Mac图片保存及等比缩放

//保存图片

• (void )saveImage:(NSImage *)image imageName:(NSString *)name{
  [image lockFocus];
  //先设置 下面一个实例
  NSBitmapImageRep *bits = [[NSBitmapImageRep alloc]initWithFocusedViewRect:NSMakeRect(0, 0, image.size.width, image.size.height)];//138.32为图片的长和宽
  [image unlockFocus];
  //再设置后面要用到得 props属性
  NSDictionary *imageProps = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:0] forKey:NSImageCompressionFactor];
  //之后 转化为NSData 以便存到文件中
  NSData *imageData = [bits representationUsingType:NSPNGFileType properties:imageProps];
  //设定好文件路径后进行存储就ok了 /Users/mjt/Pictures
  NSString *path = [NSString stringWithFormat:@"~/Pictures/%@.png",name];
  BOOL isSuccess = [imageData writeToFile:[[NSString stringWithString:path] stringByExpandingTildeInPath]atomically:YES]; //保存的文件路径一定要是绝对路径，相对路径不行
  NSLog(@"Save Image: %d", isSuccess);
  // NSImage *imag = [[NSImage alloc] initWithContentsOfFile:path];
  // NSImageView *iamgview = [NSImageView imageViewWithImage:image];
  // [self.bgView addSubview:iamgview];
  // iamgview.frame = NSMakeRect(0, 0, 400, 300);
  }
  // 等比缩放

• (NSImage)resizeImage2:(NSImage)sourceImage forSize:(CGSize)targetSize {
  CGSize imageSize = sourceImage.size;
  CGFloat width = imageSize.width;
  CGFloat height = imageSize.height;
  CGFloat targetWidth = targetSize.width;
  CGFloat targetHeight = targetSize.height;
  CGFloat scaleFactor = 0.0;
  CGFloat scaledWidth = targetWidth;
  CGFloat scaledHeight = targetHeight;
  CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

  if (CGSizeEqualToSize(imageSize, targetSize) == NO) {
  CGFloat widthFactor = targetWidth / width;
  CGFloat heightFactor = targetHeight / height;

    // scale to fit the longer
    scaleFactor = (widthFactor>heightFactor)?widthFactor:heightFactor;
    scaledWidth  = ceil(width * scaleFactor);
    scaledHeight = ceil(height * scaleFactor);
    
    // center the image
    if (widthFactor > heightFactor) {
        thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
    } else if (widthFactor < heightFactor) {
        thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
    }
  

  }

  NSImage *newImage = [[NSImage alloc] initWithSize:NSMakeSize(scaledWidth, scaledHeight)];
  CGRect thumbnailRect = {thumbnailPoint, {scaledWidth, scaledHeight}};
  NSRect imageRect = NSMakeRect(0.0, 0.0, width, height);

  [newImage lockFocus];
  [sourceImage drawInRect:thumbnailRect fromRect:imageRect operation:NSCompositeCopy fraction:1.0];
  [newImage unlockFocus];

  return newImage;
  }