C窗体PictureBox以显示纯色而不是图像

不使用图像-设置PictureBox的BackColor属性:

imgBox.BackColor = Color.Red;

要防止空指针异常,请创建一个空白的BMP

myPicBox.Image = new Bitmap(myPicBox.Width, myPicBox.Height);
Graphics graphics = Graphics.FromImage(myPicBox.Image);

Brush brush = new SolidBrush(Color.Gray);

graphics.FillRectangle(brush, new System.Drawing.Rectangle(0, 0, myPicBox.Width, myPicBox.Height));

直接设置背景色怎么样?

imgbox.BackColor = Color.Red;

创建图形上下文并使用它绘制。

using(Graphics g = Graphics.FromImage(bmRed))
{
  g.FillRectangle(new SolidBrush(Color.Red),0,0,imgbox.Width,imgbox.Height);
}

单个语句:

Graphics.FromImage(PicBox.Image=new bitmap(PicBox.Size)).FillRectangle(Brushes.Red,new Rectangle (Point.EMPTY,PicBox.Size));