C# 在 Winforms 中画一条线
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Drawing a line in Winforms
提问by Joshscorp
I am having trouble drawing a line within a group box in a simple windows form.
我无法在一个简单的 Windows 窗体中的组框中绘制一条线。
here is my code:
这是我的代码：
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
DrawLShapeLine(groupBox1.CreateGraphics(), 10, 10, 20, 40);
}
public void DrawLShapeLine(System.Drawing.Graphics g, int intMarginLeft, int intMarginTop, int intWidth, int intHeight)
{
Pen myPen = new Pen(Color.Black);
myPen.Width = 2;
// Create array of points that define lines to draw.
int marginleft = intMarginLeft;
int marginTop = intMarginTop;
int width = intWidth;
int height = intHeight;
int arrowSize = 3;
Point[] points =
{
new Point(marginleft, marginTop),
new Point(marginleft, height + marginTop),
new Point(marginleft + width, marginTop + height),
// Arrow
new Point(marginleft + width - arrowSize, marginTop + height - arrowSize),
new Point(marginleft + width - arrowSize, marginTop + height + arrowSize),
new Point(marginleft + width, marginTop + height)
};
g.DrawLines(myPen, points);
}
}
If I attach the DrawLShapeLine method to a button click event, it draws fine, but it does not draw on load of the form.
如果我将 DrawLShapeLine 方法附加到按钮单击事件，它可以很好地绘制，但不会在加载窗体时绘制。
Please advice.
请指教。
采纳答案by Fredrik M?rk
Hook up an event handler for the Paintevent of the GroupBoxand call DrawLShapeLinefrom within that event handler instead. You should then use the Graphicsobject supplied by in event arguments:
为 的Paint事件连接一个事件处理程序，GroupBox并DrawLShapeLine从该事件处理程序内部调用。然后，您应该使用Graphics事件参数中提供的对象：
private void groupBox1_Paint(object sender, PaintEventArgs e)
{
DrawLShapeLine(e.Graphics, 10, 10, 20, 40);
}
As your code looks now it will attempt to paint in the GroupBoxwhen the form requires painting. The group box may be painted at any other occasion, which will the line you paint disappear.
正如您的代码现在所看到的那样，它会尝试GroupBox在表单需要绘制时进行绘制。组框可以在任何其他场合绘制，这将使您绘制的线条消失。
回答by lc.
I'm not sure if something else is going on, but you should draw the line on the GroupBox's Paint event, not the Form's.
我不确定是否发生了其他事情，但是您应该在GroupBox'Paint 事件而不是Form's上画线。
回答by Natrium
Quick & dirty:
快速和肮脏：
How about creating a panel with the width of 1 pixel and give it a backgroundcolor?
如何创建一个宽度为 1 像素的面板并给它一个背景色？
回答by JG in SD
Another option would be to use the line control that is available in Visual Basic Power Packs.
另一种选择是使用 Visual Basic Power Pack 中可用的行控件。
If you have Visual Studio 2008 SP1, or Visual Studio 2010, you won't need to download anything.
如果您有 Visual Studio 2008 SP1 或 Visual Studio 2010，则无需下载任何内容。
If you do not see the Visual Basic PowerPacks control in the Toolbox, right click in the Toolbox and select Show All in the context menu.
如果在工具箱中没有看到 Visual Basic PowerPacks 控件，请右键单击工具箱并在上下文菜单中选择全部显示。
回答by noelicus
Add a label with no text, a 3D border and a height of 2 (you have to set the height in the properties page, not with the GUI)!
添加一个没有文本的标签、一个 3D 边框和 2 的高度（您必须在属性页面中设置高度，而不是在 GUI 中）！
