标题: C#读取JPG图像Exif信息类
作者: dnawo
日期: 2010-01-14 11:28 PM
分类: Web编程
内容: 复制内容到剪贴板 程序代码using System;
using System.IO;
using System.Text;
using System.Collections.Generic;
namespace ConsoleApplication1
{
/// <summary>
/// 类 名：Exif
/// 功 能：读取JPG图像Exif信息
/// 编 写：dnawo
/// 日 期：2010-01-14
/// 备 注：暂不支持IFD1信息读取,JPG支持Intel和Motorola字节序
/// </summary>
class Exif
{
#region JPG属性项类
/// <summary>
/// JPG属性项结构
/// </summary>
struct PropertyItem
{
/// <summary>
/// 标识
/// </summary>
public int Tag;
/// <summary>
/// 类型
/// </summary>
public int Type;
/// <summary>
/// 值个数,Type占字节数*Count=Value长度
/// </summary>
public long Count;
/// <summary>
/// 值
/// </summary>
public byte[] Value;
}
#endregion
#region 私有字段
private bool _Endian = false;//true little; false big;
private long _OffsetAPP1 = 0;
private long _OffsetTIFF = 0;
private long _OffsetIFD0 = 0;
private long _OffsetIFD1 = 0;
private long _OffsetExifIFD = 0;
private long _OffsetGPSIFD = 0;
private string _ImageFile = string.Empty;
private List<PropertyItem> _Exif = new List<PropertyItem>();
private int[] _PropertyItemTypeLength = new int[] { 0, 1, 1, 2, 4, 8, 8, 4, 8, 4, 8 };//每种类型Type占字节数
#endregion
#region 对象属性,可自行扩展
/// <summary>
/// 图片标题
/// </summary>
public string ImageTitle
{
get
{
byte[] b = GetValue(270);
if (b != null)
return ASCIIToString(b);
else
return string.Empty;
}
}
/// <summary>
/// 厂商
/// </summary>
public string Make
{
get
{
byte[] b = GetValue(271);
if (b != null)
return ASCIIToString(b);
else
return string.Empty;
}
}
/// <summary>
/// 机型
/// </summary>
public string Model
{
get
{
byte[] b = GetValue(272);
if (b != null)
return ASCIIToString(b);
else
return string.Empty;
}
}
/// <summary>
/// 软件
/// </summary>
public string Software
{
get
{
byte[] b = GetValue(305);
if (b != null)
return ASCIIToString(b);
else
return string.Empty;
}
}
/// <summary>
/// 时间
/// </summary>
public string DateTime
{
get
{
byte[] b = GetValue(36867);
if (b != null)
return ASCIIToString(b);
else
return string.Empty;
}
}
/// <summary>
/// 水平分辨率
/// </summary>
public string XResolution
{
get
{
byte[] b = GetValue(282);
if (b != null)
return RationalToSingle(b, 0);
else
return string.Empty;
}
}
/// <summary>
/// 垂直分辨率
/// </summary>
public string YResolution
{
get
{
byte[] b = GetValue(283);
if (b != null)
return RationalToSingle(b, 0);
else
return string.Empty;
}
}
/// <summary>
/// 分辨率单位
/// </summary>
public string ResolutionUnit
{
get
{
byte[] b = GetValue(296);
if (b != null)
return ShortToString(b, 0);
else
return string.Empty;
}
}
/// <summary>
/// 方向
/// </summary>
public string orientation
{
get
{
byte[] b = GetValue(274);
if (b != null)
{
switch (ShortToString(b, 0))
{
case "1":
return "上/左";
case "2":
return "上/右";
case "3":
return "下/右";
case "4":
return "下/左";
case "5":
return "左/上";
case "6":
return "右/上";
case "7":
return "右/下";
case "8":
return "左/下";
default:
return "未知";
}
}
else
return string.Empty;
}
}
/// <summary>
/// GPS纬度
/// </summary>
public string GPSLatitude
{
get
{
byte[] b = GetValue(2);
if (b != null)
return string.Format("{0}°{1}′{2}″", RationalToSingle(b, 0), RationalToSingle(b, 8), RationalToSingle(b, 16));
else
return string.Empty;
}
}
/// <summary>
/// GPS经度
/// </summary>
public string GPSLongitude
{
get
{
byte[] b = GetValue(4);
if (b != null)
return string.Format("{0}°{1}′{2}″", RationalToSingle(b, 0), RationalToSingle(b, 8), RationalToSingle(b, 16));
else
return string.Empty;
}
}
/// <summary>
/// GPS高度
/// </summary>
public string GPSAltitude
{
get
{
byte[] b = GetValue(6);
if (b != null)
return RationalToSingle(b, 0) + "m";
else
return string.Empty;
}
}
#endregion
#region 构造函数
/// <summary>
/// 构造函数
/// </summary>
/// <param name="imagefile">图像文件路径</param>
public Exif(string imagefile)
{
if (string.IsNullOrEmpty(imagefile) || !File.Exists(imagefile))
{
throw new FileNotFoundException(this._ImageFile + "加载失败，请检查路径后再次尝试。");
}
else
{
this._ImageFile = imagefile;
//存放临时内容
byte[] bytes2 = new byte[2];
byte[] bytes4 = new byte[4];
byte[] bytes12 = new byte[12];
using (FileStream file = new FileStream(this._ImageFile, FileMode.Open))
{
//寻找APP1偏移
while (file.Read(bytes2, 0, bytes2.Length) > 0)
{
if (bytes2[0] == 0xFF && bytes2[1] == 0xE1)
{
this._OffsetAPP1 = file.Position - 2;
break;
}
}
if (this._OffsetAPP1 > 0)
{
//跳过APP1长度,2字节
file.Seek(2, SeekOrigin.Current);
//判断是否为Exif
if (file.Read(bytes4, 0, bytes4.Length) > 0)
{
if (Encoding.ASCII.GetString(bytes4) == "Exif")
{
//跳过固定2字节,0x0000
file.Seek(2, SeekOrigin.Current);
//TIFF偏移位置
this._OffsetTIFF = file.Position;
//获取字节序方式
if (file.Read(bytes2, 0, bytes2.Length) > 0)
{
if (bytes2[0] == 0x49 && bytes2[1] == 0x49) //Intel
this._Endian = true;
else //Motorola
this._Endian = false;
/*** 暂不支持Motorola解析
if (!this._Endian)
{
file.Dispose();
throw new ArgumentOutOfRangeException("暂不支持Motorola字节序解析，可联系 270250392@qq.com 处理！");
}
***/
//跳过固定2字节,0x2A00
file.Seek(2, SeekOrigin.Current);
if (file.Read(bytes4, 0, bytes4.Length) > 0)
{
//IFD0偏移位置
this._OffsetIFD0 = BitConverter.ToInt32(MM2II(bytes4), 0);
//跳转到IFD0
file.Seek(this._OffsetTIFF + this._OffsetIFD0, SeekOrigin.Begin);
//获取IFD0项个数
int ifd0count;
int id, value;
if (file.Read(bytes2, 0, bytes2.Length) > 0)
{
ifd0count = BitConverter.ToInt16(MM2II(bytes2), 0);
//ExifIFD、GPSIFD偏移
for (int i = 0; i < ifd0count; i++)
{
if (file.Read(bytes12, 0, bytes12.Length) > 0)
{
id = BitConverter.ToUInt16(MM2II(bytes12, 0, 2), 0);//ToUInt16
value = BitConverter.ToInt32(MM2II(bytes12, 8, 4), 0);
switch (id)
{
case 34665://ExifIFD,0x8769
this._OffsetExifIFD = value;//注意,该偏移从TIFF开始计算,下同
break;
case 34853://GPSIFD,0x8825
this._OffsetGPSIFD = value;
break;
}
}
}
//IFD1偏移
if (file.Read(bytes4, 0, bytes4.Length) > 0)
this._OffsetIFD1 = BitConverter.ToUInt32(MM2II(bytes4), 0);
}
}
}
}
else
{
file.Dispose();
throw new FileLoadException(this._ImageFile + "解析失败，该文件不包含Exif信息，请检查后再次尝试。");
}
}
}
else
{
file.Dispose();
throw new FileLoadException(this._ImageFile + "解析失败，该文件不包含App1节，请检查后再次尝试。");
}
}
//避免文件被占用，放到这边解析
if (this._OffsetIFD0 > 0)
ParseIFD(this._OffsetTIFF + this._OffsetIFD0);
if (this._OffsetExifIFD > 0)
ParseIFD(this._OffsetTIFF + this._OffsetExifIFD);
if (this._OffsetGPSIFD > 0)
ParseIFD(this._OffsetTIFF + this._OffsetGPSIFD);
}
}
#endregion
#region 私有函数
/// <summary>
/// IFD解析
/// </summary>
/// <param name="offset">IFD偏移位置,从SeekOrigin.Begin开始</param>
private void ParseIFD(long offset)
{
byte[] bytes2 = new byte[2];
byte[] bytes4 = new byte[4];
byte[] bytes12 = new byte[12];
PropertyItem pi;
using (FileStream file = new FileStream(this._ImageFile, FileMode.Open))
{
file.Seek(offset, SeekOrigin.Begin);
int ifdcount;
long offset1, offset2;
if (file.Read(bytes2, 0, bytes2.Length) > 0)
{
ifdcount = BitConverter.ToInt16(MM2II(bytes2), 0);
for (int i = 0; i < ifdcount; i++)
{
if (file.Read(bytes12, 0, bytes12.Length) > 0)
{
pi = new PropertyItem();
pi.Tag = BitConverter.ToUInt16(MM2II(bytes12, 0, 2), 0);
pi.Type = BitConverter.ToUInt16(MM2II(bytes12, 2, 2), 0);
pi.Count = BitConverter.ToUInt32(MM2II(bytes12, 4, 4), 0);
if (pi.Type <= 12)
{
if (this._PropertyItemTypeLength[pi.Type] * pi.Count <= 4)
{
pi.Value = new byte[] { bytes12[8], bytes12[9], bytes12[10], bytes12[11] };
}
else
{
offset1 = file.Position;
offset2 = BitConverter.ToUInt32(MM2II(bytes12, 8, 4), 0);
file.Seek(this._OffsetTIFF + offset2, SeekOrigin.Begin);
byte[] b = new byte[this._PropertyItemTypeLength[pi.Type] * pi.Count];
file.Read(b, 0, b.Length);
pi.Value = b;
file.Seek(offset1, SeekOrigin.Begin);//跳回
}
}
_Exif.Add(pi);
}
}
}
}
}
/// <summary>
/// 返回指定id的PropertyItem.Value
/// </summary>
/// <param name="id"></param>
/// <returns></returns>
private byte[] GetValue(int id)
{
for (int i = 0; i < _Exif.Count; i++)
{
if (_Exif[i].Tag == id)
return _Exif[i].Value;
}
return null;
}
/// <summary>
/// Byte转String
/// </summary>
/// <param name="b"></param>
/// <param name="startindex"></param>
/// <returns></returns>
private string ByteToString(byte[] b, int startindex)
{
return ((char)b[startindex]).ToString();
}
/// <summary>
/// Short转String
/// </summary>
/// <param name="b"></param>
/// <param name="startindex"></param>
/// <returns></returns>
private string ShortToString(byte[] b, int startindex)
{
return BitConverter.ToInt16(MM2II(b, startindex, 2), 0).ToString();
}
/// <summary>
/// Rational转Single
/// </summary>
/// <param name="b"></param>
/// <param name="startindex"></param>
/// <returns></returns>
private string RationalToSingle(byte[] b, int startindex)
{
return (BitConverter.ToSingle(MM2II(b, startindex, 4), 0) / BitConverter.ToSingle(MM2II(b, startindex + 4, 4), 0)).ToString();
}
/// <summary>
/// ASCII转String
/// </summary>
/// <param name="b"></param>
/// <returns></returns>
private string ASCIIToString(byte[] b)
{
return Encoding.ASCII.GetString(b);
}
/// <summary>
/// Motorola字节序转Intel字节顺
/// </summary>
/// <param name="b"></param>
/// <returns></returns>
private byte[] MM2II(byte[] b)
{
return MM2II(b, 0, b.Length);
}
/// <summary>
/// Motorola字节序转Intel字节序
/// </summary>
/// <param name="b"></param>
/// <param name="index"></param>
/// <param name="length"></param>
/// <returns></returns>
private byte[] MM2II(byte[] b, int index, int length)
{
byte[] b1 = new byte[length];
if (this._Endian)
{
for (int i = index; i < index + length; i++)
b1[i - index] = b[i];
}
else
{
for (int i = index; i < index + length; i++)
b1[i - index] = b[(index + length) - (i - index) - 1];
}
return b1;
}
#endregion
#region 对象方法
/// <summary>
/// 重写ToString
/// </summary>
/// <returns></returns>
public override string ToString()
{
return string.Format("标题：{0}\r\n厂商：{1}\r\n机型：{2}\r\n软件：{3}\r\n时间：{4}\r\n水平分辨率：{5}\r\n垂直分辨率：{6}\r\nGPS纬度：{7}\r\nGPS经度：{8}\r\nGPS高度：{9 }\r\n",
this.ImageTitle,
this.Make,
this.Model,
this.Software,
this.DateTime,
this.XResolution,
this.YResolution,
this.GPSLatitude,
this.GPSLongitude,
this.GPSAltitude
);
}
#endregion
}
}
调用示例：
复制内容到剪贴板 程序代码Exif exif = new Exif(@"e:\www\test.jpg");
Console.WriteLine(exif.GPSLatitude);
参考资料
·PropertyItem.Id：http://msdn.microsoft.com/zh-cn/vstudio/system.drawing.imaging.propertyitem.id.aspx
·EXIF 2.1：http://www.exif.org/Exif2-1.PDF
·EXIF 2.2：http://www.exif.org/Exif2-2.PDF
·EXIF简介：http://park2.wakwak.com/~tsuruzoh/Computer/Digicams/exif-e.html
·维基百科：http://zh.wikipedia.org/wiki/EXIF
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