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