从父借鉴​​PictureBox的一条线 [英] Draw a line on PictureBox from parent

问题描述

我有一个图片框为用户控件。我说这个用户控制在主窗体上。现在，我必须按一个按钮，创建用户控制线。在我的项目，我每次按下这个按钮时，我想送两个的PointF（x和y）的用户控制参数，并绘制了新的路线，除了存在之一。我至今的油漆时PictureBox的加载事件。

 私人无效pictureBox1_Paint（对象发件人，PaintEventArgs的E）
 {
笔graphPen =新朋（Color.Red，2）; 
的PointF pt1D =新的PointF（）; 
的PointF pt2D =新的PointF（）; 
 pt1D.X = 0; 
 pt1D.Y = 10; 
 pt2D.X = 10; 
 pt2D.Y = 10; 
 
 e.Graphics.DrawLine（graphPen，pt1D，pt2D）; 
} 
  

解决方案

假设你想画在点击按钮就行，这里是你的代码的修改版本：

 列表<的PointF>点=新的List<&的PointF GT;（）; 
笔graphPen =新朋（Color.Red，2）; 
 
私人无效btnDrawLines_Click（对象发件人，EventArgs五）
 {
图形G = picBox.CreateGraphics（）; 
的PointF pt1D =新的PointF（）; 
的PointF pt2D =新的PointF（）; 
 pt1D.X = 0; 
 pt1D.Y = 10; 
 pt2D.X = 10; 
 pt2D.Y = 10; 
 g.DrawLine（graphPen，pt1D，pt2D）; 
 points.Add（pt1D）; 
 points.Add（pt2D）; 
} 
 
私人无效picBox_Paint（对象发件人，PaintEventArgs的E）
 {
的for（int i = 0; I< points.Count;我+ = 2） 
 e.Graphics.DrawLine（graphPen，点[I]，指向第[i + 1]）; 
} 
  

请注意，你可以得到一个Graphics通过对象图片框类的<​​code>的createGraphics（）方法是一样的 e.Graphics 对象在油漆事件处理程序。

I have a PictureBox as UserControl. I added this User Control on the main form. Now I have to press a button and create a line on the user control. On my project, every time I press this button, I want to send to user control parameters of two PointF(x and y) and draw a new line, in addition to the existent one. I have so far the Paint event when picturebox is loaded.

private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
  Pen graphPen = new Pen(Color.Red, 2);
  PointF pt1D = new PointF();
  PointF pt2D = new PointF();
  pt1D.X = 0;
  pt1D.Y = 10;
  pt2D.X = 10;
  pt2D.Y = 10;

  e.Graphics.DrawLine(graphPen, pt1D, pt2D);
}

解决方案

Assuming that you want to draw the line on the click of the button, here's a modified version of your code:

List<PointF> points = new List<PointF>();
Pen graphPen = new Pen(Color.Red, 2);

private void btnDrawLines_Click(object sender, EventArgs e)
{
    Graphics g = picBox.CreateGraphics();
    PointF pt1D = new PointF();
    PointF pt2D = new PointF();
    pt1D.X = 0;
    pt1D.Y = 10;
    pt2D.X = 10;
    pt2D.Y = 10;    
    g.DrawLine(graphPen, pt1D, pt2D);
    points.Add(pt1D);
    points.Add(pt2D);
}

private void picBox_Paint(object sender, PaintEventArgs e)
{
    for (int i = 0; i < points.Count; i+=2)
        e.Graphics.DrawLine(graphPen, points[i], points[i + 1]);
}

Note that you can get a Graphics object through the PictureBox class's CreateGraphics() method which is the same as the e.Graphics object in the Paint event handler.

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