//加水印一直用的这个帮助方法
public static void ZoomAuto(System.IO.Stream fromFile, string savePath, System.Double targetWidth, System.Double targetHeight, string watermarkText, string watermarkImage,out int NewWidth,out int NewHeight)
{
//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(“黑体”, 10);
System.Drawing.Brush brushWater = new SolidBrush(Color.White);
gWater.DrawString(watermarkText, fontWater, brushWater, 10, 10);
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(255, 0, 255, 0);
colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);
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), 0, 0, wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes);
gWater.Dispose();
}
wrImage.Dispose();
}
}
}
NewWidth = initImage.Width;
NewHeight = initImage.Height;
//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);
NewWidth = (int)newWidth;
NewHeight = (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(0, 0, newImage.Width, newImage.Height), new System.Drawing.Rectangle(0, 0, 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(“宋体”, 10);
System.Drawing.Brush brushWater = new SolidBrush(Color.White);
gWater.DrawString(watermarkText, fontWater, brushWater, 10, 10);
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(255, 0, 255, 0);
colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);
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), 0, 0, wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes);
gWater.Dispose();
}
wrImage.Dispose();
}
}
}
//保存缩略图
try {
newImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Png);
}
catch(Exception ex)
{
throw new Exception(“系统出错误了，请重新尝试或者换一张照片”);
}
//释放资源
newG.Dispose();
newImage.Dispose();
initImage.Dispose();
}
}