MonoTouch将彩色UIImage转换为alpha到灰度和模糊？

问题描述

我正在尝试从颜色PNG和alpha中找到用于生成模糊灰度 UIImage 的配方。 ObjC中有配方，但MonoTouch不绑定 CGRect 函数，所以不知道如何做到这一点。有什么想法？

I am trying to find a recipe for producing a a blurred grayscale UIImage from a color PNG and alpha. There are recipes out there in ObjC but MonoTouch does not bind the CGRect functions so not sure how to do this. Any ideas?

以下是灰度的一个ObjC示例：

Here is one ObjC example of grayscale:

(UIImage *)convertImageToGrayScale:(UIImage *)image
{
  // Create image rectangle with current image width/height
  CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height);

  // Grayscale color space
  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();

  // Create bitmap content with current image size and grayscale colorspace
  CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0,   colorSpace, kCGImageAlphaNone);

  // Draw image into current context, with specified rectangle
  // using previously defined context (with grayscale colorspace)
  CGContextDrawImage(context, imageRect, [image CGImage]);

  // Create bitmap image info from pixel data in current context
  CGImageRef imageRef = CGBitmapContextCreateImage(context);

  // Create a new UIImage object
  UIImage *newImage = [UIImage imageWithCGImage:imageRef];

  // Release colorspace, context and bitmap information
  CGColorSpaceRelease(colorSpace);
  CGContextRelease(context);
  CFRelease(imageRef);

  // Return the new grayscale image
  return newImage;
}

推荐答案

使用MonoTouch CGRect 映射到 RectangleF 。存在许多应该映射到 GCRect 提供的每个函数的扩展方法。使用它们移植ObjectiveC代码应该没有任何问题。

When using MonoTouch CGRect is mapped to RectangleF. A lot of extension methods exists that should map to every function provided by GCRect. You should not have any problem in porting ObjectiveC code using them.

如果缺少某些内容，请填写错误报告@ 我们会尽快修复它（并在可能的情况下提供解决方法）。

If something is missing please fill a bug report @ http://bugzilla.xamarin.com and we'll fix it asap (and provide a workaround when possible).

如果您有链接，请编辑您的问题并添加。这样可以更方便地帮助您：）

If you have links then please edit your question and add them. That will make it easier to help you :)

更新

这是一个，逐行，C＃转换你的例子。它似乎对我有用（而且它比Objective-C更容易;）

Here's a, line-by-line, C# translation of your example. It seems to works for me (and it's much easier to my eyes than Objective-C ;-)

    UIImage ConvertToGrayScale (UIImage image)
    {
        RectangleF imageRect = new RectangleF (PointF.Empty, image.Size);
        using (var colorSpace = CGColorSpace.CreateDeviceGray ())
        using (var context = new CGBitmapContext (IntPtr.Zero, (int) imageRect.Width, (int) imageRect.Height, 8, 0, colorSpace, CGImageAlphaInfo.None)) {
            context.DrawImage (imageRect, image.CGImage);
            using (var imageRef = context.ToImage ())
                return new UIImage (imageRef);
        }
    }

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