f#代码实际上比C#代码慢500倍。我究竟做错了什么?
我试图使两种语言的代码基本相同。 SetPixel在f#中的运行速度要慢得多是没有道理的。
F#:
module Imaging
open System.Drawing;
#light
type Image (width : int, height : int) = class
member z.Pixels = Array2D.create width height Color.White
member z.Width with get() = z.Pixels.GetLength 0
member z.Height with get() = z.Pixels.GetLength 1
member z.Save (filename:string) =
let bitmap = new Bitmap(z.Width, z.Height)
let xmax = bitmap.Width-1
let ymax = bitmap.Height-1
let mutable bob = 0;
for x in 0..xmax do
for y in 0..ymax do
bitmap.SetPixel(x,y,z.Pixels.[x,y])
bitmap.Save(filename)
new() = Image(1280, 720)
end
let bob = new Image(500,500)
bob.Save @"C:\Users\White\Desktop\TestImage2.bmp"
C#:
using System.Drawing;
namespace TestProject
{
public class Image
{
public Color[,] Pixels;
public int Width
{
get
{
return Pixels.GetLength(0);
}
}
public int Height
{
get
{
return Pixels.GetLength(1);
}
}
public Image(int width, int height)
{
Pixels = new Color[width, height];
for (int x = 0; x < Width; x++)
{
for (int y = 0; y < Height; y++)
{
Pixels[x, y] = Color.White;
}
}
}
public void Save(string filename)
{
Bitmap bitmap = new Bitmap(Width, Height);
for (int x = 0; x < bitmap.Width; x++)
{
for (int y = 0; y < bitmap.Height; y++)
{
bitmap.SetPixel(x, y, Pixels[x, y]);
}
}
bitmap.Save(filename);
}
}
class Program
{
static void Main(string[] args)
{
Image i = new Image(500, 500);
i.Save(@"C:\Users\White\Desktop\TestImage2.bmp");
}
}
}
最佳答案
您在F#中对Pixels
属性的定义是错误的:每次访问其值时(例如,在Save
的内部循环中),将重新评估该定义。您应该改用以下形式:
member val Pixels = Array2D.create width height Color.White
调用构造函数时,它将只对右侧进行一次评估,然后缓存该值。
关于c# - Bitmap.SetPixel在f#中的作用比在C#中慢,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/18341505/