Recently contacted the CAD two times development, records the development process. Read a lot of information. (blue17300589)

Recently contacted the CAD two times development, records the development process. Read a lot of information.

C # read DWG files

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 ("File not Found");
}

FileStream Dwgf=null; File stream
int Possentinel; Location of File description block
BinaryReader Br=null; Reading binary files
int Typepreview; Thumbnail format
int posbmp; Thumbnail position
int lenbmp; Thumbnail size
Short biBitCount; Thumbnail bit Depth
Bitmapfileheader BiH; BMP file Header, DWG file does not contain bitmap file header, to add up
Byte[] Bmpinfo; BMP file body included in DWG file
MemoryStream Bmpf = new MemoryStream (); Save a bitmap stream of memory files
BinaryWriter bmpr = new BinaryWriter (BMPF); Write binary file classes
System.Drawing.Image myimg = null;
Try
{

DWGF = new FileStream (FileName, FileMode.Open, FileAccess.Read); File stream

br = new BinaryReader (DWGF);
Dwgf.seek (Seekorigin.begin); Start reading from 13th byte
Possentinel = Br.   ReadInt32 (); The 13th to 17th byte indicates the position of the thumbnail description block
Dwgf.seek (Possentinel + seekorigin.begin); Move the pointer to the 31st byte of the thumbnail description block
Typepreview = Br.   ReadByte (); The 31st byte is thumbnail format information, 2 is BMP format, and 3 is WMF format
if (Typepreview = 1)
{
}
else if (Typepreview = 2 | | Typepreview = 3)
{
Posbmp = Br. ReadInt32 (); The location of the bitmap saved by the DWG file
Lenbmp = Br. ReadInt32 (); Size of bitmap
Dwgf.seek (Posbmp +, seekorigin.begin); Move the pointer in place of the tile
biBitCount = Br. ReadInt16 (); Read bit depth
Dwgf.seek (Posbmp, Seekorigin.begin); Read all bitmap content from the beginning of a bitmap block standby
Bmpinfo = Br. Readbytes (lenbmp); Bitmap information that does not contain the header of the file
Br. Close ();
Dwgf.close ();
Bih.bftype = 19778; To create a bitmap file header
if (biBitCount < 9)
{
Bih.bfsize = 4 * (int) (Math.pow (2, biBitCount)) + lenbmp;
}
Else
{
Bih.bfsize = + lenbmp;
}
bih.bfreserved1 = 0; Reserved bytes
Bih.bfreserved2 = 0; Reserved bytes
Bih.bfoffbits = 14 + 40 + 1024; Image data offset
The following begins writing to the bitmap file header
Bmpr. Write (Bih.bftype); File type
Bmpr.   Write (bih.bfsize); File size
Bmpr. Write (bih.bfreserved1); 0
Bmpr. Write (BIH.BFRESERVED2); 0
Bmpr. Write (bih.bfoffbits); Image data offset
Bmpr. Write (Bmpinfo); Write bitmap
Bmpf. Seek (0, seekorigin.begin); The pointer moves to the beginning of the file
myimg = System.Drawing.Image.FromStream (Bmpf); Create a bitmap file object
Bmpr. Close ();
Bmpf. Close ();
}
return myimg;
}
catch (EndOfStreamException)
{
throw new EndOfStreamException ("file is not a standard DWG format file and cannot be previewed.") ");
}
catch (IOException ex)
{
if (ex. Message = = "Attempts to move the file pointer to the beginning of the file. /r/n ")
{
throw new IOException ("file is not a standard DWG format file and cannot be previewed.") ");
}
else if (ex. Message = = "File" + filename + "" is being used by another process, so the process cannot access the file. ")
{
Copy files, continue previewing
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 ();

}
}

The background color read is white, the effect is poor, a lot of color display does not come out, at that time to show DWG file out of error, asked some experts, (hehe, others told themselves to take out is a white background, need to change their background color, in this despise himself) so continue to use the C # operation returned Image object , change the background color

<summary>
Show DWG files
</summary>
<param name= "Pwidth" > Width to display </param>
<param name= "Pheight" > Height to display </param>
<returns></returns>
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;
}