[转载]C#生成缩略图,加文字或图片水印 - 范涛 - 博客园

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[转载]C#生成缩略图,加文字或图片水印 – 范涛 – 博客园.

最近做东西,客户要求上传商品大图,自动生成缩略图,要求等比缩放,正好能在指定的大小内显示,(即如果高超出的比宽超出的多,就把高缩到指定高度,宽也等比缩放,反之宽也如此)
从网上找了如下代码(出处不明),但发现他的生成缩略图的方式有四种,但都不是我想要的,于是在上面加了case “DB”://等比缩放(不变形,如果高大按高,宽大按宽缩放) 这种方式实现了我想要的功能

/**/
///
/// 生成缩略图
///

///源图路径(物理路径) ///缩略图路径(物理路径) ///缩略图宽度 ///缩略图高度 ///生成缩略图的方式 public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode,string type)
{
System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);

int towidth = width;
int toheight = height;

int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;

switch (mode)
{
case "HW"://指定高宽缩放(可能变形)
break;
case "W"://指定宽,高按比例
toheight = originalImage.Height * width / originalImage.Width;
break;
case "H"://指定高,宽按比例
towidth = originalImage.Width * height / originalImage.Height;
break;
case "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 * height / towidth;
x = 0;
y = (originalImage.Height - oh) / 2;
}
break;
case "DB"://等比缩放(不变形,如果高大按高,宽大按宽缩放)
if ((double)originalImage.Width / (double)towidth < (double)originalImage.Height / (double)toheight)
{
toheight = height;
towidth = originalImage.Width * height / originalImage.Height;
}
else
{
towidth = width;
toheight = originalImage.Height * width / originalImage.Width;
}
break;
default:
break;
}

//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

//新建一个画板
System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

//设置高质量插值法
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

//设置高质量,低速度呈现平滑程度
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//清空画布并以透明背景色填充
g.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
g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight),
new System.Drawing.Rectangle(x, y, ow, oh),
System.Drawing.GraphicsUnit.Pixel);

try
{
//保存缩略图
if (type=="JPG")
{
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
if (type=="BMP")
{
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Bmp);
}
if (type=="GIF")
{
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Gif);
}
if (type=="PNG")
{
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Png);
}
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}

/**/
///
/// 在图片上增加文字水印
///

///原服务器图片路径 ///生成的带文字水印的图片路径 protected void AddShuiYinWord(string Path, string Path_sy)
{
string addText = "测试水印";
System.Drawing.Image image = System.Drawing.Image.FromFile(Path);
System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
g.DrawImage(image, 0, 0, image.Width, image.Height);
System.Drawing.Font f = new System.Drawing.Font("Verdana", 16);
System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Blue);

g.DrawString(addText, f, b, 15, 15);
g.Dispose();

image.Save(Path_sy);
image.Dispose();
}

/**/
///
/// 在图片上生成图片水印
///

///原服务器图片路径 ///生成的带图片水印的图片路径 ///水印图片路径 protected void AddShuiYinPic(string Path, string Path_syp, string Path_sypf)
{
System.Drawing.Image image = System.Drawing.Image.FromFile(Path);
System.Drawing.Image copyImage = System.Drawing.Image.FromFile(Path_sypf);
System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
g.DrawImage(copyImage, new System.Drawing.Rectangle(image.Width - copyImage.Width, image.Height - copyImage.Height, copyImage.Width, copyImage.Height), 0, 0, copyImage.Width, copyImage.Height, System.Drawing.GraphicsUnit.Pixel);
g.Dispose();

image.Save(Path_syp);
image.Dispose();
}
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