Question

我想在PictureBox中的图像上绘制网格。
但是，绘制网格时，图像消失了。
如何解决此代码？选中CheckBox或使用TrackBar更改网格大小时，它将绘制网格。

private void grid()
{
    int x, y;
    int w = pictureBox1.Size.Width;
    int h = pictureBox1.Size.Height;
    int inc = trackBar1.Value;

    BackImage = new Bitmap(w, h);
    Pen myPen = new Pen(Color.Green);

    Graphics gr = Graphics.FromImage(BackImage);
    gr.Clear(SystemColors.Control);

    if (checkBox1.Checked == true)
    {
        myPen.Color = Color.Green;

        for (x = 0; x < w; x += inc)
            gr.DrawLine(myPen, x, pictureBox1.Location.Y, x, h);

        for (y = 0; y < h; y += inc)
            gr.DrawLine(myPen, pictureBox1.Location.X, y, w, y);
    }
    Invalidate();
    myPen.Dispose();
}

private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
   grid();
    Refresh();
}

private void trackBar1_Scroll(object sender, EventArgs e)
{
   grid();
   Refresh();
}

private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
    if (BackImage != null)
    e.Graphics.DrawImage(BackImage, 0, 0);
}

Answer 1

将PictureBox的 Image 属性设置为所需的图像，然后在PictureBox的 Paint（）事件中使用提供的private void checkBox1_CheckedChanged(object sender, EventArgs e) { pictureBox1.Invalidate(); } private void trackBar1_Scroll(object sender, EventArgs e) { pictureBox1.Invalidate(); } private void pictureBox1_Paint(object sender, PaintEventArgs e) { if (checkBox1.Checked) { int x, y; int w = pictureBox1.Size.Width; int h = pictureBox1.Size.Height; int inc = trackBar1.Value; Graphics gr = e.Graphics; if (checkBox1.Checked == true) { for (x = 0; x < w; x += inc) gr.DrawLine(Pens.Green, x, 0, x, h); for (y = 0; y < h; y += inc) gr.DrawLine(Pens.Green, 0, y, w, y); } } }：

int main()
{
   char file_info[250]="I like pineapples!";
   FILE *fptr;
   if ((fptr = fopen("try.bin","wb")) == NULL){
       printf("Error! opening file");
       exit(1);
   }

      fwrite(&file_info, sizeof(char), 250, fptr);

   fclose(fptr);
fptr=fopen("try.bin","rb");
 char file_array[250];

fread(file_array,sizeof(char),250,fptr); // read one character

int i=0,num=0,j=0,count=0;
printf("Offset               Bytes             Characters\n");
printf("------  -----------------------------  ----------");
 for(i=0;i<strlen(file_array);i++){

     if(i%10==0)
        {
            if(i>=9){
            count=j;
            printf("  ");
            for(;j<count+10;j++)
            {
                printf("%c",file_info[j]);
            }
            }
            printf("\n %5d ",num*10);
            num++;

        }


 printf(" %x",file_array[i]);
 }
 fclose(fptr);

 return 0;
}

如何在PictureBox上绘制网格以保留其中包含的图像？

1 个答案: