旋转图像并以旋转状态保存图像

5 回答

• 2

  我找到了问题的解决方案

  使用以下方法

  - (UIImage*)upsideDownBunny:(CGFloat)radians withImage:(UIImage*)testImage {
      __block CGImageRef cgImg;
      __block CGSize imgSize;
      __block UIImageOrientation orientation;
      dispatch_block_t createStartImgBlock = ^(void) {
          // UIImages should only be accessed from the main thread
  
          UIImage *img =testImage
          imgSize = [img size]; // this size will be pre rotated
          orientation = [img imageOrientation];
          cgImg = CGImageRetain([img CGImage]); // this data is not rotated
      };
      if([NSThread isMainThread]) {
          createStartImgBlock();
      } else {
          dispatch_sync(dispatch_get_main_queue(), createStartImgBlock);
      }
      CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
      // in iOS4+ you can let the context allocate memory by passing NULL
      CGContextRef context = CGBitmapContextCreate( NULL,
                                                   imgSize.width,
                                                   imgSize.height,
                                                   8,
                                                   imgSize.width * 4,
                                                   colorspace,
                                                   kCGImageAlphaPremultipliedLast);
      // rotate so the image respects the original UIImage's orientation
      switch (orientation) {
          case UIImageOrientationDown:
              CGContextTranslateCTM(context, imgSize.width, imgSize.height);
              CGContextRotateCTM(context, -radians);
              break;
          case UIImageOrientationLeft:
              CGContextTranslateCTM(context, 0.0, imgSize.height);
              CGContextRotateCTM(context, 3.0 * -radians / 2.0);
              break;
          case UIImageOrientationRight:
              CGContextTranslateCTM(context,imgSize.width, 0.0);
              CGContextRotateCTM(context, -radians / 2.0);
              break;
          default:
              // there are mirrored modes possible
              // but they aren't generated by the iPhone's camera
              break;
      }
      // rotate the image upside down
  
      CGContextTranslateCTM(context, +(imgSize.width * 0.5f), +(imgSize.height * 0.5f));
      CGContextRotateCTM(context, -radians);
      //CGContextDrawImage( context, CGRectMake(0.0, 0.0, imgSize.width, imgSize.height), cgImg );
      CGContextDrawImage(context, (CGRect){.origin.x = -imgSize.width* 0.5f , .origin.y = -imgSize.width* 0.5f , .size.width = imgSize.width, .size.height = imgSize.width}, cgImg);
      // grab the new rotated image
      CGContextFlush(context);
      CGImageRef newCgImg = CGBitmapContextCreateImage(context);
      __block UIImage *newImage;
      dispatch_block_t createRotatedImgBlock = ^(void) {
          // UIImages should only be accessed from the main thread
          newImage = [UIImage imageWithCGImage:newCgImg];
      };
      if([NSThread isMainThread]) {
          createRotatedImgBlock();
      } else {
          dispatch_sync(dispatch_get_main_queue(), createRotatedImgBlock);
      }
      CGColorSpaceRelease(colorspace);
      CGImageRelease(newCgImg);
      CGContextRelease(context);
      return newImage;
  }
  

  用这个方法调用

  UIImage  *rotated2 = [self upsideDownBunny:rotation];
  

  其中rotation是0到360之间的sliderValue .

  现在我们可以保存旋转状态 .

  回复于 2024-05-14T00:30:55+08:00
• 0

  我尝试了上面的代码，它正在工作，但仅适用于SQUARE图像，这是另一个有效的解决方案，它将重绘图像并保持正确的宽度/高度：

  - (UIImage *) rotatedImage:(UIImage *)imageRotation and:(CGFloat) rotation
  {
  // Calculate Destination Size
  CGAffineTransform t = CGAffineTransformMakeRotation(rotation);
  CGRect sizeRect = (CGRect) {.size = imageRotation.size};
  CGRect destRect = CGRectApplyAffineTransform(sizeRect, t);
  CGSize destinationSize = destRect.size;
  
  // Draw image
  UIGraphicsBeginImageContext(destinationSize);
  CGContextRef context = UIGraphicsGetCurrentContext();
  CGContextTranslateCTM(context, destinationSize.width / 2.0f, destinationSize.height / 2.0f);
  CGContextRotateCTM(context, rotation);
  [imageRotation drawInRect:CGRectMake(-imageRotation.size.width / 2.0f, -imageRotation.size.height / 2.0f, imageRotation.size.width, imageRotation.size.height)];
  
  // Save image
  UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  return newImage;
  

  }

  这里的旋转参数是Radian . 您可以通过在函数上方添加此转换（或直接在.m文件中）来执行转换

  #define M_PI   3.14159265358979323846264338327950288   /* pi */
  #define DEGREES_TO_RADIANS(angle) (angle / 180.0 * M_PI)
  

  最后，我用动画调用了这个：

  [UIView animateWithDuration:0.5f delay:0 options:UIViewAnimationCurveEaseIn animations:^{
      //Only used for the ANIMATION of the uiimage
      imageView.transform = CGAffineTransformRotate(editorPad.transform, DEGREES_TO_RADIANS(90));
  }completion:^(BOOL finished) {
      // Workaround : Need to set previous transformation back or the next step will turn the image more
      imageView.transform = CGAffineTransformRotate(imageView.transform, DEGREES_TO_RADIANS(-90));
      imageView.image = [self imageView.image and:DEGREES_TO_RADIANS(90)];
  }];
  

  我希望这也有帮助！

  干杯 .

  回复于 2024-05-14T00:30:55+08:00
• 3

  进一步处理的一种方法是按顺序应用更多转换，如：

  CGAffineTransform transform = CGAffineTransformScale(previousTransform, newScale, newScale);
  

  在这种情况下，您可以对旋转的图像应用缩放 .

  如果您需要保存此信息以便能够在稍后的某个时间点重做转换，则可以简单地存储旋转角度，缩放系数（在我的示例中）以及再次构建转换 .

  您还可以考虑将 CGAffineTransform 存储在您的 class 或其他机制的ivar中 .

  编辑：

  如果通过保存意味着保存到文件，您可以使用以下代码将视图转换为图像：

  NSData *data;
  NSBitmapImageRep *rep;
  rep = [self bitmapImageRepForCachingDisplayInRect:[self frame]];
  [self cacheDisplayInRect:[self frame] toBitmapImageRep:rep];
  data = [rep TIFFRepresentation];
  

  然后将NSData保存到文件中

  对于PNG：

  UIGraphicsBeginImageContext(self.bounds.size);
   [self.layer renderInContext:UIGraphicsGetCurrentContext()];
   UIImage* image1 = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();
   NSData *imageData = UIImagePNGRepresentation(image1);
   [imageData writeToFile:filePath atomically:YES];
  

  回复于 2024-05-14T00:30:55+08:00
• 0

  您可以将旋转的图像渲染到另一个图像中：

  UIGraphicsBeginImageContext(aCGRectToHoldYourImage);
  CALayer* layer = myRotatedImageView.layer;
  
  [layer renderInContext:UIGraphicsGetCurrentContext()];
  UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  

  然后从中获取PNG数据并将其保存到文件中

  NSData* myPNGData = [viewImage UIImagePNGRepresentation];
  [myPNGData writeToFile:@"aFileName.png" atomically:YES];
  

  Proviso，我把它键入StackOverflow，而不是编译器:-)

  回复于 2024-05-14T00:30:55+08:00
• 0

  保存UIImageView的变换值，并在下次要使用此UIImageView或甚至在另一个UIImageView中时应用此变换值 .

  回复于 2024-05-14T00:30:55+08:00