/// <summary>
/// 转换图片格式
/// </summary>
/// <param name="originalStream">源图片流</param>
/// <param name="newFormat">图片输出格式</param>
/// <returns>新图片流</returns>
public static Stream FormatPicture(Stream originalStream, PictureFormat newFormat)
{
System.Drawing.Image originalImage = System.Drawing.Image.FromStream(originalStream);
System.Drawing.Imaging.ImageFormat imageFormat = GetImageFormat(newFormat);
System.IO.MemoryStream newStream = new MemoryStream();
try
{
//以指定格式保存图片
string outputFile = Path.GetTempPath() + Guid.NewGuid().ToString() + ".png";
originalImage.Save(outputFile, imageFormat);
FileStream fs = File.Open(outputFile, FileMode.Open);
newStream = new MemoryStream(ConvertStream.ToBuffer(fs));
fs.Close();
File.Delete(outputFile);
}
catch (Exception ex)
{
throw ex;
}
finally
{
originalImage.Dispose();
}
return(newStream);
}
/// <summary>
/// 转换图片格式
/// </summary>
/// <param name="originalBase64">源图片Base64</param>
/// <param name="newFormat">图片输出格式</param>
/// <returns>新图片流</returns>
public static Stream FormatPicture(string originalBase64, PictureFormat newFormat)
{
char[] charBuffer = originalBase64.ToCharArray();
byte[] bytes = Convert.FromBase64CharArray(charBuffer, 0, charBuffer.Length);
System.Drawing.Image originalImage = System.Drawing.Image.FromStream(new MemoryStream(bytes));
System.Drawing.Imaging.ImageFormat imageFormat = GetImageFormat(newFormat);
System.IO.MemoryStream newStream = new MemoryStream();
try
{
//以指定格式保存图片
string outputFile = Path.GetTempPath() + Guid.NewGuid().ToString() + "." + newFormat.ToString();
originalImage.Save(outputFile, imageFormat);
FileStream fs = File.Open(outputFile, FileMode.Open);
newStream = new MemoryStream(ConvertStream.ToBuffer(fs));
fs.Close();
File.Delete(outputFile);
}
catch (Exception ex)
{
throw ex;
}
finally
{
originalImage.Dispose();
}
return(newStream);
}
/// <summary>
/// 将Stream转换成Byte[]
/// </summary>
/// <param name="stream"></param>
/// <returns></returns>
public static MemoryStream ToMemoryStream(Bitmap bitmap, ImageFormat imageFormat)
{
System.IO.MemoryStream newStream = new MemoryStream();
try
{
//以指定格式保存图片
string outputFile = Path.GetTempPath() + Guid.NewGuid().ToString() + "." + imageFormat.ToString();
bitmap.Save(outputFile, imageFormat);
FileStream fs = File.Open(outputFile, FileMode.Open);
newStream = new MemoryStream(ConvertStream.ToBuffer(fs));
fs.Close();
File.Delete(outputFile);
}
catch (Exception ex)
{
throw ex;
}
finally
{
bitmap.Dispose();
}
return(newStream);
}
/// <summary>
/// 转换图片格式
/// </summary>
/// <param name="originalStream">源图片流</param>
/// <param name="formatWidth">格式化宽度</param>
/// <param name="formatHeight">格式化高度</param>
/// <param name="cut">是否裁剪，true:裁剪、false:不裁剪</param>
/// <param name="newFormat">图片输出格式</param>
/// <returns>新图片流</returns>
public static Stream FormatPicture(Stream originalStream, int formatWidth, int formatHeight, bool cut, PictureFormat newFormat)
{
System.Drawing.Image originalImage = System.Drawing.Image.FromStream(originalStream);
if (formatWidth > 0 && formatHeight == 0)
{
formatHeight = ConvertObject.ToInt32(Math.Round(formatWidth * (float)originalImage.Height / originalImage.Width));
}
if (formatHeight > 0 && formatWidth == 0)
{
formatWidth = ConvertObject.ToInt32(Math.Round(formatHeight * (float)originalImage.Width / originalImage.Height));
}
int towidth = formatWidth;
int toheight = formatHeight;
int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;
if (cut)
{
//指定高宽裁减（不变形）
if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
{
oh = originalImage.Height;
ow = originalImage.Height * towidth / toheight;
y = 0;
x = (originalImage.Width - ow) / 2;
}
else
{
ow = originalImage.Width;
oh = originalImage.Width * formatHeight / towidth;
x = 0;
y = (originalImage.Height - oh) / 2;
}
}
else
{
//默认指定高度宽度，失真缩放
//指定宽度缩放
if (formatHeight <= 0)
{
formatWidth = originalImage.Width * formatHeight / originalImage.Height;
}
//指定高度缩放
else if (formatWidth <= 0)
{
formatHeight = originalImage.Height * formatWidth / originalImage.Width;
}
}
//新建一个bmp图片
System.Drawing.Image image = new System.Drawing.Bitmap(formatWidth, formatHeight);
//新建一个画板
System.Drawing.Graphics graphics = System.Drawing.Graphics.FromImage(image);
//设置高质量插值法
graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
//设置高质量,低速度呈现平滑程度
graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//清空画布并以透明背景色填充
graphics.Clear(System.Drawing.Color.Transparent);
//在指定位置并且按指定大小绘制原图片的指定部分
graphics.DrawImage(
originalImage,
new System.Drawing.Rectangle(0, 0, formatWidth, formatHeight),
new System.Drawing.Rectangle(x, y, ow, oh),
System.Drawing.GraphicsUnit.Pixel
);
originalImage.Dispose();
System.Drawing.Imaging.ImageFormat imageFormat = GetImageFormat(newFormat);
MemoryStream newStream = new MemoryStream();
try
{
//以指定格式保存图片
string outputFile = Path.GetTempPath() + Guid.NewGuid().ToString();// +".jpg";
image.Save(outputFile, imageFormat);
FileStream fs = File.Open(outputFile, FileMode.Open);
newStream = new MemoryStream(ConvertStream.ToBuffer(fs));
fs.Close();
File.Delete(outputFile);
}
catch (Exception ex)
{
throw ex;
}
finally
{
originalImage.Dispose();
}
return(newStream);
}
