/// <summary>
/// 图片操作帮助类
/// </summary>
public class ImgHelper
{
/// <summary>
/// 从文件获取图片
/// </summary>
/// <param name="fileName">文件名</param>
/// <returns></returns>
public static Image GetImgFromFile(string fileName)
{
return Image.FromFile(fileName);
}
/// <summary>
/// 从base64字符串读入图片
/// </summary>
/// <param name="base64">base64字符串</param>
/// <returns></returns>
public static Image GetImgFromBase64(string base64)
{
byte[] bytes = Convert.FromBase64String(base64);
MemoryStream memStream = new MemoryStream(bytes);
Image img = Image.FromStream(memStream);
return img;
}
/// <summary>
/// 从URL格式的Base64图片获取真正的图片
/// 即去掉data:image/jpg;base64,这样的格式
/// </summary>
/// <param name="base64Url">图片Base64的URL形式</param>
/// <returns></returns>
public static Image GetImgFromBase64Url(string base64Url)
{
string base64 = GetBase64String(base64Url);
return GetImgFromBase64(base64);
}
/// <summary>
/// 压缩图片
/// 注:等比压缩
/// </summary>
/// <param name="img">原图片</param>
/// <param name="width">压缩后宽度</param>
/// <returns></returns>
public static Image CompressImg(Image img, int width)
{
return CompressImg(img, width, (int)(((double)width) / img.Width * img.Height));
}
/// <summary>
/// 压缩图片
/// </summary>
/// <param name="img">原图片</param>
/// <param name="width">压缩后宽度</param>
/// <param name="height">压缩后高度</param>
/// <returns></returns>
public static Image CompressImg(Image img, int width, int height)
{
Bitmap bitmap = new Bitmap(img, width, height);
return bitmap;
}
/// <summary>
/// 将图片转为base64字符串
/// 默认使用jpg格式
/// </summary>
/// <param name="img">图片对象</param>
/// <returns></returns>
public static string ToBase64String(Image img)
{
return ToBase64String(img, ImageFormat.Jpeg);
}
/// <summary>
/// 将图片转为base64字符串
/// 使用指定格式
/// </summary>
/// <param name="img">图片对象</param>
/// <param name="imageFormat">指定格式</param>
/// <returns></returns>
public static string ToBase64String(Image img, ImageFormat imageFormat)
{
MemoryStream memStream = new MemoryStream();
img.Save(memStream, imageFormat);
byte[] bytes = memStream.ToArray();
string base64 = Convert.ToBase64String(bytes);
return base64;
}
/// <summary>
/// 将图片转为base64字符串
/// 默认使用jpg格式,并添加data:image/jpg;base64,前缀
/// </summary>
/// <param name="img">图片对象</param>
/// <returns></returns>
public static string ToBase64StringUrl(Image img)
{
return "data:image/jpg;base64," + ToBase64String(img, ImageFormat.Jpeg);
}
/// <summary>
/// 将图片转为base64字符串
/// 使用指定格式,并添加data:image/jpg;base64,前缀
/// </summary>
/// <param name="img">图片对象</param>
/// <param name="imageFormat">指定格式</param>
/// <returns></returns>
public static string ToBase64StringUrl(Image img, ImageFormat imageFormat)
{
string base64 = ToBase64String(img, imageFormat);
return $"data:image/{imageFormat.ToString().ToLower()};base64,{base64}";
}
/// <summary>
/// 获取真正的图片base64数据
/// 即去掉data:image/jpg;base64,这样的格式
/// </summary>
/// <param name="base64UrlStr">带前缀的base64图片字符串</param>
/// <returns></returns>
public static string GetBase64String(string base64UrlStr)
{
string parttern = "^(data:image/.*?;base64,).*?$";
var match = Regex.Match(base64UrlStr, parttern);
if (match.Groups.Count > 1)
base64UrlStr = base64UrlStr.Replace(match.Groups[1].ToString(), "");
return base64UrlStr;
}
/// <summary>
/// 将图片的URL或者Base64字符串转为图片并上传到服务器，返回上传后的完整图片URL
/// </summary>
/// <param name="imgBase64OrUrl">URL地址或者Base64字符串</param>
/// <returns></returns>
public static string GetImgUrl(string imgBase64OrUrl)
{
if (imgBase64OrUrl.Contains("data:image"))
{
Image img = ImgHelper.GetImgFromBase64Url(imgBase64OrUrl);
string fileName = $"{GuidHelper.GenerateKey()}.jpg";
string dir = Path.Combine(GlobalSwitch.WebRootPath, "Upload", "Img");
if (!Directory.Exists(dir))
Directory.CreateDirectory(dir);
img.Save(Path.Combine(dir, fileName));
return $"{GlobalSwitch.WebRootUrl}/Upload/Img/{fileName}";
}
else
return imgBase64OrUrl;
}
#region 获取html中所有图片的url
/// <summary>
/// 获取html中所有图片的url
/// </summary>
/// <param name="sHtmlText"></param>
/// <returns></returns>
public static string[] GetImageUrlList(string sHtmlText)
{
// 定义正则表达式用来匹配 img 标签
Regex regImg = new Regex(@"<img\b[^<>]*?\bsrc[\s\t\r\n]*=[\s\t\r\n]*[""']?[\s\t\r\n]*(?<imgUrl>[^\s\t\r\n""'<>]*)[^<>]*?/?[\s\t\r\n]*>", RegexOptions.IgnoreCase);
// 搜索匹配的字符串
MatchCollection matches = regImg.Matches(sHtmlText);
int i = 0;
string[] sUrlList = new string[matches.Count];
// 取得匹配项列表
foreach (Match match in matches)
sUrlList[i++] = match.Groups["imgUrl"].Value;
return sUrlList;
}
#endregion
#region 更改html文本中的图片地址
/// <summary>
/// 更改html文本中的图片地址
/// </summary>
/// <param name="sHtmlText">带html的文本</param>
/// <param name="thumbUrl">服务器上的文件路径</param>
/// <returns></returns>
public static string UpdateImageUrl(string sHtmlText, string thumbUrl)
{
// 定义正则表达式用来匹配 img 标签
Regex regImg = new Regex(@"<img\b[^<>]*?\bsrc[\s\t\r\n]*=[\s\t\r\n]*[""']?[\s\t\r\n]*(?<imgUrl>[^\s\t\r\n""'<>]*)[^<>]*?/?[\s\t\r\n]*>", RegexOptions.IgnoreCase);
// 搜索匹配的字符串
MatchCollection matches = regImg.Matches(sHtmlText);
// 取得匹配项列表
foreach (Match match in matches)
{
if (sHtmlText.Contains(match.Groups["imgUrl"].Value))
{
string uphtml = sHtmlText.Replace(match.Groups["imgUrl"].Value, thumbUrl);
return uphtml;
}
}
return null;
}
#endregion
#region 更改html文本中的Base64编码图片地址
/// <summary>
/// 更改html文本中的Base64编码图片地址
/// </summary>
/// <param name="sHtmlText">带html的文本</param>
/// <param name="path">路径</param>
/// <returns></returns>
public static string UpdateImgBase64Url(string sHtmlText,string path="")
{
// 定义正则表达式用来匹配 img 标签
Regex regImg = new Regex(@"<img\b[^<>]*?\bsrc[\s\t\r\n]*=[\s\t\r\n]*[""']?[\s\t\r\n]*(?<imgUrl>[^\s\t\r\n""'<>]*)[^<>]*?/?[\s\t\r\n]*>", RegexOptions.IgnoreCase);
// 搜索匹配的字符串
MatchCollection matches = regImg.Matches(sHtmlText);
// 取得匹配项列表
foreach (Match match in matches)
{
if (sHtmlText.Contains(match.Groups["imgUrl"].Value))
{
var url= GetImgAllUrl(match.Groups["imgUrl"].Value, path.IsNullOrEmpty() ? "Upload/Img" : path);
string uphtml = sHtmlText.Replace(match.Groups["imgUrl"].Value, url);
return uphtml;
}
}
return null;
}
#endregion
#region 将图片的Base64字符串转为图片并上传到服务器，返回上传后的图片地址
/// <summary>
/// 将图片的URL或者Base64字符串转为图片并上传到服务器，返回上传后的图片地址
/// </summary>
/// <param name="imgBase64O">Base64字符串</param>
/// <param name="path">路径</param>
/// <returns></returns>
public static string GetImgAllUrl(string imgBase64O, string path="")
{
if (imgBase64O.Contains("data:image"))
{
Image img = ImgHelper.GetImgFromBase64Url(imgBase64O);
string fileName = $"{GuidHelper.GenerateKey()}.jpg";
string dir = Path.Combine(GlobalSwitch.WebRootPath, path.IsNullOrEmpty() ? "Upload/Img" : path);
if (!Directory.Exists(dir))
Directory.CreateDirectory(dir);
img.Save(Path.Combine(dir, fileName));
return $"{GlobalSwitch.WebRootUrl}/{path}/{fileName}";
}
else
return imgBase64O;
}
#endregion
}
