1、示例环境：VS2010，MFC对话框工程，主要是对话框的OnPaint函数中

2、首先，一般大多数人比较熟悉的CPen的用法如下：

     CPaintDC dc(this);CPen pen1(PS_SOLID, 1, RGB(0, 0, 0));CPen* pOldPen = dc.SelectObject(&pen1);dc.MoveTo(50, 50);dc.LineTo(500, 50);dc.SelectObject(pOldPen);

3、会发现想要绘制粗细大于1的虚线（或是其它非PS_SOLID风格线条）时，绘制出来的都是实线：

<pre name="code" class="cpp">        CPaintDC dc(this);CPen pen1(PS_DASH, 2, RGB(0, 0, 0));CPen* pOldPen = dc.SelectObject(&pen1);dc.MoveTo(50, 50);dc.LineTo(500, 50);pen1.DeleteObject();dc.SelectObject(pOldPen);

4、下面介绍另一种CPen对象的创建方法，以解决上述问题：

（1）对话框OnPaint函数中添加示例代码：

     CPaintDC dc(this);LOGBRUSH logBrush;logBrush.lbStyle = BS_SOLID;logBrush.lbColor = RGB(0, 0, 0);CPen pen2(PS_DASH | PS_GEOMETRIC | PS_ENDCAP_ROUND, 2, &logBrush);CPen* pOldPen = dc.SelectObject(&pen2);dc.MoveTo(50, 50);dc.LineTo(500, 50);pen2.DeleteObject();dc.SelectObject(pOldPen);

（2）这样粗细大于1的虚线就画出来了：

5、下面是MSDN中的一段相关内容，英文好的话可以读一读：

CPen::CreatePen

This method initializes a pen with the specified style, width, and color. The pen can be subsequently selected as the current pen for any device context.

BOOL CreatePen (
int nPenStyle,
int nWidth,
COLORREF crColor );

Parameters

nPenStyle

Specifies the style for the pen. For a list of possible values, see the nPenStyle parameter in the CPen::CPen constructor.

nWidth

Specifies the width of the pen.

For the first version of CreatePen, if this value is zero, the width in device units is always 1 pixel, regardless of the mapping mode.
For the second version of CreatePen, if nPenStyle is PS_GEOMETRIC, the width is given in logical units. If nPenStyle is PS_COSMETIC, the width must be set to 1.

crColor

Contains an RGB color for the pen.

Return Value

Nonzero, or the handle of a logical pen, if successful; otherwise, it is zero.

Remarks

Pens that have a width greater than 1 pixel should always have either the PS_NULL, PS_SOLID, or PS_INSIDEFRAME style.

If a pen has the PS_INSIDEFRAME style and a color that does not match a color in the logical color table, the pen is drawn with a dithered color. The PS_SOLID pen style cannot be used to create a pen with a dithered color. The style PS_INSIDEFRAME is identical to PS_SOLID if the pen width is less than or equal to 1.

The width of a cosmetic pen is always 1; the width of a geometric pen is always specified in world units. After an application creates a logical pen, it can select that pen into a device context by calling the CDC::SelectObject function. After a pen is selected into a device context, it can be used to draw lines and curves.

If nPenStyle is PS_COSMETIC and PS_USERSTYLE, the entries in the lpStyle array specify lengths of dashes and spaces in style units. A style unit is defined by the device in which the pen is used to draw a line.
If nPenStyle is PS_GEOMETRIC and PS_USERSTYLE, the entries in the lpStyle array specify lengths of dashes and spaces in logical units.
If nPenStyle is PS_ALTERNATE, the style unit is ignored and every other pixel is set.

When an application no longer requires a given pen, it should call the CGdiObject::DeleteObject method or destroy the CPen object so the resource is no longer in use. An application should not delete a pen when the pen is selected in a device context.

Windows CE does not support the following overloaded implementation of the CPen::CreatePen method:

BOOL CreatePen(
int nPenStyle,
int nWidth,
const LOGBRUSH* pLogBrush,
int nStyleCount = 0,
const DWORD* lpStyle = NULL );

In Windows CE version 1.0, only solid pens can draw wide lines.

Example

CPen myPen1, myPen2;// Create a solid red pen of width 2.
myPen1.CreatePen(PS_SOLID, 2, RGB(255,0,0));// Create a geometric pen.
LOGBRUSH logBrush;
logBrush.lbStyle = BS_SOLID;
logBrush.lbColor = RGB(0,255,0);
myPen2.CreatePen(PS_DOT|PS_GEOMETRIC|PS_ENDCAP_ROUND, 2, &logBrush);

Requirements

  Windows CE versions: 1.0 and later
  Header file: Declared in Afxwin.h
  Platform: H/PC Pro, Palm-size PC, Pocket PC

6、最后，介绍一些CPen风格，以作备份：

（1）画笔的样式：

PS_SOLID      -- 实线画笔
PS_DASH       -- 虚线画笔, 只有当画笔宽度为1或更小（以设备单位计算）时才有效
PS_DOT        -- 点线画笔, 只有当画笔宽度为1或更小（以设备单位计算）时才有效
PS_DASHDOT    -- 虚线和点交替, 只有当画笔宽度为1或更小（以设备单位计算）时才有效
PS_DASHDOTDOT -- 创建一支虚线和两点交替的画笔。只有当画笔宽度为1或更小（以设备单位计算）时才有效
PS_NULL       -- 空画笔
PS_INSIDEFRAME-- 创建一支画笔，该画笔在Windows GDI输出函数所产生的封闭形状的框架内画线，此输出函数指定一个限定矩形（例如，Ellipse，Rectangle，RoundRect，Pie和Chord成员函数），当此风格用于没有指定限定矩形的Windows GDI输出函数（例如LineTo成员函数）时，此画笔的绘制区域不受框架的限制

PS_GEOMETRIC -- 几何画笔
PS_COSMETIC -- 装饰画笔
PS_ALTERNATE -- 创建一支交替设置像素的画笔（此风格只用于装饰画笔）
PS_USERSTYLE -- 创建一支使用用户提供的风格数组的画笔

（2）笔帽的样式：

PS_ENDCAP_ROUND -- 尾帽是圆的
PS_ENDCAP_SQUARE -- 尾帽是方的
PS_ENDCAP_FLAT -- 尾帽是平面的(注: 没有笔帽)

（3）连接的样式：

PS_JOIN_BEVEL -- 连接是斜截式的
PS_JOIN_MITER -- 当连接在::SetMiterLimit函数所设置的当前限制之内时, 连接是斜接式的. 如果连接超出这个限制则成为斜截式的
PS_JOIN_ROUND -- 连接是圆的

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