WritableBitmap:编译器抱怨无法找到类型,但intellisense可以找到它

Question

我通过将C#中的程序转换为F#来学习F#

问题在于WritableBitmap,编译器抱怨:
The type tableBitmap is not defined
这是代码:

module MandelbrotBitmap
open System.Windows.Media
open System.Windows.Media.Imaging

type Mandelbrot(width:int) as this =
    let mutable _width = width
    let mutable _height = 10
    let mutable bitmap = new WritableBitmap( _width, _heights, 96.0, 96.0,
       PixelFormats.Bgr32, None)

    member this.Width 
        with get() = _width
        and set(newVal) = _width <- newVal

将None在instanciation是我尝试更换null原表达.
我PresentationCore和WindowsBase我的参考资料.

      bitmap = new WriteableBitmap(
                (int)sizeInfo.NewSize.Width, 
                (int)sizeInfo.NewSize.Height, 
                96, 96, PixelFormats.Bgr32, null);

这篇msdn文章描述了WriteableBitmap

我的问题是; 什么是编译器抱怨？

Answer 1

你有两个拼写错误:WritableBitmap应该是WriteableBitmap,_heights应该是_ height.此外,null并且None不可互换,当您使用.NET框架类时,您必须经常使用null,这是F#的互操作功能.最后一个问题,如果你想在WriteableBitmap构造函数中的行之间拆分你的参数,你需要确保下一行是缩进的,new因为空格在F#中很重要.这是最终的,固定的WriteableBitmap构造函数调用:

new WriteableBitmap( _width, _height, 96.0, 96.0, 
    PixelFormats.Bgr32, null)