 2) yBy:+
   (NSHeight(rotatedBounds) / 2)];
  [transform rotateByDegrees:degrees];
  [transform translateXBy:-(NSWidth(rotatedBounds) / 2) yBy:-
   (NSHeight(rotatedBounds) / 2)];

  // draw the original image, rotated, into the new image
  [rotatedImage lockFocus];
  [transform set];
  [image drawInRect:imageBounds fromRect:NSZeroRect
     operation:NSCompositeCopy fraction:1.0] ;
  [rotatedImage unlockFocus];

  return  rotatedImage;
}

现在已成功旋转图像。后来，当我尝试使用以下代码保存JPEG时：

-(void)saveDocument:(id)sender
{
  NSData *imageData = [image TIFFRepresentation];
  NSBitmapImageRep *imageRep = [NSBitmapImageRep imageRepWithData:imageData];
  NSDictionary *imageProps = 
    [NSDictionary dictionaryWithObject:[NSNumber numberWithFloat:1.0] 
                  forKey:NSImageCompressionFactor];
  imageData = [imageRep representationUsingType:NSJPEGFileType 
                                     properties:imageProps];
  [imageData writeToFile:[_imageURL path] atomically:YES];
}

结果JPEG文件被错误翻转......我做错了什么？

非常感谢任何想法，Petr

Answer 1

- [NSImage lockFocusFlipped：]可以提供帮助。

Answer 2

最后，我确实找到了正确的解决方案。

- (BOOL)isFlipped
{
  return NO;
}

然后设置NSImage非常重要（感谢pointum！）

[_image lockFocusFlipped:YES];

从现在开始，当我保存图像时，他被正确旋转并翻转。

在NSView中保存图像

2 个答案: