Question

C# 从panel中画一条竖线

想从panel中画一条竖线怎么就是画不出来呢 郁闷 感觉没有写错啊。。。。。 Graphics graphics = this.panel1.CreateGraphics(); //graphics.DrawLine(new Pen(Color.Black,2), 0, this.panel1.Top, this.panel1.Left + 5, this.panel1.Bottom); Brush gridBrush = new SolidBrush(Color.Magenta), backColorBrush = new SolidBrush(Color.Magenta); Pen mypen1 = new Pen(gridBrush); graphics.DrawLine(mypen1, new PointF(this.panel1.Location.X - 4, this.panel1.Location.Y), new PointF(this.panel1.Location.X - 4, this.panel1.Location.Y+this.panel1.Bottom));

Answer 1

试试下面的方法
//注意二维坐标系的定义
private void button1_Click(object sender, EventArgs e)
{
Graphics graphics = this.panel1.CreateGraphics();

//绘制中线
graphics.Clear(Color.LightYellow);
float x1 = this.panel1.Width / 2;
float y1 = 0;
float x2 = this.panel1.Width / 2;
float y2 = this.panel1.Height;

//注意坐标系的定义
graphics.DrawLine(new Pen(Color.Black, 2), x1, y1, x2, y2);
string temp = string.Format("({0},{1}）", x1, y1);
graphics.DrawString(temp, this.Font, Brushes.Black, x1, y1);
temp = string.Format("({0},{1}）", x2, y2);
SizeF strSize = graphics.MeasureString(temp, this.Font);
graphics.DrawString(temp, this.Font, Brushes.Black, x2 - strSize.Width, y2-strSize.Height);

//绘制对角线
Brush gridBrush = new SolidBrush(Color.Magenta), backColorBrush = new SolidBrush(Color.Magenta);
Pen mypen1 = new Pen(gridBrush);

x1 = 0;
y1 = 0;
x2 = this.panel1.Width;
y2 = this.panel1.Height;
graphics.DrawLine(mypen1, x1, y1, x2, y2);

temp = string.Format("({0},{1}）", x1, y1);
graphics.DrawString(temp, this.Font, Brushes.Black, x1, y1);
temp = string.Format("({0},{1}）", x2, y2);
strSize = graphics.MeasureString(temp, this.Font);
graphics.DrawString(temp, this.Font, Brushes.Black, x2 - strSize.Width, y2 - strSize.Height);

}

Answer 2

不该这么画，panel1写它的onpainted事件，将你的代码放进去，不要用 Graphics graphics = this.panel1.CreateGraphics(); 产生Graphics对象，用事件e中的Graphics对象即可。

Answer 3

你试试在DrawLine函数后面加上graphics.Flush()函数，这个函数是强制刷新缓冲区，显示图像，而无视Paint函数