gdi+ 画半透明图片用什么类什么函数？

需要使用一个矩阵算法，具体实例如下：

private void pictureBox1_Paint(object sender, PaintEventArgs e)

{

//Get the DrawSurface

g = e.Graphics

Bitmap bmp = new Bitmap(".//linux.jpg")

g.FillRectangle(Brushes.White, this.ClientRectangle)

//Create a color matrix

float[][] matrixItems ={

new float[]{1,0,0,0,0},

new float[]{0,1,0,0,0},

new float[]{0,0,1,0,0},

new float[]{0,0,0,0.6f,0},

new float[]{0,0,0,0,1}

}

ColorMatrix colorMatrix = new ColorMatrix(matrixItems)

ImageAttributes imageAtt = new ImageAttributes()

imageAtt.SetColorMatrix(colorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap)

//Now draw the image to the form

g.DrawImage(bmp, this.pictureBox1.ClientRectangle, 0.0f, 0.0f, bmp.Width, bmp.Height, GraphicsUnit.Pixel, imageAtt)

imageAtt.Dispose()

注意矩阵matrixItems其中的0.6f 它就是透明度，可以随意调整；

long factorial(int m) //用于求阶乘

{

if(m==0||m==1)

return 1

else return m*factorial(m-1)

}

long forSum(int n)//用于求阶乘之和

{

int i=0

long y=0

for(i=1i<=ni++)

{

y+=factorial(i)

}

return y

}

#include <stdio.h>

int main()

{

long y=0

int n=0

printf("请输入一个 n:")

scanf("%d",&n)

printf("y=%d\n",forSum(n))

printf("n=%d\n",n)

return 0

}

第二题：

int weiShu(int x) //用于判断数x是几位数

{

int flag=0

do

{

x=x/10

flag++

}while(x!=0)

return flag

}

#include <stdio.h>

{

int flag=0,x=0,i=0

int sum=0

printf("请输入一个数 x=")

scanf("%d",&x)

flag=weiShu(x)

for(i=1i<=flagi++)

{

sum+=x%10

x=x/10

}

printf("%d各个位上数字之和是%d\n",x,sum)

}

个人认为最好的还是第一种:

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