DWG文件信息的读取

读取dwg文件中的文本信息

需要机器上装AUTOcad，惭愧！我的机器本来在做工业设计时装了AUTOcad。近来因为别的新项目，机器不够用就给删掉了。看来下个新项目来临之前，我要新添一台机器，最好是服务器。项目多起来了，只有PC是不行的。版本控制（要命的事）是个问题。

 

方法（1）
1using System;
2using System.Collections.Generic;
3using System.Text;
4using System.IO;
5
6namespace AutoCADFilter
7{
8    public class Filter
9    {
10        public Filter()
11        {
12
13        }
14        /**////

15        /// 读取dwg文件中的文本信息
16        ///

17        /// 读取dwg文件中的文本信息
18        /// 文本内容
19        private string ReadDwg(string path)
20        {
21
22            string content = "";
23            string filename = "";
24            FileInfo finfo = new FileInfo(path);
25            filename = finfo.Name;
26            AutoCAD.AcadApplication ap = new AutoCAD.AcadApplication();
27            lock (ap)
28            {
29                try
30                {
31                    AutoCAD.AcadDocument ad = ap.Documents.Open(path,true, null);
32                    for (int i = 0; i < ad.ModelSpace.Count; i++)
33                    {
34                        if (ad.ModelSpace.Item(i).ObjectName.ToLower().Equals("acdbmtext"))
35                        {
36                            AutoCAD.IAcadMText im = (AutoCAD.IAcadMText)ad.ModelSpace.Item(i);
37                            content += im.TextString;
38                        }
39                        else if (ad.ModelSpace.Item(i).ObjectName.ToLower().Equals("acdbtext"))
40                        {
41                            AutoCAD.IAcadText im = (AutoCAD.IAcadText)ad.ModelSpace.Item(i);
42                            content += im.TextString;
43                        }
44                    }
45                    ad.Close(false, filename);
46                }
47                finally
48                {
49
50                    ap.Quit();
51                }
52            }
53            return content;
54        }
55
56        public string Parse(string path)
57        {
58            return ReadDwg(path);
59
60        }
61    }
62}

 

 

C# 读取CAD文件缩略图（DWG文件） (方法2)

 

在不使用任务插件的情况下读取DWG文件的缩略图，以便在没有安装AutoCAD的计算机上浏览。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace 浏览dwg
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            ViewDWG viewDwg = new ViewDWG();
            pictureBox1.Image = viewDwg.GetDwgImage("c:\\1.dwg");
        }
        class ViewDWG
        {
            struct BITMAPFILEHEADER
            {
                public short bfType;
                public int bfSize;
                public short bfReserved1;
                public short bfReserved2;
                public int bfOffBits;
            }
            public Image GetDwgImage(string FileName)
            {
                if (!(File.Exists(FileName)))
                {
                    throw new FileNotFoundException("文件没有被找到");
                }
                FileStream DwgF; //文件流
                int PosSentinel; //文件描述块的位置
                BinaryReader br; //读取二进制文件
                int TypePreview; //缩略图格式
                int PosBMP;       //缩略图位置
                int LenBMP;       //缩略图大小
                short biBitCount; //缩略图比特深度
                BITMAPFILEHEADER biH; //BMP文件头，DWG文件中不包含位图文件头，要自行加上去
                byte[] BMPInfo;       //包含在DWG文件中的BMP文件体
                MemoryStream BMPF = new MemoryStream(); //保存位图的内存文件流
                BinaryWriter bmpr = new BinaryWriter(BMPF); //写二进制文件类
                Image myImg = null;
                try
                {
                    DwgF = new FileStream(FileName, FileMode.Open, FileAccess.Read);   //文件流
                    br = new BinaryReader(DwgF);
                    DwgF.Seek(13, SeekOrigin.Begin); //从第十三字节开始读取
                    PosSentinel = br.ReadInt32(); //第13到17字节指示缩略图描述块的位置
                    DwgF.Seek(PosSentinel + 30, SeekOrigin.Begin); //将指针移到缩略图描述块的第31字节
                    TypePreview = br.ReadByte(); //第31字节为缩略图格式信息，2 为BMP格式，3为WMF格式
                    if (TypePreview == 1)
                    {
                    }
                    else if (TypePreview == 2 || TypePreview == 3)
                    {
                        PosBMP = br.ReadInt32(); //DWG文件保存的位图所在位置
                        LenBMP = br.ReadInt32(); //位图的大小
                        DwgF.Seek(PosBMP + 14, SeekOrigin.Begin); //移动指针到位图块
                        biBitCount = br.ReadInt16(); //读取比特深度
                        DwgF.Seek(PosBMP, SeekOrigin.Begin); //从位图块开始处读取全部位图内容备用
                        BMPInfo = br.ReadBytes(LenBMP); //不包含文件头的位图信息
                        br.Close();
                        DwgF.Close();
                        biH.bfType = 19778; //建立位图文件头
                        if (biBitCount < 9)
                        {
                            biH.bfSize = 54 + 4 * (int)(Math.Pow(2, biBitCount)) + LenBMP;
                        }
                        else
                        {
                            biH.bfSize = 54 + LenBMP;
                        }
                        biH.bfReserved1 = 0; //保留字节
                        biH.bfReserved2 = 0; //保留字节
                        biH.bfOffBits = 14 + 40 + 1024; //图像数据偏移
                        //以下开始写入位图文件头
                        bmpr.Write(biH.bfType); //文件类型
                        bmpr.Write(biH.bfSize); //文件大小
                        bmpr.Write(biH.bfReserved1); //0
                        bmpr.Write(biH.bfReserved2); //0
                        bmpr.Write(biH.bfOffBits); //图像数据偏移
                        bmpr.Write(BMPInfo); //写入位图
                        BMPF.Seek(0, SeekOrigin.Begin); //指针移到文件开始处
                        myImg = Image.FromStream(BMPF); //创建位图文件对象
                        bmpr.Close();
                        BMPF.Close();
                    }
                    return myImg;
                }
                catch (Exception ex)
                {
                    throw new Exception(ex.Message);
                }
            }
        }

    }
}

C#读取DWG文件(方法3)

struct BITMAPFILEHEADER
{
public short bfType;
public int bfSize;
public short bfReserved1;
public short bfReserved2;
public int bfOffBits;
}
public static System.Drawing.Image GetDwgImage(string FileName)
{
if (!(File.Exists(FileName)))
{
throw new FileNotFoundException("文件没有被找到");
}

FileStream DwgF=null; //文件流
int PosSentinel; //文件描述块的位置
BinaryReader br=null; //读取二进制文件
int TypePreview; //缩略图格式
int PosBMP; //缩略图位置
int LenBMP; //缩略图大小
short biBitCount; //缩略图比特深度
BITMAPFILEHEADER biH; //BMP文件头，DWG文件中不包含位图文件头，要自行加上去
byte[] BMPInfo; //包含在DWG文件中的BMP文件体
MemoryStream BMPF = new MemoryStream(); //保存位图的内存文件流
BinaryWriter bmpr = new BinaryWriter(BMPF); //写二进制文件类
System.Drawing.Image myImg = null;
try
{

DwgF = new FileStream(FileName, FileMode.Open, FileAccess.Read); //文件流

br = new BinaryReader(DwgF);
DwgF.Seek(13, SeekOrigin.Begin); //从第十三字节开始读取
PosSentinel = br.ReadInt32(); //第13到17字节指示缩略图描述块的位置
DwgF.Seek(PosSentinel + 30, SeekOrigin.Begin); //将指针移到缩略图描述块的第31字节
TypePreview = br.ReadByte(); //第31字节为缩略图格式信息，2 为BMP格式，3为WMF格式
if (TypePreview == 1)
{
}
else if (TypePreview == 2 || TypePreview == 3)
{
PosBMP = br.ReadInt32(); //DWG文件保存的位图所在位置

DwgF.Seek(PosSentinel + 16, SeekOrigin.Begin);//原来这一句是没有的，通过和VC版的单步调试相比较得来，

//如果没有这一句，比较小的dwg能够打开，但是大的（比如1.5M以上）打开就会出错，原因不详

LenBMP = br.ReadInt32(); //位图的大小
DwgF.Seek(PosBMP + 14, SeekOrigin.Begin); //移动指针到位图块
biBitCount = br.ReadInt16(); //读取比特深度
DwgF.Seek(PosBMP, SeekOrigin.Begin); //从位图块开始处读取全部位图内容备用
BMPInfo = br.ReadBytes(LenBMP); //不包含文件头的位图信息
br.Close();
DwgF.Close();
biH.bfType = 19778; //建立位图文件头
if (biBitCount < 9)
{
biH.bfSize = 54 + 4 * (int)(Math.Pow(2, biBitCount)) + LenBMP;
}
else
{
biH.bfSize = 54 + LenBMP;
}
biH.bfReserved1 = 0; //保留字节
biH.bfReserved2 = 0; //保留字节
biH.bfOffBits = 14 + 40 + 1024; //图像数据偏移
//以下开始写入位图文件头
bmpr.Write(biH.bfType); //文件类型
bmpr.Write(biH.bfSize); //文件大小
bmpr.Write(biH.bfReserved1); //0
bmpr.Write(biH.bfReserved2); //0
bmpr.Write(biH.bfOffBits); //图像数据偏移
bmpr.Write(BMPInfo); //写入位图
BMPF.Seek(0, SeekOrigin.Begin); //指针移到文件开始处
myImg = System.Drawing.Image.FromStream(BMPF); //创建位图文件对象
bmpr.Close();
BMPF.Close();
}
return myImg;
}
catch (EndOfStreamException)
{
throw new EndOfStreamException("文件不是标准的DWG格式文件，无法预览！");
}
catch (IOException ex)
{
if (ex.Message == "试图将文件指针移到文件开头之前。\r\n")
{
throw new IOException("文件不是标准的DWG格式文件，无法预览！");
}
else if (ex.Message == "文件“" + FileName + "”正由另一进程使用，因此该进程无法访问该文件。")
{
//复制文件，继续预览
File.Copy(FileName, Application.StartupPath + @"\linshi.dwg", true);
Image image = GetDwgImage(Application.StartupPath + @"\linshi.dwg");
File.Delete(Application.StartupPath + @"\linshi.dwg");
return image;
}
else
{
throw new Exception(ex.Message);
}
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
finally
{
if (DwgF != null)
{
DwgF.Close();
}
if (br != null)
{
br.Close();
}
bmpr.Close();
BMPF.Close();

}
}

读取出来的背景色为白色，效果比较差，很多颜色显示不出来，当时认为显示DWG文件出错误了，问了些高手，（呵呵，别人告诉自己本身取出的就是白色背景，需要自己改变背景色，在此鄙视一下自己）所以继续用C#操作返回的IMAGE对象，改变背景色

///

///显示DWG文件
///

/// 要显示的宽度
/// 要显示的高度
///
public static System.Drawing.Image ShowDWG(int Pwidth,int PHeight,string FilePath)
{
System.Drawing.Image image = GetDwgImage(FilePath);
Bitmap bitmap = new Bitmap(image);
int Height = bitmap.Height;
int Width = bitmap.Width;
Bitmap newbitmap = new Bitmap(Width, Height);
Bitmap oldbitmap = (Bitmap)bitmap;
Color pixel;
for (int x = 1; x < Width; x++)
{
for (int y = 1; y < Height; y++)
{

pixel = oldbitmap.GetPixel(x, y);
int r = pixel.R, g = pixel.G, b = pixel.B;
if (pixel.Name == "ffffffff" || pixel.Name == "ff000000")
{
r = 255 - pixel.R;
g = 255 - pixel.G;
b = 255 - pixel.B;
}

newbitmap.SetPixel(x, y, Color.FromArgb(r, g, b));
}
}
Bitmap bt = new Bitmap(newbitmap, Pwidth, PHeight);

return newbitmap;
}