网站中，对用户图片上传处理是很有必要的。对于一些常用的处理，对图片各种形式的压缩，各种形式的水印。
1.裁剪正方形头像方法
/// <summary>
/// 正方型裁剪
/// 以图片中心为轴心，截取正方型，然后等比缩放
/// 用于头像处理
/// </summary>
/// <param name="fromFile">原图Stream对象</param>
/// <param name="fileSaveUrl">缩略图存放地址</param>
/// <param name="side">指定的边长（正方型）</param>
/// <param name="quality">质量（范围0-100）</param>
public static void CutForSquare(System.IO.Stream fromFile, string fileSaveUrl, int side, int quality)
{
//创建目录
string dir = Path.GetDirectoryName(fileSaveUrl);
if (!Directory.Exists(dir))
Directory.CreateDirectory(dir); //原始图片（获取原始图片创建对象，并使用流中嵌入的颜色管理信息）
System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true); //原图宽高均小于模版，不作处理，直接保存
if (initImage.Width <= side && initImage.Height <= side)
{
initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
}
else
{
//原始图片的宽、高
int initWidth = initImage.Width;
int initHeight = initImage.Height; //非正方型先裁剪为正方型
if (initWidth != initHeight)
{
//截图对象
System.Drawing.Image pickedImage = null;
System.Drawing.Graphics pickedG = null; //宽大于高的横图
if (initWidth > initHeight)
{
//对象实例化
pickedImage = new System.Drawing.Bitmap(initHeight, initHeight);
pickedG = System.Drawing.Graphics.FromImage(pickedImage);
//设置质量
pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//定位
Rectangle fromR = new Rectangle((initWidth - initHeight) / , , initHeight, initHeight);
Rectangle toR = new Rectangle(, , initHeight, initHeight);
//画图
pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
//重置宽
initWidth = initHeight;
}
//高大于宽的竖图
else
{
//对象实例化
pickedImage = new System.Drawing.Bitmap(initWidth, initWidth);
pickedG = System.Drawing.Graphics.FromImage(pickedImage);
//设置质量
pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//定位
Rectangle fromR = new Rectangle(, (initHeight - initWidth) / , initWidth, initWidth);
Rectangle toR = new Rectangle(, , initWidth, initWidth);
//画图
pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
//重置高
initHeight = initWidth;
} //将截图对象赋给原图
initImage = (System.Drawing.Image)pickedImage.Clone();
//释放截图资源
pickedG.Dispose();
pickedImage.Dispose();
} //缩略图对象
System.Drawing.Image resultImage = new System.Drawing.Bitmap(side, side);
System.Drawing.Graphics resultG = System.Drawing.Graphics.FromImage(resultImage);
//设置质量
resultG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
resultG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//用指定背景色清空画布
resultG.Clear(Color.White);
//绘制缩略图
resultG.DrawImage(initImage, new System.Drawing.Rectangle(, , side, side), new System.Drawing.Rectangle(, , initWidth, initHeight), System.Drawing.GraphicsUnit.Pixel); //关键质量控制
//获取系统编码类型数组,包含了jpeg,bmp,png,gif,tiff
ImageCodecInfo[] icis = ImageCodecInfo.GetImageEncoders();
ImageCodecInfo ici = null;
foreach (ImageCodecInfo i in icis)
{
if (i.MimeType == "image/jpeg" || i.MimeType == "image/bmp" || i.MimeType == "image/png" || i.MimeType == "image/gif")
{
ici = i;
}
}
EncoderParameters ep = new EncoderParameters();
ep.Param[] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)quality); //保存缩略图
resultImage.Save(fileSaveUrl, ici, ep); //释放关键质量控制所用资源
ep.Dispose(); //释放缩略图资源
resultG.Dispose();
resultImage.Dispose(); //释放原始图片资源
initImage.Dispose();
}
}
2.裁剪自定义尺寸图片并缩放
/// <summary>
/// 指定长宽裁剪
/// 按模版比例最大范围的裁剪图片并缩放至模版尺寸
/// </summary>
/// <param name="fromFile">原图Stream对象</param>
/// <param name="fileSaveUrl">保存路径</param>
/// <param name="maxWidth">最大宽(单位:px)</param>
/// <param name="maxHeight">最大高(单位:px)</param>
/// <param name="quality">质量（范围0-100）</param>
public static void CutForCustom(System.IO.Stream fromFile, string fileSaveUrl, int maxWidth, int maxHeight, int quality)
{
//从文件获取原始图片，并使用流中嵌入的颜色管理信息
System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true); //原图宽高均小于模版，不作处理，直接保存
if (initImage.Width <= maxWidth && initImage.Height <= maxHeight)
{
initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
}
else
{
//模版的宽高比例
double templateRate = (double)maxWidth / maxHeight;
//原图片的宽高比例
double initRate = (double)initImage.Width / initImage.Height; //原图与模版比例相等，直接缩放
if (templateRate == initRate)
{
//按模版大小生成最终图片
System.Drawing.Image templateImage = new System.Drawing.Bitmap(maxWidth, maxHeight);
System.Drawing.Graphics templateG = System.Drawing.Graphics.FromImage(templateImage);
templateG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
templateG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
templateG.Clear(Color.White);
templateG.DrawImage(initImage, new System.Drawing.Rectangle(, , maxWidth, maxHeight), new System.Drawing.Rectangle(, , initImage.Width, initImage.Height), System.Drawing.GraphicsUnit.Pixel);
templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
}
//原图与模版比例不等，裁剪后缩放
else
{
//裁剪对象
System.Drawing.Image pickedImage = null;
System.Drawing.Graphics pickedG = null; //定位
Rectangle fromR = new Rectangle(, , , );//原图裁剪定位
Rectangle toR = new Rectangle(, , , );//目标定位 //宽为标准进行裁剪
if (templateRate > initRate)
{
//裁剪对象实例化
pickedImage = new System.Drawing.Bitmap(initImage.Width, (int)System.Math.Floor(initImage.Width / templateRate));
pickedG = System.Drawing.Graphics.FromImage(pickedImage); //裁剪源定位
fromR.X = ;
fromR.Y = (int)System.Math.Floor((initImage.Height - initImage.Width / templateRate) / );
fromR.Width = initImage.Width;
fromR.Height = (int)System.Math.Floor(initImage.Width / templateRate); //裁剪目标定位
toR.X = ;
toR.Y = ;
toR.Width = initImage.Width;
toR.Height = (int)System.Math.Floor(initImage.Width / templateRate);
}
//高为标准进行裁剪
else
{
pickedImage = new System.Drawing.Bitmap((int)System.Math.Floor(initImage.Height * templateRate), initImage.Height);
pickedG = System.Drawing.Graphics.FromImage(pickedImage); fromR.X = (int)System.Math.Floor((initImage.Width - initImage.Height * templateRate) / );
fromR.Y = ;
fromR.Width = (int)System.Math.Floor(initImage.Height * templateRate);
fromR.Height = initImage.Height; toR.X = ;
toR.Y = ;
toR.Width = (int)System.Math.Floor(initImage.Height * templateRate);
toR.Height = initImage.Height;
} //设置质量
pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //裁剪
pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel); //按模版大小生成最终图片
System.Drawing.Image templateImage = new System.Drawing.Bitmap(maxWidth, maxHeight);
System.Drawing.Graphics templateG = System.Drawing.Graphics.FromImage(templateImage);
templateG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
templateG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
templateG.Clear(Color.White);
templateG.DrawImage(pickedImage, new System.Drawing.Rectangle(, , maxWidth, maxHeight), new System.Drawing.Rectangle(, , pickedImage.Width, pickedImage.Height), System.Drawing.GraphicsUnit.Pixel); //关键质量控制
//获取系统编码类型数组,包含了jpeg,bmp,png,gif,tiff
ImageCodecInfo[] icis = ImageCodecInfo.GetImageEncoders();
ImageCodecInfo ici = null;
foreach (ImageCodecInfo i in icis)
{
if (i.MimeType == "image/jpeg" || i.MimeType == "image/bmp" || i.MimeType == "image/png" || i.MimeType == "image/gif")
{
ici = i;
}
}
EncoderParameters ep = new EncoderParameters();
ep.Param[] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)quality); //保存缩略图
templateImage.Save(fileSaveUrl, ici, ep);
//templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg); //释放资源
templateG.Dispose();
templateImage.Dispose(); pickedG.Dispose();
pickedImage.Dispose();
}
} //释放资源
initImage.Dispose();
}
3.按指定尺寸等比缩放
/// <summary>
/// 图片等比缩放
/// </summary>
/// <param name="fromFile">原图Stream对象</param>
/// <param name="savePath">缩略图存放地址</param>
/// <param name="targetWidth">指定的最大宽度</param>
/// <param name="targetHeight">指定的最大高度</param>
/// <param name="watermarkText">水印文字(为""表示不使用水印)</param>
/// <param name="watermarkImage">水印图片路径(为""表示不使用水印)</param>
public static void ZoomAuto(System.IO.Stream fromFile, string savePath, System.Double targetWidth, System.Double targetHeight, string watermarkText, string watermarkImage)
{
//创建目录
string dir = Path.GetDirectoryName(savePath);
if (!Directory.Exists(dir))
Directory.CreateDirectory(dir); //原始图片（获取原始图片创建对象，并使用流中嵌入的颜色管理信息）
System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true); //原图宽高均小于模版，不作处理，直接保存
if (initImage.Width <= targetWidth && initImage.Height <= targetHeight)
{
//文字水印
if (watermarkText != "")
{
using (System.Drawing.Graphics gWater = System.Drawing.Graphics.FromImage(initImage))
{
System.Drawing.Font fontWater = new Font("微软雅黑", );
System.Drawing.Brush brushWater = new SolidBrush(Color.Gray);
gWater.DrawString(watermarkText, fontWater, brushWater, (initImage.Width - ), (initImage.Height - ));
gWater.Dispose();
}
} //透明图片水印
if (watermarkImage != "")
{
if (File.Exists(watermarkImage))
{
//获取水印图片
using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage))
{
//水印绘制条件：原始图片宽高均大于或等于水印图片
if (initImage.Width >= wrImage.Width && initImage.Height >= wrImage.Height)
{
Graphics gWater = Graphics.FromImage(initImage); //透明属性
ImageAttributes imgAttributes = new ImageAttributes();
ColorMap colorMap = new ColorMap();
colorMap.OldColor = Color.FromArgb(, , , );
colorMap.NewColor = Color.FromArgb(, , , );
ColorMap[] remapTable = { colorMap };
imgAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap); float[][] colorMatrixElements = {
new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f},
new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f},
new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f},
new float[] {0.0f, 0.0f, 0.0f, 0.5f, 0.0f},//透明度:0.5
new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}
}; ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements);
imgAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
gWater.DrawImage(wrImage, new Rectangle(initImage.Width - wrImage.Width, initImage.Height - wrImage.Height, wrImage.Width, wrImage.Height), , , wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes); gWater.Dispose();
}
wrImage.Dispose();
}
}
} //保存
initImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
else
{
//缩略图宽、高计算
double newWidth = initImage.Width;
double newHeight = initImage.Height; //宽大于高或宽等于高（横图或正方）
if (initImage.Width > initImage.Height || initImage.Width == initImage.Height)
{
//如果宽大于模版
if (initImage.Width > targetWidth)
{
//宽按模版，高按比例缩放
newWidth = targetWidth;
newHeight = initImage.Height * (targetWidth / initImage.Width);
}
}
//高大于宽（竖图）
else
{
//如果高大于模版
if (initImage.Height > targetHeight)
{
//高按模版，宽按比例缩放
newHeight = targetHeight;
newWidth = initImage.Width * (targetHeight / initImage.Height);
}
} //生成新图
//新建一个bmp图片
System.Drawing.Image newImage = new System.Drawing.Bitmap((int)newWidth, (int)newHeight);
//新建一个画板
System.Drawing.Graphics newG = System.Drawing.Graphics.FromImage(newImage); //设置质量
newG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
newG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //置背景色
newG.Clear(Color.White);
//画图
newG.DrawImage(initImage, new System.Drawing.Rectangle(, , newImage.Width, newImage.Height), new System.Drawing.Rectangle(, , initImage.Width, initImage.Height), System.Drawing.GraphicsUnit.Pixel); //文字水印
if (watermarkText != "")
{
using (System.Drawing.Graphics gWater = System.Drawing.Graphics.FromImage(newImage))
{
System.Drawing.Font fontWater = new Font("微软雅黑", );
System.Drawing.Brush brushWater = new SolidBrush(Color.Gray);
gWater.DrawString(watermarkText, fontWater, brushWater, (newImage.Width - ), (newImage.Height - ));
gWater.Dispose();
}
} //透明图片水印
if (watermarkImage != "")
{
if (File.Exists(watermarkImage))
{
//获取水印图片
using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage))
{
//水印绘制条件：原始图片宽高均大于或等于水印图片
if (newImage.Width >= wrImage.Width && newImage.Height >= wrImage.Height)
{
Graphics gWater = Graphics.FromImage(newImage); //透明属性
ImageAttributes imgAttributes = new ImageAttributes();
ColorMap colorMap = new ColorMap();
colorMap.OldColor = Color.FromArgb(, , , );
colorMap.NewColor = Color.FromArgb(, , , );
ColorMap[] remapTable = { colorMap };
imgAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap); float[][] colorMatrixElements = {
new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f},
new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f},
new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f},
new float[] {0.0f, 0.0f, 0.0f, 0.5f, 0.0f},//透明度:0.5
new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}
}; ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements);
imgAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
gWater.DrawImage(wrImage, new Rectangle(newImage.Width - wrImage.Width - , newImage.Height - wrImage.Height - , wrImage.Width, wrImage.Height), , , wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes);
gWater.Dispose();
}
wrImage.Dispose();
}
}
} //保存缩略图
newImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Jpeg); //释放资源
newG.Dispose();
newImage.Dispose();
initImage.Dispose();
}
}
4.在图片上添加平铺倾斜文字水印
/// <summary>
/// 在图片上添加平铺倾斜文字水印
/// </summary>
/// <param name="sourcePicture">源图片文件</param>
/// <param name="waterWords">需要添加到图片上的文字</param>
/// <returns></returns>
public static void DrawWords(string sourcePicture, string waterWords)
{
string FullPath = sourcePicture;
Image img = Image.FromFile(FullPath); // 获取图片的宽和高
int width = img.Width;
int height = img.Height; Graphics g = Graphics.FromImage(img); // 字体 字号 字体样式
Font drawFont = new Font("微软雅黑", , FontStyle.Italic, GraphicsUnit.Pixel); SizeF fontSize = g.MeasureString(waterWords, drawFont); float xpos = ;
float ypos = ; // 倾斜 -30°
g.RotateTransform(-); // 循环打印文字水印
for (int i = -width / ; i < width * 1.5; i += )
{
xpos = i;
for (int j = -height / ; j < height * 1.5; j += )
{
ypos = j;
g.DrawString(waterWords, drawFont, new SolidBrush(Color.FromArgb(, , , )), xpos, ypos);
}
} ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
ImageCodecInfo ici = null;
foreach (ImageCodecInfo codec in codecs)
{
if (codec.MimeType.IndexOf("jpeg") > -)
ici = codec;
}
EncoderParameters encoderParams = new EncoderParameters();
long[] qualityParam = new long[]; // 图片质量：0 - 100
qualityParam[] = ; EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qualityParam);
encoderParams.Param[] = encoderParam; System.Drawing.Image newImage = new System.Drawing.Bitmap((int)img.Width, (int)img.Height);
//新建一个画板
System.Drawing.Graphics newG = System.Drawing.Graphics.FromImage(newImage); //设置质量
newG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
newG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //置背景色
newG.Clear(Color.White);
//画图
newG.DrawImage(img, new System.Drawing.Rectangle(, , newImage.Width, newImage.Height), new System.Drawing.Rectangle(, , img.Width, img.Height), System.Drawing.GraphicsUnit.Pixel);
img.Dispose();
g.Dispose();
newImage.Save(FullPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}