C#关于图片的相关处理

public class ImageHelper
{
/// <summary>
/// 图片转换成字节流
/// </summary>
/// <param name="img">要转换的Image对象</param>
/// <returns>转换后返回的字节流</returns>
public static byte[] ImgToByt(Image img)
{
MemoryStream ms = new MemoryStream();
byte[] imagedata = null;
img.Save(ms, ImageFormat.Jpeg);
imagedata = ms.GetBuffer();
return imagedata;
}

/// <summary>
/// 字节流转换成图片
/// </summary>
/// <param name="byt">要转换的字节流</param>
/// <returns>转换得到的Image对象</returns>
public static Image BytToImg(byte[] byt)
{
MemoryStream ms = new MemoryStream(byt);
Image img = Image.FromStream(ms);
return img;
}

/// <summary>
/// 根据图片路径返回图片的字节流byte[]
/// </summary>
/// <param name="imagePath">图片路径</param>
/// <returns>返回的字节流</returns>
private static byte[] GetImageByte(string imagePath)
{
Stream files;
try
{
//如果本地含有图片则从本地读取，反之从服务器下载
var localurl = AppDomain.CurrentDomain.BaseDirectory + imagePath.Substring(imagePath.IndexOf('D'));
files = new FileStream(localurl, FileMode.Open);
}
catch
{
files = DownLoadImage(imagePath);
}

byte[] imgByte = new byte[files.Length];
files.Read(imgByte, 0, imgByte.Length);
files.Close();
return imgByte;
}

/// <summary>
/// 将图片下载到流
/// </summary>
/// <param name="path">图片路径</param>
/// <returns></returns>
public static Stream DownLoadImage(string path)
{
WebRequest request = WebRequest.Create(@path);
WebResponse response = request.GetResponse();
return response.GetResponseStream();
}

public static bool ThumbnailCallback()
{
return false;
}

/// <summary>
/// 字节流转换成图片路径
/// </summary>
/// <param name="byt">要转换的字节流</param>
/// <param name="id">用户Id</param>
/// <param name="catalogPath">存储目录</param>
/// <returns>转换得到的Image对象</returns>
public static string GetImageUrl(string id,byte[] byt,string catalogPath)
{
string catalog = "DownLoads/" + catalogPath;
var filename = id + ".jpg";
var path = string.Format("{0}/{1}", catalog, filename);
var existpath = AppDomain.CurrentDomain.BaseDirectory + @path;
if (File.Exists(@existpath))
{
return BaseHelper.GetValue("Server") + path;
}
else
{
MemoryStream ms = new MemoryStream(byt);
Image img = Image.FromStream(ms);

string root = AppDomain.CurrentDomain.BaseDirectory + catalog;
if (!Directory.Exists(@root))
{
Directory.CreateDirectory(@root);
}

img.Save(AppDomain.CurrentDomain.BaseDirectory + @path);
return BaseHelper.GetValue("Server") + @path;
}
}

/// <summary>
/// 获取缩略图路径
/// </summary>
/// <param name="id"></param>
/// <param name="url"></param>
/// <param name="catalogPath"></param>
/// <param name="size"></param>
/// <returns></returns>
public static string GetThumbnailUrl(string id, string url, string catalogPath,int size)
{
string catalog = "DownLoads/" + catalogPath;
var filename = id + ".jpg";
var path = string.Format("{0}/{1}", catalog, filename);
var existpath = AppDomain.CurrentDomain.BaseDirectory + path;
if (File.Exists(@existpath))
{
return BaseHelper.GetValue("Server") + @path;
}
else
{
FileStream ms = new FileStream(@url, FileMode.Open);
Image img = Image.FromStream(ms);

//压缩图片大小
var myCallback = new Image.GetThumbnailImageAbort(ThumbnailCallback);
Image myThumbnail = img.GetThumbnailImage(size, size, myCallback, IntPtr.Zero);

string root = AppDomain.CurrentDomain.BaseDirectory + catalog;
if (!Directory.Exists(@root))
{
Directory.CreateDirectory(@root);
}

myThumbnail.Save(AppDomain.CurrentDomain.BaseDirectory + @path);
return BaseHelper.GetValue("Server") + path;
}
}

/// <summary>
/// 判断用户图片是否已缓存
/// </summary>
/// <param name="filename"></param>
/// <returns></returns>
public static string IsExist(string filename)
{
var filepath = @"DownLoads/Temp/" + filename + ".jpg";
var path = AppDomain.CurrentDomain.BaseDirectory + @filepath;
return File.Exists(@path) ? BaseHelper.GetValue("Server") + @filepath : string.Empty;
}

/// <summary>
/// 获取用户的Base64缩略图
/// </summary>
/// <param name="stream">图片流</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图宽度</param>
/// <param name="isfixWidthHeight">是否固定高宽</param>
/// <returns></returns>
public static string GetBase64Image(int width,int height, Stream stream,bool isfixWidthHeight=false)
{
try
{
Image img = Image.FromStream(stream);
//var id = BaseHelper.CreateGuid();
//压缩图片大小
var myCallback = new Image.GetThumbnailImageAbort(ThumbnailCallback);
Image myThumbnail;
if (isfixWidthHeight)
{
myThumbnail = img.GetThumbnailImage(width, height, myCallback, IntPtr.Zero);
}
else
{
int startX = 0,startY=0;
var w = img.Width;
var h = img.Height;
int getX = w, getY = h;
float dw =(float) w/width;
float dh =(float) h/height;
if (Equals(dw, dh))
{
myThumbnail = img.GetThumbnailImage(width, height, myCallback, IntPtr.Zero);
}
else
{
//按比例截取中间部分
if (dw > dh)
{
getX = Convert.ToInt32(width * dh);
startX = Convert.ToInt32((w - getX) / 2);
}
else
{
getY = Convert.ToInt32(height * dw);
startY = Convert.ToInt32((h - getX)/2);
}

Bitmap destBitmap = new Bitmap(getX, getY);//目标图
Rectangle destRect = new Rectangle(0, 0, getX, getY); //生成图区域
Rectangle srcRect = new Rectangle(startX, startY, getX, getY);//截取区域
Graphics g = Graphics.FromImage(destBitmap);
g.DrawImage(img, destRect, srcRect, GraphicsUnit.Pixel);
//SaveImage(destBitmap,id + "_Src");
myThumbnail = destBitmap.GetThumbnailImage(width, height, myCallback, IntPtr.Zero);
}
}
//SaveImage(myThumbnail,id+"_Thu");

//将压缩图片转为Base64字符串
return ImageToBase64(myThumbnail);
}
catch
{
return null;
}

}

/// <summary>
/// 将图片流转为base64编码
/// </summary>
/// <param name="stream"></param>
/// <returns></returns>
public static string GetBase64Image(Stream stream)
{
Image img = Image.FromStream(stream);
return ImageToBase64(img);
}

/// <summary>
/// 获取用户的Base64缩略图
/// </summary>
/// <param name="byt">图片存储字节</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图宽度</param>
/// <returns></returns>
public static string GetBase64Image(int width, int height, byte[] byt)
{
MemoryStream ms = new MemoryStream(byt);
return GetBase64Image(width,height,ms);
}

/// <summary>
/// 将图片字节转为base64编码
/// </summary>
/// <param name="byt"></param>
/// <returns></returns>
public static string GetBase64Image(byte[] byt)
{
MemoryStream stream = new MemoryStream(byt);
Image img = Image.FromStream(stream);
return ImageToBase64(img);
}

/// <summary>
/// 获取用户的Base64缩略图
/// </summary>
/// <param name="imagePath">图片存储路径</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图宽度</param>
/// <returns></returns>
public static string GetBase64Image(int width, int height, string imagePath)
{
var stream = DownLoadImage(imagePath);
return GetBase64Image(width, height, stream);
}

/// <summary>
/// 将图片数据转换为Base64字符串
/// </summary>
/// <param name="img"></param>
public static string ImageToBase64(Image img)
{
return "data:image/jpg;base64," + Convert.ToBase64String(ImgToByt(img));
}

/// <summary>
/// 将图片流转换为Base64字符串
/// </summary>
/// <param name="ms"></param>
/// <returns></returns>
private static string StreamToBase64(MemoryStream ms)
{
return "data:image/gif;base64," + Convert.ToBase64String(ms.GetBuffer());
}

/// <summary>
/// 将Base64字符串转换为图片
/// </summary>
/// <param name="str"></param>
private static Image Base64ToImage(string str)
{
byte[] bytes = Convert.FromBase64String(str);
return BytToImg(bytes);
}

/// <summary>
/// 导出图片
/// </summary>
/// <param name="img">图片</param>
/// <param name="fileName">文件名</param>
private static void SaveImage(Image img,string fileName=null)
{
string root = AppDomain.CurrentDomain.BaseDirectory + "DownLoads/Thumbnail";
if (!Directory.Exists(@root))
{
Directory.CreateDirectory(@root);
}
string  path = fileName == null ? @root + "/" + BaseHelper.CreateGuid() + ".jpg" : @root + "/" + fileName + ".jpg";

img.Save(path);
}

/// <summary>
/// 裁剪图片
/// </summary>
/// <param name="stream">图片流</param>
/// <param name="startX">开始坐标X</param>
/// <param name="startY">开始坐标Y</param>
/// <param name="getX">截取横向距离</param>
/// <param name="getY">截取纵向距离</param>
/// <returns>图片base64编码</returns>
public static string CutImage(Stream stream, int startX, int startY, int getX, int getY)
{
Image img = Image.FromStream(stream);

int w = img.Width;
int h = img.Height;

if (startX < w && startY < h)
{
if (getX + startX > w)
{
getX = w - startX;
}
if (startY + getY > h)
{
getY = h - startY;
}
}
//var id = BaseHelper.CreateGuid();

Bitmap destBitmap = new Bitmap(getX, getY);//目标图
Rectangle destRect = new Rectangle(0, 0, getX, getY); //生成图区域
Rectangle srcRect = new Rectangle(startX, startY, getX, getY);//截取区域
Graphics g = Graphics.FromImage(destBitmap);
g.DrawImage(img, destRect, srcRect, GraphicsUnit.Pixel);
//SaveImage(destBitmap,id + "_Src");
return ImageToBase64(destBitmap);
}

/// <summary>
/// 生成验证码
/// <param name="width">验证码宽度</param>
/// <param name="height">验证码高度</param>
/// </summary>
public static void DrawVerifyCode(int width=0,int height=0)
{
MemoryStream ms = new MemoryStream();
DrawValidationCode validationCode = new DrawValidationCode {FontMinSize = 20, FontMaxSize = 24};
if (width != 0) validationCode.Width = width;
if (height != 0) validationCode.Height = height;

validationCode.CreateImage(ms);

var id = BaseHelper.CreateGuid(); //生成ID
var code = validationCode.ValidationCode;  //验证码字符串
var image = StreamToBase64(ms);  //验证码图片
var createTime = DateTime.Now;  //生成时间

//将图片存储到本地
string root = AppDomain.CurrentDomain.BaseDirectory + "DownLoads/VerifyCode";
if (!Directory.Exists(@root))
{
Directory.CreateDirectory(@root);
}
Image img = Image.FromStream(ms);
img.Save(@root + "/" + id + ".jpg");
}

/// <summary>
/// 根据姓名生成默认缩略图
/// </summary>
/// <param name="name">姓名</param>
/// <param name="width"></param>
/// <param name="height"></param>
/// <returns></returns>
public static string DrawDefaultIcon(string name,int width=40,int height=40)
{
if (!string.IsNullOrEmpty(name))
{
var text = name.Substring(0, 1);
Bitmap bit = new Bitmap(width + 1, height + 1);
Graphics g = Graphics.FromImage(bit);
g.SmoothingMode = SmoothingMode.HighQuality;
g.Clear(Color.Transparent);
Rectangle rectangle = new Rectangle(0, 0, width, height);
// 如要使边缘平滑，请取消下行的注释
g.SmoothingMode = SmoothingMode.HighQuality;

//设置文本背景色
SolidBrush[] sbrush =
{
new SolidBrush(Color.FromArgb(110,184,131)),
new SolidBrush(Color.FromArgb(216,174,72)),
new SolidBrush(Color.FromArgb(235,167,164)),
new SolidBrush(Color.FromArgb(166,116,163)),
new SolidBrush(Color.FromArgb(196,217,28)),
new SolidBrush(Color.FromArgb(91,186,216)),
new SolidBrush(Color.FromArgb(55,163,210)),
new SolidBrush(Color.FromArgb(129,172,60)),
new SolidBrush(Color.FromArgb(234,171,94))
};

Random r=new Random();
//Thread.Sleep(10);
g.FillEllipse(sbrush[r.Next(sbrush.Length)], rectangle);

Font font = new Font(new FontFamily("微软雅黑"), 14, FontStyle.Regular);

g.DrawString(text, font, new SolidBrush(Color.White), new Rectangle(1, 8, width, height), new StringFormat { Alignment = StringAlignment.Center });

MemoryStream ms = new MemoryStream();
bit.Save(ms, ImageFormat.Png);
return "data:image/png;base64," + Convert.ToBase64String(ms.GetBuffer());
}
return null;
}
}