我正在尝试使用MVC3的Web
Image助手创建缩略图.
原始图像是具有透明背景的.png.当我尝试使用以下内容调整大小时：
var image = blob.DownloadByteArray();
new WebImage(image)
.Resize(50,50)
.Write();
解决方法
上面这个答案很棒,但我做了一些微调并实现了图像的“保持比例”,这样我们就不会得到拉伸的图像了.
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Web.Helpers;
public static class ResizePng
{
private static IDictionary<string,ImageFormat> _transparencyFormats = new Dictionary<string,ImageFormat>(StringComparer.OrdinalIgnoreCase) { { "png",ImageFormat.Png },{ "gif",ImageFormat.Gif } };
public static WebImage ResizePreserveTransparency(this WebImage image,int width,int height)
{
ImageFormat format = null;
if (!_transparencyFormats.TryGetValue(image.ImageFormat,out format))
{
return image.Resize(width,height);
}
//keep ratio *************************************
double ratio = (double)image.Width / image.Height;
double desiredRatio = (double)width / height;
if (ratio > desiredRatio)
{
height = Convert.ToInt32(width / ratio);
}
if (ratio < desiredRatio)
{
width = Convert.ToInt32(height * ratio);
}
//************************************************
using (Image resizedImage = new Bitmap(width,height))
{
using (Bitmap source = new Bitmap(new MemoryStream(image.GetBytes())))
{
using (Graphics g = Graphics.FromImage(resizedImage))
{
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.DrawImage(source,width,height);
}
}
using (MemoryStream ms = new MemoryStream())
{
resizedImage.Save(ms,format);
return new WebImage(ms.ToArray());
}
}
}
}
